Fahr syndrome

Clinical History

A 75-year-old male, k/c of Hodgkin’s lymphoma and mitral valve prolapse, presented to the emergency department with an insidious onset of chronic headaches getting progressively worse.
Neurological examination was completely normal and his blood biochemistry was normal including his serum calcium levels.

Imaging Findings

This patient underwent a non-contast enhanced axial CT of the head in order to investigate his neurological complaints (Fig. 1a, 1b, 2, 3).

This showed dense symmetrical convergent calcifications in the caudate and lenticular nuclei, obliterating the intervening anterior limb of the internal capsule (Fig. 1a, 1b). Gyriform calcification is also seen in the subcortical white matter of the posterior parietal and occipital lobes (most evident on Fig. 1b). Dense bilateral cerebellar calcification, in the region of the dentate nuclei, was also observed (Fig. 2). The whole series of images is shown in Fig. 3. No previous imaging was available for comparison. These findings were communicated to the referring neurologist. Screening of the first and second degree relatives of this patient by an unenhanced CT of the brain was unfruitful.

Discussion

Fahr’s disease, also known as bilateral striopallidodentate calcinosis, is a rare, idiopathic genetically dominant neurological disorder characterised by symmetrical calcification of the basal ganglia, dentate nuclei of the cerebellum, and centrum semiovale. The subcortical white matter may also be affected. Sporadic and familial cases have been reported with or without abnormal calcium/phosphorus metabolism [1].

Clinically it may present with rigid hypokinetic syndrome, mood disorders and cognitive impairment [2]. Parkinsonian symptoms, such as tremors, muscle rigidity, mask-like facies, shuffling gait, and a "pill-rolling" motion of the fingers, may be seen late in the course of the disease.

Associations reported in the literature include hypoparathyroidism and pseudohypoparathyroidism as well as endocrine polyadenomatosis (trabecular adenoma of the thyroid and clear cell adenoma of the adrenals) with hyponatremia [3].
The high resolving capability of CT enables easy detection of calcium and is the preferred method of localising and assessing the extent of cerebral calcification. On the other hand, the MR signal intensity of these calcific deposits is variable due to the lower proton density of calcium and other mineral ions present in higher concentrations. The calcific deposits may even appear hyperintense, due to proteins and mucopolysaccharides binding the mineral ions. They might also be undetected on MRI when they are in an intermediary stage [4]. Calcifications seem to be progressive, since they are generally more extensive in older individuals.

The diagnosis of Fahr’s disease relies on the imaging findings in the right clinical setting. Other causes of intracranial calcification should be excluded. Another pivotal role of imaging is that of establishing whether other family members are affected by Fahr’s disease, distinguishing between familial and sporadic cases. It should also be noted that a negative CT does not exclude development of Fahr’s disease later on in life. The minimum age at which a negative CT scan can exclude the disease is not yet established [5].

There is no cure for Fahr’s syndrome, nor is there a standard pattern of progression. The prognosis for any individual with Fahr’s syndrome is variable and hard to predict. There is no reliable correlation between age, extent of calcium deposits in the brain, and neurological deficit. Progressive neurological deterioration generally results in disability and death.

Differential Diagnosis List

Final Diagnosis

Fahr syndrome

URL:	https://www.eurorad.org/case/9159
DOI:	10.1594/EURORAD/CASE.9159
ISSN:	1563-4086