What is Electronystagmography?

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ELECTRONYSTAGMOGRAPHY
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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.

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• 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.

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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.

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• 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.

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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.

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