INTRODUCTION

Magnetic resonance imaging guided laser interstitial thermal therapy (MRIgLITT) has been proven to be safe and effective in the treatment of focal epilepsy with different etiologies. It has also been used to disconnect brain tissue in more extense or diffuse epilepsies with corpus callosotomy and even a hemispherotomy.

After conducting a highly realistic simulation in cadaver, we performed a surgery of temporo-parieto-occipital disconnection (TPO) by MRIgLITT assisted by a robotic arm for refractory epilepsy of the posterior quadrant.

CASE REPORT

The patient was a 14 year-old right-handed teenager evaluated in our Epilepsy Surgery Unit for epilepsy that debuted at the age of eight. The patient had suffered a perinatal ischemic event that left him with a large left temporal porencephalic cyst. He suffered initially isolated and later daily seizures. Initially seizures were oculocephalogyric and of loss of awareness. After he was 10 years old, there appeared episodes of visual distortions without loss of consciousness and restless events with episodes of nervousness and feeling that someone was chasing him. Seizures persisted despite multiple antiepileptic drugs. VEEG revealed intercritic left temporo-occipital anomalies, and left temporo-occipital seizures were registered. The cerebral MRI with epilepsy protocol showed the previously known large left temporo-parietal cystic cavity compatible with a porencephaly. The Wada test revealed a right language dominance and a left TPO was proposed.

We planned to perform the disconnection by MRIgLITT. 5 trajectories were designed: 4 parietal and 1 temporal.

The 4 parietal trajectories entered the parietal lobe through the anterior part of the superior and inferior parietal lobes just posterior to the post-central sulcus. Just 1 temporal trajectory was planned along the temporal mesial structures (amigdala, hypocampus) with an occipital entry point. A superior temporal gyrus trajectory was not needed in this case as this area was occupied by the porencephalic cyst.

Laser fiber insertion was performed by the robotic arm Neuromate and the laser ablation in a 1.5 T intraoperative MRI.

The patient did not suffer any complication during or after the surgery, was discharged 4 days after the procedure, and did not suffer any further seizures with a follow up of 1 year.

CONCLUSION

Performing a TPO disconnection by MRIgLITT has been feasible and effective. The robotic arm has been a good assitance to insert the laser fibers. A larger sample is needed, but this initial experience is encouraging.

Introduction

Stereotactic laser amygdalohippocampotomy (SLAH) is an established minimally invasive procedure for mesial temporal epilepsy that aims to maximally conserve brain tissue. The principal surgical alternative is the well-established anterior temporal lobectomy (ATL), which sacrifices more tissue, but achieves marginally higher rates of seizure freedom. Seizure freedom from SLAH is typically achieved in approximately half of patients. Reports of the surgical management of the remaining failed cases are sparse. A framework for this treatment is needed that rationalises between patients who will not benefit from any anterotemporal surgery, the SLAH-ATL treatment gap, and cases which fail due to inadequate SLAH.

Methods

We retrospectively reviewed a continuous series of SLAH operations at our institution. Cases where additional operations were performed to treat refractory epilepsy were identified and characterised. Engel scores before repeat surgery and at follow up were established based on chart review. Complications of repeat surgery and associated cognitive changes were collated.

Results

Over an eight-year period, 108 patients underwent primary SLAH; of these, 21 patients (19%) underwent further surgery. The median time to second surgery was 14 months (Q₁-Q₃: 7-38). There was a trend for quicker SLAH failure in the earlier patients compared to the later patients in the series. Similarly, 82% of repeat surgeries were carried out in the earliest quartile of patients. Twelve patients had repeat SLAH, and three patients had laser ablation at an alternative site. Eight patients underwent ATL, two of which were after a failed repeat SLAH. At 1-year follow up, six patients (50%) achieved seizure freedom after repeat SLAH and five patients (63%) achieved seizure freedom after ATL, one of which was after two failed SLAHs. Two patients undergoing a second laser ablation outside the mesial temporal lobe achieved seizure freedom at 1-year. [note: detailed complication review and quantitative cognitive data will be available at time of conference]

Conclusions

Following therapeutic failure of SLAH, repeat SLAH and ATL are both reasonably safe procedures that can be highly efficacious. Important considerations for repeat surgery include the degree of surgical experience with SLAH and the possible marginal benefit from an additional procedure relative to existing improvement. Among surgeons who are inexperienced with SLAH, a repeat SLAH is reasonable in failed cases. Conversely, a preference for ATL over repeat SLAH is reasonable if the original SLAH was performed by a surgeon with expertise in the procedure. However, the patient must accept that this strategy comes freighted with the risk of cognitive deterioration without clinical improvement, and a similar chance of success as the original operation.

Introduction: Planning of invasive intracerebral Stereo-EEG (sEEG) in non-lesional focal drug resistant epilepsy is challenging and accurate non-invasive spatial information about the hypothetical organization of the epileptic focus is needed. Planning of sEEG is even more demanding, if patients with non-lesional epilepsy underwent prior epilepsy surgery.

Methods: Between 10/2019 and 10/2022 14 patients with non-lesional focal epilepsy with suspected monofocal epilepsy based on electro-clinical findings underwent sEEG implantation based on non-invasive video-EEG-monitoring and multimodal imaging. Four patients underwent prior epilepsy surgery, and two of them had prior invasive subdural EEG. All patients underwent multimodal diagnostics including high-resolution 3 T epilepsy MRI and MRI morphometry. A subgroup of patients underwent functional imaging using electromagnetic source imaging, or FDG-PET. sEEG was planned considering findings from all available methods coregistered within the sEEG planning system.

Results: Nine (± 2) sEEG electrodes were implanted per patient considering the primary hypothesis and usually several secondary hypotheses of the epileptic focus. No bleeding complication occurred. In sEEG recordings, a focal seizure onset could be identified in 11/14 patients, who underwent subsequent epilepsy surgery. Eighty percent (9/11 patients) had Engel 1 postsurgical outcome, and 2/11 patients had Engel 2 postsurgical outcome. In 2/14 patients multifocal epilepsy was diagnosed based on sEEG findings and only in 1/14 patients, the epileptic focus could not be identified.

Conclusion: In patients with non-lesional focal epilepsy and suspected mono-focal epilepsy sophisticated sEEG diagnostics considering advanced multimodal imaging is highly successful identifying the seizure onset zone. After such identification and exclusion of multifocal epilepsy patients based on sEEG findings subsequent epilepsy surgery often results in seizure-free postsurgical outcomes.

Introduction

Brain biopsy is a minimally invasive surgical technique which allows the surgeon to obtain a sample of abnormal brain tissue for examination, to determine a diagnosis and further treatment options. The purpose of this study was to evaluate the safety and accuracy of the stereotactic “frame-based” and the “frameless” image-guide biopsy techniques.

Material and Methods

We retrospectively reviewed the medical records of 465 patients diagnosed with brain lesions, that underwent a cerebral biopsy procedure in our department over the course of 15 years (November 2008 to March 2023). The planning of the procedures was on pre-biopsy imaging scans (MRI or CT). The stereotactic and neuroimaging tools used for the biopsy procedure included the Leksell stereotactic system (Elekta), Zamorano-Duchovny (ZD) stereotactic system (Inomed) and frameless StealthStation S8 Surgical Navigation System (Medtronic). We performed frameless stereotactic brain biopsy starting from January 2021.

Results

In total, 465 patients underwent a brain biopsy procedure, of which 262 males (56.34%) and 203 females (43.65%). The mean (±SD) age at diagnosis was 51.9 (± 16.8) years.  We accomplished frame-based stereotactic brain biopsies in 398 (85.59%) cases and frameless neuronavigation-guided brain biopsies in 67 (14.4%) cases. The most common diagnosis was glioblastoma (42.15%) followed by grade 2 or 3 astrocytoma (15.26%), brain metastases (9.24%) and primary central nervous system lymphoma (7.09%). The diagnostic yield was 96.7% (385 cases) for stereotactic frame-based biopsy and 94% (63 cases) for frameless biopsy. In 17 (3.65%) cases, no definite diagnosis was obtained. Postoperative neurological morbidity rate was 2.58% (12 cases), of which 2.36% (11 cases) for stereotactic frame-based biopsy and 0.21% (1 case) for frameless neuronavigation assisted brain biopsy. Postoperative mortality rate was 0.43% (2 cases). 

Conclusions

Brain biopsy represents the main choice for the approach of small or deep-seated lesions which are infiltrative or located in eloquent areas of the brain. Neuronavigation-guided biopsy is a precise, safe, and easy to perform procedure. It is preferable to frame based stereotactic biopsy, being a less time-consuming procedure, that also allow the multi-target biopsy approach of the lesion. 

Introduction

Laser interstitial thermotherapy (LITT) is the selective ablation of a lesion using heat from a laser device. It is a solution for patients whose location is difficult to access due to anatomical reasons.

We report the experience of the neurosurgery team of the Amiens’s University Hospital about 8 patients.

Material and methods :

All the patients were evaluated in a multidisciplinary staff. Different tumor profiles were included :pinealocytoma, glioblastoma, optic glioma, ganglioglioma.

The laser probes are placed in stereotaxic condition using the Rosa robot. Their correct positions are checked using an intraoperative CT-scan.

MRI allows real-time monitoring of the ablation volume.

It is possible to use the probes in a multi-tiered way, in oreder to increase the treated volume without increasing the risk related to the approach.

Results :

Pineal region

Patient 1: use of two probes allowing ablation of 85% of the tumor volume.

Patient 2: use of a single probe with 90% ablation.

Both had diplopia postoperatively, transient for patient 1 and definitive for patient 2.

Inter-opto-chiasmatic lesion

Patient 3: use of 6 probes, 2 of which are multi-staged, allowing ablation of 90% of the tumor volume. Postoperative evolution marked by major edema with hydrocephalus requiring the use of a ventriculoperitoneal shunt. Visual acuity and visual fields identical to the peroperative situation.

