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Electronystagmography is an important test done to evaluate patients with vertigo, dizziness, and balance problems. The study of eye movements provides a lot of information about the functioning of the brain and the balance system.
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ELECTRONYSTAGMOGRAPHY • Electronystagmography is an important test done to evaluate patients with vertigo, dizziness and balance problems. The study of eye movements provides a lot of information about the functioning of the brain and the balance system. ENG is used to second eye movements in different conditions and with different tests. By analyzing these movements, we are able to understand the area affected by the disorder.
ENG detects eye movements by virtue of a change in the cornea – retinal potential during these movements. The changes in potential are picked up by surface electrodes placed near the eyes of the patient. Findings of ENG must be correlated with the history given by the patient and other neuro – ontological tests to identify the cause of vertigo or dizziness.
FEATURES • Uses electrodes to record corneo – retinal potential. • The sensitivity of recording is 2° (which is less than VNG) due to distantly placed electrodes. • Able to record horizontal eye movements. Vertical eye movement recording is not very accurate. Cannot record torsion. • The detailed finding of oculomotor tests not possible.
Artefacts due to blinking electromagnetic and electrical disturbances and EEG activity of the brain can interfere with the interpretation of results. • Detection of posterior canal BPPV not possible in many cases as a torsional element not detected. • Reviewing and replaying tests not possible.
Test Conducted During ENG • Test for spontaneous nystagmus – Nystagmus is the jerky oscillatory movement of the eyes caused by disturbances in the balance system. In many cases, this nystagmus cannot be accurately diagnosed by naked eye examination. • Test for gaze – This test checks the ability to hold gaze at a point. Patients with balance disorders may have problems in holding their eyes steady on a fixed point. • Saccades – This test checks the ability to move the eyes and appropriately focus on another object of interest. 3 parameters are measured. • Smooth pursuit – A light moving like a pendulum is presented to be followed by the patient with eye movements without moving the head. The ability to track it with the required velocity and precision is measured.
