Fahr syndrome, also known as bilateral striatopallidodentate calcinosis, is characterised by abnormal vascular calcium deposition, particularly in the basal ganglia, cerebellar dentate nuclei, and white matter, with subsequent atrophy.

It can be either primary (usually autosomal dominant) or secondary to a large number of underlying illnesses or metabolic disturbances. 

There is confusion in the literature as to whether Fahr disease and Fahr syndrome are synonymous or not. Generally, the terms are used interchangeably, further divided into:

- primary: equivalent to familial cerebral ferrocalcinosis or primary familial brain calcification (now the preferred term), with no underlying other cause, and

- secondary: due to an underlying metabolic, infective or other cause

It has been argued, however, that the term Fahr disease should be reserved for – and, in fact, perhaps replaced by – primary familial brain calcification, whereas Fahr syndrome should be used only for secondary causes.

Calcification of basal ganglia is very common, and age dependent, with small amounts of calcification confined to the globus pallidus, considered a 'normal' finding in the elderly. 

Symptomatic onset for primary familial brain calcification (Fahr disease) tends to be between age 40 and 60. Incidence is unknown.

Symptoms of this disease include deterioration of motor functions and speech, seizures, and other involuntary movement. Other symptoms are headaches, dementia, and vision impairment. Characteristics of Parkinson's Disease may also be similar to Fahr's Syndrome. It usually presents with clumsiness, fatigability, unsteady gait, slow or slurred speech, difficulty swallowing, involuntary movements or muscle cramping. Seizures of various types are common. Neuropsychiatric symptoms, which may be the first or the most prominent manifestations, range from mild difficulty with concentration and memory to changes in personality and/or behavior, to psychosis and dementia.

Computed tomography or magnetic resonance imaging is usually the trigger for suspecting Fahr's disease and important for identifying the calcification pattern. Symmetric calcification of the globus pallidus, thalamus, and dentate nucleus is the most common pattern in IBGC, but other parts of the brain such as the cerebellum are involved. Treatment of Fahr's disease is currently limited and is largely symptomatic. A better understanding of this condition in light of genetic findings is important to improve the clinical diagnosis and develop specific treatment options.