The head stabilization reflex by stimulation of accessory nerve

The head stabilization reflex (HSR) was described by a new technique of sti mulating the accessory nerve and then the reflex muscle responses' were rec orded electromyographically from the contralateral sternocleidomastoid musc le. Thirty-two normal control subjects and 22 patients with various neurolo gical disorders were studied. The HSR obtained from the contralateral stern ocleidomastoid muscle was very stable with a mean latency of about 45 ms an d was regularly obtained by the supramaximal stimulation of the ipsilateral accessory nerve from the normal subjects. The HSR was absent in 9 out 11 p atients with cerebellar syndrome. The HSR seemed to be a oligo-polysynaptic /plurosegmental reflex under the strong control of the cerebellum. (C) 1999 Elsevier Science B.V. All rights reserved.