Get Help Common Eye Conditions Hemifacial Spasm Hemifacial Spasm Hemifacial spasm (HFS) is a neurological disorder that is characterised by a frequent involuntary spasm (contraction) of the muscles of one side of the face. Facial spasms usually occur around the eye of the affected side and are most commonly caused by blood vessels constricting the facial nerve. Other causes include facial nerve injury, a tumour or in rare cases, there is no apparent cause. Gradually the spasms will progress down to the lower facial muscles eventually causing the mouth to be pulled to one side. This disorder can occur in both men and women but is more prevalent in middle aged women. The safest and most effective treatment for a Hemifacial spasm is injection with a toxin into the area to temporarily alleviate spasms. However the effect of the medication will wear off over a number of months, and repeat treatment is required. A more invasive treatment procedure is ‘Microvascular Decompression’. It is a highly technical surgical procedure with many side effects involving the surgical separation of one or more blood vessels that are constricting upon the facial nerve (7th cranial nerve) as it exits the brainstem. This form of treatment is only considered when all other forms of treatment have been exhausted.