OBJECTIVE: Stereoelectroencephalography (SEEG) has become the predominant method for intracranial seizure localization. When imaging, semiology, and scalp EEG findings are not in full agreement or definitively localizing, implanted SEEG recordings are used to test candidate seizure onset zones (SOZs). Discovered SOZs may then be targeted for resection, laser ablation, or neurostimulation. If an SOZ is eloquent, resection and ablation are both contraindicated, so identifying functional representation is crucial for therapeutic decision-making. The authors present a novel functional brain mapping technique that utilizes task-based electrophysiological changes in SEEG during behavioral tasks and test this in pediatric and adult patients.
METHODS: SEEG was recorded in 20 patients with epilepsy who ranged in age from 6 to 39 years (12 female, 18 of 20 patients < 21 years of age) and underwent implanted monitoring to identify seizure onset. Each performed 1) visually cued simple repetitive movements of the hand, foot, or tongue while electromyography was recorded; and 2) simple picture-naming or verb-generation speech tasks while audio was recorded. Broadband changes in the power spectrum of the SEEG recording were compared between behavior and rest.
RESULTS: Electrophysiological functional mapping of movement and/or speech areas was completed in all 20 patients. Eloquent representation was identified in both cortex and white matter and generally corresponded to classically described functional anatomical organization as well as other clinical mapping results. Robust maps of brain activity were identified in healthy brain, regions of developmental or acquired structural abnormality, and SOZs.
CONCLUSIONS: Task-based electrophysiological mapping using broadband changes in the SEEG signal reliably identifies movement and speech representation in pediatric and adult epilepsy patients.

BACKGROUND: Ablative surgery is an intervention of last resort for treatment-resistant obsessive-compulsive disorder (TROCD). Our center has been using bilateral anterior capsulotomy (BAC) for the past 20 years for patients eligible for limbic surgery. This report details our experience with BAC for TROCD.
METHODS: Five patients with OCD met eligibility criteria for BAC. Entry protocols were complex and took around 6 months to complete. Stereotactic radiofrequency was used to produce the capsulotomies. Lesion length varied between 5.7 and 16.9 mm in the coronal plane. Patients were followed between 4 and 20 years.
RESULTS: All 5 patients (100%) were responders as defined by the widely accepted criteria of a reduction of ≥35% in Yale-Brown Obsessive Compulsive Scale (YBOCS) score at 18-month follow-up. Four patients remained responders at the 48 months. One patient was lost to follow-up. Responder status when viewed from the perspective of the YBOCS was sustained over the 4- to 20-year follow-up with one relapse 19 years postsurgery when medications were discontinued. Real-world psychiatric outcomes were different as other vulnerabilities surfaced illustrating the multifactorial determinants of mental health. No patient had any significant long-term neurocognitive or physical side effects.
CONCLUSIONS: BAC should remain an option of last resort for patients with severe OCD who remain unresponsive to all other interventions.

OBJECTIVE: Deep brain stimulation (DBS) has become an effective and safe treatment in patients with Parkinson\'s disease (PD) not responding to conventional treatments. With the growing body of literature regarding the use of DBS in different movement disorders, there remain controversies regarding performing awake or asleep DBS. This systematic review provides the most comprehensive review of the literature comparing the two techniques from various aspects in detail.
METHODS: A systematic review of the PubMed, Scopus, Web of Science, and Cochrane Library databases was conducted. All studies comparing any aspects of asleep and awake DBS were included. Risk of bias was assessed using the Risk of Bias in Non-Randomized Studies of Interventions tool. Meta-analysis was conducted with consideration of baseline characteristics.
RESULTS: Thirty-one studies with 2563 PD patients were included. A total of 1423 patients underwent asleep DBS. The two groups were comparable regarding their baseline characteristics. The follow-up ranged from 3 to 60 months. The two DBS techniques were comparable in terms of motor symptom improvements and levodopa equivalent daily doses. However, the asleep technique showed slightly better improvements in Mattis Dementia Rating Scale and Parkinson\'s Disease Questionnaire scores. Moreover, the asleep technique was associated with more surgical adverse events, whereas pneumocephalus and psychological disorders such as mood, affect, and cognitive disorders were more common in the awake technique. Subgroup analyses revealed no significant differences in outcomes between asleep and awake DBS when categorized by targeted brain nuclei, use of intraoperative or preoperative imaging, and whether microelectrode recordings were used.
CONCLUSIONS: These findings suggest comparable clinical outcomes between the two DBS approaches. The two methods had their salient differences in terms of lead passes and specific adverse events. The decision to perform awake or asleep DBS should be based on the patient\'s preference, the surgeon\'s experience, the availability of advanced intraoperative imaging, and the patient\'s tolerance for specific adverse events.

