What is the pathophysiology of gaze-evoked nystagmus?

Updated: Oct 17, 2018
  • Author: Christopher M Bardorf, MD, MS; Chief Editor: Edsel Ing, MD, MPH, FRCSC  more...
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Answer

Gaze-evoked nystagmus is produced by the attempted maintenance of an extreme eye position. It is the most common form of nystagmus. Gaze-evoked nystagmus is due to a deficient eye position signal in the neural integrator network. Thus, the eyes cannot be maintained at an eccentric orbital position and are pulled back toward primary position by the elastic forces of the orbital fascia. Then, corrective saccade moves the eyes back toward the eccentric position in the orbit. [12]

Gaze-evoked nystagmus may be caused by structural lesions that involve the neural integrator network, which is dispersed between the vestibulocerebellum, the medulla (region of the nucleus prepositus hypoglossi and adjacent medial vestibular nucleus [NPH/MVN]), and the interstitial nucleus of Cajal (INC). Patients recovering from a gaze palsy go through a period where they are able to gaze in the direction of the previous palsy, but they are unable to sustain gaze in that direction; therefore, the eyes drift slowly back toward primary position followed by a corrective saccade. When this is repeated, a gaze-evoked or gaze-paretic nystagmus results.

Gaze-evoked nystagmus often is encountered in healthy patients; in which case, it is called end-point nystagmus. End-point nystagmus usually can be differentiated from gaze-evoked nystagmus caused by disease, in that the former has lower intensity and, more importantly, is not associated with other ocular motor abnormalities.


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