Estudo funcional das vias auditivas periféricas e centrais em pacientes com acromegalia

Abstract

Acromegaly is a rare endocrine disease. Few studies have evaluated its association with hearing loss (HL) or disturbance in conduction of the auditory neural impulse. The results are conflicting. The aim is to evaluate central and peripheral auditory transmission in acromegalic patients. Besides, to evaluate the prevalence and characteristics of HL in patients with acromegaly. A cross-sectional study was carried out on 36 patients with acromegaly in a specialized ambulatory in Fortaleza-Ceará. Patients with abnormal otoscopy, family history of hearing loss, use of ototoxic drugs or occupational noise exposure were excluded. Initially, the group was evaluated by pure tone audiometry. HL was considered when pure tone average was > 25 DBHL for low frequencies (250, 500, 1000 e 2000 Hz) or high frequencies (3000, 4000, 6000 e 8000 Hz). The whole group was divided in: acromegaly with HL (Acro HL) and without HL (AcroNHL) and compared in regards to hormonal levels and metabolic parameters. Additionally that group of patients with acromegaly was divided into 2 subgroups: with (n=16) and without (n=20) diabetes mellitus/impaired glucose tolerance (DM/IGT). The results were compared among these subgroups and a control group (n=20) regarding the brainstem auditory evoked potentials (BAEP) parameters.Kolmogorov-Smirnov test was used to evaluate the normality of distribution when necessary. Qui-quadrado, Student t test and Pearson correlation coefficient were carried out. The level of statistical significance chosen was at p<0.05 (statistical package for social sciences-SPSS 12.0). Among 36 patients evaluated, 14 (38,9%) showed sensorioneural HL (Acro HL), being 9 bilateral and 5 unilateral cases. No one had mixed or conductive HL. The prevalence of diabetes/impaired glucose tolerance was similar between the groups. The frequencies 250, 3000, 4000, 6000 and 8000 Hz were the most affected and with a similar pattern in both ears. The group with acromegaly showed a prolonged peak I latency in the right ear in comparison to the control group (p=0,007), with no difference regarding the interpeak intervals in any sides. This pattern was the same when comparing the DM/IGT subgroup to controls. Also, we found a prolonged peak I latency in the right ear in relation to the left ear in the group with acromegaly.In conclusion, a high prevalence of sensorineural HL was shown in patients with acromegaly. Nevertheless, no correlation was observed between this dysfunction and clinical or metabolic characteristics of the disease. Patients with acromegaly associated with DM/IGT showed a delayed neural impulse in the auditory nerve unilaterally in the right side, evidencing a non-homogenous neuropathic effect of the carbohydrate metabolism disturbances on the auditory nerve.