Effects of Tonic Muscle Activation on Amplitude-Modulated Cervical Vestibular Evoked Myogenic Potentials (AMcVEMPs) in Young Females: Preliminary Findings

A tone-burst stimulation of 500 Hz seems to be clinically most appropriate to elicit vestibular evoked myogenic potentials (VEMPs) because those VEMPs can be recorded at the lowest stimulus intensity possible. However, little is known about gender and age-related changes of the amplitude in tone-burst (500 Hz) evoked VEMPs. The aim of the present paper was therefore to investigate the influence of gender and age on VEMP amplitude in relation to the tonic muscle activity. VEMPs of 64 healthy subjects were recorded ipsilaterally during air- or bone-conducted tone burst stimulation. The EMG of the tonically activated sternocleidomastoid muscle was recorded ipsilaterally with surface electrodes. Averages were taken for P1/N1 amplitudes of male and female volunteers within 3 different age groups. Although the amplitude decreased with increasing age the tonic activity was not significant different between the age groups. Consequently the relation between VEMP amplitude and tonic muscle activity decreased with increasing age. The normative values of the age-dependent relation between VEMP amplitude and tonic muscle activity were described by the 90% confidence interval of the individual values. Normative thresholds were calculated. Normal saccular receptor function could be diagnosed if the VEMP amplitude is above (or equal to) the normative value at a given tonic muscle activity and age. Normative data as described above are required to diagnose isolated saccular defects, which are indicative of a vestibular disorder.

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The Influence of Tonic Muscle Activation on Human Jaw Displacement Tremor

Journal of Dental Research ◽

10.1177/00220345880670080401 ◽

1988 ◽

Vol 67 (8) ◽

pp. 1081-1085

Author(s):

R.S. McCarroll ◽

J.H. De Vries

Keyword(s):

Individual Variation ◽

Muscle Activation ◽

Physiological Basis ◽

Tonic Muscle ◽

Tremor Frequency ◽

The Relationship

Jaw displacement tremor was investigated. Both tremor amplitude and tremor frequency were found to increase with increasing muscle activation. Co-contraction of jaw elevator and jaw depressor muscles was employed in order to vary muscle activation levels without the teeth being in occlusion. Reproducibility of tremor changes was statistically significant for each individual investigated. The relationship between tremor frequency and tremor amplitude, over the range of muscle activation investigated, varied per individual. It is hypothesized that the physiological basis for this inter-individual variation is differences in the development of jaw stiffness with increasing muscle activation between subjects. This explanation may be the basis, at least in part, for the clinical presence of objective jaw stiffness in one subject and its absence in another.

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Does the method of sternocleidomastoid muscle activation affect the vestibular evoked myogenic potential response?

Journal of Vestibular Research ◽

10.3233/ves-2006-164-504 ◽

2007 ◽

Vol 16 (4-5) ◽

pp. 187-191 ◽

Cited By ~ 2

Author(s):

Brandon Isaacson ◽

Emily Murphy ◽

Helen Cohen

Keyword(s):

Muscle Activation ◽

Body Position ◽

Sternocleidomastoid Muscle ◽

Vestibular Evoked Myogenic Potentials ◽

Emg Activity ◽

Potential Response ◽

Vestibular Evoked Myogenic Potential ◽

Amplitude Response ◽

Myogenic Potential ◽

Significant Difference

The objective of this study was to assess the effects of different methods of sternocleidomastoid muscle (SCM) activation on vestibular evoked myogenic potentials (VEMP). Forty normal volunteers were tested using three different methods of SCM activation: sitting with the head turned away from the test ear (SIT), supine with the head held straight up (SHU), and supine with the head held up and turned away from the test ear (SHT). Dependent measures were latency, and amplitude. Head and body position significantly affected the amplitude of the VEMP, but had no significant effect on latency. Testing subjects in the supine position with the head up and turned toward the non-test ear yielded the most robust amplitude response and sternocleidomastoid EMG activity. When amplitude measures where corrected according to tonic electromyographic (EMG) activity no significant difference was noted between the three different test positions. The increased amplitude in the supine with head turned position can be directly attributed to increased tonic SCM EMG activity.

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Sports Concussions (TBI), Imbalance, and Dizziness

Perspectives on Neurophysiology and Neurogenic Speech and Language Disorders ◽

10.1044/nnsld25.1.36 ◽

2015 ◽

Vol 25 (1) ◽

pp. 36-41 ◽

Cited By ~ 1

Author(s):

Steven M. Doettl

Keyword(s):

Assessment Tools ◽

Vestibular Evoked Myogenic Potentials ◽

Post Injury ◽

Management Tools ◽

Concussion Management ◽

Post Concussion Syndrome ◽

Behavioral Marker ◽

Valid Assessment ◽

Injury Assessment

It has been widely accepted that the assessment of balance after concussion plays a large role in determining deficit. Qualitative balance assessments have been an established piece of the post-injury assessment as a clinical behavioral marker of concussion for many years. Recently more specific guidelines outlining the role of balance evaluation in concussion identification and management have been developed as part of concussion management tools. As part of the ongoing development of concussions protocols, quantitative assessment of balance function following concussion has also been identified to have an important role. Frequently imbalance and dizziness reported following concussion is assumed to be associated with post-concussion syndrome (PCS). While imbalance and dizziness are common complaints in PCS, they can also be a sign of additional underlying pathology. In cases of specific dizziness symptoms or limited balance recovery beyond the initial post-concussive period, a quantitative vestibular assessment may also be needed. Electronystagmography and videonystagmography (ENG/VNG), rotary chair testing (RCT), and vestibular evoked myogenic potentials (VEMPs) have all been identified as valid assessment tools for vestibular dysfunction following traumatic brain injury (TBI). The assessment of balance and dizziness following sports-related concussions is an integral piece of the puzzle for removal from play, assessment of severity, and management.

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