Assessment of peripheral neuronal activity with Nerve Conduction Studies in subclinical hypothyroidfemales from rural area of Bankura district of West Bengal

Abstract

Objective : Like overt cases, whether subclinical hypothyroidism also causes supressed neuronal transmission is still debated . In this study, we tried to explore whether neuronal transmission is impaired in peripheral nerves in subclinical hypothyroidism with the help of Nerve Conduction Studies. Methods: 30 subclinical hypothyroid cases and 30 age sex matched euthyroid control were examined. All the subjects were assessed for Nerve Conduction velocity (NCV).Latency ,amplitude of CMAP(Compound Motor Action Potential) and conduction velocity of peripheral nerves like median and ulnar of both hands were considered. Findings were compared between groups by unpaired Students T- test andassociation among thyroid function parameters and NCV findings were tested by Pearsons co efficient of correlation (r value). Every where p< 0.05 was considered as significant. Results: Subclinical hypothyroids showed significantly higher distal latencies but lower conduction velocities of both median and ulnar nerves than the euthyroid controls (p<0.05 in each case). Amplitude of CMAP of both the nerves were not significantly different between the groups.Level of T3 was found to have a significant negative correlation withdistal latencies of Median and ulnar nerves (r value = -0.51 and -0.38 respectively, P<0.05 in each case) whereas a positive correlation with their conduction velocities (r- value = 0.27 and 0.55 respectively, p< 0.05 in each case). TSH however did not show any significant correlation with NCV parameters. Conclusion: Subclinical hypothyroidism may cause impairment in peripheral nerve conduction but the severity of such neurodeficit is not correlated with the level of TSH but with the level of T3.