Ataxia and nystagmus induced by injection of local anesthetics in the neck

Vertigo, ataxia, and nystagmus were induced in animals and man by injecting local anesthetics into the neck. This presumably interrupted the flow of afferent information from neck muscle and joint receptors. Ataxia in man was associated with a broad‐based, staggering gait; hypotonia of the ipsilateral arm and leg; and a strong sensation of ipsilateral falling or tilting. Nystagmus was stronger in the rabbit and cat than in the monkey and was not induced in man. In the rabbit, section of the cervical roots on one siEN reactivated signs of a previous labyrinthectomy, regardless of the side of operation. Neck‐afferent nystagmus was not dependent on the cerebellum, and the activity responsible for it appeared to ascend ipsilaterally through ventral portions of the cervical spinal cord. The data demonstrate the dependence of neck‐afferent nystagmus on the vestibular system and suggest that in the presence of previous vestibular lesions, neck joint or muscle disorders may be a cause of clinical vertigo, ataxia, or nystagmus.