Microsurgery of a rare case of abducens schwannoma: surgical techniques.

Abstract

Abducens schwannoma is relatively very rare, and accounts for only about 1% of all intracranial schwannomas. Here, we report microsurgical resection of a rare case of cisternal-segment abducens schwannoma in a female patient. Upon physical examination, the patient showed no eye movement symptoms, and facial & auditory nerves function were normal, but showed slight unsteady walking and positive Romberg sign. Magnetic resonance imaging (MRI) scan of the brain revealed a mass located at the right cerebellopontine angle (CPA), and the tumor was partially enhanced after contrast MRI scan. Thus, schwannoma is suspected before surgery, but it's difficult to identify its origin by MRI images. Considering tumor compression to brain stem and available microsurgical techniques nowadays, we selected craniotomy surgery for the patient, and classic retro-sigmoid approach was recommended, which is a safe and commonly used surgical approach. During the surgery, the tumor was found to arise from the abducens nerve, and a total resection of the schwannoma was finally achieved under intra-operative neuro-monitoring. The patient tolerated the surgery very well, but had transient abducens paralysis and ataxia after surgery, and gradually improved in 3 months. The follow-up brain MRI images 3 months after surgery indicated no residual or relapse of the tumor.