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Neurosurgical management in lateral meningocele syndrome: case report

Erik C. Brown, Kunal Gupta, and Christina Sayama

Lateral meningocele syndrome (LMS) is a rare genetic connective tissue disorder. It is associated with morphological changes similar to those of other connective tissue disorders, with the unique distinction of multiple, often bilateral and large, lateral meningoceles herniating through the spinal foramina. In some cases, these lateral meningoceles can cause pain and discomfort due to their presence within retroperitoneal tissues or cause direct compression of the spinal nerve root exiting the foramen; in some cases compression may also involve motor weakness. The presence of lateral meningoceles imposes unique challenges related to CSF flow dynamics, especially with concurrent Chiari malformation, which also occurs with increased frequency in individuals with LMS.

The authors present the case of a 6-month-old female with LMS with multiple lateral meningoceles throughout the thoracic and lumbar spine. The infant experienced a focal neurological abnormality due to enlargement of her lateral meningoceles following decompression of a symptomatic Chiari malformation and endoscopic third ventriculostomy. The finding was reversed through implantation of a ventriculoperitoneal shunt, which reduced the burden of CSF upon the lateral meningoceles. Such a case compels consideration that CSF flow dynamics in addition to altered connective tissue play a role in the presence of lateral meningoceles in patients within this and similar patient populations.

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Repeat surgery for pediatric epilepsy: a systematic review and meta-analysis of resection and disconnection approaches

Victor M. Lu, Erik C. Brown, John Ragheb, and Shelly Wang

OBJECTIVE

Resection and disconnection surgeries for epilepsy in the pediatric demographic (patients ≤ 18 years of age) are two separate, definitive intervention options in medically refractory cases. Questions remain regarding the role of surgery when seizures persist after an initial incomplete surgery. The aim of this study was to review the contemporary literature and summarize the metadata on the outcomes of repeat surgery in this specific demographic.

METHODS

Searches of seven electronic databases from inception to July 2022 were conducted using PRISMA guidelines. Articles were screened using prespecified criteria. Metadata from the articles were abstracted and pooled by random-effects meta-analysis of proportions.

RESULTS

Eleven studies describing 12 cohorts satisfied all criteria, reporting outcomes of 170 pediatric patients with epilepsy who underwent repeat resection or disconnection surgery. Of these patients, 55% were male, and across all studies, median ages at initial and repeat surgeries were 7.2 and 9.4 years, respectively. The median follow-up duration after repeat surgery was 47.7 months. The most commonly reported etiology for epilepsy was cortical dysplasia. Overall, the estimated incidence of complete seizure freedom (Engel class I) following repeat surgery was 48% (95% CI 40%–56%, p value for heterogeneity = 0.93), and the estimated incidence of postoperative complications following repeat surgery was 25% (95% CI 12%–39%, p = 0.04). There were six cohorts each that described outcomes for repeat resection and repeat disconnection surgeries. There was no statistical difference between these two subgroups with respect to estimated incidence of complete seizure freedom (p value for interaction = 0.92), but postoperative complications were statistically more common following repeat resection (p ≤ 0.01).

CONCLUSIONS

For both resection and disconnection surgeries, repeat epilepsy surgery in children is likely to confer complete seizure freedom in approximately half of the patients who experience unsuccessful initial incomplete epilepsy surgery. More data are needed to elucidate the impact on efficacy based on surgical approach selection. Judicious discussion and planning between the patient, family, and a multidisciplinary team of epilepsy specialists is recommended to optimize expectations and outcomes in this setting.

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Thalamic responsive neurostimulation for the treatment of refractory epilepsy: an individual patient data meta-analysis

Lauren L. Bystrom, Adam S. Levy, Erik C. Brown, Marytery Fajardo, and Shelly Wang

OBJECTIVE

In recent years, the treatment of drug-resistant epilepsy (DRE) has made greater use of surgery and expanded options for neurostimulation or neuromodulation. Up to this point, responsive neurostimulation (RNS) has been very promising but has mainly used only the cortex as a target. In this individual patient data meta-analysis (IPDMA), the authors sought to establish if a novel RNS target, the thalamus, can be used to treat DRE.

METHODS

The literature regarding the management of DRE by targeting the thalamus with RNS was reviewed per IPDMA guidelines. Five databases were searched with keywords [((Responsive neurostimulation) OR (RNS)) AND ((thalamus) OR (thalamic) OR (Deep-seated) OR (Diencephalon) OR (limbic))] in March 2022.

