Objective: Hemifacial spasm caused by a cerebellopontine angle lipoma is extremely rare. We describe a patient with left-sided hemifacial spasm caused by vascular compression of the facial and vestibulocochlear cranial nerves by the anteroinferior cerebellar artery embedded within a cerebellopontine angle lipoma.
Clinical presentation: A 77-year-old man presented with a 10-year history of left-sided facial spasms that progressively worsened over time and significantly interfered with his ability to read, drive, and interact in social situations. Neurological examination showed obvious left hemifacial spasm, including orbicularis oculi and levator labii muscles. Magnetic resonance imaging revealed characteristic abnormal signal within the cerebellopontine angle cistern that was consistent with lipoma abutting the anteroinferior cerebellar artery.
Intervention: Surgical exploration with standard retrosigmoid craniectomy and subarachnoid dissection of the cerebellopontine angle was performed. The offending anteroinferior cerebellar artery branch was dissected away from the VIIth and VIIIth cranial nerves. Teflon felt was interposed between the artery and nerves after the artery was dissected off the surface of the lipoma. Electrophysiological monitoring showed resolution of the abnormal hemifacial spasm response during the procedure. No attempt was made to resect the lipoma, given the risk to injury of the brainstem and perforating blood vessels. Postoperatively, the patient's symptoms were completely resolved.
Conclusion: This case demonstrates that relief of the vascular compression, when present, of the VIIth cranial nerve is sufficient for resolution of hemifacial spasm symptoms, even when associated with nearby, benign lesions.