About 15 in every 100,000 women have hemifacial spasms, a condition in which the patient has frequent and involuntary contractions of the facial muscles, according to the University of Maryland Medical School. With a hemifacial spasm, the muscle contractions occur on only one side of the face.
Both women and men can have this neuromuscular condition, though women have it more often. Patients begin having symptoms of this disorder in their 40s.
To diagnose hemifacial spasms, a physician will conduct a neurological exam. Different scans may be ordered to rule out conditions that can cause these symptoms.
For example, a doctor may order a magnetic resonance imaging (MRI) scan to see if the facial spasms are caused by a tumor or a brain aneurysm. Another test that may be done is an electromyogram, or EMG.
An EMG measures the electrical activity of the muscles, both when they are at rest and when they are contracted. The Mayfield Clinic noted that in many cases, an EMG is done with a nerve conduction velocity (NCV) study to test electrical activity of both the muscles and nerves.
Several treatment options are available for hemifacial spasms. One option is medication, such as anticonvulsant drugs, which interfere in the nerve’s firing of electrical signals.
Examples of anticonvulsant drugs used for hemifacial spasms include phenytoin and carbamazepine. Another medication option is muscle relaxants, such as clonazepam, baclofen and diazepam.
The Mayfield Clinic stated that the latter group of drugs can help with mild cases of hemifacial spasms, but can cause side effects such as dependence, drowsiness, nausea, unsteadiness and skin rashes.
The National Institute of Neurological Disorders and Stroke noted that the most effective treatment for hemifacial spasms is botulinum toxin injections. Botulinum toxin, also called Botox, works by paralyzing the muscle by blocking release of the neurotransmitter acetylcholine. If the muscle does not receive acetylcholine, it does not receive the message to move.
In the treatment of hemifacial spasms, Botox is given to the patient in one to three injections.