RESULTS

The median (interquartile range) age at implantation was 17 (13.5–27.5) years (n = 42) with an epilepsy duration of 12.1 (5.8–15.3) years. In total, 52.4% of patients had previously undergone epilepsy surgery, 28.6% had prior vagus nerve stimulation, and 2.4% had prior RNS. The median preimplant seizure frequency was 12 per week. The median seizure reduction at last follow-up was 73%. No study in this IPDMA reported complications, although 7 cases (16.3%) did require reoperation. Behavioral improvements and reduced antiepileptic drug dose or quantity were reported for 80% and 28.6% of patients, respectively.

CONCLUSIONS

This review indicates that thalamic RNS may be safe and effective for treating DRE. Long-term and controlled studies on thalamic RNS for DRE would further elucidate this technique’s potential benefits and complications and help guide clinical judgment in the management of DRE.

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Minimally invasive endoscopic repair of refractory lateral skull base cerebrospinal fluid rhinorrhea: case report and review of the literature

Brandon Lucke-Wold, Erik C. Brown, Justin S. Cetas, Aclan Dogan, Sachin Gupta, Timothy E. Hullar, Timothy L. Smith, and Jeremy N. Ciporen

Cerebrospinal fluid (CSF) leaks occur in approximately 10% of patients undergoing a translabyrinthine, retrosigmoid, or middle fossa approach for vestibular schwannoma resection. Cerebrospinal fluid rhinorrhea also results from trauma, neoplasms, and congenital defects. A high degree of difficulty in repair sometimes requires repetitive microsurgical revisions—a rate of 10% of cases is often cited. This can not only lead to morbidity but is also costly and burdensome to the health care system. In this case-based theoretical analysis, the authors summarize the literature regarding endoscopic endonasal techniques to obliterate the eustachian tube (ET) as well as compare endoscopic endonasal versus open approaches for repair. Given the results of their analysis, they recommend endoscopic endonasal ET obliteration (EEETO) as a first- or second-line technique for the repair of CSF rhinorrhea from a lateral skull base source refractory to spontaneous healing and CSF diversion. They present a case in which EEETO resolved refractory CSF rhinorrhea over a 10-month follow-up after CSF diversions, wound reexploration, revised packing of the ET via a lateral microscopic translabyrinthine approach, and the use of a vascularized flap had failed. They further summarize the literature regarding studies that describe various iterations of EEETO. By its minimally invasive nature, EEETO imposes less morbidity as well as less risk to the patient. It can be readily implemented into algorithms once CSF diversion (for example, lumbar drain) has failed, prior to considering open surgery for repair. Additional studies are warranted to further demonstrate the outcome and cost-saving benefits of EEETO as the data until now have been largely empirical yet very hopeful. The summaries and technical notes described in this paper may serve as a resource for those skull base teams faced with similar challenging and otherwise refractory CSF leaks from a lateral skull base source.

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Validation of Recursive Partitioning Analysis and Diagnosis-Specific Graded Prognostic Assessment in patients treated initially with radiosurgery alone

Clinical article

Anna Likhacheva, Chelsea C. Pinnix, Neil Parikh, Pamela K. Allen, Nandita Guha-Thakurta, Mary McAleer, Erik P. Sulman, Anita Mahajan, Almon Shiu, Dershan Luo, Max Chiu, Paul D. Brown, Sujit S. Prabhu, and Eric L. Chang

Object

Brain metastases present a therapeutic challenge because patients with metastatic cancers live longer now than in the recent past due to systemic therapies that, while effective, may not penetrate the blood-brain barrier. In the present study the authors sought to validate the Diagnosis-Specific Graded Prognostic Assessment (DS-GPA), a new prognostic index that takes into account the histological characteristics of the primary tumor, and the Radiation Therapy Ontology Group Recursive Partitioning Analysis (RPA) system by using a single-institution database of patients who were treated initially with stereotactic radiosurgery (SRS) alone for brain metastases.

Methods

Investigators retrospectively identified adult patients who had undergone SRS at a single institution, MD Anderson Cancer Center, for initial treatment of brain metastases between 2003 and 2010 but excluded those who had undergone craniotomy and/or whole-brain radiation therapy at an earlier time; the final number was 251. The Leksell Gamma Knife was used to treat 223 patients, and a linear accelerator was used to treat 28 patients. The patient population was grouped according to DS-GPA scores as follows: 0–0.5 (7 patients), 1 (33 patients), 1.5 (25 patients), 2 (63 patients), 2.5 (14 patients), 3 (68 patients), and 3.5–4 (41 patients). The same patients were also grouped according to RPA classes: 1 (24 patients), 2 (216 patients), and 3 (11 patients). The most common histological diagnoses were non–small cell lung cancer (34%), melanoma (29%), and breast carcinoma (16%). The median number of lesions was 2 (range 1–9) and the median total tumor volume was 0.9 cm3 (range 0.3–22.9 cm3). The median radiation dose was 20 Gy (range 14–24 Gy). Stereotactic radiosurgery was performed as the sole treatment (62% of patients) or combined with a salvage treatment consisting of SRS (22%), whole-brain radiation therapy (12%), or resection (4%). The median duration of follow-up was 9.4 months.

