Blepharo means "eyelid". Spasm means "uncontrolled muscle contraction". The term blepharospasm ['blef-a-ro-spaz-m] can be applied to any abnormal blinking or eyelid tic or twitch resulting from any cause, ranging from dry eyes to Tourette's syndrome to tardive dyskinesia. 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". It is both a cranial and a focal dystonia. Cranial refers to the head and focal indicates confinement to one part.

Blepharospasm is a type of dystonia, which indicates a sustained muscular contraction of an involuntary nature. Blepharospasm usually begins with a gradual onset, often precipitated by eye irritation or emotional stresses. With progression of the disorder, episodes of blepharospasm tend to worsen in severity, often resulting in embarrassment and even loss of vision temporarily due to lid closure. In some cases, the spasms are so prolonged and forceful that the patient is functionally blind for up to several hours.

What causes Blepharospasm is largely unknown, although some educated guesses are being made. In most cases, blepharospasm seems to develop spontaneously. Some blepharospasm patients have a history of dry eyes and/or light sensitivity, but others report no previous eye problems before onset of initial symptoms.

Generally, the spasms occur during the day, disappear in sleep, and reappear after waking. As the condition progresses, the spasms may intensify, forcing the eyelids to remain closed for long periods of time, and thereby causing substantial visual disturbance or functional blindness. It is important to note that the blindness is caused solely by the uncontrollable closing of the eyelids and not by a dysfunction of the eyes. BEB occurs in both men and women, although it is especially common in middle-aged and elderly women.

The early symptoms of blepharospasm include occasional, involuntary winking, blinking, or squinting of one or both eyes. It may also manifest itself as an increased difficulty in keeping the eyes open. Light sensitivity is a common occurrence with blepharospasm patients. As the condition progresses, the eyelid spasms increase in frequency and severity until they are unremitting, leaving both eyelids clamped shut and the eyebrows pulled down. In some cases, only one eye is affected.

A specific etiology for blepharospasm has yet to be identified. Some patients with blepharospasm report a familial occurrence of the affliction. In families with autosomal dominant familial dystonia, affected members may have a generalized or segmental dystonia, while other members have various focal dystonias, such as isolated blepharospasm.

blepharospasm (BEB) is a rare neurological disorder in which affected individuals experience involuntary muscle spasms and contractions of the muscles around the eyes. These spasms come and go (intermittent). Symptoms may begin as eye twitching, blinking and/or irritation. Eventually, BEB causes involuntary closure of the eyes. The exact cause of BEB is unknown. The disorder is one of a group of disorders collectively known as dystonia.

Excessive blinking and/or eye irritation usually signal the onset of blepharospasm. Initially, it may only occur in response to triggers such as stress, tiredness or bright light. If the condition progresses, the spasms happen more frequently. This not only makes performing everyday tasks difficult, but may make it impossible for the affected person to see at all.