Introduction: Hypothyroidism, a common endocrinological disorder is quite prevalent in its subclinical state in the adult population. Nervous system involvement is frequent in hypothyroidism with documentation of peripheral and central conduction delays as abnormal latency prolongations in Brainstem Auditory Evoked Potential (BAEP) records. Subclinical hypothyroidism however, has been less extensively studied for investigating the involvement of the auditory functions.
Aim: To assess the auditory functions and Central Nervous System (CNS) involvement in the patients with subclinical hypothyroidism by recording BAEP.
Materials and methods: The study comprised of 50 females (25 females with subclinical hypothyroidism and 25 age-matched healthy females) in the age-group of 30-50 years. BAEP absolute and Interpeak Latencies (IPLs) (I, III and V, I-III, III-V and I-V) were compared between the two groups by unpaired t-test. The p<0.05 was considered as statistically significant.
Results: Mean BAEP absolute latencies (III and V) increased in the subjects with subclinical hypothyroidism as compared to controls (p<0.001) (both the ears) and wave I absolute latency also increased with p<0.001 (both the ears) by unpaired t-test. Among IPLs (interpeak latencies), III-V and I-V IPLs exhibited increase (p<0.01), while I-III IPL did not vary with statistical significance (both the ears) in the two groups.
Conclusion: Patients with subclinical hypothyroidism were found to demonstrate central as well as peripheral auditory pathway affections. BAEPs can prove valuable and sensitive tests to detect involvement of the CNS and auditory dysfunctions earlier in hypothyroidism.
Keywords: Absolute latency; Auditory pathways; Interpeak latency; Thyroid stimulating hormone.