[Hemifacial spasm. Etiology and management]

Hemifacial spasm (HFS) is an involuntary contracture of the facial muscles innervated by the ipsilateral facial nerve. We studied the etiology of these HFS.

This retrospective study included 233 patients with HFS who came to the ophthalmologist for quarterly botulinum neurotoxin A injection. Of these, we analyzed the 198 patients for whom MRI scans were performed. We recorded patient clinical data and clarified the etiology of their HFS.

The 198 patients (62.6% women) had a mean age of 55.7±14years. An etiology was found in 52.5% of cases. In 34.5% of HFS, MRI revealed vascular compression where the facial nerve emerged from the brainstem. We specify the arteries involved. Brain tumors accounted for 1.5% of cases. MRI was normal in 64.5% of cases. In these secondary cases of HFS, we found 8.5% peripheral facial palsy, 4% post-traumatic HFS and 4% secondary to an eye injury. Stress was found in 17% of patients.

This study illustrates the need for MRI with attention to the posterior fossa in the work-up of HFS in order to identify primary HFS associated with vascular compression of the facial nerve and to rule out a rare but serious posterior fossa tumor. The treatment of HFS is based on quarterly injections of botulinum neurotoxin/A (NTBo/A), the three brands of which have market approval. The injection pattern and frequency is customized according to the results. In cases of insufficient response to injections of NTBo/A, neurosurgical microvascular decompression may be considered for cases of primary HFS.