Eyelid twitching, medically known as eyelid myokymia, is due to small, fast contractions of the muscle around the eye that controls closure of the eyelids; This muscle is called the orbicularis oculi. Typical presentation of myokymia is unilateral (one-sided) and impacts the lower eyelid more commonly than the upper eyelid. This condition is typically benign, in other words is not associated with any systemic or ocular disease and resolves without treatment. It is important to note that myokymia is not secondary to muscle loss or weakness, nor is it due to malfunction of one of the cranial nerves. In rare cases, eyelid myokymia may be a precursor to another condition called a blepharospasm which can be more difficult to treat. This condition will be discussed in greater detail below.
The main eyelid muscle (orbicularis oculi) is mostly composed of involuntary, fast twitch, striated muscle. The twitching occurs in intervals of about 100 microseconds, so it is often felt by patients, but not able to be observed by others. These contractions tend to be intermittent and transient. Though the pathophysiology is not well understood, some causative factors may be stress, fatigue, and/or excessive caffeine or alcohol intake. In very rare cases, myokymia has been found in patients with demyelinating conditions which is when the insulating sheaths around nerves and nerve endings are damaged. The most common demyelinating disease of the central nervous system is multiple sclerosis.
Differential diagnoses for myokymia include but are not limited to:
Hemifacial spasm:unilateral facial contraction due to dysfunction of cranial nerve seven, the facial nerve. The main function of cranial nerve seven is facial expression, but it also helps control taste and salivation. Patients appear to be winking even though they are not trying to do so.
Essential blepharospasm:presents as uncontrolled, bilateral (both eyes) blinking and lid closure. It is secondary to dystonia, a movement disorder that causes muscles to contract or spasm involuntarily. Blepharospasm was originally thought to be due to an underlying psychological disorder. However, it is now recognized as a neurological disorder that is due to an area in the brain that causes one to blink spontaneously and uncontrollably. BOTOX is a well-proven and effective treatment.
Multiple sclerosis: demyelination of nerves throughout the central nervous system. This rarely causes to myokymia. Patients with multiple sclerosis typically present with symptoms such as muscle fatigue, weakness, and pain on eye movements.
If no other underlying causes are suspected, myokymia is typically not treated. Physician’s typically recommend avoiding causative factors such as stress and caffeine/alcohol intake or encourage patients to get more sleep. If the eyelid twitching becomes more severe over time or does not resolve spontaneously, BOTOX injections can be used to alleviate symptoms. Typically, treatment will be administered over a course of 12-18 weeks, or as the physician sees fit. Negative side effects of Botox include facial paralysis, dry eye, and eyelid drooping also known as ptosis.