Patient 4: use of a single frontal probe for 50% ablation.

Deep lesions

Patient 5: use of a single multi-level probe for ablation of 100% of the tumor volume.

Patient 6: uses 2 multi-stage probes allowing 70% coverage of the tumor volume.

High functional risk lesions

Patient 7: uses 3 multi-stage probes to cover 100% of the tumor volume.

 Patient 8: use of a single probe for 100% ablation of the tissular lesion.

The mean tumor volume is 29.98 cm³. Of the 8 patients, 6 had a treated tumor volume over 85%. For an average volume of 85.6%. The evolution at a distance is of the scar type with progressive decruise in volume. Three patients (patient 1,2 and 3) had postoperative complications, one of which was permanent (patient 2).

Conclusion

LITT is now fully integrated into the management of cranial oncology. From our experience, it can be used in many different histological entities.

From our experience there is no volume limit. Morbidity in our experience is essentially linked to postoperative edema and/or central-lesional necrosis which can temporarily increase the mass effect

Objective: Trigeminal schwannomas are rare and can present as either limited to the Cavum Meckeli, bi- or rarely three-compartimental. Clinically most often facial dysesthesias, numbness or pain leeds to immaging and diagnosis of these tumors. Meningeomas and metastses have to be considered as differential diagnosis. Due to its location and vicinity to vital structures total microsurgical resection can be difficult therefore radiosurgery could be an alternative option. 

Methods: We evaluated the outcomes retrospectively of our patients with trigeminal newly diagosed schwannoma treated with radiosurgery in an ambulatory setting. A MRI scan was performed at the day of treatment and fused to either CCT or CBCT using a stereotactic ring or thermoplastic mask. The patient were then routinely followed to evaluate treatment effects on tumor size, clinical symptoms and side effects. 

Results: 13 patients treated between the years 2009-2022 were included into this study. The average age was 49 years (15-71 years). Mean tumor volume was 3,2 ccm (1,45-7,25 ccm). Tumors shrank in 7 patients, in 4 patients the tumor volume remained unchanged. There was one recurrent tumor after 5 years of stable tumor volume. This patient was subsequently operated and after having another relaps a second radiosurgical treatment was necessary. There was one slight tumor enlargement wich remained then unchanged for the last 5 years. Therefore 92 % had good local tumor controll regarding the follow up time of in average 48 months (2-156 months). Prescribed marginal dosis ranged from 13-15 Gy to the 50-55% isodose. The 10 Gy volume of the brainstem in average was 0,1 ccm. In 3 patients mild facial paresthesias or  numbness was noted after the treatment. In the majority pre-existing symptoms improved or resolved after the treatment.

Conclusion: Radiosurgery is proven to be an effective and safe treatment option for trigeminal schwannomas and long-term results are available. In our patients side effects are rare. Given the fact of absent invasivness radiosurgery shoud be discussed as an alternative treatment to microsurgical resection in the first place but also in patients with residual/ recurrent tumor after microsurgical treatment.

Magnetic Resonance-Guided Focused Ultrasound Without Anesthesia

Lucinda T. Chiu MD^{1*^}, Julia M. Mueller BS^1*, Fiona Lynn APN¹, Rachel G. Lewis RN¹, Shama Patel DNP¹, Matthew Wodziak MD², Neepa Patel MD², Sepehr Sani MD¹

Affiliations:

¹Department of Neurosurgery, Rush University Medical Center, Chicago, IL, USA

²Department of Neurology, Rush University Medical Center, Chicago, IL, USA

^* Lucinda Chiu and Julia Mueller contributed equally to this work.
^ Lucinda Chiu is the speaker

Topic: Movement Disorders

Keywords: MRgFUS; tremor; anesthesia

OBJECTIVE

Magnetic resonance guided focused ultrasound (MRgFUS) is an effective treatment option for essential tremor (ET) and tremor dominant Parkinson’s disease (TDPD). In an effort to minimize adverse events and maximize patient comfort, MRgFUS is often performed with sedation or in the presence of an anesthesiologist. This study explores the safety and efficacy of performing MRgFUS without anesthesia.

METHODS

This is a single academic center retrospective review of 180 ET and TDPD patients who underwent MRgFUS treatment without anesthesia. Patient demographics, intra-procedural treatment parameters, peri-procedural adverse events, and 3-month Clinical Rating Scale for Tremor (CRST-B) scores were compared to MRgFUS studies that utilized varying degrees of anesthesia.

RESULTS

The most common side effects during treatment were facial/tongue paresthesia (26.3%), followed by nausea (22.3%), dysarthria (8.6%), and scalp pain (8.0%). No anxiolytic, pain, or antihypertensive medications were administered during treatment.  The most common immediate adverse event after MRgFUS procedure were gait imbalance (58.3%). There was a significant reduction of 83.1% (83.4% ET and 80.5% TDPD) of the mean CRST scores of the treated hand when comparing 3-month and baseline scores (1.8 vs. 10.9, n=109, P<0.0001). There were no early treatment terminations due to patient discomfort. 

CONCLUSION

MRgFUS without intra-procedural anesthesia for carefully selected and appropriately counseled patients is safe, feasible, and well-tolerated, without an increase in peri-procedural adverse events.

BACKGROUND: Visualization of the dorsolateral subthalamic nucleus (STN) remains challenging on 1.5 and 3Tesla T2-weighted MRI. Our previously defined hotspot serves as a MRI landmark for dorsolateral STN identification in Deep Brain Stimulation (DBS). We aimed to validate the use of this hotspot in a separate trial cohort of Parkinson’s Disease (PD) patients, and refine the hotspot location.

METHODS: In this post-hoc analysis of a randomized controlled trial, responses to DBS were categorized using hemi-body improvement on the MDS-UPDRS motor examination: (1) non-responding (<30% improvement), (2) responding (30–70% improvement) and (3) optimally responding (>70% improvement) and compared to our previous cohort. Then, a refined hotspot was calculated by averaging stereotactic coordinates of the current ‘optimally responding’ group relative to the medial STN border. Subsequently, the Euclidean distance from each active contact to the hotspot was calculated.

RESULTS: 37 non-responding body-sides (17%), 108 responding body-sides (51%) and 67 optimally responding body-sides (32%) were included. The non-responder group showed an improvement of 10%, which was significantly higher than the 6% deterioration in the historical control group (P=0.037). Motor improvement correlated significantly to the Euclidean distance from active contact to the refined ‘hotspot’ (2.8mm lateral, 1.1mm anterior, and 2.2mm superior to the medial STN border) (P=0.001).

CONCLUSION: Implementation of the hotspot for STN targeting improved the motor response after DBS. We used this to refine the hotspot at 2.8mm lateral, 1.1mm anterior, and 2.2mm superior relative to the medial STN border, that visualizes a readily implementable target within the dorsolateral STN which can be used for optimizing DBS motor outcome. 

Objective: We evaluated the effect of at-home adaptive deep brain stimulation (aDBS) on motor symptoms and quality of life (QoL) in five patients with Parkinson’s disease (PD). 

Background: DBS at continuous amplitudes (cDBS) is an effective therapeutic option for PD, but residual motor fluctuations can limit the therapeutic window. In-clinic and brief at-home algorithms that adjust stimulation based on invasive neural biomarkers of PD have shown better clinical outcomes than cDBS [1-3]. The effectiveness of blinded at-home adaptive DBS (aDBS) has not previously been reported.

Methods: Five PD patients were implanted with electrodes in the subthalamic nucleus (STN) and sensorimotor cortex, connected to an investigational sensing-enabled DBS device. cDBS was optimized by clinical movement disorder neurologists over 6-12 months. Then, a study neurologist characterized residual bothersome symptoms for each patient, which included bradykinesia, dyskinesia, stimulation-induced dysarthria, and peak-dose dystonia. We then determined the optimal range of aDBS stimulation amplitudes, and recorded neural data over the full range of these amplitudes. Non-parametric cluster-based permutation tests and linear discriminant analysis were used to identify symptom-related neural signals, not restricting our analysis to a priori defined frequency bands. These were used to set up an aDBS control policy to minimize residual motor signs. aDBS and clinically optimized cDBS were then applied in randomized blocks of 1-4 days for a total of 10-30 days per condition at patient’s homes, while patients blinded of the stimulation condition. As outcome measures, we obtained patients’ self-reports, motor scores from wearables, and QoL scores (EQ-5D).

Results: The optimal signals for aDBS were finely tuned gamma oscillations entrained at half stimulation frequency (65-80 Hz), for most hemispheres, either in the motor cortex or STN. A linear mixed-effects model showed that aDBS using individualized biomarkers improved bothersome symptoms compared to cDBS, without worsening of remaining symptoms. 

Conclusions: This is the first study to demonstrate the greater effectiveness of aDBS than cDBS for controlling parkinsonian motor signs, in a real-life setting with patients blinded. Using a data driven method for optimized biomarker determination, finely tuned gamma oscillations were most efficient as signatures of residual motor signs and as control signals for aDBS.

[1] Little et al. Annals of neurology, 2013

[2] Arlotti, Neurology, 2018

[3] R. Gilron et al., Nat. Biotechnol., 2021.

Deep Brain Stimulation(DBS) for Parkinson’s Disease(PD) in most centres is still done with the patient awake to allow for microelectrode recording (MER) and intraoperative clinical testing.However,technical advances in MR imaging today,raise the question of whether MER still has added value in DBS surgery.

AIM:To find the correlation between intra-op MER and MRI in localising the upper border of Subthalamic Nucleus (STN) in patients undergoing awake DBS for PD.

