Developmental Venous Anomaly: An Unusual Etiology of Hemifacial Spasm: Case Report and Literature Review

Abstract

Abstract Hemifacial spasm (HFS) is most commonly caused by arterial compression of the facial nerve at the root exit zone. Pure venous compression is rare, and HFS secondary to a developmental venous anomaly (DVA) represents an exceptionally uncommon etiology. We report a rare case of HFS caused by a cerebellar DVA with a dominant draining vein producing venous neurovascular conflict at the cerebellopontine angle (CPA) and review the relevant literature. We present the case of a 55-year-old man with progressively disabling right-sided HFS. Brain magnetic resonance imaging demonstrated a cerebellar DVA characterized by multiple medullary veins converging into a prominent collector vein extending into the right CPA and compressing the cisternal segment of the facial nerve. Surgical exploration was performed through a retrosigmoid approach with meticulous arachnoid dissection and preservation of venous drainage. The analysis is not applicable for a case report. Intraoperative findings confirmed a dense perineural venous network consistent with a DVA forming a caput medusae configuration around the VII–VIII nerve complex. Gentle mobilization of the venous structures allowed adequate decompression of the facial nerve without venous sacrifice or interposition material. The HFS resolved immediately after surgery. The postoperative course was complicated by transient cerebellar edema and respiratory distress requiring intensive care management, with progressive recovery. At 6-month follow-up, the patient remained free of HFS without neurological deficit. HFS secondary to compression by a DVA is exceedingly rare. High-resolution MRI plays a crucial role in identifying venous neurovascular conflict. When surgery is considered in medically refractory cases, decompression should aim to relieve nerve compression while strictly preserving venous drainage to avoid potentially catastrophic venous complications.