SUBCLINICAL HYPOTHYROIDISM DOES NOT LEAD TO ALTERATIONS EITHER IN PERIPHERAL-NERVES OR IN BRAIN-STEM AUDITORY-EVOKED POTENTIALS (BAEPS)

Functional alterations in the central nervous system and peripheral ne rves are well documented in overt hypothyroidism, but not in subclinic al hypothyroidism. Twenty-seven patients with subclinical hypothyroidi sm were compared with a control group of 20 age- and sex-matched subje cts to determine whether subclinical hypothyroidism can lead to altera tions in peripheral nerves or in the brainstem auditory evoked potenti als (BAEPs). None of the patients had carpal tunnel syndrome or any ot her neurological or metabolic disturbances, Disease duration (expresse d as the time from diagnosis of subclinical hypothyroidism to the time of neurological testing) ranged from less than 1 month to 6 months (m edian 2.5 months). We studied the distal motor latency, nerve conducti on velocity (NCV), compound muscle action potentials, and F response i n the median and peroneal nerves whereas the sensory nerve conduction velocity and sensory potential amplitude were measured in the sural an d median nerves, Electrophysiological parameters and interpeak latenci es yielded no significant difference between patient and control group s, The present study indicates that subclinical hypothyroidism of shor t duration does not lead to abnormalities of peripheral nerves or brai nstem auditory evoked potentials.