Nystagmus

Nystagmus is an eye condition characterized by rapid, jerking eye movements. It does not always cause noticeable symptoms, but it can be associated with dizziness and vision problems. Several different neurological illnesses can cause nystagmus.

Typically, nystagmus is detected during a physical examination that involves an eye evaluation. It may be an early sign of a neurological condition, such as multiple sclerosis (MS), or it can develop as an already established neurological illness progresses. You may need treatment to help reduce your nystagmus and/or the accompanying effects.

In this article, we will explore the symptoms and causes of nystagmus, as well as how it is diagnosed and treated.

What Is Nystagmus?

Nystagmus is a condition where the eyes move on their own, typically in quick, jerky movements. Nystagmus looks like a rapid, rhythmic, horizontal (side to side) motion in the eyes. Vertical (up and down) or rotary (moving in a circle) nystagmus can also occur, but these patterns are not typical.

Nystagmus typically affects both eyes, but it can rarely affect just one eye. The jerking movements are not usually present all the time, and nystagmus is often more noticeable when looking to one side or the other. In severe cases, eye jerking can be present all the time, even when looking straight ahead (not to the side).

Symptoms of Nystagmus

Common symptoms of adult-acquired nystagmus (which differs from congenital nystagmus) include:

• Dizziness
• Vertigo (a feeling that the room is spinning or that you are spinning)
• Diminished balance
• Nausea or vomiting
• Double or blurred vision
• Headaches, irritability
• A sense that visible objects are rhythmically jumping

You can experience all or some of these symptoms when you have nystagmus. However, when nystagmus is present for a long time, the symptoms are not evident.

Sometimes, nystagmus can be so severe that it affects your balance. Sudden episodes (such as when it is induced by twirling) can make you so dizzy that you could fall and get hurt.

Causes of Nystagmus

Nystagmus is a symptom of some neurological illnesses and conditions that involve the inner ear. Many neurological diseases can be associated with eye jerking. Some of the conditions that cause nystagmus are serious and life-threatening, such as a brain tumor. Others are not associated with serious health risks, such as lazy eye.

Common Risk Factors

The conditions that increase your risk of nystagmus do not always produce it. Nystagmus is a relatively uncommon sign of neurological or inner ear disease.

Twirling: Twirling around in a circle for a few minutes and then stopping can cause a brief period of nystagmus that affects both eyes. This is generally harmless, but you may feel dizzy for minutes or even the day afterward.

Strabismus (lazy eye): A congenital (from birth) difference may cause the eyes to be misaligned, causing a visibly obvious effect: a lazy eye. Sometimes, nystagmus can occur with a lazy eye, especially when you look to the extreme left or right.

Ménière’s disease: A condition characterized by episodes of severe vertigo and possible hearing loss, Ménière’s disease is often associated with rhythmic eye jerking, especially during the attacks.

Multiple sclerosis (MS): This condition can cause various neurological symptoms because it can affect different areas of the brain, spinal cord, and/or optic nerve (the nerve that controls vision). MS may cause permanent or intermittent episodes of nystagmus in one or both eyes.

Brain tumor: A primary brain tumor (a tumor that starts in the brain) or a metastatic cancer from elsewhere in the body can invade or impinge on the cranial nerves, brainstem, or cerebellum in a manner that causes nystagmus to develop.

Labyrinthitis: Inflammation of the inner ear is described as labyrinthitis. It can occur due to an infection or inflammatory disease, or it may be idiopathic (without an identifiable cause). This condition can cause dizziness, nausea, and vomiting, and your eye examination may show nystagmus. Generally, labyrinthitis is characterized by severe symptoms, but it is not typically associated with serious or life-threatening health risks.

Stroke: An interruption in blood flow in the brain can cause brain damage. In rare instances, a stroke can result in nystagmus.

Paraneoplastic syndrome: Several types of cancer can produce antibodies (immune cells) that attack a person’s own body, causing paraneoplastic syndrome, a rare cancer side effect. Nystagmus is one of the common symptoms of paraneoplastic syndromes. Ovarian cancers and adrenal cancers are examples of cancers that may have this effect.

Congenital difference: Some children are born with nystagmus, and it may begin during infancy. Symptoms can also occur during later childhood due to a hereditary condition. Childhood nystagmus can result from ocular albinism, an X-linked genetic disorder characterized by vision abnormalities and decreased pigment in the iris (the colored part of the eye around the pupil) of affected males.

Medications: Some medications can cause nystagmus as a side effect. Examples include Dilantin (phenytoin), Tegretol (carbamazepine), and barbiturates. These medications interfere with nerve function, and the nystagmus should wear off after the medication is metabolized from the body.

Alcohol: Alcohol intoxication can temporarily affect the nerves that control balance, resulting in coordination problems and nystagmus.

Trauma: A traumatic injury can cause damage to the brain, nerves, or muscles that control eye movement, resulting in nystagmus.

Control of Eye Movements 

A few areas of the brain and inner ear are involved with coordinating eye movements. A permanent injury or temporary deficit involving any of these areas can interfere with regular eye movements, causing several potential vision and/or balance problems, including nystagmus.

Nystagmus can result from impairment of any of the following structures:

Cerebellum: The cerebellum is the region of your brain that controls balance. Damage to the cerebellum, such as from a tumor or stroke, may cause nystagmus. Additionally, the antibodies in paraneoplastic syndromes cause nystagmus by targeting the cerebellum.

