Fahr Disease

A 45-year-old woman presents with a 2-year history of progressive involuntary movements (chorea and dystonia), parkinsonian features (bradykinesia and rigidity), cognitive decline, and psychiatric manifestations including depression, paranoid delusions, and visual hallucinations. She has had multiple generalized tonic-clonic seizures. Family history is significant for similar symptoms in her father and older brother. Laboratory evaluation shows normal serum calcium (9.4 mg/dL), phosphorus (3.6 mg/dL), and parathyroid hormone (48 pg/mL). Non-contrast CT brain demonstrates extensive bilateral symmetric hyperdense calcifications in the globus pallidus, putamen, caudate nuclei, thalami, and dentate nuclei. The imaging pattern marked **C** in the diagram is consistent with which diagnosis?