What is smooth pursuit tracking in electronystagmography (ENG)?

Updated: Aug 06, 2019
  • Author: Angela G Shoup, PhD; Chief Editor: Arlen D Meyers, MD, MBA  more...
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The smooth pursuit system is responsible for following targets within the visual field. Tracking can be evaluated horizontally and vertically. As a rule, vertical tracking is not as smooth as horizontal, even in healthy subjects. Care should be taken in interpreting smooth pursuit test results in geriatric and pediatric patients. Tracking is also affected by attention and patient cooperation.

In smooth pursuit tracking, the patient is instructed to follow a sinusoidal moving target with his or her eyes only. The target can be a pendulum, metronome, or computer-generated stimulus.

Tracking test results should resemble a smooth sinusoid. Breakup of movement may indicate CNS pathology. Nystagmus may be seen in tracking test results when also observed in spontaneous (center gaze) recordings.

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