Supratentorial intraparenchymal schwannoma: Systematic review of the literature with an illustrative case.

OBJECTIVE

Intraparenchymal schwannomas are a rare subtype of central nervous system tumor, with descriptions of this pathology within the neurosurgical literature exclusively consisting of case reports and small case series. The present study details an illustrative case of a young patient with this rare tumor type who was recently treated at our institution via craniotomy for resection of her intracranial neoplasm. We then conducted a systematic review of the published patient data on supratentorial intraparenchymal schwannomas, including a meta-analysis aimed at quantifying postoperative seizure-freedom rates in this patient population.

METHODS

The present study included both a surgical case report in addition to a PRISMA-compliant systematic review that involved individual-patient data (IPD) meta-analysis. The systematic review searched PubMed, the Cochrane Library, and Scopus, with 63 articles meeting inclusion criteria. The IPD meta-analysis utilized the nonparametric Kaplan-Meier estimator and a parametric Bayesian Weibull accelerated-failure-time (AFT) model to estimate seizure-freedom time after surgery.

RESULTS

Our case report detailed a right frontal craniotomy for tumor resection in a 23-year old female. Gross total resection was achieved and postoperative pathology was ultimately consistent with WHO grade I schwannoma, with the neoplastic tissue staining positive for S-100 and SOX-10, in addition to being negative for OLIG-2 and positive for GFAP. Molecular profiling also detected a CHD7-VGLL3 fusion. Among the 63 articles identified via our systematic review, a total of 82 patients with supratentorial, intraparenchymal schwannomas were identified. Using the parametric AFT model, median seizure-free survival time was calculated as 133.43 months (95% CrI = 65.89-296.29 months; 90% CrI = 72.40-260.25 months; 50% CrI = 103.15-175.89 months), while the probability of remaining seizure-free 12, 36, and 60 months after surgery being 95.28% (95% CrI = 88.52-99.15%), 85.00% (95% CrI = 70.95-95.32%), and 74.75% (95% CrI = 54.05-90.44%), respectively. The observed postoperative seizure-freedom rate of 83.8% was statistically significantly greater than the 70% lower-bound benchmark established for low-grade epilepsy-associated neuroepithelial tumors (p = 0.044).

CONCLUSION

The present study provides quantitative seizure-freedom estimates for patients undergoing surgical resection of epileptogenic intraparenchymal schwannoma, a rare disease entity with fewer than 100 reported cases in the neurosurgical literature. Given the inherent constraints of quantifying treatment outcomes of a rare disease, the ability to obtain such estimates underscores the utility of Bayesian methods for statistical inference under data-limited conditions. Our meta-analysis suggests that most patients can expect at least multiple years of seizure-freedom postoperatively following resection of an epileptogenic intraparenchymal schwannoma.