Benign essential blepharospasm (BEB) and hemifacial spasm (HFS) are chronic and disabling medical conditions. Both disorders result in constant and uncontrollable blinking, which interferes with the performance and enjoyment of many day-to-day activities and may even render a patient functionally blind and occupationally handicapped. For example, many people with eyelid spasm will avoid driving altogether due to the fear of eyelids involuntarily closing and rendering them functionally blind. Sometimes the blinking is so emotionally unsettling that patients may become desperate, frustrated, and angry. It is not unusual for patients with blepharospasm and hemifacial spasm to be evaluated by a number of different specialists (including psychiatrist!) before the correct diagnosis is established. Frustration and lack of an explanation for their symptoms may lead to anxiety and/or depression. Diagnosis of blepharospasm is based on the patient’s history and observed characteristics of the spasm. The unwary doctor may wrongly attribute the patient’s symptoms to anxiety or depression, thus delaying the correct diagnosis and management.
Blepharospasm: Blepharospasm is a neurological condition characterized by forcible closure of the eyelids. Blepharo means “eyelid”. Spasm means “uncontrolled muscle contraction”. The term blepharospasm can be applied to any abnormal blinking or eyelid tic or twitch resulting from any cause, ranging from dry eyes to Tourette’s. The blepharospasm referred to here is officially called benign essential blepharospasm (BEB) to distinguish it from the less serious secondary blinking disorders.
“Benign” indicates the condition is not life threatening and “essential” is a medical term meaning “of unknown cause”. Imaging study, such as CT or MRI, is typically not required.
Patients with blepharospasm have normal eyes. The visual disturbance is solely due to the involuntary forceful closure of the eyelids. Most commonly, blepharospasm begins in the mid-50s but may occur in adults at any age and affects women more frequently than men. In the beginning, there is increased blinking with sunlight, excessive air pollution, wind, noise, movement of the head, or stress. This progresses to involuntary spasms, often occurring initially on only one side but ultimately affecting both sides.
Blepharospasm should not be confused with:
- Ptosis – drooping of the eyelid caused by weakness or paralysis of the levator muscle of the upper eyelid
- Blepharitis – an inflammatory condition of the eyelids due to infection or allergies
- Hemifacial spasm – a non-dystonic condition involving various muscles on one side of the face, often including the eyelid, caused by irritation of the facial nerve. The muscle contractions are more rapid and transient than those of blepharospasm, and the condition is always confined to one side
Hemifacial Spasm: Hemifacial spasm is an involuntary twitching of the facial muscles, usually affecting the entire one side of face and not just the eyelids.
In contrast to benign essential blepharospasm, hemifacial spasm affects only one half of the face and does not progress to the other side. The facial muscles are controlled by the facial nerve (seventh cranial nerve), which originates at the brainstem and exits the skull below the ear where it separates into five main branches. The facial nerve is primarily a motor nerve, meaning it controls muscles that move the eyebrows, close the eyes, and move the mouth and lips. In 92% of cases, the spasm starts near the eye and progresses down the face over time. In the other 8%, it starts near the chin and progresses upward. The twitching is usually not painful, but it can be embarrassing and interfere with normal expression and vision.
What causes hemifacial spasm?
Hemifacial spasm can be caused by injury to the facial nerve, a tumor or blood vessel compressing the nerve, or Bell’s palsy. The most common cause is compression of the facial nerve by the anterior inferior cerebellar artery where the nerve exits your brainstem. The compression causes the nerve to misfire, making your facial muscles to contract. This condition is similar in etiology to trigeminal neuralgia, an irritation of the fifth cranial nerve that causes severe facial pain. Both hemifacial spasm and trigeminal neuralgia are caused by nerve compression from a blood vessel. In hemifacial spasm, the compression is on the facial (motor) nerve whereas, in trigemial neuralgia, it affects the trigeminal (sensory) nerve. Due to possible compression on the facial nerve causing hemifacial spasm, unlike bilateral essential blepharospasm, which has no known etiology and does not require an imaging study, MRI/MRA or CT/CTA is commonly obtained for people with hemifacial spasm. Treatment: Although there is no cure for involuntary spasm of eyelids/face, botulinum toxin (Botox® and Xeomin®) injection has become the treatment of choice for both conditions of blepharospasm and hemifacial spasm. Botulinum toxin temporarily paralyzes the muscles. For those patients with inadequate relief of their symptoms from botulinum toxin injections, oral medications and surgery are other possible treatment options. Everyone responds to botulinum toxin differently. Although most people with blepharospasm and hemifacial spasm will achieve very satisfactory results from botulinum toxin injections, the dose may vary widely.
Therefore, the proper dose for a particular patient with blepharo or hemifacial spasm can only be determined after a few injections. Unfortunately, the effect of botulinum toxin dissipates after an average of 3 months, and most people will require reinjections every 3 months. Although blepharospasm has no curative treatment, hemifacial spasm does. The procedure is a neurosurgical decompression of the nerve. It is accomplished by exposing the nerve and placing a padding between the nerve and the adjacent artery. The procedure is successful in eliminating the hemifacial spasm in about 85% of patients. This procedure is performed by a neurosurgeon and carries considerable risk since it is a brain surgery. Most people with hemifacial spasm will elect to receive botulinum toxin injections instead of having a brain surgery.