This narrative review explores the current landscape of functional neurosurgery in Africa, focusing on the challenges and opportunities facing the field. Drawing upon existing literature and expert insights, the review highlights the scarcity of resources, including trained personnel, infrastructure, and specialized equipment, as major hurdles impeding the widespread adoption of advanced neurosurgical techniques. Despite these challenges, the review identifies a growing recognition of the importance of functional neurosurgery in addressing neurological disorders prevalent across the continent. Efforts to enhance training programs, establish collaborations with international partners, and leverage technology are discussed as promising strategies to overcome logistical barriers. Moreover, the review underscores the significance of addressing cultural beliefs and stigmas surrounding neurological conditions to ensure equitable access to care and promote acceptance of neurosurgical interventions. By navigating these challenges and embracing emerging opportunities, functional neurosurgery in Africa holds the potential to significantly impact neurological health outcomes and enhance overall well-being.

OBJECTIVE: Deep brain stimulation (DBS) of the centromedian nucleus (CM) is used to treat diverse brain diseases including epilepsy, Tourette syndrome, and disorders of consciousness. However, the CM is challenging to visualize on routine MRI. Many surgeons use an indirect targeting method based on established stereotactic coordinates. The authors aimed to quantify how often a DBS electrode\'s contacts were positioned within the CM using this approach, and to identify alternative indirect coordinates that are more accurate.
METHODS: Indirect targeting of the CM was performed on 100 MR images obtained in healthy adults, and the resulting coordinates were warped to a common brain template. To estimate positions of DBS contacts along this trajectory, the authors developed a probable electrode location (PEL) mask, modeled on trajectory angles obtained from prior clinical cases. Euclidean and x, y, and z distances between the centroids of the PEL mask and an atlas-based CM mask were measured and defined as error. The percentage of overlaps between the PEL mask and nearby thalamic nuclei was determined. To assess the clinical utility of this methodology, the analysis was validated using 20 MR images obtained in patients with generalized epilepsy, a common clinical indication for CM-DBS.
RESULTS: Using standard indirect coordinates, the authors found the average Euclidean error to be 4.40 ± 1.05 mm, and the x, y, and z errors were 4.19 ± 0.97 mm, 0.73 ± 0.65 mm, and 0.66 ± 0.69 mm, respectively. The PEL mask overlap was 52% with the CM and 65% with the ventral posteromedial nucleus. Variation in third ventricular width was the dominant contributor to these errors (r = -0.71). To overcome this variation, the authors developed alternative indirect coordinates: 4.5 mm lateral to the posterolateral corner of the third ventricle at the level of the posterior commissure. With this refinement, the average Euclidean error was reduced to 1.24 ± 0.5 mm, with 84% of the PEL mask within the CM.
CONCLUSIONS: The unavailability of advanced MRI for direct targeting limits access to CM-DBS in resource-constrained neurosurgical programs. Standard indirect coordinates do not provide optimal targeting of the CM, with most contacts laterally placed in the sensory thalamus. The proposed indirect approach may therefore increase the accuracy and availability of CM-DBS, while reducing side effects.

BACKGROUND: Functional Neurosurgery (FNS) is a non-invasive and highly efficacious neurosurgical subspecialty but lower middle-income countries (LMICs) are disadvantaged in terms of access and availability of FNS. Through this study we have tried to assess the availability, exposure, utilization, and perceived barriers to five major FNS modalities including deep brain stimulation (DBS), vagal nerve stimulation (VNS), stereotactic radiosurgery (SRS), MRI-guided focused ultrasound (MRgfUS) and percutaneous rhizotomy in LMICs.
METHODS: We designed a survey using google forms while following the CHERRIES guidelines. Responses were collected from practicing neurosurgeons, neurosurgical fellows, and residents in LMICs. Statistical analysis was performed using SPSS software 26.0 RESULTS: A total of 100 responses were recorded of which 96 % were males. 68 % worked in an educational setup. Respondents had the most exposure to SRS (36 %) followed by DBS (28 %) while MRgFUS was the least exposed modality (4 %) (p<0.001). For all modalities except MRgFUS, majority of the respondents were \'Fairly confident\' (p<0.001). No statistically significant association was observed in the availability of the modalities with the type of working setup. Majority of the respondents did not consider legal issues (p=0.003) and patient preferences (p=0.007) to be perceived barriers for any modality. Accessibility, affordability, Lack of training were not significant factors for any modality except DBS (52 %, p<0.001; 55 %, p<0.001 and 53 %, p=0.002 respectively) CONCLUSION: An integrated approach including international collaborations, traveling fellowships, novel policies must be adopted to enhance the reach of FNS to LMICs to share the extensive neurosurgical burden and to ease the neurosurgical decision making.

