Medical term:

nystagmus

Nystagmus

Definition

Rhythmic, oscillating motions of the eyes are called nystagmus. The to-and-fro motion is generally involuntary. Vertical nystagmus occurs much less frequently than horizontal nystagmus and is often, but not necessarily, a sign of serious brain damage. Nystagmus can be a normal physiological response or a result of a pathologic problem.

Description

The eyes play a critical role in maintaining balance. They are directly connected to other organs of equilibrium, most important of which is the inner ear. Paired structures called the semicircular canals deep in the skull behind the ears sense motion and relay that information to balance control centers in the brain. The eyes send visual information to the same centers. A third set of sensors consists of nerve endings all over the body, particularly in joints, that detect position. All this information is integrated to allow the body to navigate in space and gravity.

It is possible to fool this system or to overload it with information so that it malfunctions. A spinning ride at the amusement park is a good way to overload it with information. The system has adapted to the spinning, expects it to go on forever, and carries that momentum for some time after it is over. Nystagmus is the lingering adjustment of the eyes to tracking the world as it revolves around them.

Nystagmus can be classified depending upon the type of motion of the eyes. In pendular nystagmus the speed of motion of the eyes is the same in both directions. In jerk nystagmus there is a slow and fast phase. The eyes move slowly in one direction and then seem to jerk back in the other direction.

Nystagmus can be present at birth (congenital) or acquired later on in life. A certain type of acquired nystagmus, called spasmus nutans, includes a head tilt and head bobbing and generally occurs between four to 12 months of age. It may last a few months to a few years, but generally goes away by itself.

Railway nystagmus is a physiological type of nystagmus. It happens when someone is on a moving train (thus the term railway) and is watching a stationary object which appears to be going by. The eyes slowly follow the object and then quickly jerk back to start over. Railway nystagmus (also called optokinetic nystagmus) is a type of jerk nystagmus. This phenomenon can be used to check vision in infants. Nystagmus can also be induced by fooling the semicircular canals. Caloric stimulation refers to a medical method of testing their connections to the brain, and therefore to the eyes. Cold or warm water flushed into the ear canal will generate motion signals from the inner ear. The eyes will respond to this signal with nystagmus if the pathways are intact.

Causes and symptoms

There are many causes of nystagmus. Nystagmus may be present at birth. It may be a result of the lack of development of normal binocular fixation early on in life. This can occur if there is a cataract at birth or a problem is some other part of the visual system. Some other conditions that nystagmus may be associated with include:

Albinism. This condition is caused by a decrease in pigmentation and may affect the eyes.
Disorders of the eyes. This may include optic atrophy, color blindness, very high nearsightedness (myopia) or severe astigmatism, or opacities in the structures of the eyes.
Acute labyrinthitis. This is an inflammation in the inner ear. The patient may have dizziness (vertigo), nausea and vomiting, and nystagmus.
Brain lesions. Disease in many parts of the brain can result in nystagmus.
Alcohol and drugs. Alcohol and some medications (e.g., anti-epilepsy medications) can induce or exaggerate nystagmus.

Multiple sclerosis. A disease of the central nervous system.

Diagnosis

Nystagmus is a sign, not a disease. If abnormal, it indicates a problem in one of the systems controlling it. An ophthalmologist and/or neuro-ophthalmologist should be consulted.

Treatment

There is one kind of nystagmus that seems to occur harmlessly by itself. The condition, benign positional vertigo, produces vertigo and nystagmus when the head is moved in certain directions. It can arise spontaneously or after a concussion. Motion sickness medicines sometimes help. But the reaction will dissipate if continuously evoked. Each morning a patient is asked to produce the symptom by moving his or her head around until it no longer happens. This prevents it from returning for several hours or the entire day.

Prisms, contact lenses, eyeglasses, or eye muscle surgery are some possible treatments. These therapies may reduce the nystagmus but may not alleviate it. Again, because nystagmus may be a symptom, it is important to determine the cause.

Resources

Organizations

American Academy of Ophthalmology. 655 Beach Street, P.O. Box 7424, San Francisco, CA 94120-7424. http://www.eyenet.org.

American Optometric Association. 243 North Lindbergh Blvd., St. Louis, MO 63141. (314) 991-4100. http://www.aoanet.org.

nystagmus

[nis-tag´mus]

involuntary, rapid, rhythmic movement (horizontal, vertical, rotatory, or mixed, i.e., of two types) of the eyeball. adj., adj nystag´mic.

amaurotic nystagmus nystagmus in the blind or in those with defects of central vision.

amblyopic nystagmus nystagmus due to any lesion interfering with central vision.

aural nystagmus labyrinthine nystagmus.

caloric nystagmus rotatory nystagmus in response to caloric stimuli in the ear, seen during the caloric test.

