Nystagmus

Last updated 20.09.12

 

Index

 

Definition

-  Failure to hold lateral gaze

 

Features

-  Disturbance of ocular muscle tone maintaining eyes in midline

-  Correction is the rapid movement

-  Defined by rapid movement direction

-  Left nystagmus is rapid movement correcting leftwards

-  Characterise direction, latency & fatiguability

-  Often not present at rest & only elicited when eyes are deviated

-  Physiologically occurs at extremes of gaze

 

Classification

-  Jerky Horizontal = orizontal ossilations

-  Vestibular

-  Acute lesions nystagmus contralaterally

-  Chronic lesions nystagmus ipsilaterally

-  Cerebellar (ipsilateral)

-  Toxins

-  Internuclear opthalmoplegia (other eye fails to adduct)

-  Jerky Vertical = vertical ossilations

-  Bran stem lesion

-  Upbeat suggests mid brain or 4th ventricle

-  Downbeat suggests foramen magnum lesion

-  EtOH

-  Phenytoin

-  Pendular = equal duration of phases of eye movement

-  Retinal

-  Congenital

 

Causes

-  Vestibular (peripheral)

-  Tonic drive from left sends eyes to right, vice versa

-  Always transient

-  Cerebellar (central)

-  Nystagmus contralateral to lesion

-  Static: persists as long as head kept in provoking position

 

 

 

References

 

Tally & OConnor 5th Edition