Retrosigmoid Intradural Suprameatal Approach (RISA): A Single-Center Experience with 19 Cases

Background: Several surgical approaches were introduced to overcome the risk of complication for the management of tumors involving the posterior fossa and adjacent part of middle fossa.

Objective: The retrosigmoid intradural suprameatal approach (RISA) was introduced in 1983; modification and variation have been suggested. We introduce the variable indications and surgical outcomes of patients treated with RISA in a single center.

Methods: Nineteen patients (9 men and 10 women) were treated with RISA between July 2014 and June 2019. Their diagnoses were meningiomas (petroclival, petrous apex, sphenopetroclival, and cerebellopontine angle) and schwannomas (trochlear, trigeminal, and vestibular). Surgical outcomes and related complications were analyzed.

Results: Extent of tumor removal was variable; 5 in 19 had achieved gross total resection (26.3%), 6 achieved near total (31.6%), 7 achieved subtotal (36.8%), and 1 achieved partial (5.3%) resection. Three patients had a change in brainstem auditory evoked potential intraoperatively, which resulted in persistent hearing loss in two patients. Two patients had a temporal ipsilateral third nerve palsy. Preoperative hypesthesia in five patients was not improved postoperatively. Postoperative facial nerve palsy in four patients was recovered in three patients. One patient with neurofibromatosis type 2 died with a complication not related to the surgery.

Conclusion: RISA is a useful approach that results with acceptable treatment-related complications for the treatment of various posterior fossa tumors having a lesion reaching a part of middle fossa.

 

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No conflict of interest has been declared by the author(s).