Cheyne's nystagmus a peculiar rhythmical eye movement resembling Cheyne-Stokes respiration in rhythm.

congenital nystagmus (congenital hereditary nystagmus) nystagmus usually present at birth, usually horizontal and pendular, but occasionally jerky and pendular; the nystagmus may be caused by or associated with optic atrophy, coloboma, albinism, bilateral macular lesions, congenital cataract, severe astigmatism, and glaucoma.

dissociated nystagmus that in which the movements in the two eyes are dissimilar.

end-position nystagmus that occurring only at extremes of gaze.

fixation nystagmus that occurring only on gazing fixedly at an object.

gaze nystagmus nystagmus made apparent by looking to the right or to the left.

labyrinthine nystagmus vestibular nystagmus due to labyrinthine disturbance.

latent nystagmus that occurring only when one eye is covered.

lateral nystagmus involuntary horizontal movement of the eyes.

optokinetic nystagmus nystagmus induced by looking at objects moving across the visual field.

pendular nystagmus nystagmus in which the oscillations of the eyes have an equal rate, amplitude, direction, and type of movement.

positional nystagmus that which occurs, or is altered in form or intensity, on assumption of certain positions of the head.

retraction nystagmus (nystagmus retracto´rius) a spasmodic backward movement of the eyeball occurring on attempts to move the eye; a sign of midbrain disease.

rotatory nystagmus involuntary rotation of the eyes about the visual axis.

secondary nystagmus nystagmus occurring after the abrupt cessation of rotation of the head, caused by the labyrinthine fluid continuing to move.

spontaneous nystagmus that occurring without specific stimulation of the vestibular system.

vertical nystagmus involuntary up-and-down movement of the eyes.

vestibular nystagmus nystagmus due to disturbance of the labyrinth or of the vestibular nuclei; the movements are usually jerky.

nys·tag·mus

(nis-tag'mŭs),

Involuntary rhythmic oscillation of the eyeballs, either pendular or with a slow and fast component.

[G. nystagmos, a nodding, fr. nystazō, to be sleepy, nod]

Farlex Partner Medical Dictionary © Farlex 2012

nystagmus

(nĭ-stăg′məs)

A rapid, involuntary, oscillatory motion of the eyeball.

nys·tag′mic (-mĭk) adj.

nystagmus

Ophthalmology Rapid involuntary oscillary eye movements Directions Horizontal, vertical, rotary. See Caloric nystagmus, Irritative nystagmus, Paralytic nystagmus, Recovery nystagmus, Opticokinetic nystagmus, Seesaw nystagmus.

nys·tag·mus

(nis-tag'mŭs)

Rhythmic oscillation of the eyeballs, either pendular or jerky.

[G. nystagmos, a nodding, fr. nystazō, to be sleepy, nod]

nystagmus

Persistent, rapid, rhythmical, jerky or wobbling movement of the eyes, usually together. The movement is usually transverse and most commonly of a ‘sawtooth’ pattern with a slow movement in one direction followed by a sudden recovery jerk in the other. This kind of nystagmus is often CONGENITAL and, in this case, although associated with some reduction in visual acuity, is usually of little significance. Nystagmus may also be pendular or, when vision is very poor, of a searching type. Acquired nystagmus is always of significance as it implies an acquired disorder of the nervous system.