OBJECTIVE: The objective of this study was to develop and evaluate the feasibility and safety of a novel transaxial surgical approach for the delivery of human induced pluripotent stem cell-derived dopaminergic neuroprogenitor cells (DANPCs) into the putamen nucleus using nonhuman primates and surgical techniques and tools relevant to human clinical translation.
METHODS: Nine immunosuppressed, unlesioned adult cynomolgus macaques (4 females, 5 males) received intraputaminal injections of vehicle or DANPCs (0.9 × 105 to 1.1 × 105 cells/µL) under real-time intraoperative MRI guidance. The infusates were combined with 1-mM gadoteridol (for intraoperative MRI visualization) and delivered via two tracks per hemisphere (ventral and dorsal) using a transaxial approach. The total volumes of infusion were 25 µL and 50 µL for the right and left putamen, respectively (infusion rate 2.5 µL/min). Animals were evaluated with a battery of clinical and behavioral outcome measures and euthanized 7 or 30 days postsurgery; full necropsies were performed by a board-certified veterinary pathologist. Brain tissues were collected and processed for immunohistochemistry, including against the human-specific marker STEM121.
RESULTS: The optimized surgical technique and tools produced successful targeting of the putamen via the transaxial approach. Intraoperative MR images confirmed on-target intraputaminal injections in all animals. All animals survived to scheduled termination without clinical evidence of neurological deficits. The first 4 animals to undergo surgery had mild brain swelling noted at the end of surgery, of which 3 had transient reduced vision; administration of mannitol therapy and reduced intravenous fluid during the surgical procedure addressed these complications. Immunostaining against STEM121 confirmed the presence of grafted cells along the injection track within the targeted putamen area of DANPC-treated animals. All adverse histological findings were limited in scope and consistent with surgical manipulation, injection procedure, and postsurgical inflammatory response to the mechanical disruption caused by the cannula insertion.
CONCLUSIONS: The delivery system, injection procedure, and DANPCs were well tolerated in all animals. Prevention of mild brain swelling by mannitol dosing and reduction of intravenous fluids during surgery allowed visual effects to be avoided. The results of the study established that this novel transaxial approach can be used to correctly and safely target cell injections to the postcommissural putamen and support clinical investigation.

OBJECTIVE: Hypoglossal-facial nerve anastomosis (HFA) is the most commonly used surgical treatment for severe facial palsy that does not respond to conservative treatments. A major complication of HFA is the loss of tongue function. The authors aimed to evaluate whether anastomosing the transected hypoglossal nerve using the ramus descendens hypoglossi could prevent tongue deviation and dysfunction in patients undergoing HFA.
METHODS: In this randomized trial, adult patients with severe peripheral facial palsy (House-Brackmann grade V or VI) who did not respond to at least 6 months of conservative treatment were randomized at a 1:1 ratio to undergo either HFA alone (control group) or HFA plus anastomosis between the hypoglossal nerve and descendens hypoglossi (intervention group). The primary endpoint was tongue deviation angle at 12 months. Key secondary endpoints included tongue disability (chewing difficulty, swallowing defect, and articulation defect), tongue disability index (TDI; range 1-4, with a higher score indicating more severe disability), and facial nerve function.
RESULTS: Twenty patients were enrolled (10 in each group). At 12 months, the tongue deviation angle was significantly lower in the intervention group than in the control group (7.8° ± 5.1° vs 23.6° ± 9.6°, p < 0.001). Although not statistically significant, the intervention group had lower rates of chewing difficulty (1/10 vs 3/10, p = 0.58), swallowing defect (1/10 vs 5/10, p = 0.14), and articulation defect (2/10 vs 6/10, p = 0.17). TDI was significantly lower in the intervention group (1.5 ± 0.6 vs 2.5 ± 0.3, p < 0.001). The percentage of the patients achieving House-Brackmann grade II or III was 80% in each group.
CONCLUSIONS: Anastomosis of the descendens hypoglossi to the transected hypoglossal nerve attenuated tongue deviation in patients undergoing HFA for facial palsy, without compromising facial nerve function. Clinical trial registration no: ChiCTR2000034372 (Chinese Clinical Trials Registry).

