Flexible low-profile external ventricular drain catheter for real-time brain monitoring.

External ventricular drainage is one of the most common neurosurgical procedures in the world for acute hydrocephalus, which must be performed carefully by a neurosurgeon. Although various neuromonitoring external ventricular drain (EVD) catheters have been utilized, they still suffer from rigidity and bulkiness to mitigate post-EVD placement trauma. Here, we introduce a flexible and low-profile smart EVD catheter using a class of technologies with sensitive electrical materials, seamless integration, and flexible mechanics, which serves as a highly soft and minimally invasive device to monitor electrical brain signals. This device reliably captures biopotentials in real time while exhibiting remarkable flexibility and reliability. The seamless integration of its sensory system promises a minimally invasive EVD placement on brain tissue. This work validates the device's distinct characteristics and performances through in vitro experiments and computational analysis. Collectively, this device's exceptional patient- and user-friendly attributes highlight its potential as one of the most practical EVD catheters.

Clinical evaluation of a stereotactic system for single-stage deep brain stimulation surgery under general anesthesia: technical note.

OBJECTIVE: Conventional frame-based stereotactic systems have circumferential base frames, often necessitating deep brain stimulation (DBS) surgery in two stages: intracranial electrode insertion followed by surgical re-preparation and pulse generator implantation. Some patients do not tolerate awake surgery, underscoring the need for a safe alternative for asleep DBS surgery. A frame-based stereotactic system with a skull-mounted "key" in lieu of a circumferential base frame received US FDA clearance. The authors describe the system's application for single-stage, asleep DBS surgery in 8 patients at their institution and review its workflow and technical considerations. METHODS: Eight patients underwent DBS lead insertion and IPG implantation in a single surgical preparation under general anesthesia using the system. Postoperative CT imaging confirmed lead placement. RESULTS: Eight patients underwent implantation of 15 total leads targeting the ventral intermediate nucleus (4 patients), globus pallidus internus (GPi; 3 patients), and subthalamic nucleus (STN; 1 patient). Intraoperative microelectrode recording was conducted for GPi and STN targets. Postoperative CT imaging revealed a mean ± SD radial error of 1.24 ± 0.45 mm (n = 15 leads), without surgical complications. CONCLUSIONS: The stereotactic system facilitated safe and effective asleep, single-stage DBS surgery, maintaining traditional lead accuracy standards.

Enhancing outcomes in deep brain stimulation: a comparative study of direct targeting using 7T versus 3T MRI.

OBJECTIVE: The aim of this study was to compare outcomes of direct targeting in deep brain stimulation (DBS) for essential tremor using 7T MRI versus 3T MRI. The authors hypothesized that 7T MRI direct targeting would be noninferior to 3T MRI in early tremor outcomes. METHODS: A retrospective study was conducted on patients undergoing unilateral thalamic DBS for essential tremor between 2021 and 2023. Two matched cohorts were assessed, one using 7T MRI and the other using 3T MRI for surgical planning. The primary endpoint was the percentage improvement in the Fahn-Tolosa-Marin Tremor Rating Scale (TRS) scores. Additionally, the authors assessed optimized programming settings and variance in electrode position on postoperative imaging. Demographic and clinical data were compared using the nonparametric Mann-Whitney U-test. The squared Euclidean distance of each contact from the group mean centroid was calculated and averaged across the entire cohort to provide the variance (i.e., the mean squared distance) of electrode contact position. RESULTS: A total of 34 patients were analyzed, with 17 in each cohort. There were no significant differences in demographic information or mean surgical dates between the groups. There were no differences in intraoperative target repositioning or adverse events. The 7T group had a significantly greater TRS improvement than the 3T group (64.9% ± 11.4% vs 50.9% ± 16.4%, p = 0.004). Patients in the 7T cohort also had a lower mean stimulation current compared with those in the 3T cohort (2.0 ± 0.8 mA vs 2.7 ± 0.9 mA, p = 0.01). Image evaluation revealed that although the mean electrode position was comparable between 7T and 3T, the 7T electrode positioning was more clustered, indicating a lower variance in the final electrode location. The mean Euclidean distance between the individual electrode tips and the group centroid was significantly less at 7T than at 3T (1.82 ± 0.68 mm vs 2.75 ± 0.81 mm, p = 0.001). CONCLUSIONS: Despite concerns for increased artifacts and distortions at 7T, the authors show that these effects can be mitigated with an appropriate workflow, leading to improved surgical outcomes with direct targeting using 7T MRI. Their results suggest similar accuracy but greater precision in targeting with 7T MRI compared with 3T MRI, resulting in lower stimulation currents and improved tremor reduction. Future studies are needed to assess outcomes related to 7T MRI in targeting other subcortical structures.

