Electroencephalographic changes during and after treatment of hyperthyroidism.

Abstract

ABSTRACT EEG and thyroid function tests have been studied in 32 hyperthyroid patients before, during and after antithyroid treatment. EEG abnormalities such as increase in alpha rhythm, slow rhythms, spikes and sharp waves and fast activity were found in 81% of the patients before treatment. A statistically significant correlation was found between the degree of EEG abnormalities and the severity of hyperthyroidism. During treatment and the period of observation which was extended to an average of 2½ year, a slight decrease in the occurrence of all abnormalities was observed, but even in the period 24–36 months after the start of the therapy, 65% of the patients still had abnormal EEG's. These persistent abnormalities in EEG suggest that hyperthyroidism might cause irreversible damage to the brain cells. It should be realized that hyperthyroidism may be the cause of considerable EEG abnormalities however not only in the acute state of the disease but also several years after an otherwise successful antithyroid treatment.