ABSTRACT
A 16-year-old male presented to hospital following an episode of unusual behavior on the football pitch, where he was witnessed as grossly ataxic by his teammates. The assessment demonstrated marked cerebellar signs on examination but no other neurological deficit. The investigation showed the evidence of biochemical thyrotoxicosis with free T4 at 37 pmol/L (normal reference range: 11-27) and thyrotropin (TSH) < 0.003 mU/L. Following admission, full investigations including computed tomographic brain scan with contrast, lumbar puncture with cerebrospinal fluid examination, magnetic resonance imaging, and magnetic resonance angiography did not reveal abnormalities. He was initiated on carbimazole 40 mg every day. Thyroid ultrasonography revealed a goiter with increased blood flow, and his thyroid antibodies showed positive thyroid peroxidase antibodies but negative TSH receptor antibodies. Electroencephalogram did not reveal any abnormalities. His neurological disability resolved completely after his thyroid function normalized. The association of cerebellar syndromes is well described with hypothyroidism; however, it is hitherto undescribed with thyrotoxicosis. The causal relationship is plausible because alternative etiologies were excluded, and the normalization of thyroid function with treatment was coupled with complete resolution of the neurological syndrome. Cerebellar syndromes may well be one of the presenting features of thyrotoxicosis, and this should be in the list of its differential diagnosis.