Clinical Significance of Saccade Abnormalities

Chung, Woon Kyo; Choi, Young Jun; Lee, Won Sang; Lee, Jeong Joon; Chun, Hee Sun

Abstract

BACKGROUND AND OBJECTIVES
The saccadic eye movement means rapid eye movement in order to fixate an intended target with fovea. Frontal lobe, brain stem and paramedian pontine reticular formation operate the saccade movement in the central nervous system. Although saccadic abnormalities were usually seen in the CNS lesion(most commonly in the cerebellar lesion) some normal individuals consistently undershoot or overshoot the target(corrective saccade). Because there are several possibilities for serious error when interpreting the saccade test, clinical usefulness of saccade test may be uncertain. We study the saccade movement in out dizzy patients to find out the definite usefulness of saccadic abnormality and cause of dizziness according to the saccadic abnormalities. MATERIAL AND METHOD: For 4 years, 1994.1.-1997.12, 53 patients showed saccade abnormalities and they were classified into 5 categories-undershoot, overshoot, slow velocity of saccade, impaired saccade and fail of saccade. Spontaneous nystagmus, gaze nystagmus, pursuit test and optokinetic test were also performed. We analyzed the cause of saccade abnormality and other associated eye movement disorders.
RESULTS
Almost all saccade abnormalities were seen in central disease(71%), but some could be seen in specific cases of peripheral disease(11%) and in other conditions(18%). In peripheral lesion, only saccade undershoot was seen without other abnormal eye movement. In central lesion, all kinds of saccade movement were seen with or without other abnormal eye movement disorders, but there was no correlation between the sites of lesion and types of saccade. Spontaneous nystagmus was seen in 6 patients, but there was no correlation between the causes of vertigo and the types of saccade abnormality.
CONCLUSION
Saccade test must be clinically useful for differentiating between the central and peripheral lesion using the types of saccade abnormality and other abnormal eye movement. But many factors that affect saccade movement should be considered when interpreting the test results.