How to face the hemifacial spasm

Hemifacial spasm (HFS) is one of the various movement disorders affecting the face and is characterised by subtle or sustained contractions of muscles innervated by the seventh cranial nerve. The contractions may persist during sleep and are sometimes exacerbated by stress or mastication. Depending on the area involved, the result might be dysarthria, vision impairment, tinnitus, social discomfort, etc.
There are various clinical situations where diagnosing HFS is not as easy as generally considered, particularly due to phenomenological overlaps with other movement disorders. The differential diagnosis with other movement disorders such as blepharospasm, post-facial palsy (synkinesis), motor tics and functional spasm, is mainly based on clinical observation of the pattern of muscle con- tractions. For instance, the other Babinski sign (simultaneous raise of the eye- brow and eye occlusion, due to the contractions of orbicularis oculi and frontalis muscles) has a good specificity for HFS and help to distinguish HFS from blepharospasm.
Nevertheless, the aetiological diagnosis might be substantially improved by specific imaging investigations such as brain MRI, or electromyography. An organized approach is essential as some causes might be serious and/or treatable, as HFS can be secondary to tumoral, vascular or inflammatory lesions in the pathway of the facial nerve.
Therapeutic options for primary HFS include botulinum toxin injections and microvascular decompression in the root-exit zone of the 7th nerve in the brainstem, and often imply thorough clinical and paraclinical investigations prior to their execution.