Radiologic Classification of Hippocampal Sclerosis in Epilepsy.

Temporal lobe epilepsy is a common form of epilepsy that is often associated with hippocampal sclerosis (HS). Although HS is commonly considered a binary assessment in radiological evaluation, it is known that histopathological changes occur in distinct clusters. Some subtypes of HS only affect certain subfields, resulting in minimal changes to the overall volume of the hippocampus. This is likely a major reason why whole hippocampal volumetrics have underperformed versus expert readers. With recent advancements in MRI technology, it is now possible to characterize the substructure of the hippocampus more accurately. However, this is not consistently addressed in radiographic evaluations. The histological subtype of HS is critical for prognosis and treatment decision making, necessitating improved radiological classification of HS. The International League Against Epilepsy (ILAE) has issued a consensus classification scheme for subtyping HS histopathological changes. This review aims to explore how the ILAE subtypes of HS correlate with radiographic findings, introduce a grading system that integrates radiological and pathological reporting in HS, and outline an approach to detecting HS subtypes using MRI. This framework will not only benefit current clinical evaluations, but also enhance future studies involving high-resolution MRI in temporal lobe epilepsy.ABBREVIATIONS: CA = cornu ammonis; DG = dentate gyrus; HS = hippocampal sclerosis; ILAE = International League Against Epilepsy; SRLM = strata radiatum, lacunosum, and moleculare layers; TLE = temporal lobe epilepsy.

Diagnostic utility of 7T neuromelanin imaging of the substantia nigra in Parkinson's disease.

Parkinson's disease (PD) is a prevalent neurodegenerative disorder that presents a diagnostic challenge due to symptom overlap with other disorders. Neuromelanin (NM) imaging is a promising biomarker for PD, but adoption has been limited, in part due to subpar performance at standard MRI field strengths. We aimed to evaluate the diagnostic utility of ultra-high field 7T NM-sensitive imaging in the diagnosis of PD versus controls and essential tremor (ET), as well as NM differences among PD subtypes. A retrospective case-control study was conducted including PD patients, ET patients, and controls. 7T NM-sensitive 3D-GRE was acquired, and substantia nigra pars compacta (SNpc) volumes, contrast ratios, and asymmetry indices were calculated. Statistical analyses, including general linear models and ROC curves, were employed. Twenty-one PD patients, 13 ET patients, and 18 controls were assessed. PD patients exhibited significantly lower SNpc volumes compared to non-PD subjects. SNpc total volume showed 100% sensitivity and 96.8% specificity (AUC = 0.998) for differentiating PD from non-PD and 100% sensitivity and 95.2% specificity (AUC = 0.996) in differentiating PD from ET. Contrast ratio was not significantly different between PD and non-PD groups (p = 0.07). There was also significantly higher asymmetry index in SNpc volume in PD compared to non-PD cohorts (p < 0.001). NM signal loss in PD predominantly involved the inferior, posterior, and lateral aspects of SNpc. Akinetic-rigid subtype showed more significant NM signal loss compared to tremor dominant subtype (p < 0.001). 7T NM imaging demonstrates potential as a diagnostic tool for PD, including potential distinction between subtypes, allowing improved understanding of disease progression and subtype-related characteristics.

Trends in the Utilization of Surgical Modalities for the Treatment of Drug-Resistant Epilepsy: A Comprehensive 10-Year Analysis Using the National Inpatient Sample.

BACKGROUND AND OBJECTIVES: Epilepsy is considered one of the most prevalent and severe chronic neurological disorders worldwide. Our study aims to analyze the national trends in different treatment modalities for individuals with drug-resistant epilepsy and investigate the outcomes associated with these procedural trends in the United States. METHODS: Using the National Inpatient Sample database from 2010 to 2020, patients with drug-resistant focal epilepsy who underwent laser interstitial thermal therapy (LITT), open surgical resection, vagus nerve stimulation (VNS), or responsive neurostimulation (RNS) were identified. Trend analysis was performed using piecewise joinpoint regression. Propensity score matching was used to compare outcomes between 10 years prepandemic before 2020 and the first peak of the COVID-19 pandemic. RESULTS: This study analyzed a total of 33 969 patients with a diagnosis of drug-resistant epilepsy, with 3343 patients receiving surgical resection (78%), VNS (8.21%), RNS (8%), and LITT (6%). Between 2010 and 2020, there was an increase in the use of invasive electroencephalography monitoring for seizure zone localization (P = .003). There was an increase in the use of LITT and RNS (P < .001), while the use of surgical resection and VNS decreased over time (P < .001). Most of these patients (89%) were treated during the pre-COVID pandemic era (2010-2019), while a minority (11%) underwent treatment during the COVID pandemic (2020). After propensity score matching, the rate of pulmonary complications, postprocedural hematoma formation, and mortality were slightly higher during the pandemic compared with the prepandemic period (P = .045, P = .033, and P = .026, respectively). CONCLUSION: This study indicates a relative decrease in the use of surgical resections, as a treatment for drug-resistant focal epilepsy. By contrast, newer, minimally invasive surgical approaches including LITT and RNS showed gradual increases in usage.

