Adult-Onset Isolated Hemichorea Revealing Iatrogenic Hypoparathyroidism and Bilateral Basal Ganglia Calcification

Isolated hemichorea (HC) in adults has a relatively restricted differential diagnosis including stroke of contralateral basal ganglia nuclei, nonketotic hyperglycemia, and basal ganglia toxoplasmosis in HIV infection. Hypoparathyroidism-related basal ganglia calcification can potentially cause neurological problems, including movement disorders, that are usually bilateral in keeping with bilateral symmetric lesions. We report a patient with video-documented isolated, adult-onset HC due to iatrogenic hypoparathyroidism and bilateral basal ganglia calcification. A 47-year-old woman presented with isolated adult-onset HC of 2 years' duration as the presenting and only neurological feature of hypoparathyroidism and bilateral extensive basal ganglia calcification, 20 years after thyroidectomy-induced hypoparathyroidism. Significant improvement in the unilateral hyperkinesia was noted after correction of hypocalcemia and hypoparathyroidism at 3 months. Isolated HC in adults is a rare presenting feature of hypoparathyroidism with bilateral basal ganglia calcification and is treatable with correction of the underlying metabolic abnormality. In all cases with a movement disorder and brain calcification, hypoparathyroidism should be actively sought as this treatable condition must not be missed.