Abstract

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

Case Description: 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.

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

Keywords: Hemifacial spasm, Meningioma, Neurovascular compression syndrome, Posterior fossa tumor

INTRODUCTION

Hemifacial spasms are attacks of involuntary paroxysmal muscle contractions commonly presenting as unilateral involvement of the orbicularis oculi and oris muscles. These spasms are estimated to present in approximately 1% of intracranial tumors[ 18 ] of varying locations and types, including cerebellopontine angle tumors such as epidermoid tumors, meningiomas, schwannomas, lipomas, and metastatic tumors; fourth ventricle tumors such as choroid plexus papillomas, ependymomas, and subependymomas; cerebellar tumors such as gangliogliomas and gangliocytomas; meningiomas attached to the tentorial cerebelli, foramen magnum, and posterior fossa floor; brainstem gliomas; and cerebral glioblastomas.[ 1 - 3 , 5 - 7 , 9 - 12 , 14 - 17 , 19 ] Abnormal muscle response (AMR), a distinct and abnormal electrophysiological presentation, is frequently observed in the orbicularis oris and oculi muscles of patients with hemifacial spasms.[ 13 ] Recently, intraoperative AMR monitoring during microvascular decompression surgeries has been documented as useful for predicting postoperative outcomes in patients with hemifacial spasms.[ 4 ]

Herein, we report a patient with posterior fossa meningioma presenting with a hemifacial spasm which improved following tumor resection, with significant alterations in the AMR findings.

CASE DESCRIPTION

A 62-year-old woman experienced spasms of progressively increasing frequency for 2 months in the right orbicularis oculi muscle, with subsequent involvement of the orbicularis oris muscle. At presentation, the patient exhibited intermittent hemifacial spasms, primarily affecting the right orbicularis oculi muscle [ Video 1 ]. Cerebral magnetic resonance imaging (MRI) revealed an intensely enhanced dural-based tumor in the right posterior fossa [ Figure 1 ]. On constructive interference in steady-state (CISS) imaging, the right cerebellopontine angle cistern showed marked narrowing with ventral displacement of the right cerebellar hemisphere. The right facial nerve could not be identified [ Figure 2 ]. The patient underwent suboccipital tumor resection in the prone position. AMR was used as an intraoperative monitor. The zygomatic branch of the right facial nerve was stimulated at the level of the lower edge of the zygomatic arch, and two needle electrodes were placed in the lower part of the right orbicularis oculi muscle for deriving the muscle response.[ 13 ] Before tumor resection, the late variable components of AMR were consistently recorded. However, immediately following the resection of the elastic hard tumor, these components completely disappeared [ Figure 3 ]. No additional surgical maneuvers were performed to explore the root exit zone of the facial nerve. Microscopic examination of the resected specimen revealed fascicular proliferation of anaplastic cells with spindle-shaped nuclei [ Figure 4 ]. Immunohistochemical examination revealed positive staining for epithelial membrane antigen and negative for progesterone receptor, cluster of differentiation (CD)34 and signal transducer and activator of transcription 6. These findings were consistent with a meningioma. Postoperatively, the patient’s hemifacial spasm significantly improved [ Video 2 ]. The CISS sequence performed on postoperative day 5 showed restoration of the narrowed right cerebellopontine angle cistern, with clear visualization of the right facial nerve. No neurovascular contact was evident around the root exit zone [ Figure 5 ]. To date, the patient has been followed up for more than 6 months, with no recurrence of the hemifacial spasm.

Video 1