Epidermoid Cysts of the Posterior Fossa and Petroclival Region: Treatment and Outcome

Objectives: Surgical management of epidermoid cysts is still a challenge. One of the most important goals in epidermoid management is total tumor removal, but the tendency of these tumors to adhere to cranial nerves and to the brainstem creates technical problems in their complete removal. The approach to epidermal cysts of the CPA and petroclival region is determined by the tumor extension.

Patients and Methods: From 1988 to 2004, among 239 operations for CPA tumors (retrosigmoid approach in sitting position) and 11 procedures for tumors in the petroclival region (petrosal approach), there were 26 operations for epidermal cysts and 19 for recurrent cysts. Continuous monitoring of selected neurophysiological functions was introduced as a routine in CPA and petroclival region surgery in 1998.

Results: No perioperative mortality occurred during the short postoperative period. One serious complication occurred due to air embolism, which resulted in coma and prolonged vegetative state. In 13 patients (including 3 recurrences), tumor resection was complete as far as could be assessed. After a long observation period, the facial nerve status was good (H-B I or II) after 18 procedures (70%), acceptable (H-B III or IV) after 4 procedures (15%), and not acceptable after 4 procedures (15%). Fifteen out of 20 (75%) patients had measurable hearing postoperatively.

Conclusions: The goal of treatment should be total tumor resection, but not at the cost of vital structures. Intraoperative, multimodal monitoring of neural function is one of the important tools for success.