Nystagmus: Eyes in Motion 2017-10-18T08:54:28+00:00

Nystagmus: Eyes in Motion

eyesMany children with complex medical issues, especially those with brain injuries or cerebral palsy, may experience nystagmus, or involuntary eye movements. While some forms of nystagmus are not serious, others may be the result of treatable conditions. Finding the cause of the nystagmus and treating it, if possible, may result in improved vision for your child.

Causes and Types of Nystagmus

We all experience nystagmus from time to time. Try spinning in a chair for a few minutes or going on a roller coaster, and you may find your eyes twitching involuntarily in response to your disorientation.

Some children are born with nystagmus, either as an isolated condition, or associated with an underlying anomaly, such as albinism, cataracts, Noonan syndrome, or a brain injury at birth. Other children may develop nystagmus later on, either due to an acquired condition, a medication reaction, or a progressive disease.

Among children who are complex, many have nystagmus from birth due to brain injuries or other neurological conditions that impair the brain’s ability to control the eyes. Other children who are complex may also develop nystagmus as part of a progressive neurological disorder. In these children, an attempt may be made to treat nystagmus with medication, but more often than not, it is a persistent symptom that can only be addressed through compensatory strategies.

In some children, nystagmus may develop due to a newly acquired disorder of the eyes, ears, or vestibular system. The vestibulo-ocular reflex can be affected whenever a disorder occurs that impacts the inner ear, balance, or the eyes. This reflex is largely controlled by the inner ear, and helps the eyes stabilize and see even when the head is moving. Nystagmus may occur if the inner ear does not work properly, the vestibular system is affected by dizziness, or the eye is unable to respond to the ear’s signals.

There are many different forms of nystagmus, defined by which way the pupil moves. Nystagmus can be unilateral or bilateral, affecting one eye or both. The pattern may be horizontal, moving from side to side, or vertical, moving from top to bottom or bottom to top. In some cases, the nystagmus may always go in one direction, such as horizontally to the left, and in other cases, the pattern may vary. The pupil may even rotate in a circle in some children.

The following is a list of types of nystagmus and their causes:¹

  • Seesaw nystagmus
    • Rostral midbrain lesions
    • Parasellar lesions (eg, pituitary tumors)
    • Visual loss secondary to retinitis pigmentosa
  • Downbeat nystagmus
    • Lesions of the vestibulocerebellum and underlying medulla, including the following:
      • Arnold-Chiari malformation
      • Demyelination (eg, multiple sclerosis)
      • Microvascular disease with vertebrobasilar insufficiency
      • Brain stem encephalitis
      • Tumors at the foramen magnum (eg, meningioma, cerebellar hemangioma)
    • Trauma
    • Drugs (eg, alcohol, lithium, antiseizure medications)
    • Nutritional (eg, Wernicke encephalopathy, parenteral feeding, magnesium deficiency)
    • Heat stroke
    • Approximately 50% have no identifiable cause
  • Upbeat nystagmus
    • Medullary lesions, including perihypoglossal nuclei, the adjacent medial vestibular nucleus, and the nucleus intercalatus (structures important in gaze holding)
    • Lesions of the anterior vermis of the cerebellum
    • Benign paroxysmal positional vertigo
  • Periodic alternating nystagmus
    • Arnold-Chiari malformation
    • Demyelinating disease
    • Spinocerebellar degeneration
    • Lesions of the vestibular nuclei
    • Head trauma
    • Encephalitis
    • Syphilis
    • Posterior fossa tumors
    • Binocular visual deprivation (eg, ocular media opacities)
  • Pendular nystagmus
    • Demyelinating disease
    • Monocular or binocular visual deprivation
    • Oculopalatal myoclonus
    • Internuclear ophthalmoplegia
    • Brain stem or cerebellar dysfunction
  • Spasmus nutans
    • Usually occurs in otherwise healthy children
    • Chiasmal, suprachiasmal, or third ventricle gliomas may cause a condition that mimics spasmus nutans
  • Torsional – Lateral medullary syndrome (Wallenberg syndrome)
  • Abducting nystagmus of internuclear ophthalmoplegia
    • Demyelinating disease
    • Brain stem stroke
  • Gaze evoked
    • Drugs – Anticonvulsants (eg, phenobarbital, phenytoin, carbamazepine) at therapeutic dosages
    • Alcohol

Diagnosis

In many cases, if a child has an underlying neurological disorder or a progressive disease, nystagmus may be explained by the contributory condition. But if the nystagmus is new or of sudden onset, a child may need a diagnostic workup.

In some children, assessing the pattern of the nystagmus and determining any other symptoms can help to identify a diagnosis. For example, nystagmus with dizziness suggests a vestibular or balance disorder, while nystagmus with deafness may be caused by labyrinthitis, an inflammation of the inner ear.

Other children may require visual and vestibular testing, such as visual reflex testing. If the ear is suspected as a cause, caloric testing, which introduces hot or cold water into the ear inducing nystagmus, may help solidify a diagnosis.

Treatment

Treatment for nystagmus depends on the underlying cause of the disorder. For example, if there is a problem with the inner ears, treatment of that condition may eliminate the problem. Similarly, treatment of brain tumors, removal of a medication causing the problem, or treatment of eye conditions can improve or eliminate the nystagmus. Physical therapy for balance or vestibular problems may help individuals with these conditions improve their nystagmus.

In cases where the underlying disorder cannot be treated, other treatments may be possible. For example, the use of prisms may help certain types of nystagmus. Other types may improve with botox injections or surgery of the eyes. Medications that relax muscles or target the nerves, such as Baclofen, Benzodiazepines such as Valium, or Neurontin/Lyrica, may help in some cases.

Unfortunately, many children continue to have nystagmus despite treatment, or are not eligible for treatment. In these cases, the best treatment is vision therapy, which may help them to overcome the visual side effects of nystagmus, which may include problems with visual acuity and depth perception. Many children can learn or be taught to find the “null point” in their vision, which is the best position of the head and eye that allows them to see clearly.

Nystagmus can be a challenging condition, affecting multiple senses as well as balance. Determining the type of nystagmus and attempting to treat it or learn to compensate for it can dramatically improve vision, hearing, and/or balance for some children.

Author: Susan Agrawal • Date: 2/26/2012

1http://emedicine.medscape.com/article/1199177-clinical#a0218

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