METHODS:We performed a retrospective analysis of 25 patients of PD who underwent awake STN DBS with intra-operative MER at our institute from March 2020 to May 2023.We located the upper border of STN in each electrode on T2 weighted MRI done sequences and compared it with its corresponding upper limit of intra-operatively obtained MER data.Each set of data was analysed by two different researchers to eliminate reporting bias.A correlation analysis was thus performed for two sets of data for a total of 50 electrodes.t-test/ManWhitney test was used to check the significance between difference in MRI and MER data of both sides individually.The correlation co-efficient was estimated for these variables.

RESULTS:There were total of 17 males and 8 females with a mean age of 58.28 yrs +/-9.78.The mean value of distance of upper border of STN from target identified on MRI was

-3.95mm +/-0.74 and for MER was – 3.53mm +/-1.16 for all electrodes.For right side electrodes mean value was -3.82mm+/-0.82 on MRI and -3.32mm+/-1.47 on MER;for left side electrodes the mean value was -4.08mm+/-0.64 on MRI and -3.74mm+/-0.71 on MER.The mean difference between the right MRI and MER values was -0.52 mm+/-0.96 and for the left -0.34mm+/-0.71:the negative value depicting that the upper border of STN identified on MRI was a higher value than the corresponding MER data,in terms of distance from the target.There was no statistical significance of difference between the two sides(p<0.45).The correlation co-efficient was +0.8(p<0.05) for the MRI and MER data of right electrodes and +0.43 (p<0.02)for the left electrodes,which was strongly positive,both of which were statistically significant.The overall correlation co-efficient of all the 50 electrodes was +0.69 which was strongly positive with statistical significance(p value<0.05).

CONCLUSION:We concluded statistically that there was strong positive correlation between MRI and MER data in locating the upper border of STN overall as well as on each side individually.Hence we propose to totally eliminate the need of MER,as it provides no additional information;moreover it increases the overall operative time and with added risk of brain shift from multiple trajectories,as indicated by numerous previous studies.However a larger group of subjects is needed to confirm these findings.

Cerebral white matter tract lesions from multiple etiologies may prevent descending cortical spinal inputs from effectively activating spinal motoneurons leading to muscle paresis or paralysis. Importantly, in the cases where the damage to the cortico-spinal projections is incomplete, the spared connections could be targeted to enhance or facilitate the residual motor functions. Here we hypothesized that, by engaging direct excitatory connections to motor cortex neurons, deep brain stimulation (DBS) of the motor thalamus could facilitate activation of motor cortex and the spared cortico-spinal fiber outputs to the spinal motoneurons, to improve movements of the paretic limb. We showed in terminal non-human primate’ experiments and intraoperatively in humans receiving DBS implants into motor thalamus, that DBS immediately increased the amplitude of motor thalamus evoked potentials recorded in motor cortex as well as motor output of arm, hand, and face muscles. This potentiation persisted in the presence of cerebral white matter tract lesions. Finally, we demonstrated that motor thalamus DBS improved voluntary force control and speech output in a chronically implanted traumatic brain injury patient with severe upper extremity and speech production deficits. Collectively, these results demonstrate that motor thalamus DBS could be used as an effective assistive therapeuctic device to improve post-lesional upper-limb  motor performance and speech production.

Background: Drug resistant epilepsy (DRE) may affect about 30% of patients suffering from epilepsy. Deep brain stimulation of the anterior nucleus of the thalamus (ANT DBS) is a neuromodulation therapy for patients with refractory focal seizures evolving into bilateral tonic-clonic seizures when pharmacotherapy as well other neuromodulation techniques including vagus nerve stimulation or responsive neurostimulation have failed. The aim of the present study was to describe our preliminary results regarding the efficacy and safety of ANT DBS in 10 patients suffering from DRE.

Methods: We prospectively analyzed the clinical data for patients with DRE who underwent ANT DBS. Moreover, we meticulously confirmed the location of implanted DBS leads within the ANT.

Results: Ten patients with a mean age of 38.5 years (range, 30-48 years) at ANT DBS surgery (mean duration of DRE 28.6 years, range 16-41 years) were included in this prospective study. The median seizure count in three months period preceding surgery (baseline seizure count) was 43.2 (range, 4-150). ANT DBS caused seizure reduction 3 months after procedure as well as at last follow-up (mean 13.6 months, range 3-32 months) by 60.4 % and 73.3 %, respectively. Patients with temporal lobe epilepsy had a remarkable reduction of seizure frequency. No patient suffered transient or permanent neurological deficits.

Conclusions: ANT DBS is a safe and efficacious treatment for DRE. Clinical efficacy of ANT DBS may support more widespread utilization of this neuromodulation technique.

Introduction 

Focal seizures produce an increase in local cerebral metabolism and blood flow. This alteration lead to focal changes in the brain temperature. In our study, we want to explore focal temperature changes arising from the hippocampal seizure onset zone or epileptogenic zone (EZ) using a dedicated thermal lead in a penicillin-induced model of mesial temporal lobe epilepsy in non-human primate (NHP). This approach could help refine EZ localization and improve surgical outcomes

Methods 

Study was performed on two Macaca fascicularis. A device capable of recording temperature and produce cooling was inserted unilaterally in the NHP hippocampus. The device has several temperature sensors and a cannula for penicillin injection in order to create an EZ near the tip. Penicillin was injected (10 min at 1-2µl/min) into the hippocampus. Electrical Signals were recorded using a sEEG lead implanted 2 mm from the EZ, and thermal recordings via thermocouples inside de EZ. Recordings were acquired during 15 trials of 5-7 h each

Results

We analyze temperature recordings at 0.5 mm from de penicillin injection site, the equivalent to the EZ using two thermocouples at the tip of the cooling lead. Variation of temperature were recorded during seizures(Delta T°S) and were classified in groups according whether the brain was in baseline steady state(33.5°C) or during brain cooling (at 21°C,23°C and 17°C). We compare this with the temperature variation occurring during no-seizures periods before injection. Animals had a baseline brain temperature of 33.50°C±1.85 °C and a stable body temperature, measured with an infrared skin thermometer, between 36-37°C. Brain temperature variability was determined in both animals during multiple 2 min intervals without seizures and before injections. Temperature variation during no seizure period was 0.05±0.02°C. In contrast, during penicillin-generated seizures, we found that an increase of 0.29±0.2°C occurred when brain temperature was at baseline (33.5°C). More interesting , when we carried out measurements of Delta T°S during focal cooling (Brain temperature in EZ of 23°C, 21°C and 17°C), we found a Delta T°S of 0.35±0.05°C, 0.35 ±0.19°C and 1.60±0.34°C respectively. There was a clear increase in Delta T°S related to the reduction in temperature in the EZ, (p<0.0001). There was no correlation between seizure duration and DeltaT°S

Conclusion

Human studies revealed a direct spatial-temporal relationship of elevated cerebral blood flow and metabolism during seizures. Several authors have found changes in temperature in the brain related to neuronal activity and seizures. Our data show this relationship in an indirect way using implantable thermal sensors. This could lead the way towards developing thermography brain maps capable of better identification of EZ for presurgical evaluation           

Background: Hearing loss in the elderly has been associated with difficulties in speech comprehension and cognitive decline. Not least, it is a possible risk factor for dementia. We already showed in adult rats that hearing loss leads to reduced neuronal activity in the medial prefrontal cortex (mPFC). To investigate the impact of hearing loss on cognitive function and communication, we here tested adult rats in behavioral paradigms for motor activity, attention and impulse control), as well as social interaction, including ultrasound vocalization (USV).

Methods: In a cohort of adult male Sprague Dawley rats, hearing loss was induced under general anaesthesia with intracochlear injection of neomycin (n=11). Naive (n=10) and sham-operated rats (n=7) served as control. Hearing loss was verified after surgery with auditory brainstem response (ABR) measurement. Furthermore, the rats were tested for motor activity (Open Field), motor coordination (Rotarod) and social interaction before surgery and at week 1, 2, 4, 8, 16, and 24 after surgery. From week 8 onwards, the rats were tested in the Five Choices Serial Reaction Time Task (5CSRTT) for visuospatial attention, impulse control, learning, and memory. In this paradigm, rats have to react to a light stimulus in one of five holes of the aperture, which is shortened from session to session.

Results: In the Open Field deaf rats moved significantly faster and a longer distance in total than the naive and sham-operated controls (both p<0.05). Moreover, the motor coordination tested on Rotarod was disturbed in deaf rats (p<0.05). Although social interaction was not altered, the frequency of ultrasound vocalization was significantly less in deaf rats compared to the control group (p<0.05). Learning the paradigm of the 5CSRTT was significantly impeded in the deaf group for the first training session (p<0.05). Although shortening the light stimulus in the subsequent sessions had no effect, the accuracy, which is associated with attention, was reduced in deaf rats (p<0.05). Retesting in week 20 and 24 did not indicate a long-term memory deficit in the deaf group.

Conclusion: Hearing loss in adult rats leads to hyperlocomotion, less USV while social interaction, and deficits in initial visuospatial attention and learning, which may be related to compromised neuronal activity in the mPFC. Therefore, this model may be used to test the effect of neuromodulatory stimulation on cognitive decline attributed to hearing impairment.

Background: Symptomatic idiopathic delayed onset edema (IDE) is a complication which can occur after electrode placement in deep brain stimulation (DBS) surgery. Due to the potential duration and severity of neurological deficits, it can cause a heavy burden on the patient. The cortical area used for electrode entrance may be associated with the occurrence of symptomatic IDE.

Objective: To evaluate possible influence of cortical entry of DBS electrodes on symptomatic IDE occurrence in patients from 2014 - 2021.

