The Cervical Vestibular-Evoked Myogenic Potentials (cVEMPs) Recorded Along the Sternocleidomastoid Muscles During Head Rotation and Flexion in Normal Human Subjects

Abstract

Tone burst-evoked myogenic potentials recorded from tonically contracted sternocleidomastoid muscles (SCM) (cervical VEMP or cVEMP) are widely used to assess the vestibular function. Since the cVEMP response is mediated by the vestibulo-collic reflex (VCR) pathways, it is important to understand how the cVEMPs are determined by factors related to either the sensory components (vestibular end organs) or the motor components (SCM) of the VCR pathways. Compared to the numerous studies that have investigated effects of sound parameters on the cVEMPs, there are few studies that have examined effects of SCM-related factors on the cVEMPs. The goal of the present study is to fill this knowledge gap by testing three SCM-related hypotheses. The first hypothesis is that contrary to the current view, the cVEMP response is only present in the SCM ipsilateral to the stimulated ear. The second hypothesis is that the cVEMP response is not only dependent on tonic level of the SCM, but also on how the tonic level is achieved, i.e., by head rotation or head flexion. The third hypothesis is that the SCM is compartmented and the polarity of the cVEMP response is dependent on the recording site. Seven surface electrodes were positioned along the left SCMs in 12 healthy adult subjects, and tone bursts were delivered to the ipsilateral or contralateral ear (8 ms plateau, 1 ms rise/fall, 130 dB SPL, 50-4000 Hz) while subjects activated their SCMs by head rotation (HR condition) or chin downward head flexion (CD condition). The first hypothesis was confirmed by the finding that the contralateral cVEMPs were minimal at all recording sites for all the tested tones during both HR and CD conditions. The second hypothesis was confirmed by the finding that the ipsilateral cVEMPs were larger in HR condition than in CD condition at recording sites above and below the SCM midpoint. Finally, the third hypothesis was confirmed by the finding that the cVEMPs exhibit reversed polarities at the sites near the mastoid and the sternal head. These results improve understanding of the cVEMP generation and suggest that the SCM-related factors should be taken into consideration when developing standardized clinical cVEMP testing protocols.

Splenius capitis is a reliable target for measuring cervical vestibular evoked myogenic potentials in adults

“…We compared the characteristics of the SCM cVEMP recorded using the standard clinical arrangement with that recorded from SPL using a simpler alternative posture. Previous work has demonstrated that the SCM cVEMP consists of a biphasic positive–negative response with peak latencies of ~ 13 and 23 ms, respectively, although more recent work has demonstrated variability in polarity depending on electrode position (Wei et al ., ; Ashford et al ., ; Rosengren et al ., ). IM recordings confirm that the p13 and n23 responses relate to a reduction and subsequent rebound of SCM activity, respectively (Colebatch & Rothwell, ).…”

“…Note as well that SCM is also compartmentalized into multiple subvolumes with different attachments (Kamibayashi & Richmond, 1998). Recent work has shown that cVEMP waveform polarity on SCM can be inverted if the active electrode in the standard belly-tendon montage is placed outside of the conventional recording zone (Wei et al, 2013;Ashford et al, 2016;Rosengren et al, 2016).…”

The Influence of Motoric Maneuvers on Cervical Vestibular Evoked Myogenic Potentials (cVEMPs)

“…Previous research has shown that the amplitude of the cVEMP is influenced by how an individual is asked to produce SCM contraction. For example, Ashford et al 26 evaluated the cVEMP from subjects who produced SCM contraction by lifting their heads toward the midline as well as turning their heads and elevating their heads from a supine position. They found that at certain locations along the SCM muscle, rotating and elevating the head to produce SCM contraction resulted in larger cVEMP amplitudes as compared with flexion of the head toward the midline.…”

Weak Vestibular Response in Persistent Developmental Stuttering

“…Cervical VEMPs are predominantly ipsilateral, but may sometimes have a contralateral component ( Colebatch and Rothwell, 2004 ; Ashford et al, 2016 ). Use of binaural stimuli limited variation due to any between participant difference in the extent of contralateral activity, because ipsilateral and contralateral components of the VEMP from each ear were present at both SCM muscles.…”