Hemifacial spasm

What is hemifacial spasm?

Hemifacial spasm (HFS) is characterised by intermittent, painless and involuntary contraction of the muscles innervated by the facial nerve. It affects one side of the face only. It usually starts by affecting the muscles around the eye and progresses to involved the entire half of the face.

What causes hemifacial spasm?

Like trigeminal neuralgia, hemifacial spasm is commonly caused by compression of the nerve which innervates the facial muscles as it exits the brainstem.


In the first instance, HFS can be managed with injections of botulinum toxin (botox) into the affected muscle(s). However, with time these may become less effective and cause increasing facial weakness. The most effective long-term treatment, in many cases, curing HFS is microvascular decompression surgery.

The risks of surgery are potentially serious, including facial weakness or numbness, hearing loss, double vision, anaesthesia dolorosa (a very painful and numb face), infection, stroke and even death, but significant complications are fortunately rare.