Awake Craniotomy Program Implementation.

Importance: Implementing multidisciplinary teams for treatment of complex brain tumors needing awake craniotomies is associated with significant costs. To date, there is a paucity of analysis on the cost utility of introducing advanced multidisciplinary standardized teams to enable awake craniotomies. Objective: To assess the cost utility of introducing a standardized program of awake craniotomies. Design, Setting, and Participants: A retrospective economic evaluation was conducted at Mayo Clinic Florida. All patients with single, unilateral lesions who underwent elective awake craniotomies between January 2016 and December 2021 were considered eligible for inclusion. The economic perspective of the health care institution and a time horizon of 1 year were considered. Data were analyzed from October 2022 to May 2023. Exposure: Treatment with an awake craniotomy before standardization (2016-2018) compared with treatment with awake craniotomy after standardization (2018-2021). Main Outcomes and Measures: Patient demographics, perioperative, and postoperative outcomes, including length of stay, intensive care (ICU) admission, extent of resection, readmission rates, and 1-year mortality were compared between patients undergoing surgery before and after standardization. Direct medical costs were estimated from Medicare reimbursement rates for all billed procedures. A cost-utility analysis was performed considering differences in direct medical costs and in 1-year mortality within the periods before and after standardization of procedures. Uncertainty was explored in probability sensitivity analysis. Results: A total of 164 patients (mean [SD] age, 49.9 [15.7] years; 98 [60%] male patients) were included in the study. Of those, 56 underwent surgery before and 108 after implementation of procedure standardization. Procedure standardization was associated with reductions in length of stay from a mean (SD) of 3.34 (1.79) to 2.46 (1.61) days (difference, 0.88 days; 95% CI, 0.33-1.42 days; P = .002), length of stay in ICU from a mean (SD) of 1.32 (0.69) to 0.99 (0.90) nights (difference, 0.33 nights; 95% CI, 0.06-0.60 nights; P = .02), 30-day readmission rate from 14% (8 patients) in the prestandardization cohort to 5% (5 patients) (difference, 9%; 95% CI, 19.6%-0.3%; P = .03), while extent of resection and intraoperative complication rates were similar between both cohorts. The standardized protocol was associated with mean (SD) savings of $7088.80 ($12 389.50) and decreases in 1-year mortality (dominant intervention). This protocol was found to be cost saving in 75.5% of all simulations in probability sensitivity analysis. Conclusions and Relevance: In this economic evaluation of standardization of awake craniotomy, there was a generalized reduction in length of stay, ICU admission time, and direct medical costs with implementation of an optimized protocol. This was achieved without compromising patient outcomes and with similar extent of resection, complication rates, and reduced readmission rates.

Implantable Subdural Cortical Stimulation for Chronic Intractable Pain Treatment-The Mayo Experience and Review of Literature.

OBJECTIVES: Motor cortex stimulation (MCS) is an effective technique in treating chronic intractable pain for some patients. However, most studies are small case series (n < 20). Heterogeneity in technique and patient selection makes it difficult to draw consistent conclusions. In this study, we present one of the largest case series of subdural MCS. MATERIALS AND METHODS: Medical records of patients who underwent MCS at our institute between 2007 and 2020 were reviewed. Studies with at least 15 patients were summarized for comparison. RESULTS: The study included 46 patients. Mean age was 56.2 ± 12.5 years (SD). Mean follow-up was 57.2 ± 41.9 months. Male-to-female ratio was 13:33. Of the 46 patients, 29 had neuropathic pain in trigeminal nerve territory/anesthesia dolorosa; nine had postsurgical/posttraumatic pain; three had phantom limb pain; two had postherpetic pain, and the rest had pain secondary to stroke, chronic regional pain syndrome, and tumor. The baseline numeric rating pain scale (NRS) was 8.2 ± 1.8 of 10, and the latest follow-up score was 3.5 ± 2.9 (mean improvement of 57.3%). Responders comprised 67% (31/46)(NRS ≥ 40% improvement). Analysis showed no correlation between percentage of improvement and age (p = 0.352) but favored male patients (75.3% vs 48.7%, p = 0.006). Seizures occurred in 47.8% of patients (22/46) at some point but were all self-limiting, with no lasting sequelae. Other complications included subdural/epidural hematoma requiring evacuation (3/46), infection (5/46), and cerebrospinal fluid leak (1/46). These complications resolved with no long-term sequelae after further interventions. CONCLUSION: Our study further supports the use of MCS as an effective treatment modality for several chronic intractable pain conditions and provides a benchmark to the current literature.

