Nystagmus
Background
- Nystagmus = involuntary eye movement
- The semicircular canals of the vestibules and the extraocular muscles of the eye function together physiologically to help control gaze when the head is in motion
- Nystagmus is an aberration in this stabilization of the ocular muscles when the head is in motion
Clinical Features
- Rapid, uncontrolled, rhythmic oscillation of the eye
- May be horizontal, vertical, and/or rotary
Differential Diagnosis
Congenital Nystagmus
- Optic nerve hypoplasia
- Macular disease
- Noonan syndrome
Acquired Nystagmus
- Head trauma, tympanic membrane rupture
- Brain tumor
- Stroke
- Chiari malformation
- Meniere's disease, BPPV, labyrinthitis, Vestibular Neuritis
- Multiple sclerosis
- Wernicke-Korsakoff syndrome, thiamine deficiency
- Tox causes:
- Alcohol intoxication, benzodiazepines, barbiturates, GHB
- Ketamine, Phencyclidine
- Amphetamines, MDMA
- Marijuana
- Lithium
- Phenytoin, fosphenytoin, carbamazepine, oxcarbazepine, lacosamide, gabapentin
- Salicylates, NSAID toxicity
Evaluation
- Differentiate monocular vs. binocular
- Monocular suggests medial pontine stroke or medial longitudinal fasciculus damage
- Look for contralateral internuclear opthalmoplegia (INO)
- Differentiate between central versus peripheral lesions[1]
| Central | Peripheral |
| Pure vertical, pendular, or rotary | Horizontal |
| Fast beat towards lesions | Fast beat away from lesion |
| Not relieved by gaze fixation | Relieved by gaze fixation |
| Cerebellar signs | No cerebellar signs |
Optokinetic Drum Test
- Optokinetic reflex develops ~6 months of age
- Slow pursuit of eyes towards direction of vertical bar movement with quick saccade towards the opposite side to find the next bar to fixate on
- Abnormal in congenital nystagmus
- In parietal or parietal-occipital lesions, optokinetic nystagmus is impaired when the drum is rotated towards side of lesion
"H in space" Test
- Trace H in space
Caloric Reflex Test (also known as Vestibular Caloric Stimulation)
- The best clinical test for the Vestibulo-Optic reflex
- Water irrigated into the external auditory canal will exaggerate nystagmus if present
- Temperature of the irrigated water will control the direction.
- Cold water will exaggerate a nystagmus to move contralaterally
- Warm water will exaggerate a nystagmus to move ipsilaterally
COWS: Cold Opposite, Warm Same.
Management
Stabilize patient and manage primary cause of illness.
Disposition
See Also
External Links
References
- Bardorf CM et al. Acquired Nystagmus Clinical Presentation. Updated My 13, 2016. http://emedicine.medscape.com/article/1199177-clinical?src=refgatesrc1#b4.
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