Vestibular Evoked Myogenic Pot

This brief, non-invasive test is usually used to assess people with dizziness. It complements the VNG testing and is often performed at the same time.  While the VNG test evaluates the lateral semicircular canal, the VEMP test targets another portion of the vestibular system, the saccule.

PROCEDURE

The patient lies down on her back and an electrode is attached to the skin of the neck.  The patient must then raise her head, unsupported, which tenses the anterior neck muscles, while the stimulus is introduced the ear.  The test only takes one minute to perform and cause little or no discomfort.  Unlike the VNG test, the VEMP test does not cause dizziness.  It will not record a signal if there is even a mild conductive hearing loss.

WHAT CAN IT TELL US

This a new diagnostic test and its interpretatin and modifications are still evolving.  To date, the most reliable diagnoses made by this test are:

1.)  superior canal dehiscence.  A thinning of the bone between the superior semicircular canal and the brain causes a dizzy sensation induced by loud noises.

2.)  vestibular nerve disorders.  

acoutic neuroma.

Ramsay-Hunt syndrome.  A condition of facial nerve weakness (drooping appearance of one side of the face) and sometimes combined with a hearing loss due to recurrence of herpes zoster (chicken-pox virus.)

3.)  bilateral vestibular nerve loss.
 

Vestibular Evoked Myogenic Potential (VEMP) Testing

This test is used to evaluate one branch of the vestibular (balance) system. The patient is asked to turn their head while listening to tones in each ear. Each test run lasts about one minute.