Occasional Nystagmus

4/4/2022 admin

Nystagmus is the most common issue causing visual impairment in children, and it affects approximately 1 in 1,000 people. Certain types are more common in one sex over the other, but both men and women can be affected. ^{(Learn More)}

16.2.1 Convergence–Retraction Nystagmus. Convergence–retraction nystagmus ( Fig. 16.16a) is not truly nystagmus, but rather bilateral adducting saccades causing convergence of both eyes, without any slow phase. It is most often elicited by having the patient attempt to look up, at which time the eyes converge and retract in the orbit. Intermittent Nystagmus Symptom Checker: Possible causes include Spasmus Nutans. Check the full list of possible causes and conditions now! Talk to our Chatbot to narrow down your search. Nystagmus is a condition of involuntary (or voluntary, in some cases) eye movement, acquired in infancy or later in life, that may result in reduced or limited vision. Due to the involuntary movement of the eye, it has been called 'dancing eyes'. In normal eyesight, while the head rotates about an axis, distant visual images are sustained by rotating eyes in the opposite direction of the. The nystagmus may be explained by epileptic activation of cortical saccade or pursuit regions, which caused contraversive quick or ipsiversive slow phases, the involvement of optokinetic or motion-sensitive regions, or epileptic discharges in the vestibular cortex.

This condition is a complex eye condition that causes involuntary eye movements. It can be present at birth or acquired later in life. ^{(Learn More)}

It is important that people get a definitive diagnosis, so a doctor can provide a proper treatment regimen. This includes a comprehensive eye examination. ^{(Learn More)}

There are many treatments that can help people with nystagmus. This includes both surgical and medical options. ^{(Learn More)} Some people may benefit from using several treatment methods, while others might only need one to reduce their symptoms.

Nystagmus Types & Symptoms

In most cases, people develop nystagmus at a young age. There are five primary types of nystagmus.

Manifest nystagmus: With this type, the symptoms are present at all times.
Latent nystagmus: With this type, the symptoms only occur when the person covers one of their eyes.
Manifest-latent nystagmus: With this type, the symptoms are always there, but when the person covers one eye, the symptoms get worse.
Congenital nystagmus: This is a type of nystagmus that is present when a person is born.
Acquired nystagmus: With this type, there is an underlying disease that causes the problem, such as multiple sclerosis, diabetic neuropathy, a brain tumor, or a head injury.

Uncontrollable rapid eye movements are the most common symptom of this condition. In most cases, the eyes move from side to side. However, there are times when the movement is circular or up and down. Both eyes are usually affected. The movement can be fast, slow, or transfer back and forth between the two.

There are other possible symptoms.

Dizziness
Vision issues
Needing to hold the head in a tilted or turned position
Trouble seeing when it is dark
The sensation that the world is shaking

Nystagmus Causes

Nystagmus usually results from a neurological issue that occurs early in life or is present at birth. However, some types of this condition are acquired. This means that a person could develop them later in life.

In some cases, nystagmus is a symptom of an underlying condition, such as a stroke, trauma, or multiple sclerosis.

Other possible causes of nystagmus include:

Children may not develop normal eye movements early in life.
Astigmatism, nearsightedness, or a very high refractive error.
Inner ear inflammation.
Central nervous system diseases.
Albinism
Congenital cataracts.
Anti-epilepsy drugs and certain other medications.

Diagnosing Nystagmus

The first step is a full physical examination. During this exam, the doctor usually focuses on the inner ear and nervous system. For part of the exam, the doctor usually has the person wear special goggles that magnify the eyes.

Learning more about the person’s medical history is also important since certain conditions can cause nystagmus.

If the person has a medical condition that can cause nystagmus, specific tests might be done that focus on this. For example, the doctor may do additional neurological testing if the person has multiple sclerosis.

The doctor will evaluate the person’s eyes and how they move. One test that can be used to look for nystagmus uses the following steps:

The doctor will have the person spin for approximately 30 seconds. Once they stop, they have to stare at an object. The doctor will be looking at their gaze and any involuntary eye movements that occur.
The doctor is looking for the person’s eyes to slowly move in one direction. Then, their eyes will move quickly in the other direction.

Other tests that might be done will depend on the results of the examination and the nystagmus testing. Other diagnostic methods could include:

This testing is done to record eye movements when the person is still. Electrodes are placed on the head to examine the person’s lateral eye movements.
Head CT scan. This test is done to get a better look at the structures of the brain and head. The person will lie on a table, and their head is usually put into a holder to ensure they are still. In some cases, the doctor may want to use a contrast dye for better visualization.
Head MRI. This imaging tests gets pictures of the person’s nerve tissues and brain. The doctor may use a contrast dye to get clearer photos of certain areas. No radiation is used during an MRI. This test takes an average of 30 to 60 minutes.

The doctor might also order vestibular testing. There are several different vestibular tests that may be done.

