Encephalopathy associated with autoimmune thyroid disease: A grave situation

Background: Encephalopathy associated with autoimmune thyroid disease (EAATD) is an uncommon disorder affecting the central nervous system and associated with autoimmune thyroid disorders. It has myriad manifestations. Although most commonly seen with Hashimoto's thyroiditis, it has also been reported with Graves' disease. As it has no pathognomonic features (apart from response to steroids), it is a diagnosis of exclusion, and can be very challenging for the clinician. Clinical Description: An 11-year-old girl presented with a fever and altered sensorium for a few hours. In-depth history was unable to identify any significant history apart from recent weight loss. Salient examination findings were severe thinness, tachycardia, an enlarged thyroid gland, and altered sensorium, but the absence of neurological deficit, meningeal involvement, and increased intracranial tension. The clinical phenotype was acute encephalitis syndrome. Investigations ruled out biomarkers of infection, metabolic acidosis, hypoglycemia, dyselectrolytemia, uremia, hepatic dysfunction, and diabetic ketoacidosis. Neuroimaging was normal. Cerebrospinal fluid abnormalities were lymphocytosis, high protein, and normal glucose. A thyroid function test identified hyperthyroidism. Doppler ultrasonography revealed a diffusely enlarged and hypervascular thyroid gland. Thyrotropin-receptor antibodies were elevated (>10 IU/L). The final diagnosis was EAATD secondary to Graves' disease. Management and Outcome: Intravenous methylprednisolone (30 mg/kg/day), antithyroid drugs, and beta-blockers were started, on which she showed rapid and marked improvement. Conclusions: A detailed history, diligent clinical examination, and rational systemic approach needs to be undertaken to establish a diagnosis of EAATD.