Ido Strauss

Objective: Epileptogenic Index (EI) is a promising index to evaluate the epileptogenicity of the brain tissue and is useful in planning epilepsy surgery. We aimed to evaluate whether EI maps are consistent across seizures within patients and whether EI‐derived measures are affected by the vigilance state and anti‐seizure medication (ASM) dose. Methods: We analyzed 127 stereoelectroencephalography (SEEG) seizures from 19 patients. EI was calculated in all seizures. Within‐patient EI consistency was assessed using pairwise Spearman correlations between seizure‐specific EI maps. To assess the effects of vigilance and ASM on EI consistency, we calculated a contact‐level p _weighted EI score that combines the frequency of suprathreshold EI involvement and mean EI magnitude, separately across vigilance states and in a subset of patients with different ASM states. Results: Mean seizure‐to‐seizure EI correlations ranged from 0.11 to 0.81, indicating substantial variability in within‐patient EI consistency. Seven patients showed high consistency (≥0.6) and four showed low consistency (≤0.3). At the contact level, no differences in p _weighted EI were found between wakefulness and sleep. In contrast, p _weighted EI was significantly higher during reduced ASM compared with full ASM doses. Significance: EI maps are not uniformly stable across seizures. ASM reduction may broaden or intensify EI‐defined epileptogenic involvement, suggesting that ASM status should be considered when interpreting EI during SEEG evaluation. These findings are hypothesis‐generating and require prospective validation to determine their clinical utility for surgical planning. Plain Language Summary: The Epileptogenic Index (EI) measures the involvement of a recorded brain area during a specific seizure. This study shows that EI patterns can vary significantly between different seizures in the same patient. While sleep states do not change these patterns, reducing a patient's anti‐seizure medications increases EI values, making seizures appear to spread more broadly. These medication‐induced changes must be carefully considered to accurately map the epileptic network for surgical decisions.

Objectives: To assess 24-month clinical outcomes of vagus nerve stimulation (VNS) in individuals with higher-grade treatment-resistant depression (HG-TRD) treated within a national open-label program, focusing on depressive severity, suicidality, safety, tolerability, and rates of response and remission. Methods: A prospective, open-label, multicenter cohort study was conducted on 19 patients who underwent VNS implantation between 2020 and 2023. Clinical assessments were performed at baseline and at 6, 12, 18, and 24 months. Depressive symptoms were evaluated using the Montgomery-Åsberg Depression Rating Scale (MADRS), including item 10 for suicidality. Outcomes included mean percentage change in MADRS scores, rates of response, remission, partial response, adverse events, and adherence. Sixteen participants completed the 24-month follow-up. All analyses were exploratory. Results: MADRS scores decreased significantly by 6 months ( P P <0.001) and this improvement persisted throughout follow-up. No serious safety concerns were identified. Tolerability and long-term adherence were high, with most patients continuing active device use throughout the study period. Conclusions: In this open-label, multicenter cohort of individuals with HG-TRD, VNS was associated with substantial and durable reductions in depressive severity and suicidality over 24 months. Despite limitations related to sample size and lack of a control group, the magnitude and persistence of clinical benefit support VNS as a viable long-term treatment for carefully selected patients with severe, highly resistant depression.