Early Postoperative Seizures Following Awake Craniotomy and Functional Brain Mapping for Lesionectomy.

OBJECTIVE: Awake craniotomy with electrocorticography (ECoG) and direct electrical stimulation (DES) facilitates lesionectomy while avoiding adverse effects. Early postoperative seizures (EPS), occurring within 7 days following surgery, can lead to morbidity. However, risk factors for EPS after awake craniotomy including clinical and ECoG data are not well defined. METHODS: We retrospectively studied the incidence and risk factors of EPS following awake craniotomy for lesionectomy, and report short-term outcomes between January 1, 2020, and December 31, 2022. RESULTS: We included 138 patients (56 female) who underwent 142 awake craniotomies, average age was 50.78 ± 15.97 years. Eighty-eight (63.7%) patients had a preoperative history of tumor-related epilepsy treated with antiseizure medication (ASM), 12 (13.6%) with drug-resistance. All others (36.3%) received ASM prophylaxis with levetiracetam perioperatively and continued for 14 days. An equal number of cases (71) each utilized a novel circle grid or strip electrodes for ECoG. There were 31 (21.8%) cases of intraoperative seizures, 16 with EPS (11.3%). Acute abnormality on early postoperative neuroimaging (P = 0.01), subarachnoid hemorrhage (P = 0.01), young age (P = 0.01), and persistent postoperative neurologic deficits (P = 0.013) were associated with EPS. Acute abnormality on neuroimaging remained significant in multivariate analysis. Outcomes during hospitalization and early outpatient follow up were worse with EPS. CONCLUSIONS: We report novel findings using ECoG and clinical features to predict EPS, including acute perioperative brain injury, persistent postoperative deficits and young age. Given worse outcomes with EPS, clinical indicators for EPS should alert clinicians of potential need for early postoperative EEG monitoring and perioperative ASM adjustment.

Safety and Feasibility of a Fast-Track Pathway for Neurosurgical Craniotomy Patients: Bypassing the Intensive Care Unit.

Objective: To describe the safety and feasibility of a fast-track pathway for neurosurgical craniotomy patients receiving care in a neurosciences progressive care unit (NPCU). Patients and Methods: Traditionally, most craniotomy patients are admitted to the neurosciences intensive care unit (NSICU) for postoperative follow-up. Decreased availability of NSICU beds during the coronavirus disease-2019 delta surge led our team to establish a de-novo NPCU to preserve capacity for patients requiring high level of care and would bypass routine NSICU admissions. Patients were selected a priori by treating neurosurgeons on the basis of the potential need for high-level ICU services. After operation, selected patients were transferred to the postoperative care unit, where suitability for NPCU transfer was reassessed with checklist-criteria. This process was continued after the delta surge. Results: From July 1, 2021 to September 30, 2022, 57 patients followed the NPCU protocol. Thirty-four (59.6%) were women, and the mean age was 56 years. Fifty-seven craniotomies for 34 intra-axial and 23 extra-axial lesions were performed. After assessment and application of the checklist-criteria, 55 (96.5%) were transferred to NPCU, and only 2 (3.5%) were transferred to ICU. All 55 patients followed in NPCU had good safety outcomes without requiring NSICU transfer. This saved $143,000 and led to 55 additional ICU beds for emergent admissions. Conclusion: This fast-track craniotomy protocol provides early experience that a surgeon-selected group of patients may be suitably monitored outside the traditional NSICU. This system has the potential to reduce overall health care expenses, increase capacity for NSICU bed availability, and change the paradigm of NSICU admission.

Enhanced sensitivity of electrocorticography during awake craniotomy using a novel circular grid electrode.