Methods: A total of 575 patients underwent DBS surgery for Parkinson’s disease (PD), tremor, dystonia, pain, epilepsia, depression and obsessive compulsive disorder. Symptomatic IDE occurred in 10 PD patients, 4 tremor patients and 1 pain patient (IDE group, representing 27 trajectories). The cortical entry and surrounding edema volume of the trajectories were determined. A group of patients after DBS without IDE (non-IDE consisting of 120 PD patients; 56 tremor patients; 11 pain patients; representing 355 trajectories) was used for comparison. Edema volume was measured using CT. Cortical entry of Brodmann areas 6 (divided in pre-supplementary motor area and supplementary motor area, pre-SMA and SMA), 8 or pre-8 were determined using MRI.

Results: Average edema volume was 10 cm³ and 12 cm³ for right and left trajectories, respectively. Cortical entry occurred in 10% and 35% of SMA and pre-SMA respectively. 49% in BA8 and 6% anteriorly to BA8. Cortical entry in the SMA, 17% of the patients developed IDE. 10% in the pre-SMA, 3% in BA8.  IDE did not occur when the cortical entry was anterior to area 8.

Conclusion: Symptomatic IDE occurred in PD, tremor and pain patients after DBS. In the IDE group Brodmann area 6 was chosen more often as DBS entry compared to the non-IDE group. The more anterior situated cortical areas were less susceptible to developing symptomatic IDE. It seems sensible to avoid area 6 for electrode entry in (PD, tremor and pain) DBS cases. Possibly this area is more susceptible for symptomatic IDE due to its neuronal architecture and contributions in linking cognition to action.

Frame-based stereotactic biopsy of brainstem lesions – a single center, retrospective, comparative analysis of the transfrontal and the suboccipital, transcerebellar approach

M. Kaes¹, J.-O. Neumann^1,2, C. Beynon¹, K. Kiening^1,2, A. Unterberg¹, M. Jakobs^1,2

1 Department of Neurosurgery, Heidelberg University Hospital, Heidelberg, Germany

2 Division Stereotactic Neurosurgery, Department of Neurosurgery, Heidelberg University Hospital, Heidelberg, Germany

Objective

Both the transfrontal and the suboccipital, transcerebellar approaches are used to plan trajectories for frame-based stereotactic biopsies of brainstem lesions. Nevertheless, it remains unclear which approach is more favorable in terms of complications, diagnostic success and outcome, especially considering the location of the lesion in the brainstem. In our study we retrospectively compared the safety and diagnostic success rate of these two approaches.

Methods

A retrospective analysis of all consecutive cases of frame-based stereotactic biopsies at our center was performed looking for cases of brainstem lesions to be targeted over a 16-year period. Clinical and surgical data regarding trajectories, histopathology, complications and outcome was collected.

Results

Over a 16-year period a total of n=84 stereotactic biopsies for brainstem lesions were performed. In 36 cases the suboccipital, transcerebellar approach was used, while in the remaining 48 cases surgery was performed via the transfrontal approach. Patients demographic data and ASA-scores were comparable. Overall diagnostic yield was 90.5% (93.8% transfrontal vs. 86.1% suboccipital). Complications occurred in 11 cases (13.1%;  12.5% transfrontal vs. 13.9% suboccipital) appearing as new permanent neurological deficits in 6 cases (7.1%; 8.3% transfrontal vs. 5.6% suboccipital) and new transient neurological deficits in 5 cases (6%; 4.2% transfrontal vs. 8.3% suboccipital). Hemorrhage occurred in 7 cases with complications (8.3%; 6.3% transfrontal vs. 11.1% suboccipital). There were no statistically significant differences between the two approaches.

Conclusions

In our study we found no significant differences between the transfrontal and the suboccipital, transcerebellar approach for stereotactic biopsy of brainstem lesions in terms of diagnostic yield and safety. Therefore, our data suggests that both approaches should be considered equally for stereotactic biopsy of brainstem lesions.

Purpose

Parkinson’s disease (PD) is one of the most prevalent neurodegenerative diseases, characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta. The treatment of PD aims to alleviate motor symptoms by replacing the reduced endogenous dopamine. Currently, there are no disease-modifying agents for the treatment of PD. Zebrafish (Danio rerio) have emerged as an effective tool for new drug discovery and screening in the age of translational research. The neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is known to cause a similar loss of dopaminergic neurons in the human midbrain, with corresponding Parkinsonian symptoms. L-type calcium channels (LTCCs) have been implicated in the generation of mitochondrial oxidative stress, which underlies the pathogenesis of Parkinson’s disease. Therefore, we investigated the neurorestorative effect of LTCC inhibition in an MPTP-induced zebrafish PD model and suggested a possible drug candidate that might modify the progression of PD.

Materials and Methods

All experiments were conducted using a line of transgenic zebrafish, Tg (dat:EGFP), in which green fluorescent protein (GFP) is expressed in dopaminergic neurons. The experimental groups were exposed to 500µ㏖ MPTP from 1 to 3 days post fertilization (dpf). The drug candidates: Levodopa 1m㏖, Nifedipine 10µ㏖, Nimodipine 3.5 µ㏖, Diethylstilbestrol 0.3 µ㏖, Luteolin 100 µ㏖, Cacitriol 0.25 µ㏖ were exposed from 3 to 5 dpf. Locomotor activity was assessed by automated tracking and dopaminergic neurons were visualized in vivo by confocal microscopy.

Results

Levodopa, Nimodipine, Diethylstilbestrol, and Calcitriol had significant positive effects on the restoration of motor behavior, which was damaged by MPTP (mean velocity 0.3856, 0.3398, 0.3817, and 0.4889, respectively, vs. MPTP followed by DMSO-treated group 0.1523). Nimodipine and Calcitriol have significant positive effects on the restoration of dopaminergic neurons, which were reduced by MPTP (78.8% and 81.8% of MPTP followed by DMSO-treated group). Through locomotor analysis and dopaminergic neuron quantification, we identified the neurorestorative effects of Nimodipine and Calcitriol in Zebrafish MPTP-induced PD model.

Conclusion

The present study identified the neurorestorative effects of nimodipine and calcitriol in an MPTP-induced zebrafish model of Parkinson’s disease. They restored dopaminergic neurons which were damaged due to the effects of MPTP and normalized the locomotor activity. L-type calcium channels have potential pathological roles in neurodevelopmental and neurodegenerative disorders. Zebrafish are highly amenable to high-throughput drug screening and might, therefore, be a useful tool to work towards the identification of disease-modifying therapies for PD. Further studies including those on zebrafish genetic models to elucidate the mechanism of action of the disease-modifying candidate by investigating Ca2+ influx and mitochondrial function in dopaminergic neurons, are needed to reveal the pathogenesis of PD and develop disease-modifying treatments for PD.

Background: Deep brain stimulation (DBS) has been proven to be a powerful advanced treatment for neurological and psychiatric disorders. However, hardware-related infections (HRIs) may occur after primary implantations and replacements of implantable pulse generators (IPGs) and are a major concern. HRIs are both a burden for the patient and a financial burden for the healthcare system, but there is no clear consensus on how to prevent HRI in DBS surgery.

Objectives: We propose a protocol to prevent HRIs in DBS surgery based on our single-center five-year experience.

Methods: We retrospectively analyzed the incidence of HRI in all patients that underwent either DBS surgery or IPG replacement surgery between March 2018 and April 2023. Data on risk factors for HRI were collected for all patients (smoking status, diabetes mellitus, obesity, wound dehiscence, scalp erosion and skin-to-skin time). Our local infection prevention protocol, ranging from the preoperative to the postoperative stage, consists of several steps including smoking cessation, antiseptic washing, skin closure, antibiotic prophylaxis, and wound disinfection.

Results: A total of 245 patients (mean age 63.7 ± 8.6 years, 88 females) underwent DBS-related surgery. Primary DBS implantation was performed in 190 patients (377 DBS electrodes and 190 IPGs) and IPG replacement was performed in 55 patients (73 IPGs). There were no HRIs in any of the patients.

Conclusions: Over a 5-year period, we performed a total of 263 DBS-related procedures without any HRI. Therefore, we share our infection prevention protocol as a guideline. This may help other centers to decrease the rate of HRIs. Moreover, the protocol may be considered for other neurosurgical implant surgery.

DBS is a well-established treatment for movement disorders, but the safety and cost-effectiveness can be heavily influenced by complication rates. In the literature, infections are reported to occur in about 5% of all patients undergoing DBS (Kantzanou et al 2021). DBS-surgeries have been performed in Oulu University Hospital (OUH) since 1997. The aim of this retrospective study was to report DBS-related infections and provide recommendations for minimizing infections.

A total of 964 DBS-related surgeries were performed in OUH between 1997 and May 2023 (preliminary data), and 35 DBS-infection related revision surgeries were done, two of which were originally operated outside OUH. The DBS-infections were divided into surgical-site infections (SSI; DBS-infections within 1 year of surgery) and non-surgical-site infections (nSSI; DBS-infections not related to surgery). The number of SSIs was 30 patients leading to SSI-infection rate of 3%. Majority of SSIs occurred after primary implantation, and only 5 (17%) occurred after battery replacements.  Mean time to first revision was 88 days (SD=67) after primary implantation and 113 days (SD=150) after battery replacement. We found that SSIs were more common at the early years but became rarer when experience was gained. The most common pathogen was Staphylococcus aureus, which was present in 62.9% of cases. In 31.4 % of cases two or more bacteria were found from bacterial cultures, most commonly Staphylococcus epidermidis and Cutibacterium sp.

Preventative measures have been implemented to the surgical DBS-protocol to minimize infections. Preoperatively these include skin examination and chlorhexidine washes. Attention is paid to sufficient preoperative caloric intake to avoid catabolic state prior surgery. During the surgery hair is shaved only from the necessary area and surgical washing is performed with ethanol and chlorhexidine solution. Bicoronal incision and pericranium restoring technique is used in the head area. Antibiotic prophylaxis includes cefuroxime 1,5-3g intravenously (iv) and vancomycin 1-1,5g iv. Conventional sterilizing practices are followed, the number of people in the operating room is limited and double layer gloves are used. Postoperatively, wounds are showered and protected with patches.

