Myogenic potentials generated by a click evoked vestibulospinal reflex can be easily recorded from the tonically contracting ipsilateral sternocleidomastoid muscle (SCM). These “vestibular evoked myogenic potentials” (VEMPs) are abolished by selective vestibular nerve section1 as well as by certain peripheral vestibular diseases.2-4 Click sensitive primary vestibular neurons arise from the saccular macula in the guinea pig5 and electrical stimulation of these neurons in the cat evokes inhibitary postsynaptic potentials in ipsilateral SCM motor neurons which are abolished by transection of the medial vestibulospinal tract.6 These clinical and neurophysiological data suggest that VEMPs are mediated by a pathway consisting of the saccular macula, its primary neurons, vestibulospinal neurons from the lateral vestibular nucleus, the medial vestibulospinal tract, and finally motor neurons of the ipsilateral SCM. Therefore a lesion anywhere in this pathway could result in abnormal VEMPs. We studied VEMPs in three patients with definite multiple sclerosis7 to …