Total Resection of Brainstem Extension of Tentorial Schwannoma Using an Occipital Transtentorial Approach.

Abstract

Approximately 60 cases of schwannoma unrelated to the cranial nerve have been reported, and only 12 arose from the tentorium. We present a case of tentorial schwannoma extending into the pons and midbrain without cranial nerve involvement, which was almost totally resected with an occipital transtentorial approach. A 37-year-old man was admitted to our institution with memory disturbance beginning 2 years ago and gait disturbance from 1 year ago. Magnetic resonance imaging on admission revealed a heterogeneously enhanced 33 × 33 × 35 mm tumor in the pons and midbrain, and a dural tail sign connecting the lesion to the tentorial edge. Gross total resection of the tumor was performed with an occipital transtentorial approach. The trochlear nerve was identified and preserved, and the tumor did not involve this cranial nerve. The tumor was firmly attached to the edge of tentorium, and extended into the pons with sharp tumor border. Postoperative recovery was good, and brain magnetic resonance imaging performed 2 months after the surgical procedure revealed gross total removal of the lesion without signs of recurrence, but a slightly enhanced lesion in the right edge of the tentorium. The occipital transtentorial approach provides a direct approach to tentorial schwannoma, resulting in total resection even if the tumor extends into the pons and midbrain.