Overall, there are three main findings. First, infections are more common when starting DBS service which may be because there are new protocols that should be formed to optimize workflow. Second, mixed infections should be accounted for in the antibiotic selection, and our antibiotic prophylaxis was adjusted to also include vancomycin. Third, in our experience aggressive surgical revision is the only curative treatment option when combined with antibiotic treatment.

Background: Parkinson Disease manifests with complex motor and non-motor features from which patients affected in various degrees. Levodopa-induced dyskinesia and dystonia can be adverse effects of the medical treatment and motor fluctuations and drug-induced dyskinesias often considered indications for DBS surgery. Rescue lead practice is rather a new approach that is performed to patients with suboptimal beneficial effects achieved from previous DBS surgeries or with low side effect thresholds that narrows the therapeutical gaps. In our study, we demonstrated that rescue GPI leads implantation improved dyskinesia that occurred or progressed after ineffective STN stimulation.

Methods: Between 2019 and 2023, 4 patients diagnosed with Parkinson Disease suffered from bradykinesia, rigidity, gait imbalance and bilateral rest tremors at hands. Patients’ preoperative DBS and med off UPDRS (Unified Parkinson Disease Rating Scale) scores, AIMS (Abnormal Involuntary Movement Scale) scores, Overall Severity Index (OSI) and postoperative AIMS scores whilst DBS on Med on phase, and dyskinesia symptoms before and after revision surgery are evaluated.

Results: 3 patients received bilateral STN electrodes whereas one patient received unilateral right STN DBS surgery. Patient with unilateral right STN DBS had been operated 2 times and 2 right STN electrodes implanted with different trajectories. 2 patients received bilateral STN electrodes developed Brittle dyskinesia that responded poorly to decrease of dopaminergic medication. Patients’ preoperative DBS off-med off scores were between 74-82 which indicates further progressed Parkinson Disease. Their AIMS and OSI score were ranging between 6/3 to 7/3. The patient with unilateral STN electrodes were suffering from drug induced dyskinesia too and lower thresholds of side effects while DBS was on.

Patients who received bilateral rescue GPI electrodes and stimulated with previous IPG experienced early relief of dyskinesia. Patients’ tremor and bradykinesia symptoms ameliorated initially but continued for 3 months until they totally diminished due to GPI stimulation’s late onset of tremor response profile. Patients’ STN stimulation parameters adjusted slightly lower than previous programming parameters, since stimulation process being conducted through two separate targets: GPI and STN in those two patients. The present IPGs were not removed or used for new Gpi electrodes, because the batterie’s end of life were soon.

Conclusions: GPI stands for better dyskinesia improvement, but anti-tremor effect may be observed later then Stn stimulation. Anti-dyskinesia effect of GPI stimulation is observed mostly at ventral electrode contacts. Our patients had treated with STN DBS surgeries but optimal results without side effects were not obtained. Their secondary supplementer GPI DBS surgeries provided us with immediate anti-dyskinetic effect. When STN stimulations decreased, tremor symptoms re-emerged, and GPI contacts programmed for resolving tremor and dyskinesia accordingly. With this rescue surgery, continuing STN stimulation remains at low currents without causing side effects and sustaining supplementer GPI stimulation provides additional anti-tremor and anti-dyskinetic effects.

Purpose: Tumor-related trigeminal neuralgia (TN) is a challenging condition to manage that is commonly treated by surgical resection of the tumor. Stereotactic radiosurgery (SRS) targeting the tumor is used to control pain and tumor growth in patients unsuitable for surgery. SRS targeting the trigeminal nerve has been explored as a viable treatment for patients with tumor-related TN who are unsuitable for surgical removal of the tumor or whose pain is refractory to radiation therapies targeting the tumor. Information regarding the efficacy of this procedure is limited to only a few studies. We report the outcomes of Gamma Knife radiosurgery (GKRS) targeting the trigeminal nerve for tumor-related TN from a case series.

Methods: Retrospective review of our GKRS database identified 6 patients with unilateral tumor-related TN treated with GKRS targeting the trigeminal nerve between 2014 and 2022. Five patients had undergone previous radiation therapies targeting the tumor. Facial pain and sensory function were evaluated with the Barrow Neurological Institute (BNI) scores.

Results: Three patients achieved BNI IIIb or better pain reduction after a mean period of 4.3 months from GKRS. Maximum dose for GKRS ranged from 80 to 88 Gy. Pain recurred in 1 patient at 64 months after GKRS. No patient developed permanent facial sensory disturbances. No adverse event was recorded.

Conclusions: GKRS targeting the trigeminal nerve may be a safe and effective treatment for a subset of patients with tumor-related TN who are unsuitable for surgical removal of the tumor or are refractory to radiation therapies targeting the tumor.

Objectives: Spinal cord stimulation (SCS) is burdened with surgical complications that may require one or several surgical

revision(s), challenging its risk/benefit ratio and cost-effectiveness. Our objective was to evaluate its outcome and efficacy after

one or more SCS surgical revisions.

Materials and Methods: We identified and retrospectively analyzed 116 patients treated by tonic paresthesia-based SCS who

experienced one or more complication(s) requiring at least one surgical revision. Data collected included initial indication,

revision indication, number of revisions, and lead design (paddle or percutaneous). Outcome after SCS revision was evaluated by

pain intensity decrease (comparing baseline and postrevision Numerical Rating Scale [NRS] scores) and percentage of patients

reporting pain relief ≥50%. Outcome was analyzed according to the number of surgical revisions and the revision indications.

Results: Most of the patients (61%) underwent only one revision (mean delay after implantation 44 months). The most frequent

causes of revisions were hardware dysfunction (32%), lead migration (23%), and infection (18%). Revision(s) repaired the SCS

issue in 87% of the cases. One year after the first revision, 82% of the patients reported pain relief ≥50%, and the mean NRS

decrease was 4.0 compared with baseline (p < 0.001). Benefit of SCS revision tended to decrease with the number of revisions but

did not differ across revision indications. No serious surgical complications related to the revision occurred, except for three

hematomas occurring after repeated revisions.

Conclusions: Our data suggest that surgical revision of SCS system is safe and led to significant pain relief in most of the cases,

provided that the initial indication was good and that the previous stimulation was effective. However, success of SCS revision

decreases with the number of revisions

Objective: The main cause of trigeminal neuralgia is not fully understood, especially how a neurovascular conflict or distortion of the trigeminal nerve can lead to pain. Our aim was to determine whether the anatomical configuration of the trigeminal nerve and its adjacent structures can be a predisposing factor for the occurrence of clinically significant neurovascular conflict in trigeminal neuralgia.

Methods: We analyzed retrospectively 80 patients with idiopathic trigeminal neuralgia and 73 healthy participants with Constructive Interference in Steady State magnetic resonance imaging. The length of both trigeminal nerves from the nerve root entry zone until the entrance into the Meckel’s cave was measured, as well as the intertrigeminal distance and the prepontine distance. The length of the nerve in the painful side was correlated with the nonpainful side. Additionally, side of pain, distribution of pain, and intraoperative findings were recorded, including arterial compression, venous compression and arachnoid membranes distorting the nerve.

Results: Mean age at surgery was 56,9 years (20 to 84 years). The most common intraoperative finding was arterial compression (88,8%), followed by arachnoid adhesions distorting the nerve (73,8%), followed by a venous compression (50%). Most patients had two of these findings (60%), followed by three (26,3%) and then one single finding (13,8%). There was a statistically significant difference between the mean length of the trigeminal nerve on the pain side compared to the non-pain side (10,46 vs. 10,51). When comparing to the control group, the patients with trigeminal neuralgia had shorter trigeminal nerves (10,48 vs 11,11 mm), but no statistically significant difference when comparing the prepontine distance between two groups. Additionally, a shorter trigeminal nerve was correlated with a higher number of intraoperative findings, and especially venous compression and arachnoid adhesions.

Conclusions: Our data supports the hypothesis that a shorter trigeminal nerve is more susceptible for a clinically significant neurovascular conflict.

Introduction

Obsessive compulsive disorder (OCD) affects 2-3% of the population and is characterized by the presence of intrusive thoughts (obsessions) that lead to repetitive attitudes (compulsions) to alleviate the anxiety they produce. The main pathophysiological theory is the dysfunction of the cortico-striatal-pallidal-thalamo-cortical circuit. Between 10-25% of patients remain symptomatic despite pharmacological treatment and psychotherapy. Deep brain stimulation (DBS) has been described as an effective treatment, with different targets applied as the  anterior arm of the internal capsule, ventral striatum, nucleus accumbens, and subthalamic nucleus.

Objectives

To review and understand the publications avaliable for DBS and OCD. To analyze our database of OCD patients implanted with deep brain stimulation system.

Material and methods

We reviewed the scientific literature available in PubMed and presented a series of patients with refractory OCD implanted in our center.

Results

Deep brain stimulation was performed in 13 patients between the years 2006 and 2017. Most suffered from highly disabling obsessions and compulsions of cleaning, checking and repetition. Electrodes were placed through the anterior limb of the internal capsule to nucleus accumbens bilaterally. In 5 cases intraoperative neurophysiological recording was performed. We performed postoperative Mri in all the patients. There were no clinically significant complications, although one patient required repositioning of an electrode. Although the follow-up recorded was irregular, scales such as YBOCS, BDI and STAI were used for evaluation. Nine patients presented significant clinical improvement and are satisfied. We observed no correlation between the clinical pattern and the response to DBS.

Conclusions

Most patients obtained beneficial effect in terms of relief of their symptomatology, being the rate of complications low. Our results are comparable to the published literature. We believe that DBS is a safe treatment option for refractory OCD and should be considered as an option in selected patients.