Cranial nerves: Three pairs of cranial nerves control eye movement muscles (each eye is controlled by one nerve of each pair). Damage to these nerves can interfere with eye muscles, causing nystagmus.

• The oculomotor nerve (cranial nerve three) controls several muscles that move your eyes: the superior rectus muscle, the medial rectus muscle, the inferior rectus muscle, and the inferior oblique muscle. These muscles move your eyes straight up and down and toward your nose.
• The trochlear nerve (cranial nerve four) controls the superior oblique muscle that moves your eye in a direction that is down and away from your nose.
• The abducens nerve (cranial nerve six) controls the lateral rectus muscle, which moves your eye outward and away from your nose.
• The vestibulocochlear nerve (cranial nerve eight) mediates your sense of sound and balance. It does not control eye movement, but a deficit in this nerve can impair balance to a degree that causes nystagmus.

Brainstem: The cranial nerve fibers and the nerve fibers of the cerebellum run through the brainstem, an area of the brain that links the brain with the spinal cord. For this reason, a disease that involves the brainstem (such as bleeding or stroke) may cause nystagmus.

Inner ear: The inner ear contains many tiny structures that control hearing and help mediate balance. Inflammation, infections, and tumors involving the inner ear can cause nystagmus.

Diagnosing Nystagmus

Even if you have many associated symptoms, nystagmus is typically unnoticeable in day-to-day life. You are unlikely to notice your jerky eye movements. Seeing your nystagmus in the mirror is very difficult because the movements tend to be more intense when you look to the side. Sometimes, family or friends may notice your eyes jerking when they look at you.

During a medical examination, nystagmus is typically identified in a healthcare provider’s office. Your practitioner may check for nystagmus when doing a neurological examination during your yearly physical. Your eye muscles will be tested as you are asked to look toward each side with both eyes simultaneously and hold your gaze for a few seconds. Your eye doctor would also notice nystagmus during a routine eye examination (such as for your glasses or contact lenses).

Diagnostic examinations you may need include:

• Eye examination: There are several steps in an eye examination. Your healthcare provider will usually check your visual acuity (how well you can see close and faraway objects) with an eye chart. You will also have an examination measuring the distance between your pupils. This test can assess any differences in eye movement between your eyes and help identify a lazy eye. Your healthcare provider may measure the speed and direction of your eye movements, and this assessment can include a video of your eye movements.
• Brain imaging: Tests such as brain computerized tomography (CT) or magnetic resonance imaging (MRI) can identify structural issues in the brain and inner ear, such as tumors and strokes. These conditions can affect the function of the cerebellum, cranial nerves, or inner ear, resulting in nystagmus.
• Electronystagmography (ENG): This diagnostic study evaluates dizziness, vertigo, or nystagmus. ENG is a noninvasive test that objectively measures the function of the oculomotor and vestibular nerves and can help pinpoint whether one of these nerves is impaired.

Treating Nystagmus

Several treatments are used to help reduce the effects of nystagmus. Medications may be prescribed to decrease the eye-jerking movements. Sometimes, treatment is also needed to lessen the associated nausea and dizziness.

Additionally, if you have a neurological condition causing you to have nystagmus, you may need to use rehabilitative therapy for the management of your neurological disease.

Vision Correction

If a vision deficit is causing you to have nystagmus, you may need to use corrective lenses to help correct your vision. In some situations, surgical vision correction is considered the best option.

Control of Eye Jerking 

Prescriptions used to diminish nystagmus include oral Firdapse (amifampridine), Lioresal (baclofen), Klonopin (clonazepam), and Neurontin (gabapentin). These medications may temporarily diminish your nystagmus but are not expected to cure it.

Symptomatic Therapies 

If dizziness, nausea, and/or vomiting are problematic, your healthcare provider might recommend over-the-counter or prescription therapy to help alleviate these effects.

Medical Management of Neurological Disease 

You may need to have medical therapy to treat the cause of your nystagmus. This can include disease-modifying therapy for the management of MS, anti-inflammatory medication to manage Ménière’s disease, or antibiotics to treat an inner ear infection.

Botox

Botox (botulinum toxin) injections can weaken and relax eye muscles. This is not the same as cosmetic botox; it requires great care to avoid harming the eyes and nearby structures.

Botulinum toxin weakens muscles, and when used for the treatment of nystagmus, it reduces the compensatory nystagmus that occurs when the eye muscles are not of equal strength.

Surgery

In some situations, eye surgery can repair muscle defects causing nystagmus. You may need treatment for a brain tumor or an inner ear tumor. Treatment approaches for a tumor include surgical removal, radiation therapy, and/or chemotherapy.

Rehabilitation 

Sometimes, therapy using rehabilitation techniques may be effective in strengthening eye muscles. If mild eye muscle weakness is the cause of your nystagmus, this can alleviate the problem.

Summary

Nystagmus is often a symptom of neurological disease. If your eye jerking is causing discomfort, you may need to have it treated.

Sometimes, nystagmus doesn’t cause any bothersome symptoms and can be discovered incidentally (by chance) when your healthcare provider examines your eyes. Sometimes, nystagmus is the first clue that you have a neurological disorder. In these instances, you may need a thorough medical evaluation to identify the cause of your eye jerking. Treatment for the neurological conditions that cause nystagmus is usually necessary.