Eclipse Support
The cervical Vestibular Evoked Myogenic Potential (cVEMP) is an evoked potential measured from the sternocleidomastoid (SCM) muscle and is used to assess the vestibular system (the saccule and its afferent pathways). An amplitude asymmetry ratio is then calculated to assess if the vestibular system is working normally. VEMP tracings are easily recorded and provide valuable information to medical practitioners to assist them in the diagnosis of various disorders. Loud tone bursts, at slow rates are used to elicit this response.
The cVEMP is a test used in addition to traditional vestibular testing (e.g., VNG) to assist in the assessment of vestibular function. The cVEMP provides information about the saccule and inferior vestibular nerve, assisting medical practitioners in the diagnosis of disorders such as Superior Semicircular Canal Dehiscence (SSCD) (Milojcic et al., 2013) and Meniere’s disease (Rauch et al., 2004).
The electrode sites must be prepared and cleaned in order to obtain acceptably low skin impedances. It is recommended to have impedance values of 3kΩ or lower. The impedance values between each electrode should be balanced or similar in value.
There are different suggested activation techniques for the SCM muscle. The patient can either be sitting and instructed to turn the head only to contract/activate the SCM muscle as shown in the image below. Alternatively, the patient can be in a reclined position and asked to lift the head and turn the neck to contract the SCM muscle. Use of the patient EMG monitor will ensure consistent activation during testing.
The reference electrodes should be placed on the upper belly of the SCM muscle on both sides. The vertex electrode is placed on the clavicular joint (or on the high forehead) and the ground/common on the low forehead.
Typically, the air-conduction stimulus used is a 500Hz tone burst at high intensity level (e.g., 90/95dBnHL).
Ensure that the patient is relaxed prior to starting the test. After confirming impedances.
The Eclipse comes with pre-programmed cVEMP protocols so the system is ready to use immediately. Protocols can be created or modified easily to fit your clinical needs. Consult the Eclipse Additional Information document to learn how to create or modify a protocol. The procedure described below is simply a suggested test process and to be used only as a guideline.