Evoked resonant neural activity (ERNA) in subthalamic deep brain stimulation (DBS) for Parkinson’s Disease (PD) is emerging as a promising biomarker for lead placement and postoperative programming. The signal can be described as a high frequency, large amplitude, underdamped oscillation. Studies show stimulating from contacts with larger ERNA amplitudes results in greater clinical effects. However, the ERNA’s origin and its specificity as a PD biomarker are currently still under investigation. We had the unique opportunity to stimulate and record in the STN of a multiple system atrophy (MSA) patient. MSA is a neurodegenerative disease, which can strongly resemble PD in the early stages. Therefore, MSA is regularly misdiagnosed as PD in early stages of the disease. However, as opposed to PD, MSA does not respond well to dopaminergic medications and DBS is considered ineffective. In this analysis, we want to better understand the ERNA’s origin by comparing local evoked potentials from patients implanted in different locations, suffering from different diseases that respond differently to DBS.

We recorded DBS-evoked potentials in three different patients: in the STN in a PD and a MSA patient and in the ventral intermediate nucleus of the thalamus (VIM) of an essential tremor (ET) patient. At time of implantation, the MSA patient was diagnosed with PD. In all patients, stimulation frequency was 10Hz, and the stimulation amplitude corresponded with the side effect threshold at 130Hz (PD: 2.4mA, MSA: 4.2mA, ET: 2.4mA). A differential recording was made from the levels surrounding the stimulating level.

The characteristic oscillating response was observed when stimulating in the STN, both in the PD and MSA patient. For the contact generating the largest response, peak-to-trough amplitudes were 205.2 µV and 62.0 µV and frequency was 309.7 Hz and 303.8Hz respectively. No such response was found in the VIM of the ET patient. This suggests ERNA is not a biomarker for PD in itself, but rather for the STN network. Furthermore, the presence of ERNA in MSA, a disorder not responding well to DBS, indicates that ERNA in itself does not cause the clinical effect.

Background:  Surgical stereotactic lesioning of thalamus and basal ganglia has been used for the treatment of different neurological disorders. In the last years Magnetic Resonance–guided Focused Ultrasound surgery (MRgFUS) has emerged as a noninvasive thermal ablation method, which uses high-intensity focused ultrasound (HI-FU) energy and MRI for anatomical imaging and real-time thermal mapping. It is possible to obtain a rigorous focal point within the planned target and across the intact skull for the treatment of movement disorders.

We carried out a study on use of thalamotomy with MRgFUS in the treatment of tremor. The study was done in collaboration between Unit of Functional Neurosurgery of the University of Catanzaro and IRCCS - Centro Studio Neurolesi '' Bonino Pulejo '' of Messina.

The purpose was to demonstrate efficacy of MRgFUS method in treatment of tremor and verify improvement in quality of life of treated patients.

Methods:  Study population includes 42 patients with unilateral Essential Tremor (TE) refractory to drug therapy, chosen on the basis of inclusion and exclusion criteria and undergoing MRgFUS VIM thalamotomy from March 2019 to December 2022.

Technology used involved InSightec MRgFUS ExAblate Neurosystem with simultaneous use of a 3-Tesla MRI. Outcome assessments were carried out 1 month, 3 months, 6 months, 12 months and 24 months after treatment and t-test was used for statistical analysis. Study included T1, T2, FLAIR, DWI, and T1-weighted MR images after mdc for verification of the lesion. Clinical assessments were performed with Tremor Research Group Essential Tremor Rating Assessment Scale (TETRAS) for assessing tremor and with ADL subsection of TETRAS scale for assessing daily-life disability.

Results:  Mean score on TETRAS scale went from 24.86± 5.27 preoperatively to 5.6 ± 3.2 postoperatively with reduction in tremor of 69.78% and this result remained almost the same in follow-up. TETRAS ADL score went from 32.33 ± 7.08 to 7.93 ± 3.60 postoperatively, with reduction of 75.46%. No adverse events were reported, both in short and medium term, except for mild transient ataxia which regressed completely within six hours of treatment.

Conclusion:  MRgFUS-thalamotomy for treatment of unilateral TE has been shown to be extremely effective, reliable and free of significant adverse events. It is a method with great development potential, but thorough evaluation of its long-term effects is necessary.

Introduction:Parkinson’s disease (PD) remains a major cause of neurological disability affecting millions of patients around the world. While pharmacotherapy remains the primary treatment of PD symptoms, surgical therapies have showed a resurgence of successful treatment of patients with advanced PD and complications of drug therapy. With appropriate selection of patients, deep brain stimulation (DBS) is now considered one of the most important advances in PD therapy.

Material and methods: 

Since July 2004 to December 2023 eighty three cases (83) patients suffering from PD were operated in our department. . This study included 43 men and 40 women ranging between 44  complete form, 21trembling and18 rigid form; the age range from 37 to 70 years (mean age: 56 years and mean age onset: 40 years (lesionotomy of the GPi in 2 cases, of the VIM in 17cases, 2 cases of unilateral lesionotomy with DBS) and bilateral deep brain stimulation (DBS) in 63 patients. The coordinates X Y Z OF STN and GPI are calculated on work station after realizing a fusion between a stereotactic CT Scan and an MRI. Usually the  Stimulation of the GPI ,the STN and thalamotomy  were performed without anesthesia

Electrophysiological micro recordings and clinical per operative assessment were realized for the accuracy of the location of the electrode in the STN

Results: 

satisfactory to excellent results were more precocious in surgery of PD than

In DS  where they were tardier .in PD the comparative study of pre and post-operative scores including the UPDRS III (motor score) has noted a significant reduction of 65% in the UPDRS OFF  and  63% in the UPDRS .Thermolesion of the VIM has demonstrated efficacy on tremor in 70% the major post operative complication observed was the stimulator infection in two cases .We deplored no mortality or morbidity.

CONCLUSION:

 Parkinson disease surgery using both ablative and deep brain stimulation seems to be a reasonable option for medically intractable patients. The appropriate selection of patients provide a good outcome.

We experienced two cases of involuntary movements associated with germinoma located pineal area. First case was of a 14-year-old male with shaking of the left hand since the age of 13 who was diagnosed with pineal tumor through comprehensive examination. Combined chemotherapy and radiation therapy were administered. As a result, the patient's course was good, except for gradual worsening of his left-hand tremors. Deep brain stimulation was ruled out from the treatment plan due to the need for regular MRI follow-up, and he was referred to our department for stereotactic thalamotomy. Right Vim thalamotomy was performed, which effectively improved the symptom without any complications. The second case was of a 29-year-old male diagnosed with pineal tumor at the age of 13 after reporting impairment of vision. Tumor removal via craniotomy was performed 1 year later; based on the diagnosis of germinoma through histopathology of the mass, adjuvant radiation therapy was administered. The patient was referred to our department after experiencing involuntary movements mainly in the neck, trunk, and both arms since the age of 23. Stereotactic ablation was performed in two stages in the following order: left pallidotomy followed by right pallidothalamic tractotomy; as a result, his involuntary movements were cured without any obvious complications. In all cases, tumor location at the region of the pineal gland complicated the target plan, especially that of the Vim nucleus, due to deficits or significant deformations at the posterior commissure. Patients with involuntary movement disorders exhibit a wide range of motor symptoms, and need to undergo frequent MRI scans for their primary disease. In such patients, stereotactic ablative surgery showed potential as a useful treatment approach for involuntary motor symptoms due to its capability to simultaneously target multiple loci in the brain.

Background. According to the consensus statement of International Parkinson and Movement Disorder Society, essential tremor was defined as isolated bilateral upper limb action tremor with or without tremor in another body parts lasting at least 3 years and in the absence of other neurological signs. Deep brain stimulation (DBS) of ventrointermediate nucleus (VIM) has been approved for treatment of patients with refractory essential tremor since 1997. Despite the high efficacy of VIM stimulation, some papers indicate a loss of tremor control years or sometimes even months after programming. J. Peters and S. Tisch defined this so-called habituation phenomenon in their 2021 review paper as “a loss of benefit from electrode reprogramming over time in the setting of optimal electrode placement and programming not explained by disease progression of the tremor syndrome”. The management of this condition is still challenging, as reprogramming improvement is limited and temporary.

Posterior subthalamic area (PSA) is considered an alternative stimulation target for severe essential tremor. M. Barbe and coauthors (2018) demonstrated in randomized double-blind crossover trial that PSA DBS is no less efficient than VIM DBS for essential tremor. To date, the information regarding habituation after PSA DBS is scarce, so the goal of this demonstration is to present the patient with severe habituation after PSA stimulation and approaches to manage this condition.

Methods. Seven bilateral PSA DBS were performed in Meshalkin National Medical Research Centre since 2018. The tremor severity was assessed using Fahn-Tolosa-Marin Clinical Rating Scale for Tremor (FTM) part A. Variables are presented as mean (±SD).

Results. The group mean preoperative FTM part A score was 14.5 (±2.7). Postoperative mean FTM part A score was 5.7 (±5.1) with 60.6% reduction in tremor severity after 19±13.7 months of follow-up. The sixty years old patient with disabling kinetic tremor was treated with PSA DBS. After MRI confirmation of proper lead location, the stimulation was programmed on the 7^th postoperative day with evident tremor reduction. Despite the initial efficacy, tremor returned in 3 days, so several reprogramming options were attempted (amplitude and frequency increase, bipolar, interleaved and “on-demand” stimulation) with only temporary and partial tremor improvement. Importantly, severe “ricochet” phenomenon occurred after switching the stimulation off. The patient underwent a left-sided radiofrequency thalamotomy with persistent tremor control and significant functional improvement during one-year follow-up.

Conclusion.  Severe habituation phenomenon may occur after PSA DBS and could be effectively treated with radiofrequency thalamotomy if DBS reprogramming failed.

