Microvascular Decompressive Surgery for Hemifacial Spasm

Hemi facial spasm (HFS), a term described in 1905 by Babinski but first reported by Schultz in 1875, is a highly morbid movement disorder characterized by intermittent involuntary movement of muscles innervated by the facial nerve.

(HFS) affects roughly 10 in 100,000 individuals in fifth or sixth decades of life.

Primary HFS is commonly attributed to vascular loops compressing the seventh cranial nerve at its exit zone from the brainstem. The facial nerve compression is thought to lead to ephaptic transmission and to hyperactivity of the facial nucleus, resulting in the involuntary facial movements.

Secondary HFS frequently follows peripheral facial palsy or may arise from facial nerve damage produced by tumours, demyelinating disorders, traumatisms, and infections accounting for 1-2 & of HFS.

Over four in five primary HFS cases involve either anterior or posterior inferior cerebellar artery as the primary offender although vertebral artery, multiple vessels and veins may be involved.

EMG recordings confirm the diagnosis by showing a typical electrophysiological signature: clonic facial muscle contractions, hyperactivity, and synkinesis, lateral spread evoked responses.

Imaging can be useful for confirming that HFS is primary in nature and due to a neurovascular compression. In most cases (95% of the patients) the compressive vessel, generally an artery, is seen on MRI combined with MR-Angiography (MRA). High resolution T2-sequence is to be used to get good delineation of the facial nerve.

Many treatments for HFS have been reported, including pharmacological agents, botulinum toxin injection, facial nerve blockage, physical therapy, radiofrequency ablation, acupuncture, as well as facial nerve combing and microvascular decompression (MVD).

However, while MVD is effective, there are still significant postoperative complications.