Introduction: MR-guided laser interstitial thermal therapy (MRgLITT) is a minimally invasive technique for treating deep-seated brain lesions. However, the dynamics of imaging changes that occur after the ablation are not well characterized. This study aimed to describe the clinical outcomes and volume changes that occur over time after MRgLITT. Methods: We retrospectively collected clinical and imaging data of all adult patients who underwent MRgLITT of brain tumors (primary and metastatic) between 01/2020 and 06/2024. Volumes and diameters of the lesions were measured on gadolinium-enhanced T1-weighted images using Brainlab Elements. Local control was assessed at the last follow-up. Results: Twenty-nine patients with 32 treated lesions were available for assessment. Most lesions (n = 21) were metastatic, while 11 lesions were gliomas. The mean follow-up period was 23.4 ± 13.1 months. The average preoperative tumor volume was 2.8 ± 1.8cc. Post-ablation, the lesions’ volumes increased on average by 250% (up to 450%) in the first month after surgery compared to the preoperative volumes. The enhancing ring extended distally beyond the tip of the catheter for an average of 4.5 ± 1.8 mm. Glial lesions had a median progression-free survival of 8.5 months. The volume of metastatic lesions decreased below the preoperative volume on average 3 months after surgery. Local control was achieved in 16 of 21 metastatic lesions (76%) and was significantly better for lesions smaller than 4cc in volume and 16 mm in maximal diameter that could be completely covered by the thermal damage estimation. Nodular enhancement at 3 months post-surgery was correlated with local failure. Conclusion: MRgLITT can achieve good local control in metastatic brain lesions and should be considered early during follow-up after radiosurgery when local failure is suspected. The enhancing lesion extends beyond the tip of the catheter and enlarges during the first month post-ablation before gradually decreasing in size. Failure to decrease in size after 3 months or appearance of a nodular enhancement should raise suspicion of local failure.

Background: Percutaneous cervical cordotomy (PCC) is a lesioning procedure that targets the anterolateral quadrant of the spinal cord to interrupt spinothalamic pain pathways. It provides rapid and durable analgesia for patients with unilateral, medically refractory cancer pain below the C5 dermatome. Although its utilization has declined with the expansion of pharmacological and neuromodulatory therapies, PCC remains a critical palliative intervention for patients in whom opioid therapy is ineffective or intolerable. Summary: This narrative review delineates the neuroanatomical underpinnings, technical evolution, and contemporary clinical outcomes associated with PCC. The procedure is typically performed at the C1–2 level under CT guidance, allowing precise lesion placement verified through impedance monitoring and intraoperative electrophysiological testing. Recent adaptations – including the use of deep sedation combined with neurophysiological mapping – have broadened the eligible patient population to include individuals unable to undergo awake procedures. Across modern clinical series, PCC provides immediate and substantial analgesia in over 90% of patients, frequently enabling significant reductions in opioid consumption and improvements in quality of life. Adverse events are uncommon and typically transient, though hemiparesis, respiratory dysfunction, and mirror pain remain recognized risks. Median post-procedural survival is generally short, reflecting delayed referral patterns and underscoring the need for earlier multidisciplinary consideration. Key Messages: PCC achieves rapid, durable, and substantial analgesia in appropriately selected patients with unilateral, treatment-refractory cancer pain. Advances in imaging and neurophysiological guidance have enhanced procedural accuracy and safety. Earlier integration into palliative care pathways may optimize patient outcomes and quality of life.

BACKGROUND AND OBJECTIVES: Loss of speech due to injury or disease is devastating. Here, we report a novel speech neuroprosthesis that artificially articulates building blocks of speech based on high-frequency activity in brain areas never harnessed for a neuroprosthesis before: anterior cingulate and orbitofrontal cortices, and hippocampus. METHODS: A 37-year-old male neurosurgical epilepsy patient with intact speech, implanted with depth electrodes for clinical reasons only, silently controlled the neuroprosthesis almost immediately and in a natural way to voluntarily produce 2 vowel sounds. RESULTS: During the first set of trials, the participant made the neuroprosthesis produce the different vowel sounds artificially with 85% accuracy. In the following trials, performance improved consistently, which may be attributed to neuroplasticity. We show that a neuroprosthesis trained on overt speech data may be controlled silently. CONCLUSION: This may open the way for a novel strategy of neuroprosthesis implantation at earlier disease stages (eg, amyotrophic lateral sclerosis), while speech is intact, for improved training that still allows silent control at later stages. The results demonstrate clinical feasibility of direct decoding of high-frequency activity that includes spiking activity in the aforementioned areas for silent production of phonemes that may serve as a part of a neuroprosthesis for replacing lost speech control pathways.

