The role of temporomandibular joint dysfunction and occlusal disorders in the pathophysiology of somatogenic cochlear and vestibular syndrome

Rationale: Temporomandibular joint (TMJ) dysfunction and occlusion abnormalities can cause cochlear and vestibular disorders. This issue is at the crossroads of several disciplines: otoneurology, physiotherapy, dentistry, medical rehabilitation and posturology, which often makes it difficult to timely diagnose them and delays the onset of treatment. Aim: To assess the role of abnormal dental occlusion and TMJ disorders in the pathophysiology and clinical manifestation of cochleovestibular syndrome. Materials and methods: We examined 300 subjects with clinical signs of cochleovestibular syndrome, asymmetry of occlusion and/or TMJ dysfunction (the main group), 55 patients with signs of TMJ structural and functional disorders and occlusal disorders without a cochleovestibular syndrome (the reference group), and 35 healthy volunteers (the control group). All patients were examined by a neurologist, an ENT specialist, a dentist and a physiotherapist. A series of additional investigations of the brachiocephalic vessels, cervical spine, TMJ, auditory and vestibular function, premature tooth contacts were performed. Results: The main group patients had high values of TMJ dysfunction in the Hamburg test (5.85 vs 2.2 in the reference group) and higher proportions of patients with moderate and severe TMJ dysfunction (n = 243, 81% and n = 13, 23.7%, respectively). The functional muscle test parameters and the results of manual muscle testing in the main group patients were significantly different from those in the control group (р < 0.05), whereas most values obtained in the reference group did not differ significantly (р > 0.05). Patients with cochleoves-tibular syndrome had 2 to 3-fold higher rates of vertebrogenic dysfunctions than those from the reference group. The video nystamography technique detected the positional cervical nystagmus in 100% (n = 300) of patients from the main group, whereas there were no nystagmus in those from the reference group. Voluntary dental occlusion in the main group patients was associated with a deterioration of postural tests in 61.8% (n = 185) of patients; in the reference group patients these parameters deteriorated in 38.2% (n = 21) of cases. According to T-SCAN assessment, 300 (100%) patients from the main group had in imbalance of total distribution of the occlusion force (р < 0.05 compared to the control group). The biggest number of patients from the main group (73.7%, n = 221) had an imbalance of occlusion force within 20 to 40%, and in most patients from the reference group this parameter was in the range of 10 to 30% (85.5%, n = 47), with 14.5% (n = 8) of this group having a normal balance of the occlusion force. Cerebrovascular reactivity parameters measured by ultrasound Doppler technique demonstrated a moderately significant (р < 0.05) strain of the cerebral hemodynamic reserve in the posterior arterial system in patients with cochleovestibular syndrome. Conclusion: Cochleovestibular disorders can be caused by a dysfunction of the dentoman-dibular system and/or cervical / masticatory myofascial syndrome. After exclusion of any otogenic pathology in patients with cochleovestibular syndrome, their neurological examination should include a visual assessment of the occlusion and mandibular movements, as well as testing of the cervical and masticatory muscles. If any abnormalities of occlusion and/or TMJ and local muscle dysfunction are revealed, then a dentist and a physiotherapist consultation should be performed.