Large posterior fossa meningioma presenting with hemifacial spasm

Hemifacial spasms are involuntary paroxysmal muscle contractions commonly presenting as unilateral involvement of the orbicularis oculi and oris muscles.

A 62-year-old woman presented with spasms of progressively increasing frequency for 2 months in the right orbicularis oculi muscle, with subsequent involvement of the orbicularis oris muscle. Cerebral magnetic resonance imaging revealed an intensely enhanced dural-based tumor in the right posterior fossa. On constructive interference in steady-state (CISS) imaging, the right cerebellopontine angle cistern showed marked narrowing, and the right facial nerve could not be identified. The patient underwent tumor resection in the prone position, with intraoperative abnormal muscle response (AMR) monitoring. Upon tumor resection, the late variable components of AMR disappeared. Microscopic findings of the resected specimen were consistent with those of meningiomas. Postoperatively, the patient's hemifacial spasm significantly improved. The CISS sequence revealed restoration of the narrowed right cerebellopontine angle cistern, with clear visualization of the right facial nerve and no signs of neurovascular contact.

Large posterior fossa meningiomas can cause hemifacial spasms, and AMR might serve as a predictive indicator of the postoperative resolution of these spasms.