Results

In this patient group the median overall survival was 11.1 months. The DS-GPA prognostic index divided patients into prognostically significant groups. Median survival times were 2.8 months for DS-GPA Scores 0–0.5, 3.9 months for Score 1, 6.6 months for Score 1.5, 12.9 months for Score 2, 11.9 months for Score 2.5, 12.2 months for Score 3, and 31.4 months for Scores 3.5–4 (p < 0.0001). In the RPA groups, the median overall survival times were 38.8 months for Class 1, 9.4 months for Class 2, and 2.8 months for Class 3 (p < 0.0001). Neither the RPA class nor the DS-GPA score was prognostic for local tumor control or new lesion–free survival. A multivariate analysis revealed that patient age > 60 years, Karnofsky Performance Scale score ≤ 80%, and total lesion volume > 2 cm3 were significant adverse prognostic factors for overall survival.

Conclusions

Application of the DS-GPA to a database of patients with brain metastases who were treated with SRS appears to be valid and offers additional prognostic refinement over that provided by the RPA. The DS-GPA may also allow for improved selection of patients to undergo initial SRS alone and should be studied further.

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Intraoperative application and early experience with novel high-resolution, high-channel-count thin-film electrodes for human microelectrocorticography

Hao Tan, Angelique C. Paulk, Brittany Stedelin, Daniel R. Cleary, Caleb Nerison, Youngbin Tchoe, Erik C. Brown, Andrew Bourhis, Samantha Russman, Jihwan Lee, Karen J. Tonsfeldt, Jimmy C. Yang, Hongseok Oh, Yun Goo Ro, Keundong Lee, Mehran Ganji, Ian Galton, Dominic Siler, Seunggu Jude Han, Kelly L. Collins, Sharona Ben-Haim, Eric Halgren, Sydney S. Cash, Shadi Dayeh, and Ahmed M. Raslan

OBJECTIVE

The study objective was to evaluate intraoperative experience with newly developed high-spatial-resolution microelectrode grids composed of poly(3,4-ethylenedioxythiophene) with polystyrene sulfonate (PEDOT:PSS), and those composed of platinum nanorods (PtNRs).

METHODS

A cohort of patients who underwent craniotomy for pathological tissue resection and who had high-spatial-resolution microelectrode grids placed intraoperatively were evaluated. Patient demographic and baseline clinical variables as well as relevant microelectrode grid characteristic data were collected. The primary and secondary outcome measures of interest were successful microelectrode grid utilization with usable resting-state or task-related data, and grid-related adverse intraoperative events and/or grid dysfunction.

RESULTS

Included in the analysis were 89 cases of patients who underwent a craniotomy for resection of neoplasms (n = 58) or epileptogenic tissue (n = 31). These cases accounted for 94 grids: 58 PEDOT:PSS and 36 PtNR grids. Of these 94 grids, 86 were functional and used successfully to obtain cortical recordings from 82 patients. The mean cortical grid recording duration was 15.3 ± 1.15 minutes. Most recordings in patients were obtained during experimental tasks (n = 52, 58.4%), involving language and sensorimotor testing paradigms, or were obtained passively during resting state (n = 32, 36.0%). There were no intraoperative adverse events related to grid placement. However, there were instances of PtNR grid dysfunction (n = 8) related to damage incurred by suboptimal preoperative sterilization (n = 7) and improper handling (n = 1); intraoperative recordings were not performed. Vaporized peroxide sterilization was the most optimal sterilization method for PtNR grids, providing a significantly greater number of usable channels poststerilization than did steam-based sterilization techniques (median 905.0 [IQR 650.8–935.5] vs 356.0 [IQR 18.0–597.8], p = 0.0031).

CONCLUSIONS

High-spatial-resolution microelectrode grids can be readily incorporated into appropriately selected craniotomy cases for clinical and research purposes. Grids are reliable when preoperative handling and sterilization considerations are accounted for. Future investigations should compare the diagnostic utility of these high-resolution grids to commercially available counterparts and assess whether diagnostic discrepancies relate to clinical outcomes.

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Abstracts of the 10th Annual Meeting of the Lumbar Spine Research Society Chicago, Illinois • April 6 & 7, 2017

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Abstracts of the 2017 AANS/CNS Joint Section on Disorders of the Spine and Peripheral Nerves Las Vegas, Nevada • March 8–11, 2017