PURPOSE: Awake craniotomy with intraoperative functional brain mapping (FBM) bedside neurological testing is an important technique used to optimize resective brain surgeries near eloquent cortex. Awake craniotomy performed with electrocorticography (ECoG) and direct electrical stimulation (DES) for FBM can delineate eloquent cortex from lesions and epileptogenic regions. However, current electrode technology demonstrates spatial limitations. Our group has developed a novel circular grid with the goal of improving spatial recording of ECoG to enhance detection of ictal and interictal activity. METHODS: This retrospective study was approved by the institutional review board at Mayo Clinic Florida. We analyzed patients undergoing awake craniotomy with ECoG and DES and compared ECoG data obtained using the 22 contact circular grid to standard 6 contact strip electrode. RESULTS: We included 144 cases of awake craniotomy with ECoG, 73 using circular grid and 71 with strip electrode. No significant differences were seen regarding preoperative clinical and demographic data, duration of ECoG recording (p = 0.676) and use of DES (p = 0.926). Circular grid was more sensitive in detecting periodic focal epileptiform discharges (PFEDs) (p = 0.004), PFEDs plus (p = 0.032), afterdischarges (ADs) per case (p = 0.022) at lower minimum (p = 0.012) and maximum (p < 0.0012) intensity stimulation, and seizures (p = 0.048). PFEDs (p < 0.001), PFEDs plus (p < 0.001), and HFOs (p < 0.001) but not ADs (p = 0.255) predicted electrographic seizures. CONCLUSION: We demonstrate higher sensitivity in detecting ictal and interictal activity on ECoG during awake craniotomy with a novel circular grid compared to strip electrode, likely due to better spatial sampling during ECoG. We also found association between PFEDs and intraoperative seizures.

Spinal cord stimulation for gait impairment in Parkinson Disease: scoping review and mechanistic considerations.

OBJECTIVE: Advanced Parkinson's Disease (PD) is associated with Parkinson's Disease gait impairment (PDg), which increases the risk for falls and is often treatment-refractory. Subthalamic nucleus (STN) and globus pallidus pars interna (GPi) deep brain stimulation (DBS) often fails to improve axial symptoms like PDg. Spinal cord stimulation (SCS) has been suggested to improve PDg. SCS may benefit PDg by disrupting pathologic beta-oscillations and hypersynchrony in cortico-striatal-thalamic circuits to override excessive inhibition of brainstem locomotor regions. SCS may potentially improve locomotion by acting at any of these levels, either alone or in combination. METHODS: We conducted a comprehensive literature search and scoping review, identifying 106 patients in whom SCS was evaluated for PDg. RESULTS: Among the identified patients, 63% carried a pain diagnosis. Overall, the most common stimulation location was thoracic (78%), most commonly T9-T10. Burst (sub-perception) was the most common stimulation modality (59%). Prior treatment with DBS was used in 25%. Motor outcomes were assessed by the Unified Parkinson Disease Rating Scale (UPDRS) III-motor, UPDRS, the Timed Up and Go (TUG), and/or 10-/20-meter walking tests.Among these patients, 95 (90%) had PDg amelioration and improved motor outcomes. CONCLUSIONS: Despite small sample sizes, patient heterogeneity, and unblinded evaluations complicating interpretations of efficacy and safety, SCS may be beneficial for at least a subset of PDg. Further research is required to clarify the role of SCS for PDg and the patients most suitable to benefit from this intervention.

Can we improve electrocorticography using a circular grid array in brain tumor surgery?

Intraoperative electrocorticography (iECoG) is used as an adjunct to localize the epileptogenic zone during surgical resection of brain tumors in patients with focal epilepsies. It also enables monitoring of after-discharges and seizures with EEG during functional brain mapping with electrical stimulation. When seizures or after-discharges are present, they complicate accurate interpretation of the mapping strategy to outline the brain's eloquent function and can affect the surgical procedure. Recurrent seizures during surgery requires urgent treatment and, when occurring during awake craniotomy, often leads to premature termination of brain mapping due to post-ictal confusion or sedation from acute rescue therapy. There are mixed results in studies on efficacy with iECoG in patients with epilepsy and brain tumors influencing survival and functional outcomes following surgery. Commercially available electrode arrays have inherent limitations. These could be improved with customization potentially leading to greater precision in safe and maximal resection of brain tumors. Few studies have assessed customized electrode grid designs as an alternative to commercially available products. Higher density electrode grids with intercontact distances less than 1 cm improve spatial delineation of electrophysiologic sources, including epileptiform activity, electrographic seizures, and afterdischarges on iECoG during functional brain mapping. In response to the shortcomings of current iECoG grid technologies, we designed and developed a novel higher-density hollow circular electrode grid array. The 360-degree iECoG monitoring capability allows continuous EEG recording during surgical intervention through the aperture with and without electrical stimulation mapping. Compared with linear strip electrodes that are commonly used for iECoG during surgery, the circular grid demonstrates significant benefits in brain tumor surgery. This includes quicker recovery of post-operative motor deficits (2.4 days versus 9 days, p = 0.05), more extensive tumor resection (92.0% versus 77.6%, p = 0.003), lesser reduction in Karnofsky Performance scale postoperatively (-2 versus -11.6, p = 0.007), and more sensitivity to recording afterdischarges. In this narrative review, we discuss the advantages and disadvantages of commercially available recording devices in the operating room and focus on the usefulness of the higher-density circular grid.

