Skip to content

Fahr's disease

Summary

fleuron

  • Rare neurodegenerative disorder characterised by abnormal calcium deposits in basal ganglia and cerebral cortex
  • Presents with movement disorders, cognitive impairment, and psychiatric symptoms
  • Diagnosis based on clinical features and characteristic neuroimaging findings1

Pathophysiology

  • Bilateral calcification of basal ganglia, thalamus, and cerebral cortex
  • Disruption of calcium and phosphorus metabolism in the brain
  • Genetic factors implicated, with autosomal dominant inheritance pattern in some cases
  • Associated with mutations in SLC20A2, PDGFRB, and PDGFB genes

Demographics

  • Rare disorder with an estimated prevalence of <1/1,000,000
  • Typically presents in 4th to 6th decades of life
  • No significant gender predilection
  • Higher prevalence in certain geographic regions (e.g., Japan)

Diagnosis

  • Clinical presentation:
    • Movement disorders (e.g., parkinsonism, dystonia, chorea)
    • Cognitive impairment and dementia
    • Psychiatric symptoms (e.g., mood disorders, psychosis)
    • Seizures in some cases
  • Laboratory findings:
    • Normal serum calcium, phosphorus, and parathyroid hormone levels
    • Genetic testing for known mutations
  • Neuroimaging crucial for diagnosis

Imaging

  • CT:
    • Bilateral, symmetric calcifications in basal ganglia, thalamus, and cerebral cortex
    • Hyperdense lesions with Hounsfield units >100
  • MRI:
    • T1-weighted: Hyperintense signal in affected areas
    • T2-weighted: Variable signal intensity (hypo- to hyperintense)
    • Susceptibility-weighted imaging (SWI): Hypointense signal in calcified regions
  • PET:
    • Reduced glucose metabolism in affected brain regions

panels-1

  • While asymptomatic, this patient had a strong family history of intracranial calcification.
  • CT showed hazy calcification in the deep grey nuclei and frontal and cerebellar white matter.
  • The calcification in the deep grey nuclei caused both T1 hypointensity (blue arrow) and hyperintensity (red arrow).

panels-1

  • A 40-year-old patient undergoing treatment for a meningioma.
  • Incidentally, there were mixed dystrophic/hazy calcification in the striatum, dentate nuclei and peridentate white matter.
  • Fahr's disease was confirmed on genetic testing.

panels-1

  • A 60-year-old patient presented with abnormal gait.
  • A CT showed extensive calcification within the deep grey nuclei and the deep cerebral and cerebellar white matter.

Treatment

  • Symptomatic only. Note that identical calcification from hypoparathyroidism ("Fahr syndrome") must be excluded biochemically before diagnosing primary Fahr disease

Differential diagnosis

Differential Diagnosis Distinguishing Feature
Hypoparathyroidism Identical bilateral symmetric basal ganglia calcification on CT; dentate nuclei and subcortical white matter involvement indistinguishable from Fahr's disease
Wilson's disease T2/FLAIR signal change in putamen and thalami on MRI; no calcification; "face of the giant panda" sign
Mitochondrial disorders (MELAS) Cortical stroke-like lesions not following vascular territories; basal ganglia T2 signal change rather than calcification
Cockayne syndrome Calcifications combined with diffuse white matter signal change and cerebral atrophy; cerebellar atrophy
Aicardi-Goutières syndrome Periventricular and basal ganglia calcifications with white matter T2 signal change; progressive cerebral atrophy
Tuberous sclerosis Cortical tubers; subependymal nodules calcify on CT; very different from symmetric basal ganglia pattern
Carbon monoxide toxicity Bilateral globus pallidus T2 hyperintensity on MRI without calcification; acute onset

  1. Magrinelli et al. Basal ganglia calcification: 'Fahr's disease'. 2025. Practical neurology - Open in new tab. ↩