Long Term Surgical Oncological and Functional Outcome of Large Petroclival and Cerebellopontine Angle Epidermoid Cysts: A Multicenter Study.

Abstract Objective: To assess the long-term surgical results on cranial nerve (CN) function and tumor control in patients harboring cerebellopontine angle (CPA) and petroclival area (PCA) epidermoid cysts (EC).Methods: This is a retrospective cohort study about 56 consecutive patients operated on for a CPA or PCA EC between January 2001 and July 2019 in six participating French cranial base referral centers.Results: Sixteen patients (29%) presented a PCA EC, and 40 a CPA EC (71%). The median clinical and radiological follow-up was 46 months (range 0-409). Preoperative CN disorders were present in 84% of patients (n=47), 72% of them experienced CN deficits improvement at last follow-up consultation (n=34) : 60% of cochlear and vestibular deficits (n=9/15 in both groups), 67% of trigeminal neuralgia (n=10/15), 53% of trigeminal hypoesthesia (n=8/15), 44% of lower cranial nerve disorders (n=4/9), 38% of facial nerve deficits (n=5/8), and 43% of oculomotor deficits (n=3/7) improved or were cured after surgery. New postoperative CN deficits occurred in 48% of patients (n=27). Most of them resolved at last follow-up, except for cochlear deficits which improved in only 14% of cases (n = 1/7). Twenty-six patients (46 %) showed evidence of tumor progression after a median duration of 63 months (range 7-210). Extent of resection, tumor location and tumor size were not associated with the occurrence of new postoperative CN deficit nor tumor progression. Conclusion: A functional nerve-sparing resection of posterior fossa EC is an effective strategy to optimize the results on preexisting CN deficits and reduces the risk of permanent de novo deficits.