Pitfalls in the diagnosis of hemifacial spasm.

Hemifacial spasm (HFS), a condition characterized by involuntary unilateral facial spasms, is a disabling disorder resulting in functional compromise, patient frustration, cosmetic deformity, and social embarrassment. Compression of the seventh nerve at the root entry zone via vascular loop is presently the most widely accepted causative theory. Although less common, there are other entities that can result in HFS. Basic evaluation, including a thorough history, physical examination, and magnetic resonance imaging (MRI) scan, is important to confirm the diagnosis and rule out other causes. The relation of vascular loop syndrome to HFS is well enough established that radiologic documentation of a vascular loop is probably not necessary in every case. Here we present 12 cases of HFS, 6 without VLS. The etiology and evaluation of HFS are reviewed.