Impact of skull base cisterns invasion and extent of resection on the management of skull base intracranial epidermoid tumors.

Background: This study reports the authors' experience with microsurgical resection of skull base epidermoid tumors, examining the relationship between the number of invaded intracranial subarachnoid cisterns (SC) and the extent of resection, recurrence and outcomes.

Methods: Data from 84 patients who underwent skull base epidermoid tumor resection between 2000 and 2022 were prospectively collected and retrospectively reviewed. Clinical presentations, imaging findings (including the number of invaded cisterns), and extent of resection were analyzed for their influence on postoperative complications and long-term outcomes, including progression-free survival (PFS), intervention-free survival (IFS), and overall survival (OS).

Results: A total of 84 patients were included (51 % female), with a mean age of 41.1 years. Headache was the most common symptom (39 %). The cerebellopontine angle (CPA) was the most frequently invaded cistern (71 %). The mean number of invaded cisterns was 5.8 (median: 4; range: 1-21), and the mean tumor volume was 26.1 cc (median: 18; range: 1-201.3). Gross total resection (GTR) was achieved in 40 patients (47.6 %), near-total resection (NTR) in 12 (14.3 %), subtotal resection (STR) in 22 (26.2 %), and partial resection (PR) in 10 (11.9 %). Patients with over 5 invaded cisterns had significantly lower GTR rates (p-value < 0.001). Tumor volume was significantly associated with resection extent, tumors over 45 cc were more likely to recur (p-value = 0.004). Over a mean follow-up of 9.5 years, 32 patients (39 %) experienced tumor recurrence/regrowth. PFS was significantly longer after GTR (p < 0.001). Thirteen patients (16 %) required reoperation due to recurrence. IFS did not differ significantly between the GTR and NTR (p = 0.114). Postoperative morbidity occurred in 40 patients (48 %), with no perioperative mortality.

Conclusion: Cisterns tumor invasion is more predictive of resection success than tumor volume. GTR prolongs PFS, although IFS remains similar between GTR and NTR. Epidermoid tumor management is challenging, and surgical complication rate is significant. Maximal safe resection is recommended.

Abbreviations: SC, Subarachnoid cistern; GTR, Gross total resection; NTR, Near total resection; STR, Subtotal resection; PR, Partial resection; PFS, Progression-free survival; IFS, Intervention-free survival; OS, Overall survival; CPA, Cerebellopontine angle; CSF, Cerebrospinal fluid; ITSTA, Infratranstentorial subtemporal approach; CD, Continuous drainage VPS, Ventriculo-peritoneal shunt; CPS, Cisto-peritoneal shunt; DVT, Deep vein thrombosis; SVT, Superficial vein thrombosis; CN, Cranial nerve.