Synthetic Inversion Image Generation using MP2RAGE T1 Mapping for Surgical Targeting in Deep Brain Stimulation and Lesioning.

BACKGROUND: Advances in MRI technology have increased interest in direct targeting for deep brain stimulation (DBS). Various imaging sequences have been shown to provide increased contrast of numerous common DBS targets, such as T1-weighted, Fast Gray Matter Acquisition T1 Inversion Recovery (FGATIR), gray matter nulled, and Edge-Enhancing Gradient Echo (EDGE); however, the continual increase in the number of necessary sequences has led to an increase in imaging time, which is undesirable. Additionally, carefully timed inversion pulses can often lead to less-than-ideal contrast in some subjects, particularly in ultra-high field MRI, where B1+ field inhomogeneity can lead to substantial contrast variation. OBJECTIVES: This study proposes using 3D MP2RAGE-based T1 maps to retrospectively synthesize images of any desired inversion time, including T1-weighted, FGATIR, and EDGE contrasts, to visualize specific DBS targets at both 3T and 7T. METHOD: First, a systematic sequence optimization framework was applied to optimize MP2RAGE T1 mapping sequence parameters for the purpose of DBS planning. Next, we show that synthetic inversion-time images can be generated through a mathematical transformation of the T1 maps. The sequence was then applied to patients undergoing preoperative planning for DBS at 3T and 7T to generate synthetic contrasts used in surgical planning. RESULTS: We show that synthetic image contrasts can be generated across a full range of inversion times at 3T and 7T, including commonly used sequences for DBS targeting, such as T1-weighted, FGATIR, and EDGE. Acquisition through a single sequence shortens scan time compared to acquiring the sequences independently without affecting image quality or contrast. CONCLUSIONS: The generation of synthetic images for DBS targeting allows faster acquisition of many key sequences, as well as the ability to optimize contrast properties post-acquisition to account for the variable B1+ effects present in ultra-high field MRI. The proposed approach has the potential to reduce imaging time and improve the accuracy of DBS targeting at 1.5T, 3T, and 7T.

Temporo-Parietal Extraventricular Approach for Deep Brain Stimulation Targeting the Anterior Nucleus of the Thalamus: Institutional Experience.

BACKGROUND AND OBJECTIVES: The anterior nucleus of the thalamus (ANT) is a common target for deep brain stimulation (DBS) for drug-resistant epilepsy (DRE). However, the surgical approach to the ANT remains challenging because of its unique anatomy. This study aims to summarize our experience with the posterior temporo-parietal extraventricular (TPEV) approach targeting the ANT for DBS in DRE. METHODS: We performed a retrospective analysis of patients with DRE who underwent ANT-DBS using the TPEV approach between January 2011 and February 2021. Subjects with at least 6-month follow-up were eligible. The final lead position and number of active contacts targeting the anteroventral nucleus (AV) of the ANT were assessed using Lead-DBS. Mean seizure frequency reduction percentage and responder rate (≥50% decrease in seizure frequency) were determined. RESULTS: Thirty-one patients (mean age: 32.9 years; 52% female patients) were included. The mean follow-up period was 27.6 months ± 13.9 (29, 16-36). The mean seizure frequency reduction percentage was 65% ± 26 (75, 50-82). Twenty-six of 31 participants (83%) were responders, P < .001. Two subjects (6%) were seizure-free for at least 6 months at the last evaluation. Antiepileptic drugs dose and/or number decreased in 17/31 subjects (55%). The success rate for placing at least 1 contact at AV was 87% (27/31 patients) bilaterally. The number of active contacts at the AV was significantly greater in the responder group, 3.1 ± 1.3 (3, 2-4) vs 1.8 ± 1.1 (2, 1-2.5); P = .041 with a positive correlation between the number of active contacts and seizure reduction percentage; r = 0.445, R 2 = 0.198, P = .012. CONCLUSION: The TPEV trajectory is a safe and effective approach to target the ANT for DBS. Future studies are needed to compare the clinical outcomes and target accuracy with the standard approaches.