nystagmus

A regular, repetitive, involuntary movement of the eye whose direction, amplitude and frequency are variable. Nystagmus can be induced, acquired or congenital. (In a very small percentage of people it can even be induced voluntarily.) These eye movements typically appear as one of two types: pendular nystagmus or jerk nystagmus (Fig. N3). Jerk nystagmus is one in which there is a slow and fast phase, the nystagmus being conventionally defined by the direction of the fast phase. A feature of jerk nystagmus is the null zone (or null point) which represents the direction of gaze at which the nystagmus has the smallest amplitude. A jerk nystagmus is usually due to a motor defect that may be induced by brainstem or cerebellar lesions, drug intoxication (upbeat nystagmus in which the fast phase is in the upward direction or downbeat nystagmus in which the fast phase is downward); associated with a lesion of the central nervous system or the vestibular nerve or nuclei (central nystagmus and vestibular nystagmus); or to disease or injury to the labyrinth (labyrinth nystagmus); or to multiple sclerosis. Jerk nystagmus can also be induced physiologically, as for example optokinetic nystagmus (OKN) or train nystagmus, which occurs when watching objects that traverse the visual field rapidly, or as a result of thermal stimulation of the labyrinth of the inner ear by cold or hot water (caloric nystagmus or Barany's nystagmus), or when the eyes of a fatigued person are turned into an extreme position of gaze (end-point nystagmus), or when a person who had been spinning round is stopped (vestibular nystagmus).The other type is a nystagmus which is characterized by movements of equal velocity in each direction, the pendular nystagmus. A pendular nystagmus usually occurs as a result of poor central vision (sensory deprivation nystagmus) as in bilateral chorioretinitis, total colour blindness, albinism, congenital cataract, corneal scarring, amblyopia (amblyopic nystagmus) or in coal miners after many years of working in the dark (miner's nystagmus). In some cases one eye rotates upward and intorts while the other rotates downward, and extorts (see-saw nystagmus as a result of brainstem stroke, chiasmal lesion or multiple sclerosis). In some cases there is a mixture of the two main types; pendular in the primary position and jerk on lateral gaze (mixed nystagmus). The movements of the eyes are usually the same in both eyes (conjugate nystagmus) but in other cases they may be unrelated as a result of internuclear ophthalmoplegia (dissociated nystagmus). Examples of the latter are end-gaze nystagmus, convergence-retraction nystagmus and see-saw nystagmus. Or the eye movements are of equal amplitude and type but in opposite or different directions (disjunctive nystagmus), also commonly associated with internuclear ophthalmoplegia. There are also cases of unknown origin (idiopathic nystagmus). See hereditary spinal ataxia; Wernicke's disease; foveation period; Alexander's law; monochromat; internuclear ophthalmoplegia; oscillopsia; yoke prisms; Faden procedure; vestibulo-ocular reflex; spasmus nutans; Down's syndrome; optokinetic nystagmus test.
nystagmus blockage syndrome See nystagmus blockage syndrome.
caloric nystagmus See caloric testing.
congenital nystagmus A motor nystagmus that is present at birth or soon after. It may be inherited as X-linked recessive or autosomal dominant, or induced in the uterus, and results from decreased vision due to corneal opacity, cataract, albinism, aniridia, macular disease or optic atrophy. It is typically a horizontal jerk nystagmus and it may be associated with abnormal head movement and decreases in intensity with convergence. The visual prognosis is reasonably good, but if the head turn is excessive, extraocular muscle surgery may be needed. See spasmus nutans.
convergence-retraction nystagmus A jerk nystagmus which appears on attempted upward gaze and in which the fast phase brings the two eyes towards each other in a convergent movement with retraction of the globes into the orbit. It may result from a lesion affecting the tectum or dorsal midbrain or a pineal tumour, or form part of Parinaud's syndrome. See pinealoma.
gaze-evoked nystagmus An acquired form of horizontal nystagmus characterized by a jerk nystagmus on eccentric gaze with the fast phase towards the direction of gaze. This type of nystagmus is believed to be due to cerebellar or brainstem disease affecting the conjugate gaze centres.
occlusion nystagmus A form of nystagmus occurring when one eye is covered, or which increases in intensity when one eye is covered. The nystagmus is typically of the horizontal, jerk variety, with the fast phase occurring in the direction of the occluded eye.
physiological nystagmus See fixation movements.
rotary nystagmus A very rare form of nystagmus in which the eyeball makes a movement about the visual axis. It may result from a lesion to the vestibular nerve. See vestibular nystagmus.
sensory nystagmus A form of nystagmus thought to be due to an abnormality in the afferent mechanism. It is most often due to inadequate image stimulation of the macula, leading to abnormal development of the ocular fixation reflex. Causes include congenital cataracts, optic nerve hypoplasia, aniridia, albinism, achromatopsia, as well as Leber's congenital amaurosis.
vestibular nystagmus There are two main types of vestibular nystagmus: Peripheral vestibular nystagmus results from stimulation, injury or disease (e.g. Menière's disease) of the labyrinth or of the vestibulo-cochlear nerve (VIII). It presents as a jerk, mainly horizontal, nystagmus with a torsional component. It may be accompanied by vertigo, tinnitus and hearing loss. Fixation inhibits the nystagmus. Central vestibular nystagmus results from stimulation, injury, disease of the central vestibular pathways of the brainstem or the cerebellum, or lesion of the vestibular nuclei. It is typically a jerk nystagmus, which can be purely horizontal, vertical or torsional. It is not inhibited by fixation.

Fig. N3 The two main types of nystagmus, jerk and pendular

nys·tag·mus

(nis-tag'mŭs)

Involuntary rhythmic oscillation of the eyeballs.

[G. nystagmos, a nodding, fr. nystazō, to be sleepy, nod]

Patient discussion about nystagmus

Q. My granddaughter has Nystagmus, diagnosed when she was about 9 month old. Is there a community for Nystagmus? We have taken her to see Paediatric Ophthalmologists in Singapore on a regular basis,since last year July. The little girl seems to be sensitive to light, especially white light. She can hardly open her eyes outside the house during day time.In the late evenings. she seems to be comfortable and can actually see things well. The eyes seem to be ok with house lightings at night.

A. Not specifically for nystagmus, but there is a community about eye disorders (http://www.imedix.com/Eye_Disorder) .

More discussions about nystagmus

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