This is a rare disease that usually starts with twitching around the eye. It can spread to involve the entire face on one side. It most commonly only affects one side of the face. The cause of this condition is irritation of the facial nerve by a blood vessel. The facial nerve is one of the cranial nerves that arise directly from the brain. Its function is to control movement of most of the muscles of the face on one side. There are two facial nerves, one for each side of the face. The most important concern with this condition is to make the diagnosis. As it is a rare condition, it can often go undiagnosed for many years. Once diagnosed there is essentially two ways of treating hemifacial spasm. The first, least invasive way, is to inject Botox into the facial muscles affected. This is a temporary solution that needs to be regularly repeated. The alternative treatment that requires a brain operation is a microvascular decompression. This involves a small incision behind your ear. A window of bone is created to allow the surgeon access to the lower compartment of your brain. The brainstem, facial nerve and surrounding blood vessels are identified. The blood vessel causing the hemifacial spasm will be indenting and compressing the nerve. This blood vessel can be gently moved away and a sling fashioned around the blood vessel to keep it away from the nerve. The blood vessel may also be kept away from the nerve by placing inert material like Teflon between the blood vessel and the nerve. While this procedure does not work for everyone, when successful, it provides long term permanent results in more than 90% of cases in large series reported in the neurosurgical literature.