Die elektrophysiologische Untersuchung des vestibulo-collischen Reflexes (VCR)

Abstract

The vestibulocollic reflex (VCR) and/or the vestibular-evoked myogenic potentials (VEMP) have become a routine diagnostic tool to assess otolith function in recent years. The VCR belongs to the group of vestibulo-spinal reflexes that control posture and stance. The reflex is usually recorded from the ipsilateral sternocleidomastoid muscle (SCM) after monaural acoustic stimulation. It is elicited by intense square-wave click-tones (0.1 ms duration, 95 dB sound pressure level (SPL) above the normal hearing threshold) or short tone-bursts (STB) (80 dB SPL above normal hearing threshold). The VCR represents an unphysiological stimulation of the saccculus that reaches the vestibular nuclei in the lateral pons via the inferior vestibular nerve. After a switch-over in the medial vestibular nuclei, it travels by means of the medial vestibulospinal tract to the ipsilateral motorneurons of the SCM. There, it modulates a tonic baseline activity of the muscle. The VCR has its strength in the detection of fistulas of the semicircular canals, the dysfunction of the sacculus in Meniere's disease as well as the involvement of the inferior vestibular nerve in vestibular neuritis. It is also a good clinical method to evaluate acoustic neurinoma, the extent of a bilateral vestibulopathy and to monitor the course of therapy in basilary migraine.