Hypoglossal paralysis due to compression by a tortuous internal carotid artery in the neck.

Severe hemiatrophy of the right half of the tongue in a 22 year old patient was demonstrated to be due to compression of the hypoglossal nerve by a tortuous internal carotid artery in the neck. The nerve was trapped between an abnormal loop of the internal carotid artery and the sternocleidomastoid branch of the occipital artery. Although impairment of cranial nerve function with cases of tortuous and dilated vessels has been reported frequently, twelfth nerve palsy has never been demonstrated before.