Prevalence of somatosensory modulation of the cervical spine and temporomandibular joint in subjects with tinnitus: a systematic review

BackgroundTinnitus is defined as the perception of a sound without a corresponding external acoustic stimulus and is considered a symptom rather than a disease. In some individuals, it can be evoked or modulated by input from the somatosensory, somatomotor, and visual-motor systems. This has led to the introduction of the term: somatosensory modulation of tinnitus. In these cases, the psychoacoustic attributes of tinnitus (loudness and pitch) can change as a result of external stimuli such as strong contractions of the muscles of the head, neck, limbs, orofacial movements, and eye movements. The temporomandibular joint and cervical spine, along with the head, appear to be the musculoskeletal anatomical regions most commonly underlying somatic tinnitus. This review aims to evaluate the prevalence of somatosensory modulation of the cervical spine and temporomandibular joint in subjects with tinnitus. MethodsThe databases investigated for the review were: Embase, Pubmed, Scopus, and Web of Science. Observational studies investigating the prevalence of somatosensory modulation of the cervical spine and temporomandibular joint in subjects with tinnitus were included. No time limit was entered into the search and no age or language restrictions were applied. Results14 studies met the eligibility criteria on which the review was based. In 5 studies, the prevalence of tinnitus modulation was reported with one or more maneuvers involving TMJ, in 3 studies with one or more maneuvers involving the cervical spine and 7 studies reported the prevalence of modulation following maneuvers for both somatic regions. ConclusionThe present study confirmed that tinnitus perception and intensity can be somatically modulated in a subpopulation of individuals. The cervical spine and the ATM play a key role in the modulation of tinnitus and, based on the data collected on individual districts, the ATM appears to be the most frequently involved somatic region.