Background: Chronic pain in the pediatric population is a complex condition with an estimated prevalence as high as 10%. If untreated, it can adversely affect the psychological well being of children and lead to morbidity, opioid dependence and even mortality. Spinal cord stimulation (SCS) is a neuromodulation method approved by the FDA for pediatric use in 1989, with still limited data on its use - a recent systematic review by Karri et al. found 17 pediatric patients who received SCS implantation for chronic pain.

Methods: We retrospectively analyzed clinical data of pediatric patients who underwent SCS

implantation at the University Hospital Center Zagreb. Patients with chronic, intractable pain who failed conservative treatment were considered candidates for SCS implantation.

Results: A 14-year-old female patient with complex regional pain syndrome (CRPS) suffered from bouts of intractable pain (VAS 10/10) in her right wrist since the age of 8, accompanied by restricted range of motion in the radiocarpal joint. Similar symptoms occurred in her left foot at the age of 14. Due to failure of conservative treatment SCS was implanted for both pain regions (C2-C7 and Th10-L1). The patient was completely pain-free postoperatively, with improved range of motion of the affected joints.

A 15-year-old male patient with chronic demyelinating polineuropathy and neurogenic bladder reported intermittent intractable pain in both legs (VAS 9/10) since the age of 9. Upon failure of conservative treatment, SCS was implanted in the Th8-Th12 region. An excellent postoperative outcome was achieved, the pain resolved (VAS 3/10) and an improvement of bladder control was noted.

Conclusion: SCS in the treatment of intractable, chronic pain is an effective, albeit underutilized method in the pediatric population. Prospective, randomized studies should further evaluate the safety and efficacy of this method in a large pediatric cohort.

Aims: Vertebrobasilar dolichoectasia (VBD) causing trigeminal neuralgia is rare. We discuss the clinical presentation and the techniques and challenges in microsurgical vascular decompression of the trigeminal nerve in patients with VBD.

Material and methods: We report 2 patients with medically refractory trigeminal neuralgia due to vertebrobasilar dolichoectasia who underwent microsurgical vascular decompression of the trigeminal nerve. We highlight their clinical presentation, neuroimaging, and intra-operative findings, and discuss the microsurgical techniques employed in managing these patients.

Results: Both of our patients were males, aged 53 and 61 years. Both were normotensives, with one patient having diabetes mellitus. Both had relatively shorter duration of symptoms- 3 years and 1 year. Neuroimaging in both these patients showed a tortuous and ectatic vertebrobasilar artery abutting the trigeminal nerve which was confirmed during surgery. Both patients underwent microsurgical vascular decompression. While it was possible to separate and keep the dolichoectatic vessel away using Teflon sheets in one patient, the other patient required a sling-clip technique to achieve and maintain satisfactory decompression. Both patients had immediate relief in pain with no recurrence on follow -up (3 months and 1 year).

Discussion: Vertebrobasilar dolichoectasia (VBD) is characterised by dilatation and elongation of the vertebrobasilar arteries. VBD causing Trigeminal Neuralgia is an extremely rare condition with an incidence of 0.05%.  Although VBD is known to be associated with hypertension, both of our patients were normotensives. Both patients had a relatively short duration of symptoms indicating the severity of facial pain and relative resistance to medical management. Microsurgical vascular decompression is technically challenging in these patients – mobilizing the ectatic arteries in the narrow working spaces between the cranial nerves, futility of arachnoidal dissection and shredded Teflon alone to keep the artery away, being conscious of the branches and perforators arising from the vertebrobasilar artery during mobilization, and to work around the variations in petrous bone anatomy. In-order to achieve and maintain the decompression from the trigeminal nerve we used different techniques in these patients. In one patient, we used Teflon sheets instead of shredded Teflon (Teflon wedge technique). In the other patient, we used a Teflon sling and gently pulled the artery away from the trigeminal nerve and anchored it to the petrous dura and secured it with an aneurysm clip (sling-clip technique). Both patients had good, sustained relief in their symptoms.

Conclusion: Microsurgical vascular decompression is an effective treatment option in trigeminal neuralgia caused by vertebrobasilar dolichoectasia. This procedure can be tailored based on the intra-operative neurovascular relationship, the bony and the vascular anatomy.

Introduction

Neuropathic pain after spinal cord injury (SCI) is one of the most challenging types of pain to treat. Up to 70 % of patients after SCI experience chronic central neuropathic pain (CNP). Spinal cord stimulation (SCS) can by applied in chronic neuropathic pain in Persistent Spinal Pain Syndrome (PSPS) and in Complex Regional Pain Syndrome (CRPS) but in CNP after SCI effectiveness of SCS is limited.

The aim of our study was to evaluate SCS use in patient with severe chronic neuropathic pain after SCI.

Methods

Among 112 patients treated due to neuropathic pain of a different origin mostly in the course of PSPS and CRPS in our department from 2019 to 2022, we selected 8 individuals (4 males and 4 females) with CNP caused by SCI. In 6 patients pathophysiology of pain was associated with traumatic SCI, in other two with stroke. In 4 cases electrode leads were implanted in cervical area and in 4 other cases in thoracic area.

We have assessed the effects of SCS in patients with CNS caused by SCI using NRS score Oswestry Inventory, the EQ-5D quality of life scale with follow-up to 1 year.

Results

In follow-up of 1 year only in 2 individuals, the SCS proved to be effective with the reduction of pain over 50%, while in 6 it did not. 

Conclusion

Our results correspond with the findings in the literature. SCS in CNP after SCI has limited efficacy. Nevertheless, results of its treatment can be satisfactory in selected patients, when motor and sensory function is preserved.

• Introduction: Microelectrode Recording (MER) is considered a crucial feature of Deep Brain Stimulation (DBS). During asleep DBS, general anesthesia interferes with MERs, which are less straightforward to interpret in an intraoperative setting. Therefore, huge expertise is required to be able to base intraoperative lead localisation on MERs alone, risking sub-optimal final electrode placement. This study aims to investigate whether anatomical navigation during asleep DBS surgery is a reliable and useful additional tool. The intraoperative association of anatomical (imaging studies and 3D reconstructions) and electrophysiological (microelectrode recordings) information would in fact permit a facilitated surgical procedure.

• Methods/Materials: This study is carried out on patients undergoing asleep DBS in the Pediatric and Functional Neurosurgery Department of Padova. During surgery, intraoperative MERs are integrated with deterministic anatomical imaging of the structures crossed by the trajectory, obtained using a dedicated software. This allows to visualize exact anatomical relationships of each point along the trajectory of the lead with the 3D reconstructed areas of interest. For Subthalamic Nucleus (STN) DBS these areas include the thalamus, the zona incerta, the STN and the substantia nigra, whereas for Globus Pallidus Internus (GPi) DBS these include the striatum, GPe, GPi, and the optic tract. To investigate whether this feature of anatomical navigation is a reliable and helpful additional factor in the decision-making for the placement of the definitive electrode, we compare the intraoperatively planned electrode placement with the postoperatively reconstructed electrode position.

• Results: Preliminary results suggest that the mean distance between the intraoperatively planned target and the postoperatively reconstructed target is

• Discussion: The study suggests that the association of intraoperative anatomical navigation to MERs significantly facilitates the evaluation of the optimal lead placement, given that there seems to be no relevant difference between the intraoperatively planned electrode placement and the postoperatively reconstructed electrode position.

• Conclusion: Preliminary results suggest that the anatomical navigation is a useful and reliable tool to significantly facilitate the interpretation of intraoperative MERs.

Background

Deep brain stimulation (DBS) of the globus pallidus internus (GPi) is an effective and well-tolerated treatment for generalized dystonia. Rare reports confirm the clinical efficacy of bilateral GPi DBS for the treatment of myoclonus-dystonia syndrome.

Methods

We present a large family with genetically proven myoclonus-dystonia syndrome whose 3 members underwent bilateral GPi DBS. The study includes 1 woman and 2 men. The formal objective dystonia assessment included Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) its motor and disability parts. Myoclonus was assessed using the rest and action subscores of the Unified Myoclonus Rating Scale (UMRS). The patients were followed at regular ambulatory visits at 6 months, 1, 2 and 3 years after surgery. The baseline scores for myoclonus and dystonia were compared to postoperative scores in the stimulation on condition.

Results

At the last follow-up visit (3 years after surgery), the rest and action parts of UMRS were improved by 98.5 %, and 90.5 % respectively when compared to baseline scores. The motor and disability scales of BFMDRS were improved by 85 % and 60 % at the last follow-up visit compared to baseline BFMRDS scores. There were no hardware or stimulation induced complications over follow-up period. The stimulation settings were relatively low when compared to another dystonic syndromes treated by DBS. Positive social adjustment allowed 2 patients to regain their jobs and 1 patient continued his education.

Conclusion

Bilateral GPi DBS is safe and highly efficacious method for treatment of intractable myoclonus-dystonia syndrome. In our observations, the effect of GPi DBS is recognized after 1 month of stimulation and is excellent for additional 3 years of continues stimulation. GPi DBS should be regarded as an valuable option for patients with severe, disabling, drug-resistance form of myoclonus-dystonia syndrome.  