CWH43 Variants Are Associated With Disease Risk and Clinical Phenotypic Measures in Patients With Normal Pressure Hydrocephalus.

Background and Objectives: Variants in the CWH43 gene have been associated with normal pressure hydrocephalus (NPH). We aimed to replicate these findings, identify additional CWH43 variants, and further define the clinical phenotype associated with CWH43 variants. Methods: We determined the prevalence of CWH43 variants by whole-genome sequencing (WGS) in 94 patients with NPH. The odds of having CWH43 variant carriers develop NPH were determined through comparison with 532 Mayo Clinic Biobank volunteers without a history of NPH. For patients with NPH, we documented the head circumference, prevalence of disproportionate enlargement of subarachnoid hydrocephalus (DESH), microvascular changes on MRI quantified by the Fazekas scale, and ambulatory response to ventriculoperitoneal shunting. Results: We identified rare (MAF <0.05) coding CWH43 variants in 15 patients with NPH. Ten patients (Leu533Terfs, n = 8; Lys696Asnfs, n = 2) harbored previously reported predicted loss-of-function variants, and combined burden analysis confirmed risk association with NPH (OR 2.60, 95% CI 1.12-6.03, p = 0.027). Additional missense variations observed included Ile292Thr (n = 2), Ala469Ser (n = 2), and Ala626Val (n = 1). Though not quite statistically significant, in single variable analysis, the odds of having a head circumference above the 75th percentile of normal controls was more than 5 times higher for CWH43 variant carriers compared with that for noncarriers (unadjusted OR 5.67, 95% CI 0.96-108.55, p = 0.057), and this was consistent after adjusting for sex and height (OR 5.42, 95% CI 0.87-106.37, p = 0.073). DESH was present in 56.7% of noncarriers and only 21.4% of carriers (p = 0.016), while sulcal trapping was also more prevalent among noncarriers (67.2% vs 35.7%, p = 0.030). All 8 of the 15 variant carriers who underwent ventriculoperitoneal shunting at our institution experienced ambulatory improvements. Discussion: CWH43 variants are frequent in patients with NPH. Predicted loss-of-function mutations were the most common; we identified missense mutations that require further study. Our findings suggest that congenital factors, rather than malabsorption or vascular dysfunction, are primary contributors to the CWH43-related NPH clinical syndrome.

Cervical Radiofrequency Ablation Artifact Mimicking an Electrographic Seizure on RNS.

SUMMARY: The responsive neurostimulator continuously monitors the electrocorticogram. It delivers short bursts of high-frequency electrical stimulation when personalized patterns are detected. Intracranial EEG recording including electrocorticography is susceptible to artifacts, albeit at a lesser frequency compared with scalp recording. The authors describe a novel case of a patient with focal epilepsy, bitemporal responsive neurostimulation, and seizures without self-awareness manifest as focal impaired awareness seizures adversely affecting memory. At follow-up evaluation, the patient reported being clinically seizure-free although a single long episode was detected using the Patient Data Management System over the course of 3 years. Initial review identified a left-sided rhythmic discharge with a bilateral spatial field of involvement. In response to detection, the responsive neurostimulation delivered a series of five electrical stimulations. On further review, the patient recalled undergoing cervical radiofrequency ablation, which coincided with the appearance of the "electrographic seizure." Extrinsic electrical artifact involving monomorphic nonevolving waveforms confirmed electrical artifact identified and treated by responsive neurostimulation as an epileptic seizure. On rare occasion, implanted electrical devices may lead to misdiagnosis and mistreatment of patients because of intracranial artifact.

Current advances in the surgical treatment of glossopharyngeal neuralgia.