Objective. Our goal is to decode firing patterns of single neurons in the left ventralis intermediate nucleus (Vim) of the thalamus, related to speech production, perception, and imagery. For realistic speech brain-machine interfaces (BMIs), we aim to characterize the amount of thalamic neurons necessary for high accuracy decoding. Approach. We intraoperatively recorded single neuron activity in the left Vim of eight neurosurgical patients undergoing implantation of deep brain stimulator or RF lesioning during production, perception and imagery of the five monophthongal vowel sounds. We utilized the Spade decoder, a machine learning algorithm that dynamically learns specific features of firing patterns and is based on sparse decomposition of the high dimensional feature space. Main results. Spade outperformed all algorithms compared with, for all three aspects of speech: production, perception and imagery, and obtained accuracies of 100%, 96%, and 92%, respectively (chance level: 20%) based on pooling together neurons across all patients. The accuracy was logarithmic in the amount of neurons for all three aspects of speech. Regardless of the amount of units employed, production gained highest accuracies, whereas perception and imagery equated with each other. Significance. Our research renders single neuron activity in the left Vim a promising source of inputs to BMIs for restoration of speech faculties for locked-in patients or patients with anarthria or dysarthria to allow them to communicate again. Our characterization of how many neurons are necessary to achieve a certain decoding accuracy is of utmost importance for planning BMI implantation.

Background: The surgical treatment of brain tumors has developed over time, offering customized strategies for patients and their specific lesions. One of the most recent advances in pediatric neuro-oncological surgery is laser interstitial thermal therapy (LITT). However, its effectiveness and indications are still being evaluated. The aim of this work is to review the current literature on LITT for pediatric low-grade gliomas (pLGG) and evaluate our initial results in this context. Methods: We retrospectively reviewed our pediatric neurosurgery database for patients who received LITT treatment between November 2019 and December 2023. We collected data on the indications for LITT, technical issues during the procedure, and clinical and radiological follow-up. Results: Three patients underwent 5 LITT procedures for pLGG. The lesion was thalamo-peduncular in one patient, cingulate in one, and deep parietal in one patient. Two patients had a previous open resection done and were diagnosed with pLGG. One patient underwent a stereotaxic biopsy during the LITT procedure that was non-diagnostic. The same patient underwent a later open resection of the tumor in the cingulate gyrus. There were no surgical complications and all patients were discharged home on the first post-operative day. The follow-up period was between 20 and 40 months. Radiological follow-up showed a progressive reduction of the tumor in patients with LGG. Conclusion: Laser interstitial thermal therapy is a minimally invasive treatment that shows promise in treating deep-seated pLGG in children. The treatment has demonstrated a reduction in tumor volume, and the positive results continue over time. LITT can be used as an alternative treatment for tumors located in areas that are difficult to access surgically or in cases where other standard treatment options have failed.

BACKGROUND AND OBJECTIVES: Cordotomy, the selective disconnection of the nociceptive fibers in the spinothalamic tract, is used to provide pain palliation to oncological patients suffering from intractable cancer-related pain. Cordotomies are commonly performed using a cervical (C1-2) percutaneous approach under imaging guidance and require patients' cooperation to functionally localize the spinothalamic tract. This can be challenging in patients suffering from extreme pain. It has recently been demonstrated that intraoperative neurophysiology monitoring by electromyography may aid in safe lesion positioning. The aim of this study was to evaluate the role of compound muscle action potential (CMAP) in deeply sedated patients undergoing percutaneous cervical cordotomy (PCC). METHODS: A retrospective analysis was conducted of all patients who underwent percutaneous cordotomy while deeply sedated between January 2019 and November 2022 in 2 academic centers. The operative report, neuromonitoring logs, and clinical medical records were evaluated. RESULTS: Eleven patients underwent PCC under deep sedation. In all patients, the final motor assessment prior to ablation was done using the electrophysiological criterion alone. The median threshold for evoking CMAP activity at the lesion site was 0.9 V ranging between 0.5 and 1.5 V (average 1 V ± 0.34 V SD). An immediate, substantial decrease in pain was observed in 9 patients. The median pain scores (Numeric Rating Scale) decreased from 10 preoperatively (range 8-10) to a median 0 (range 0-10) immediately after surgery. None of our patients developed motor deficits. CONCLUSION: CMAP-guided PCC may be feasible in deeply sedated patients without added risk to postoperative motor function. This technique should be considered in a group of patients who are not able to undergo awake PCC.