Fahr syndrome in an 18-year-old male with pseudohypoparathyroidism: Clinical-radiological dissociation.

Fahr syndrome, characterized by bilateral intracranial calcifications, is a rare but clinically significant complication of chronic calcium-phosphate dysregulation in pseudohypoparathyroidism (PHP). Clinical manifestations frequently do not correlate with the extent of radiological findings, posing diagnostic challenges. An 18-year-old male with longstanding PHP presented with occipital headaches, carpopedal spasms, and depressed mood following more than two weeks of medication non-compliance. Non-contrast computed tomography (CT) of the brain confirmed extensive bilateral calcifications involving the basal ganglia, thalami, dentate nuclei, and subcortical white matter, with supportive findings on magnetic resonance imaging (MRI), including T1 hypointensity, variable T2 signal, and marked blooming artifact on susceptibility-weighted imaging (SWI). Neurological examination was largely unremarkable. Laboratory evaluation revealed hypocalcemia (serum calcium 7.2 mg/dL) with elevated intact parathyroid hormone (137 pg/mL), consistent with end-organ PTH resistance; serum phosphate (4.2 mg/dL) and 25-hydroxyvitamin D (42.4 ng/mL) were within the normal range. Electroencephalography showed no epileptiform activity. Optimization of calcium and calcitriol supplementation, together with symptomatic treatment, resulted in resolution of carpopedal spasms and significant improvement in headaches and mood at 15-day follow-up. This case illustrates the marked clinical-radiological dissociation characteristic of Fahr syndrome. Neurological evaluation or neuroimaging should be considered in PHP patients who develop new neurological or neuropsychiatric symptoms, particularly in the setting of poor biochemical control.