Glossopharyngeal neuralgia (GPN) is a neurological condition characterized by paroxysmal, stabbing-like pain along the distribution of the glossopharyngeal nerve that lasts from a couple of seconds to minutes. Pharmacological treatment with anticonvulsants is the first line of treatment; however, about 25% of patients remain symptomatic and require surgical intervention, which is usually done via microvascular decompression (MVD) with or without rhizotomy. More recently, the use of stereotactic radiosurgery (SRS) has been utilized as an alternative treatment method to relieve patient symptoms by causing nerve ablation. We conducted a systematic review to analyze whether MVD without rhizotomy is an equally effective treatment for GPN as MVD with the use of concurrent rhizotomy. Moreover, we sought to explore if SRS, a minimally invasive alternative surgical option, achieves comparable outcomes. We included retrospective studies and case reports in our search. We consulted PubMed and Medline, including articles from the year 2000 onwards. A total of 36 articles were included for review. Of all included patients with glossopharyngeal neuralgia, the most common offending artery compressing the glossopharyngeal nerve was the posterior inferior cerebellar artery (PICA). MVD alone was successful achieving pain relief immediately postoperatively in about 85% of patients, and also long term in 65-90% of patients. The most common complication found on MVD surgery was found to be transient hoarseness and transient dysphagia. Rhizotomy alone shows an instant pain relief in 85-100% of the patients, but rate of long-term pain relief was lower compared to MVD. The most common adverse effects observed after a rhizotomy were dysphagia and dysesthesia along the distribution of the glossopharyngeal nerve. SRS had promising results in pain reduction when using 75 Gy radiation or higher; however, long-term rates of pain relief were lower. MVD, rhizotomy, and SRS are effective methods to treat GPN as they help achieve instant pain relief and the decrease use of medication. Patients with MVD alone presented with less adverse effects than the group that underwent MVD plus rhizotomy. Although SRS may be a viable alternative treatment for GPN, further studies must be done to evaluate long-term treatment efficacy.

Transvenous embolization of cerebrospinal fluid-venous fistulas: Independent validation and feasibility of upper-extremity approach and using dual-microcatheter and balloon pressure cooker technique.

BACKGROUND: Transvenous embolization is emerging as a promising treatment for cerebrospinal fluid-venous fistulas (CVF) associated with spontaneous intracranial hypotension (SIH). OBJECTIVE: To perform an independent validation of the efficacy and safety of the procedure and describe the procedural techniques used at our institution. METHODS: A retrospective review was performed including consecutive patients with SIH who had undergone CVF embolization with 3-month clinical and imaging follow-up. Clinical evaluation included the Patient Global Impression of Change (PGIC) Scale and six-item Headache Impact Test (HIT-6). Bern SIH score was used for imaging evaluation on brain MRI. Post-treatment changes in scores were assessed by Wilcoxon signed rank test. Procedural technical details, including use of upper-extremity access and dual-microcatheter pressure cooker technique, were recorded. RESULTS: 18 patients (13 female, median age 60 years) were included. 17 (94%) procedures were performed with upper-extremity access and 12 (67%) using dual-microcatheter pressure cooker technique. After embolization, 16 (89%) patients reported much or very much improved at follow-up PGIC; median (IQR) HIT-6 score improved from 68 (62-72) to 36 (36-38) and Bern SIH score improved from 8 (6-8) to 3 (1.5-3.5), p values <0.001. Side effects were transient embolization site back pain in 15 (83%) and rebound intracranial hypertension requiring medical management in 9 (50%) patients. HIT-6 and Bern SIH score changes were similar between conventional and pressure cooker techniques (p values >0.05). CONCLUSION: Transvenous embolization is independently validated as a highly effective and safe treatment for CVF and is feasible using upper-extremity venous access. Dual-microcatheter and balloon/coil pressure cooker techniques may be used to optimize distribution of embolic material and potentially, treatment efficacy.

Intraoperative electrocorticography during laser-interstitial thermal therapy predicts seizure outcome in mesial temporal lobe epilepsy.

OBJECTIVE: Magnetic resonance-guided laser interstitial thermal therapy (MRLiTT) for treating temporal lobe epilepsy has recently gained popularity. We aimed to investigate the predictive value of pre-and post-MRLiTT epileptiform discharges (EDs) on intraoperative electrocorticography (iECoG) in seizure outcomes for patients with mesial temporal lobe epilepsy (mTLE). METHODS: We conducted a pilot, prospective single-center cohort study on seven consecutive patients with mTLE that underwent MRLiTT. Pre- and post-MRLiTT iECoG was performed using a 1x8 contact depth electrode along the same trajectory used for the laser catheter. RESULTS: The responders had a robust reduction in ED frequency compared to pre-MRLiTT iECoG (86% vs 13%, p < 0.01). Clinical characteristics, including risk factors for epilepsy, duration of epilepsy, presence of mesial temporal lobe sclerosis, prior intracranial monitoring, the absolute frequency of pre- or post-MRLiTT EDs, and ablation volume were not significantly associated with responder status. CONCLUSIONS: This is the first demonstration that intraoperative reduction in EDs during mesial temporal lobe MRLiTT may potentially predict seizure outcomes and may serve as an intraoperative biomarker for satisfactory ablation. However, larger prospective studies are needed to confirm our findings and evaluate the utility of iECoG during MRLiTT. SIGNIFICANCE: iECoG during mesial temporal lobe MRLiTT may help assess seizure outcomes.