Dystonia is a movement disorder characterized by involuntary muscle contractions leading to repetitive movements or abnormal postures. Deep brain stimulation (DBS) is an effective option in medically refractory forms of idiopathic dystonia, and the target is usually the globus pallidus internus (GPi) bilaterally. Mutations in hippocalcin (HPCA) - DYT2 have been reported to cause a rare autosomal-recessive (AR) form of dystonia in a few cases with different phenotypes and treatment responses. To our knowledge, there is no report about DBS in dystonia patients with HPCA mutation. Here, we will present a dystonia case with an HPCA mutation who underwent bilateral GPi DBS. A 20-year-old male patient was admitted to the outpatient clinic with mild difficulties in walking and speech starting at the age of 8 years. His complaints increased over time, and he developed dystonia of the lower limbs at the age of 17 years. The dystonia spread to the upper extremities, trunk, and cervical and facial muscles within two years. He had jerky generalized dystonia in his neurological examination, mainly including trunk, arms, legs, neck, face, bulbar and laryngeal muscles, and also had mild dysphagia for both solids and liquids. HPCA:c.G28del-C; (p.P10PfsTer80) compound heterozygous mutation was detected in the molecular analysis. Biperiden treatment was started, and his posture partially improved with 12 mg/day. Botulinum toxin treatment was performed for his segmental dystonia. On the follow-up, his symptoms worsened, and oral medication and botulinum toxin treatment response decreased. He could not eat and drink independently and had difficulty sitting and walking because of jerky movements and generalized dystonia. He started to need assistance with activities of daily living. The patient underwent bilateral GPi DBS surgery at the age of 28 years. After DBS surgery, the jerky movements and upper limb dystonia decreased on the third day. He was able to eat and drink independently.   In the first year after the surgery, he could walk and sit independently and had no dysphagia. There were no jerky movements, and he was independent with the activity of daily living with the following stimulation parameters: right GPi, -2 +C, 3.3 mA, 60 msn, 130 Hz; left GPi, -3 +C, 2,8 mA, 60 msn, 130 Hz. The preoperative BFMDRS score was 80 and decreased to 39 in the postoperative period. He also had favorable impairment in all subdomains of SF-36.  The biperiden dose was reduced to 4 mg/daily. There are a few case reports in the literature about dystonia patients with HPCA mutations. However, to our knowledge, there has been no report of DBS in these patients yet, and this is the first report. For patients with HPCA-linked dystonia, pallidal DBS can be a treatment option. It is important to note that DBS is not a cure for genetic dystonia, and there are still many unanswered questions about the long-term effectiveness of the treatment. However, in cases where medication and other therapies have failed to provide relief, DBS is a valuable option for improving symptoms and quality of life for both patient and caregiver. 

Worldwide up to 100,000 radiosurgical procedures and around 25,000 DBS implantations are carried out yearly using a stereotactic frame. Moreover, intracranial lesion biopsies and stereotactic EEG electrode placement are also done using a frame-based technique. Appropriate frame positioning on the patient’s head is mandatory for optimal and error-free stereotactical MRI imaging. The stereotactic frame must be accurately placed on the patient’s head to ensure the images align correctly with the treatment plan. Incorrect placement can lead to final target coordinates calculation errors.

Conventional Leksell G and Vantage frame mounting methods are based on the usage of ear bars [1], over-the-head Velcro or mounted bar [2], additional plates for supine placement [3, 4], or bite bars [5]. Most of these methods are suitable for the Leksell G frame but not for a Vantage frame, presented a few years ago [6]. The Vantage frame was designed to be more comfortable for patients and surgeons, and its composition improved imaging capabilities. It is attached manually to provide initial stability using adhesive straps, and then the frame is finally fixed with titanium studs to the skull bone. Its fixation now requires at least two medical staff for optimal angles and alignment. The attachment process is inconvenient and impractical, and the fixation time is long and stressful for patients. Daily clinical practice shows that an attachment could be more precise and straightforward.

This research aims to design and investigate a novel, universal 3D positioning system of a stereotactic frame suitable for use with Leksell Vantage frame. The principal scheme of such a system is presented in Figure 1.

The proposed positioning system consists of two or four inflatables, soft silicone bladders, two hand pumps with discharge valves, two adjustable air distributors, and adhesive ("velcro" type) straps for additional fixation if needed for a specific size of the patient head.

The stereotactic frame positioning system prototype was evaluated with actual patients in The Hospital of Lithuanian University of Health Sciences Kauno Klinikos.

Due to the convenient design of the stereotacic frame positioning system prototype, intuitive usability and simply manipulated fixation system, the procedure time is shortened. The standard procedure took an average of 15min 44s ± 1.24 (SD) and the prototype frame positioning system took an average of 10min 40s ± 0.62 (SD). Due to the shorter procedure time and more convenient use, less stress was found for patients and the doctor.

Obtained results showed that it is possible to use a novel 3D positioning system, presented above – the number of personnel to perform the procedure is reduced, and the procedure is performed faster due to shorter preparation and procedure time, especially if the patient is restless or has uncontrolled movements.

Acknowledgment

This research was supported by the interinstitutional project StereoUp funded by Kaunas University of Technology and the Lithuanian University of Health Sciences.

Introduction: Deep Brain Stimulation (DBS) is established as effective therapy for advanced Parkinson's disease (PD). Despite significant symptom improvements with the use of DBS, the exact mechanism of DBS functioning as well as its effect on the central nervous system remains unknown. Furthermore, many issues are unresolved; what is the mechanism of DBS in PD, does DBS induce structural changes in basal ganglia due to stimulation or is it possible to quantify the reorganization of brain structures in PD patients? The aim of this study is to determine the structural changes caused by DBS in patients with PD using volumetric and tractographic analysis of magnetic resonance imagining (MRI).

Methods: In this study 10 patients with PD will perform preoperative and postoperative MRIs, which will, with the use of computer programs for volumetric analysis alongside tractographic analysis, provide insight into DBS effect on CNS structures. Ten PD patients underwent bilateral STN DBS electrode implantation. Brain MRI scans were done prior to the procedure, in a week after the procedure, and approximately two years after the electrode implementation. In depth and detailed volumetric analysis was done using automated, observer independent volumetric software, while tractographic analysis was done using TrackVis program.

Results: Structural changes have been showed using volumetric analysis at third measuring point, while tractographic parameters also showed altered data in both second and third measuring point.

Conclusion: The result of this study enables a better understanding of DBS activity in PD patients and provide data on potential structural brain changes in patients with PD and to provide a good starting point for further research.

Introduction: In animal experimentation, welfare and severity assessments of all procedures applied to animals are necessary to meet legal and ethical requirements, as well as public interests. Injection of 6-hydroxydopamine (6-OHDA) into the nigrostriatal system of rats is used as a model for Parkinson's disease (PD) to investigate the pathophysiological background and treatment. The classical method of unilateral intranigral infusion of 6-OHDA leads to a massive destruction of nigrostriatal dopaminergic neurons and concomitant motor disturbances. After daily injection of Levodopa, these rats develop dyskinesias, a devastating side effect after long-term treatment in PD patients. In the bilateral model, 6-OHDA infused into the striatum, leads to slow and incomplete retrograde degeneration of dopaminergic neurons. This model can be used to study the development of PD or cognitive function. For severity assessment, we here quantitatively measured weight, heart rate and activity in the unilateral and bilateral 6-OHDA model, as well as during 21 days of Levodopa injection.

Methods:  In male Sprague Dawley (SD) rats (n=16) a telemetric device was subcutaneously implanted under general anesthesia and perioperative pain management. After recovery for four weeks, rats received either unilateral stereotaxic injection of 6-OHDA into the substantia nigra (n=8) or bilateral injection into the striatum (n=8). Four weeks after unilateral 6-OHDA injection, rats were subcutaneously injected with Levodopa (10 mg/kg) for 21 days. Perioperatively and during 21 days of Levodopa injection we measured weight, heart rate and activity during the first two hours after light on and light off, as well as directly before and after Levodopa injection.

Results: Striatal bilateral injection of 6-OHDA led to weight loss for the first four postoperative days (two rats nearly 20% of their preoperative weight; p<0.05), while unilateral 6-OHDA injection had no effect. Heart rate was enhanced for the first postoperative three days in both models, while activity measures were not affected after surgery.  Levodopa injection for 21 days in the unilateral 6-OHDA model had no effect on weight and heart rate, but enhanced activity measures assessed via the subcutaneous telemetric device.

Conclusion: The results indicate that perioperatively rats` wellbeing is more affected by bilateral injection of 6-OHDA with incomplete loss of nigral dopamine, although heart rate measures also indicate disturbed wellbeing after unilateral injection of 6-OHDA. The development of dyskinesias, however, has only mild and transient effects on rat`s wellbeing.

Background: To date, only one case report (1) of magnetic resonance imaging (MRI)-guided focused ultrasound (FUS) for essential tremor (ET) has demonstrated safety and efficacy of the procedure in a patient with a ventricular shunt.

Objective: To demonstrate the feasibility of FUS thalamotomy in patients with ventriculo-peritoneal shunts and tremor-dominant Parkinson's disease, provided careful planing and the strict observation of safety measures.

Methods: A 80-yr-old right-handed male with medically refractory tremor-dominant Parkinson's disease, more prominent on his right hand, and a right-sided ventricular shunt for normal pressure hydrocephalus, underwent FUS to the left ventro-intermedius (VIM) nucleus. The VIM nucleus was targeted using indirect targeting based on AC PC, refined with deterministic tractography. Clinical outcomes were measured using on-medication Clinical Rating Scale for Tremor A+B on the treated hand, with a follow-up of seven months.

Results: Shunt components required 7% of the total ultrasound transducer elements to be shut off. Nine therapeutic sonications were delivered, (maximum temperature, 69°), with constant checking of cavitation and/or defocusing. The procedure led to a 80% improvement in hand tremor and a 90% improvement in functional disability at the 7-mo follow-up. No complications were noted.

Conclusion: This is the second case reported of FUS thalamotomy in a patient with a ventricular shunt, and the first on a case of tremor-dominant Parkinson's disease. Achievement of therapeutic temperatures without cavitation and thermal spot distortion is feasible in this subset of patients.

(1) Yang AI, Chaibainou H, Wang S, Hitti FL, McShane BJ, Tilden D, Korn M, Blanke A, Dayan M, Wolf RL, Baltuch GH. Focused Ultrasound Thalamotomy for Essential Tremor in the Setting of a Ventricular Shunt: Technical Report. Oper Neurosurg (Hagerstown). 2019 Oct 1;17(4):376-381. doi: 10.1093/ons/opz013. PMID: 30888021.