Auditory brainstem response findings in hypothyroid and hyperthyroid disease.

Area of Science:

• Otolaryngology
• Endocrinology
• Neuroscience

Background:

• Retrocochlear sensorineural hearing loss has been anecdotally linked to hypothyroidism.
• Auditory Brainstem Response (ABR) is a key diagnostic tool for evaluating retrocochlear function.

Purpose of the Study:

• To investigate the association between hypothyroidism and retrocochlear sensorineural hearing loss.
• To differentiate between direct effects of hypothyroidism and confounding factors like body temperature on ABR measures.

Main Methods:

• Audiometric testing and Auditory Brainstem Response (ABR) measurements were performed on patients with hyperthyroidism and hypothyroidism.
• Data analysis included stratification by body temperature to assess its influence on ABR findings.

Main Results:

• Hyperthyroid patients showed no significant differences from controls in audiometric or ABR results.
• Hypothyroid patients exhibited a higher prevalence of hearing threshold abnormalities (36% > 25dB).
• ABR in hypothyroid patients revealed reduced wave amplitudes and prolonged I-V intervals, but these were explained by lower body temperatures.

Conclusions:

• The study found no significant auditory differences in hyperthyroid patients compared to controls.
• While hypothyroid patients showed some hearing and ABR differences, these abnormalities were attributable to low body temperature, not direct retrocochlear damage.
• Thyroxine treatment normalized ABR findings, supporting the role of body temperature in the observed abnormalities.