Review of somatosensory tinnitus Sanchez TG and Rocha CB somatosensory system, which suggests an association between auditory pathways and non-auditory path- ways.22,23 According to Levine,21 tinnitus located ipsilateral in relation to the somatic injury raises suspicions regarding a possible somatosensory component in its origin. For Wright and Ryugo,17 the dorsal medullar nucleus, formed by cuneate and gracile nuclei, occupies a position in the somatosensory system similar to that of the cochlear nucleus in the auditory system. It receives information straight from the dorsal roots, which, in turn, receive information from the proprioceptive, tactile and vibratory receptors of the body surface. Therefore the lateral cuneate nucleus is the end-point of afferent fibers from the neck, ear and suboccipital muscles, and carries information about the head and ear position, which is needed in order to process the acoustic information. Such theories relating to the anatomical relationship between both auditory and somatosensory pathways may help clarify the influence of myofascial pain on certain kinds of tinnitus as well as explain how myofascial trigger-point treatment could alleviate the symptom. Furthermore, such theories could also explain why certain patients with bilateral tinnitus reported relief in only one ear, correspond- ing with the side of the body with pain (or with the side of the body with the worst pain). According to Shore et al.,18 anatomical and physiological findings in animal studies have shown that the trigeminal and dorsal root ganglia relay some afferent somatosensory information from the periphery to secondary sensory neurons in the brain stem, specifically the spinal trigeminal nucleus and dorsal column nuclei, respectively. Each of these structures sends excitatory projections to the cochlear nucleus. Activation of the trigeminal ganglion elicits excitation in some dorsal cochlear nucleus units and inhibition in others. The modulation of firing rate and synchrony in dorsal cochlear nucleus neurons by somato- sensory input is physiologically correlated with somatic tinnitus. Among the theories attempting to explain modulation, neuroplasticity has been gaining positive recognition. Aberrant cross-modal plasticity seems to play a major role in tinnitus induced or modulated by somatosensory stimuli.24 This suggests that abnormal interactions between different sensory modalities, sensorimotor systems, neuro- cognitive and neuroemotional networks may contribute to certain aspects of tinnitus. It is widely known that reorganization or re-mapping of specific central nervous areas occurs as a normal response of brain tissue to injury.25 However, like any double-edged sword, it is not possible to predict whether injury-induced plasticity will end up in limited or cross-modal effects, which in turn may result in compensatory or negative effects with pathological changes and unwanted clinical signs, as we have observed in some cases of tinnitus modulation.26 The effects of neural plasticity can generally be divided into early modifications and modifications with a later onset.25 The remodeling of tonotopic receptive fields within auditory structures (dorsal cochlear nucleus, inferior colliculus, and auditory cortex) seems to be a late manifestation of neural plasticity. Thus, modulation of tinnitus through stimulation of the somatosensory system might be explained by activation of auditory regions through the non-classical pathway.24 1090 CLINICS 2011;66(6):1089-1094 Diagnosis of somatosensory tinnitus Somatosensory tinnitus is suspected clinically when anamnesis shows at least one of the following occurrences prior to the onset of tinnitus: (1) evident history of head or neck trauma, (2) tinnitus association with some manipula- tion of the teeth, jaw or cervical spine, (3) recurrent pain episodes in head, neck or shoulder girdle, (4) temporal coincidence of appearance or increase of both pain and tinnitus, (5) increase of tinnitus during inadequate postures during rest, walking, working or sleeping and (6) intense bruxism periods during the day or night. This type of tinnitus often changes its loudness, pitch or localization during other stimulation coming from the head and neck. The most important characteristic of such tinnitus is that its origin seems to be related to problems of the head and neck, rather than to problems of the ear. Because of that, more than ever, these patients should be evaluated by an integrated team including an experienced dentist and a physiotherapist (or other professional) to evaluate possible bone or muscular disorders of the face, teeth and neck, in order to allow prompt diagnosis with a view to beginning adequate treatment as early as possible. The phenomenon of somatosensory modulation of tinni- tus (of any origin, with temporary changes in loudness, pitch or localization during somatosensory stimulation) may occur in patients with either otological or somatosen- sory tinnitus. As somatosensory modulation is very pre- valent (65–80% of patients with tinnitus), it is wise to search for this in all cases. Upon anamnesis, patients may spontaneously report that such temporary changes occur during common daily movements with the jaw or neck (opening of the mouth, clenching of the teeth or turning of the head) or by applying pressure on the temples, mandible, cheek, mastoid or neck with a fingertip. During physical evaluation, the professional actively searches for modula- tion through different stimuli, including digital pressure of myofascial trigger points, as well as asking patients to make active movements of the neck, shoulder, mandible and eyes (to detect gaze-evoked tinnitus). Because this is a short-lived effect, any questionnaire to evaluate tinnitus before and after the maneuver is difficult to use and a simple instrument, such as the visual analogy scale, is preferred to capture quick changes. The audiogram is one of the basic complementary examinations that every patient with tinnitus should undergo. Diverse degrees of hearing loss are found in the vast majority of patients. The presence of symmetric pure tone thresholds in both ears (normal or abnormal) and unilateral or asymmetric tinnitus should direct the patient towards a more detailed evaluation of somatosensory tinnitus (besides excluding neural and central auditory diseases). One recent study showed that patients with normal hearing and chronic pain have greater improvement in their tinnitus when subjected to deactivation of myofas- cial trigger points.27 Diagnosing somatosensory tinnitus and somatosensory modulation is not difficult. It depends mostly on well- conducted anamnesis and thorough physical examination. However, as most of the data referred to herein are recent, professionals need to incorporate the information into their daily routine so as to adequately diagnose such problems. Somatosensory tinnitus is totally underdiagnosed due to the lack of publications on the subject. To date, there are no studies reporting sensitivity, specificity, diagnosis, odds