Common cases in nystagmus

 
Nystagmus may appear daunting in the examination. However, if you follow the steps outlined in the section on 
Clinical Techniques most cases can be diagnosed easily. 
Although there are many ways of classifying nystagmus (according to the type or onset etc), the following features 
can be useful in determining the causes:
  • Is the nystagmus present in primary position or only in eccentric gaze
  • Is the nystagmus pendular (equal velocity in both directions) or jerky (possessing a fast and slow phase)?
  • Is the disorder binocular or monocular/dissociated?
Algorithm in the diagnosis of nystagmus

In the examination, the examiners will usually ask you to look at the patient's eyes. Always remember to observe 
the patient's eyes closely in their primary position for at least 20 seconds so as not to miss the signs.

Remember to describe the nystagmus as follow:

  • Position: primary or gaze-related
  • Type: pendular, jerk (the direction of the nystagmus refers to the fast phase)
  • Rate: rapid or slow
  • Plane: horizontal, vertical or rotary
  • Null zone: nystagmus is minimal in this field of gaze (this may be left or right or on convergence)

The most common cases are : Ataxic nystagmus (internuclear ophthalmoplegia) is usually seen in ocular motility examiantion and latent 
nystagmus in infantile esotropia is usually presented in cover/uncover tests.

 
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Jerk nystagmus due to cerebellar disease

The nystagmus is jerky with large amplitude and low frequency. It may be present in the primary position. The nystagmus 
increases when the eyes look in the direction of the fast phase.
Other additional examination:

  • mention to the examiner that you would like to test for other cerebellar signs such as scanning speech, intention 

    • tremor, past-pointing, disdianochokinesia and wide-based gaits
  • mention you would like to test the hearing and corneal sensation for possible cerebellopontine lesion
  • ask to examine the fundus for optic atrophy (as cerebellar signs and optic neuritis are common in multiple sclerosis)


Question: 
List some of the nystagmus with localizing signs.


 
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Down-beat nystagmus

There is nystagmus in the primary position with the fast phase beating downward. The nystagmus remains down-beating 
in different directions of gaze. Lateral gaze usually accentuates the nystagmus.

Other examination

  • mention that the nystagmus is associated with cervicomedullary lesion such as Arnold-Chiari malformation. Examine the 

    • back of the neck for any surgical scar. 


Question: 
What are the causes of a down-beat nystagmus?


 

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See-saw nystagmus

There is torsional nystagmus in the primary position. When one eye elevates and intorts the other depresses and extorts 
and vice-versa. This typical of lesion in chiasmal region.

Other examination:

  • mention you would like to examine the visual field for bitemporal hemianopia
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Congenital nystagmus

There is pendular nystagmus in the primary position. This may be horizontal, vertical or rotary. The nystagmus decreases on 
convergence but increases on covering one eye. There may be abnormal eye posture in an attempt to keep the eyes in the null 
point.

Further examination:

  • mention to the examiner that you would like to examine the anterior segment for congenital cataract, aphakia from 

    • previous cataract operation, albinism, aniridia or corneal abnormalities. Also examine the posterior segment for 
    optic nerve hypoplasia, dragged discs from retinopathy of prematurity and foveal hypoplasia.


Question: 

How would you manage a child with congenital nystagmus?


 

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