Audiological Evaluation in Hypothyroid Patients and Effect of Thyroxine Replacement Therapy

Abstract

To do the audiological evaluation of patients with hypothyroidism and to assess status of hearing after thyroxin replacement therapy (TRT). Two groups were included: a hypothyroidism group (HG, n = 50), and a control group (CG, n = 50). Parameters studied: anominesic data, duration of hypothyroidism, comorbidities, cochleovestibular symptoms, biochemical and hormonal exams (TSH, FT4 and FT3), pure tone audiometry, impendence audiometry and BERA as where required. Mean age of the patients in HG was 26.5 ± 10.4 years. Male/Female ratio was 2.39. All HG patients had altered TSH values and 8% had diminished T4 values. Cochleovestibular symptoms were more common in hypothyroid patients (48%) than control (20%) p value. Pure Tone Audiometric threshold was found higher in 34% of cases. Sensorineural hearing loss was most common (76.46%) compared to conductive and mixed hearing loss. BERA showed significant prolonged absolute peak latency of wave III, inter peak latency (IPL) of wave I-III and reduced amplitude of wave Ia and Va. After thyroxine replacement therapy there was statistically significant improvement in hearing threshold in 46.42% ears (p < 0.05), (if ≥ 5 dB hearing improvement consider as significant). The significant improvement was also found in BERA, in amplitude of wave Va. Site of involvement was at several levels, middle ear, cochlear or retro-cochlear. HG patients had more cochleovestibular symptoms, higher audiometric thresholds, increase in latency of wave III, IPL of I-III and reduced Ia and Va amplitude in the BERA. After TRT improvement in hearing threshold and BERA was found.

Keywords: Brain evoked response audiometry (BERA); Control groups (CG); Hypothyroid groups (HG).