OBJECTIVE: Preoperative MR images obtained in patients with Parkinson disease (PD) undergoing deep brain stimulation (DBS) often reveal incidental radiographic abnormalities (RAs). These findings range from small changes to gross pathologies. The effect of these findings on patients\' clinical outcomes is unknown. The authors characterized RAs in patients with PD who underwent DBS and assessed clinical outcomes.
METHODS: Records of patients at the authors\' institution with PD who underwent MRI for DBS electrode implantation from 2010 through 2022 were reviewed. RAs were identified from the official preoperative MRI reports. RAs were grouped into four general categories (ischemic changes, atrophy or degenerative changes [ADCs], structural abnormalities, and tumors) and correlated with clinical outcomes (including subjective clinical response, levodopa equivalent dose [LED], and Unified Parkinson\'s Disease Rating Scale Part III [UPDRS] score) at the 1-year and last available follow-ups.
RESULTS: In this review, 160 patients were identified for initial analysis, with 135 presenting with ≥ 1 RAs. Of these 135 patients, 69.4% (111/160) had ischemic vascular changes, 39.4% (63/160) had ADCs, 16.9% (27/160) had structural changes, and 1.9% (3/160) had tumors. No differences in preoperative LED or UPDRS score were observed between these groups. After DBS, no differences in outcomes were observed between patients with RAs and those without RAs for both the 1-year and last follow-up time points, including mortality rates and times. Structural lesions were associated with lower mortality rates (OR 0.1, p = 0.04). ADCs were associated with a worse subjective clinical response at the 1-year (OR 0.50, p = 0.04) and last (OR 0.49, p = 0.03) follow-ups, but subjectively worse responses were not correlated with worse objective outcome measures.
CONCLUSIONS: Most RAs have no significant effect on clinical outcomes in PD patients undergoing DBS. Generalized ADCs may be associated with poorer subjective responses and may warrant further discussion with the patient if diagnosed on preoperative MRI.

OBJECTIVE: The aim of this study was to provide geographic comparisons of deep brain stimulation (DBS) procedures in Latin America with the US and Europe regarding primary indications, demographic information, clinical and device-related adverse events, technology used, and patient outcomes using the Medtronic Product Surveillance Registry data as of July 31, 2021.
METHODS: Two thousand nine hundred twelve patients were enrolled in the registry (2782 received DBS and 1580 are currently active). Fourteen countries contributed 44,100 years of device experience to the registry. DBS centers in Latin America are located in Colombia (n = 3), Argentina (n = 1), Brazil (n = 1), and Mexico (n = 1). Fisher\'s exact test was used to compare the difference in proportions of categorical variables between regions. The Wilcoxon signed-rank test was used for the EQ-5D index score change from baseline to follow-up.
RESULTS: The most common indication for DBS was Parkinson\'s disease across all regions. In Latin America, dystonia was the second most common indication, compared to essential tremor in other regions. There was a striking finding with respect to age-patients were an average of 10 years younger at DBS implantation in Latin America. This difference was most likely due to the greater number of patients with dystonia receiving the device implants. The intraoperative techniques were quite similar, showing the same level of quality and covering the main principles of the surgeries with some variations in the brand of frames, planning software, and microrecording systems. Rechargeable batteries were significantly more common in Latin America (72.37%) than in the US (6.44%) and Europe (9.9%). Staging of the DBS procedure differed, with only 11.84% in Latin America staging the procedure compared with 97.58% and 34.86% in the US and Europe, respectively. The EQ-5D score showed significant improvements in all regions during the first 6-12 months (p < 0.0001). However, the 24-month follow-up only showed an improvement in the scale for Latin America (p < 0.0001).
CONCLUSIONS: DBS was performed in Latin America with similar indications, techniques, and technology as in the US and Europe. Important differences were found, with Latin America implementing more regular use of rechargeable devices, including younger patients at the time of surgery, and showing more sustained quality of life improvements at 24 months of follow-up. The authors hypothesize that these disparities stem from differences in resources among regions. However, more studies are needed to standardize DBS practice across the world to improve patients\' quality of life and provide high-quality care.