Electronystagmography

Boy balancing on a fallen tree to cross a stream in a forest

What is Electronystagmography?

Electronystagmography, commonly called ENG, is a clinical test that helps your doctors diagnose your ability to maintain your balance.
Many people are unaware that the control center for our ability to balance ourselves is located in the ears. This essential capability is hidden in tiny, semi-circular canals in our middle ear that are part of the vestibular system. These small canals provide our brain with information such as our angular and linear acceleration, which allow us to navigate the world without falling flat on our faces.

 

How does all the hearing and orientation data get to the brain?

Located in the inner ear, you will find a sophisticated nerve network that collects and transmits hearing (cochlear nerve) and balance (vestibular nerve) data that is transferred via the vestibulocochlear nerve to the brain.

What does an ENG analyze?

It is used by the ENT & AA clinician to objectively assess how your visual system and vestibular (balance) system function together to produce the vestibuloocular reflex. The information from an ENG, along with other diagnostic techniques can be used to diagnose and identify the site of a lesion causing balance problems. It can also be used to rule out potential causes of dizziness. 
ENGs assess:

  • Dizziness
  • Vertigo
  •  Balance Dysfunctions

 

How does Electronystagmography work?

A standard ENG test consists of three parts:

Oculomotor Evaluation

Some systems will use dots on wall to test eye stimulus response, while others may use computer generated light stimuli to test visual responses.  Traditional ENGs use electro-oculography to objectively measure eye movements. Electrodes may be placed on your face to measure eye movements.

There are also systems that measure responsiveness using infrared or video monitoring (VNG).
The clinician is testing for involuntary eye movements (nystagmus) and will take great efforts to calibrate your gaze patterns prior to taking the test. Your patience during this phase is appreciated.

Positioning/positional testing

Typically you will be tested for optical responsiveness with your head hanging down and facing upward (supine).

Caloric stimulation of the vestibular system

The clinician will test for eye movement responses by stimulating the vestibular canals in your ears sequentially with warm and cool air. The different temperatures sensed by your vestibular system provide a specific type of eye movement response which allows the medical team to identify possible causes for poor balance.

All of this information is then combined in an ENG report that allows the team to analyze how well your visual and vestibular systems are working together.