Primary Extradural Meningioma: A Systematic Review of Diagnostic Features, Clinical Management, and Surgical Outcomes.

This systematic review consolidates the literature on primary extradural meningiomas (PEMs), a rare subset of meningiomas. We describe the clinical features, management strategies used, and treatment outcomes for published cases. A systematic review was conducted using PRISMA guidelines across multiple databases to 29 July 2024. Inclusion criteria were adult patients with primarily extradural meningioma and where individual patient clinical data were provided. Of 216 studies that met the initial search criteria, 41 satisfied the final inclusion criteria. These 41 studies included 82 patients with 84 total PEMs. The cohort was balanced between sexes with a median age of 46 (range 18-82). Frequent symptoms at initial presentation included pain/headache (46%), weakness (44%), paresthesias (24%), and a palpable superficial mass (23%). The median duration of symptoms to diagnosis was 11 months (range 0.75-120). Surgical resection was the primary treatment approach, achieving a gross total resection in 67% of cases. The majority of lesions were classified as WHO grade 1 (87%). A recurrence was identified during the published follow-up in 11% of cases and a higher WHO grade was expectedly associated with a greater risk of recurrence. The described practice was to use adjuvant radiotherapy in recurrent and high-grade cases. Most cranial lesions were located in the frontal bone, while most spinal lesions affected the cervical spine. Post-treatment symptom improvement or resolution was described in almost all patients at the last follow-up. In comparison to intradural meningiomas, PEMs largely follow a more indolent course with a longer duration of symptoms prior to diagnosis, more benign symptoms, a higher proportion of grade 1 tumors, and favorable outcomes; however, there is a small subset of PEMs with extension outside the cranium and spine that require specific considerations for management.