Electronystagmography

Electronystagmography, commonly known as ENG is a test conducted to examine patients suffering from dizziness, vertigo or balance dysfunction. Electronystagmography or ENG test is directed towards assessment of the oculomotor and vestibular systems by checking the involuntary and voluntary eye movements. Electronystagmography or ENG has three important components which are as follows:

  1. Oculomotor assessment
  2. Caloric simulation of the vestibular system and
  3. Positioning testing

Basically, the vestibular system keeps an eye on the position and movement of the head and helps to stabilize the retinal images captured by the human eyes. The image thus stabilized is integrated with other visual systems of the body and to produce the vestibulooccular reflex.

Electronystagmography or ENG test can be conducted at basic level or by using advanced technologies. However, now-a-days basic level tests are not conducted anymore giving way for advanced technological Electronystagmography or ENG tests. Traditional Electronystagmography or ENG are conducted by using electrodes which aids in eye movement measurement. Electrodes built as patches used in ECG but smaller in size are placed around the nose and eye movements are measured in relation to the ground electrode. The test is performed by putting warm and cold water simultaneously in the ears and then measuring the eye movement. The test can be performed separately for each ear.  Instead of putting water in the ears, the test can be performed by asking the patient to track any visual object or a flash of light. The electrodes attached around the nose and eye record the readings in an attached computer. The test usually takes around ninety minutes to be completed. It can record reading with head in various positions and even with closed eye lids. With more advancement in technology infrared videos are used for conducting Electronystagmography or ENG tests. Electronystagmography or ENG using infrared video is called videonystagmography or VNG. Since VNG uses infrared videos it eliminates any visual fixation points and can be conducted in complete darkness. Infrared videos provides for more detailed observation and analysis of the eye movements. ENG or VNG tests can also be used to record nystagmus. 

The patient should have complete vision for the first component of the Electronystagmography or ENG test, which is oculomotor assessment. However, the rest of the components of the Electronystagmography or ENG test can be conducted for patients with partial vision or absent vision.

If the patient has back or neck injuries then it should be told to the doctor performing the Electronystagmography or ENG test. In that case, the doctor might suggest different head positioning during the test to avoid any further complication to existing neck or back injuries. In case the doctor is using cold and warm water in the ears to conduct the test then he should confirm the ear condition prior to the test. It is also suggested that the patient should provide the doctor with the list of medication he/she is undergoing for many medication can affect the test results. In case, there are some medication which might affect the test result then the doctor suggests the patient to discontinue those medicines for twenty four to seventy two hours before undergoing Electronystagmography or ENG tests. The Electronystagmography or ENG test can cause temporary dizziness or nausea. The patient should also limit food intake before the Electronystagmography or ENG test.