Videonystagmography (VNG) or electronystagmography (ENG): This testing is done to evaluate the person’s inner ear.
Computerized dynamic visual acuity: This test looks at how a person’s vestibular issues could be impacting their vision when they are doing everyday things, such as turning their head or taking a walk.
Rotary chair test: This test can be done if the doctor is trying to see if nystagmus is due to a brain or inner ear disorder.
Subjective visual vertical: This test examines a specific inner ear organ referred to as the utricle. It helps to see if a person’s nystagmus is due to an inner ear injury, vestibular neuritis, or certain nerves being injured.
Computerized dynamic posturography: This test will see how the person uses their vestibular, sensory, and visual systems during balance.
Vestibular evoked myogenic potential: This test evaluates whether the vestibular nerve and the saccule are working properly.

Treatment Options for Nystagmus

Surgery is not often performed, but some people may benefit from a procedure called strabismus surgery. The goal of this procedure is to reduce abnormal head positioning or to reduce nystagmus amplitude. This procedure usually does not completely eliminate nystagmus, but it could result in some vision improvement.

Another possible surgical option is called a tenotomy. Research shows that this procedure may broaden the null zone, improve visual acuity, and improve target acquisition. The procedure that was studied was the four-muscle tenotomy. The improvements that the researchers observed were when the person was in the primary position.

Botox may offer temporary relief from nystagmus symptoms. This is an injectable that can paralyze a muscle temporarily. By paralyzing the right muscles, it could potentially reduce a person’s involuntary eye movements. If Botox does work, the person would need to have it injected two or more times a year to continue reaping the benefits.

Medications may be helpful for some people. The type of nystagmus a person has dictates which medications might be helpful.

Downbeat nystagmus: 3,4-diaminopyridine, 4-aminopyridine, or clonazepam
Torsional nystagmus: gabapentin
Acquired pendular nystagmus: memantine, gabapentin, or trihexyphenidyl
Seesaw nystagmus: clonazepam, alcohol, or memantine
Upbeat nystagmus: 4-aminopyridine, memantine, or baclofen
Acquired periodic alternating nystagmus: memantine or baclofen
Infantile nystagmus: memantine, topical brinzolamide, gabapentin, or acetazolamide

These medications may not be effective for all people. It could take some trial and error to determine which medications at which doses are beneficial for a particular person. These may be combined with other treatments.

For most people with congenital nystagmus, there are no treatment options. The doctor works with the patient and their parents to determine if supportive care could be beneficial for improving the person’s quality of life.

There are cases where nystagmus resolves on its own. This is typically when someone has acquired nystagmus due to a medical condition. Treating the underlying condition could resolve the nystagmus.

While there is no cure for this condition, treatments methods can be beneficial for many people. This is true for both adults and children who have the condition.

As soon as nystagmus is suspected, it is important to see an eye doctor to get a definitive diagnosis.

Bilateral Nystagmus

Some types of nystagmus affect only one eye, while others affect both. When both eyes shake, this is called bilateral nystagmus.

There are two basic types of bilateral nystagmus.

Conjugate: This is when both eyes have the same movement, as though they are synchronized.
Dissociated: This occurs when both eyes move rapidly back and forth but differently.

There are also two basic terms for the rhythm of the eyes in nystagmus.

Pendular: This means that the movements back and forth have the same velocity.
Rhythmic: This is when the movement is slower in one direction and faster or jerkier in the other.

It is therefore possible to have a combination of these. For example, you may have pendular conjugate nystagmus or rhythmic dissociated nystagmus.

While some ophthalmologists diagnose bilateral vs. unilateral nystagmus, the medical community also believes that it is possible that “unilateral” only indicates asymmetric nystagmus, with one eye more affected than the other, but both eyes still affected by the condition.

As early as 1908, bilateral nystagmus was considered the most common type, or the “true” nystagmus, with equal, simultaneous, horizontal movements in the eyes. Vertical nystagmus, rotary nystagmus, and mixed nystagmus are much rarer.

Some severe conditions may cause vertical, rather than horizontal, nystagmus. These include the following:

Intoxication
Multiple sclerosis
Spasmus nutans
Lesions in some areas of the brain
Encephalitis lethargica

The most common cause of bilateral nystagmus, in general, is a vascular disease. This may include the following:

A stroke
Antiseizure medications
Head or eye trauma that damages the blood vessels

Nystagmus has several potential causes, so it is important to get help from your ophthalmologist if you develop this condition, or your child develops it.

Your vision can be seriously impacted in some cases. In others, you may not notice nystagmus, as the body develops it as a vision coping mechanism, especially when the form is bilateral nystagmus. This can be one of several other symptoms you experience, which indicate a severe underlying medical condition that requires help.

References

Nystagmus. Nystagmus Network.

A Guide to Nystagmus. All About Vision.

Nystagmus Symptoms. American Academy of Ophthalmology.

Nystagmus. American Optometric Association.

Nystagmus. MedlinePlus.

CT Scan of the Head/Brain. Cedars-Sinai.

Head MRI. MedlinePlus.

Common Vestibular Function Tests. American Physical Therapy Association.

Four-Muscle Tenotomy Surgery for Nystagmus. (September 2014). Current Opinion in Ophthalmology.

Nystagmus Treatment. (February 6, 2019). American Academy of Ophthalmology.