[Circadian rhythm disturbance after radiotherapy for brain tumor in infantile period--clinical effect of L-thyroxine and vitamin B12].

We reported here 19-year-old man suffering from circadian sleep-wake (S-W) rhythm disturbance after total tumor resection and whole brain irradiation. This 19-year-old man was diagnosed as having astrocytoma in the right temporal lobe by CT scan and angiography at the age of 6 months. After total tumor resection and whole brain irradiation (60Co 60 Gy), he showed profound psychomotor retardation, endocrinologic dysfunction including hypothyroidism and growth hormone deficiency, and sleep-wake rhythm disturbance. At the age of 19, brain MRI revealed asymmetrical low intensity in the hypothalamic region. On endocrinological examination panhypopituitarism due to primary hypothalamic lesion was evident. His S-W rhythm was disturbed showing a dispersed type sleep, i.e., sleep periods were dispersedly distributed throughout the 24 hours. So he showed a lethargic tendency in the daytime. All-day polysomnography revealed abnormal sleep structure such as the absence of sleep spindle and hump, peripheral apnea, snoring and low oxygen saturation. After L-thyroxine supplementation his daily activity improved gradually. The decrease in short time sleep and tendency of a free-running rhythm were observed and oxygen saturation improved remarkably. Peripheral apnea and snoring disappeared. The wakening effect of L-thyroxine administration may be due to improvement of hypothyroidism symptom such as myxoedematous pharynx. In addition, it seems related to the alteration of the central S-W rhythm regulation, because free-running rhythm appeared after L-thyroxine administration. Vitamin B12 (VB12), which has been reported to be effective for sleep-wake rhythm disorders, was not effective for our patient's free-running rhythm.(ABSTRACT TRUNCATED AT 250 WORDS)