M. Ozata et al., EVALUATION OF CENTRAL MOTOR CONDUCTION IN HYPOTHYROID AND HYPERTHYROID PATIENTS, Journal of endocrinological investigation, 19(10), 1996, pp. 670-677
Deficiency or excess of thyroid hormones is associated with central ne
rvous system (CNS) disturbances. Although the CNS involvement either i
n hypothyroidism or in hyperthyroidism have previously been shown on t
he basis of visual, auditory and somatosensory evoked potentials studi
es, less is known about the function of central motor pathways in both
disorders. We studied the motor evoked potentials (MEPs) following th
e magnetic stimulation of the motor cortex and spinal roots in 20 pati
ents with hypothyroidism and in 19 patients with hyperthyroidism both
before treatment and after they became euthyroid and compared with fin
dings in 20 age-, sex- and height- matched control subjects. Disease d
uration (expressed as time from diagnosis of diseases to the time of n
eurological testing) is less than one month in both disorders. Central
motor conduction time (CMCTJ was determined as the differences betwee
n MEPs latencies after cortical and spinal stimulation. The mean CMCTs
before treatment in hypothyroid patients (8.31 +/- 1.52 msec,) and in
hyperthyroid patients (7.92 +/- 1.06 msec,) were significantly prolon
ged as compared to those in normal controls (6.82 +/- 0.83 msec, p = 0
.002 and p = 0.004, respectively). Four of the 20 (20.0%) hypothyroid
patients and 2 of 19 (10.5%) hyperthyroid patients had abnormal CMCT (
values exceeding mean + 2.5 SD of normal control); The mean CMCT value
s in both groups were not significantly decreased after euthyroidism w
as achieved, although a tendency of the decrease in CMCT was observed.
Improvement of CMCT abnormalities was observed in 1 of 4 hypothyroid
patients and in one of 2 patients with hyperthyroidism, who had CMCT a
bnormalities before treatments, after they became euthyroid. No correl
ation was found between CMCT and free T-3, free T-4, or TSH levels as
well as the onset age, the severity of the diseases or the disease dur
ation in both disorders. We conclude that abnormal CMCT could be docum
ented in few patients in both disorders. However, these alterations co
uld not be improved completely after restoration of euthyrodism. Thus,
it remains to be determined if long-term treatment would completely i
mprove CMCT abnormalities in both disorders. Since abnormal CMCT value
s in both disorders were observed only in few patients, our results al
so suggest that CMCT measurement does not have, at present time, a cli
nical usefullness to assess the peripheral action of thyroid hormones.
Thus, the data obtained need a more extensive evaluation. (C) 1996, E
ditrice Kurtis