Generalized Dystonia in Fahr’s Syndrome Secondary to Idiopathic Hypoparathyroidism: Improvement After Metabolic Correction

Dear Editor,Fahr's syndrome (FS) is a rare neurological disorder characterized by abnormal, bilateral, and symmetrical calcification of the basal ganglia.Unlike Fahr's disease, which is primary and often genetic, FS represents the secondary form of brain calcification associated with metabolic, infectious, or degenerative conditions.Although FS may present with diverse neurological manifestations, generalized dystonia is exceptionally rare.1,2 Here, we report a case of generalized dystonia associated with longstanding, undertreated idiopathic hypoparathyroidism.A 51-year-old male visited the neurology outpatient clinic with a one-month history of truncal turning movements (Supplementary Video 1 in the online-only Data Supplement).Neurological examination revealed a sustained dystonic posture characterized by rightward truncal rotation with mild ipsilateral tilt, which became more evident while standing still and was partially alleviated by voluntary movements.Asymmetric posturing was observed in the upper limbs, more pronounced on the right.Mild dysarthria was also present; however, no dystonic features were observed in the face or lower limbs, and no signs of parkinsonism or ataxia were identified.The patient had a 10-year history of idiopathic hypoparathyroidism managed with calcium supplementation, without recent medication adjustments.Past medical history was otherwise unremarkable except for hypertension.He had no prior exposure to dopamine receptor-blocking agents, antiemetics, or other medications known to cause tardive dystonia.Laboratory tests showed hypocalcemia, with serum calcium (5.2 mg/dL; reference 8.6-10.0mg/dL) and ionized calcium (1.28 mmol/L; reference 2.30-2.59mmol/L), hyperphosphatemia (5.2 mg/dL; reference 2.5-4.5 mg/dL), and markedly reduced parathyroid hormone (2.2 pg/mL; reference 15-65 pg/mL).Brain computed tomography revealed extensive, bilateral, and symmetrical intracranial calcifications involving the centrum semiovale, basal ganglia, thalamus, occipital cortex, subcortical white matter, and dentate nuclei (Fig. 1).In addition, brain MRI performed to evaluate other structural abnormalities revealed no specific findings apart from the intracranial calcifications.The patient's advanced age and absence of a family history made genetic causes of dystonia, including DYT1, unlikely, and genetic testing was therefore not pursued; however, a genetic etiology cannot be completely excluded.Nevertheless, the combined clinico-radiological and biochemical findings were consistent with a diagnosis of FS secondary to idiopathic hypoparathyroidism.The patient was treated with intravenous calcium infusion for one week, in combination with oral calcitriol, alfacalcidol, and calcium supplementation.Following treatment, serum calcium normalized, and generalized dystonia gradually improved, although the symptoms did not completely resolve.