Diagnosis

Fahr disease

Findings

Three axial noncontrasted computed tomography (CT) images are provided: the first 2 in brain windows and the last in bone window. The CT images demonstrate dense, symmetric calcifications involving the globus pallida, putamina, caudate nuclei, thalami, subcortical white matter, and dentate nuclei. Mild generalized parenchymal-volume loss is also present.

Discussion

Fahr disease is a rare neurodegenerative disorder, which is also known as idiopathic familial basal ganglia calcification, bilateral striopallidodentate calcification, and familial cerebrovascular ferrocalcinosis. The disease process is characterized by progressive deposition of calcium within the walls of the capillaries and larger arteries and veins. Patients usually present between the ages of 30 and 60 with cognitive impairment, neuropsychiatric disturbances, and extrapyramidal movement disorders. There is a bimodal distribution of clinical onset with younger patients preferentially demonstrating psychiatric symptoms and older patients presenting with dementia and extrapyramidal movement symptoms. There is no gender predilection, but many cases are familial. The disease is characterized by very slow progression of symptoms with no effective treatment options.

Fahr disease is most easily recognized by symmetric basal ganglia calcifications, most commonly affecting the globus pallidus. Many cases also involve the putamen, caudate, thalami, dentate nuclei, internal capsule, and subcortical white matter. The calcifications are best detected by CT, although susceptibility-weighted magnetic resonance imaging (MRI) sequences may be more sensitive than CT. Occasionally, MRI may demonstrate white-matter hyperintensity on T2-weighted images due to inflammation.

The differential diagnosis of basal ganglia calcifications is broad and includes metabolic causes, such as hypoparathyroidism, hyperparathyroidism, and birth hypoxia, infectious causes such as TORCH infections, Tuberculosis, neurocysticercosis, and AIDS, toxic causes such as radiation, chemotherapy, and carbon monoxide poisoning, inherited disorders, such as MELAS and Cockayne syndrome, and also may be idiopathic. Differentiation is usually by clinical symptoms and laboratory evaluation.

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