Original Contributions Somatic Craniocervical Tinnitus Cochlear Nucleus Hypothesis and the Dorsal Robert Aaron Levine MD Purpose Of all nonauditory sensory systems only the somatosensory system seems to be related to tinnitus eg temporomandibular joint syndrome and whiplash The purpose of this study is to describe the distinguishing characteristics of tinnitus associated with somatic events and to use these characteristics to develop a neurological model of somatic tinnitus Materials and Methods Case series Results Some patients with tinnitus but no other hearing complaints share several clinical features including 1 an associated somatic disorder of the head or upper neck 2 localization of the tinnitus to the ear ipsilateral to the somatic disorder 3 no vestibular complaints and 4 no abnormalities on neurological examination Pure tone and speech audiometry of the 2 ears is always symmetric and usually within normal limits Based on these clinical features it is proposed that somatic craniocervical tinnitus like otic tinnitus is caused by disinhibition of the ipsilateral dorsal cochlear nucleus Nerve fibers whose cell bodies lie in the ipsilateral medullary somatosensory nuclei mediate this effect These neurons receive inputs from nearby spinal trigeminal tract fasciculus cuneatus and facial vagal and glossopharyngeal nerve fibers innervating the middle and external ear Conclusions Somatic craniocervical modulation of the dorsal cochlear nucleus may account for many previously poorly understood aspects of tinnitus and suggests novel tinnitus treatments Am J Otolaryngoll999 20 351 362 Copyright 0 1999 by W B Saunders Company Tinnitus is common estimates of its prevalence range up to 80 of all adults About 10 of people complain of chronic tinnitus whereas 0 5 of adults describe it as interfering with their ability to lead a normal life 2 When tinnitus can be ascribed to a sound being generated within the head such as from an abnormal pattern of blood flow near the ear it is often referred to as objective tinnitus This From the Eaton Peabody Laboratory Department of Otolaryngology Massachusetts Eye and Ear Infirmary Boston MA the Neurology Service Massachusetts General Hospital Boston MA and the Department of Neurology Harvard Medical School Boston MA Supported by Grants No R21 DC03255 and PO1 DC00119 from the National Institutes of Health Presented in pan at the 1999 Midwinter Meeting of the Association for Research in Otolaryngology St Petersburg Beach FL February 14 1999 Address reprint requests to Robert Aaron Levine MD Eaton Peabody Laboratory Massachusetts Eye and Ear Infirmary 243 Charles St Boston MA 02114 3096 Copyright 0 1999 by W B Saunders Company 0196 0 09 99 2006 OOOl lO OO O American Journal of Otolaryngology Vol20 report will be restricted to subjective timritus ie tinnitus not accountable by the presence of physical sounds From a neurological perspective the clinical problem of subjective tinnitus can be conceptualized as having 2 components The first is a mechanism for the generation of neural signals somewhere in the auditory pathway that ultimately results in the higher centers critical for auditory perception receiving a neural pattern similar to those generated by external sounds The second is the affect elaborated by the forebrain in reaction to this activation of the auditory cortex 3 4 When disorders of the inner ear or auditory nerve are temporally associated with tinnitus lateralized to the affected ear it is generally considered that the ear nerve disorder is in some way related to the tinnitus we shall refer to such tinnitus as otic tinnitus However there are many other patients who have either no detectable ear nerve disorder or there is no close temporal No 6 November December 1999 pp 351 362 351 352 relationship between such a disorder and tinnitus so that the initiating event of their nonotic tinnitus is obscuree5 In this report we argue from clinical materials that there is a type of nonotic tinnitus caused by central nervous system interactions between the somatosensory system and the auditory system which may also account for many other previously poorly understood aspects of tinnitus The somatosensory system seems to be the only sensory modality that can significantly modulate tinnitus perception in physiologically intact individuals It has long been observed almost as a curiosity that tinnitus can be modulated somatically with face head and neck movements In fact recently such phenomena have been used to provide insights into tinnitus using functional imaging 6 Systematic studies estimate that more than 30 of tinnitus patients can somatically modulate their tinnitus 7 Similarly tinnitus has been associated with 2 somatic disorders temporomandibular joint syndrome and whiplash both of which are limited to the head and neck 8 9 Although eye movements can modulate tinnitus in a few patients after cerebellopontine angle surgery the nervous systems of these individuals cannot be considered physiologically intact because of their surgery their tinnitus probably represents an intermodality cross talk that is related to inappropriate postoperative reinnervation lO There have been no reports of visual gustatory or olfactory associated tinnitus To reduce the number of hypotheses that can account for this relationship between tinnitus and the somatosensory system we report here our clinical observations of cases in which the temporal association between the development of tinnitus and involvement of the somatosensory system argue for the entity somatic craniocervical tinnitus From these subjects we will 1 define the principal attributes of somatic tinnitus and 2 propose a specific hypothesis to account for these attributes Our hypothesis is consistent with experimental data regarding otic tinnitus and is supported by anatomically and physiologically established central somatic auditory interactions Furthermore our proposal is testable and predictions regarding specific treatments for somatic and otic tinnitus follow ROBERT AARON LEVINE CASE REPORTS The cases described herein have been seen in the Tinnitus Clinic of the Massachusetts Eye and Ear Infirmary Case 1 In June 1993 at the age of 52 this right handed woman injured her right shoulder In March 1994 the shoulder was repaired under general anesthesia However a frozen shoulder developed To perform manipulation of the shoulder under anesthesia on April 22 1994 she received a right interscalene block