Hemifacial spasm is usually diagnosed in persons in their mid-forties. It often begins with involuntary clonic contractions or twitching of the orbicularis oculi muscle and progresses to involve the entire musculature innervated by the facial nerve (summary by ... Hemifacial spasm is usually diagnosed in persons in their mid-forties. It often begins with involuntary clonic contractions or twitching of the orbicularis oculi muscle and progresses to involve the entire musculature innervated by the facial nerve (summary by Coad et al., 1991 and Miwa et al., 2002).
Miwa et al. (2002) reported 10 patients from 5 families with familial hemifacial spasm. The mean age at onset was 50.6 years, and 8 were affected on the left side. Most had relief with botulinum toxin injection. The ... Miwa et al. (2002) reported 10 patients from 5 families with familial hemifacial spasm. The mean age at onset was 50.6 years, and 8 were affected on the left side. Most had relief with botulinum toxin injection. The inheritance in all cases was most consistent with an autosomal dominant pattern with reduced penetrance. Two patients had surgical neurovascular decompression, which was effective. Lagalla et al. (2010) reported a 4-generation family in which 5 living members had hemifacial spasm with onset around age 60 years. Some reported worsening with stress or fatigue. Brain MRI/MRA studies showed neurovascular conflicts between the facial nerve and the basilar or vertebral arteries at the cerebello-pontine angle in 4 of 5 affected individuals. The findings were consistent with a vascular compressive etiology. There was also a history of hypertension in the family, and Lagalla et al. (2010) hypothesized that the late-onset may be related to progressive atherosclerotic vasculoarchitectural changes.