[Oto-vestibular symptoms in patients with temporomandibular joint dysfunction. Electromyographic study]

The authors analyse the otovestibular symptoms (acoupheny, muffled hearing, vertigo, hypoacusia, otalgia) present among other symptoms of craniomandibular dysfunctions. A number of hypotheses have been advanced regarding the etiopathogenesis of these symptoms, but all stem from three theories. The first theory is based on the possibility of a mechanical transmission of force from the temporomandibular joint to the middle ear by the discomalleolar ligament. Another theory hypothesises the possible direct irritation by the condyl on the auriculotemporal nerve. The most widely credited etiopathogenetic theory, which is examined in this study, is that the hypertone of the tensor muscle of the tympanum and the tensor muscle of the velum palatinum, which are innervated like the masticatory muscles of the mandibular branch of the trigeminal nerve is the effect of these same muscles' hypertone. A group of 53 adult patients was selected to verify this theory. All patients were receiving treatment for dysfunctions of the temporomandibular articulation. Initial data were collected relating to the prevalence of each of the otovestibular symptoms studied; each patient then underwent computerised electromyographic analysis while the right and lefthand masseter and temporal muscles were resting. All tests were performed by the same operator. When analysing the results, patients were divided into two groups: one group contained those patients who had no symptoms relating to the ear, and the other contained patients with at least one symptom relating to the ear. Moreover, the group of symptomatic patients was divided into subgroups of patients with 1, 2, 3, and 4 of the symptoms studied. The mean electromyographical values for each muscle examined were then compared. The following results were obtained: 67.9% of subjects examined presented at least one otovestibular symptom; the symptom that was most frequently found was the feeling of muffled hearing (41.5%), followed by otalgia and vertigo; the prevalence of otalgia was much lower (7.5%). The most interesting finding emerged from a comparison between electromyographical values in patients suffering from otovestibular symptoms and the asymptomatic group. There was no significant difference in this series between this two groups, and the mean electromyographical value was higher in the group of asymptomatic patients.