The Significance of Bilateral Basal Ganglia Calcification

Bilateral basal ganglia calcification was first recognized as a histologic entity in 1855 and described independently in that year by Virchow (1) and Bamberger (2). This phenomenon was encountered postmortem by many authors during the next eighty years but was not reported as a radiographic finding until 1935, when Fritzsche (4) and then Kasanin and Crank (5) described the roentgen appearance of this specific type of intracranial calcification in living patients. Four years later, in 1939, its occurrence in idiopathic hypoparathyroidism was described by Eaton, Camp, and Love (6). Its occurrence in pseudohypoparathyroidism, another disease characterized by abnormal calcium phosphorus metabolism, was first reported in 1945 by Sprague, Haines, and Power (14). Camp re-emphasized the association with hypoparathyroidism in 1947 (18). Anatomical Considerations The basal ganglia (Fig. 1) are masses of gray matter lying in the base of each cerebral hemisphere. They include three major structures—the caudate nucleus, the putamen, and the globus pallidus— and two minor centers—the amygdala and the claustrum. The caudate nucleus is an elongated mass of gray matter composed of a pear-shaped head, which bulges into the anterior horn of the lateral ventricle, and a slender arcuate tail, which is closely related to the atrium and temporal horn of the lateral ventricle. The putamen and globus pallidus form an oval wedge of gray matter, the lenticulate nucleus, which lies lateral to the head of the caudate nucleus. The basal ganglia are major centers of the extrapyramidal nervous system. In diseases of this system, such as parkinsonism or athetosis, they are the site of degenerative histologic lesions. It is interesting that skull films of these patients seldom display basal ganglia calcification and, conversely, only 20 per cent of patients with calcification manifest symptoms of parkinsonism or athetosis. Pathology The pathogenesis of basal ganglia calcification appears to consist in deposition of a colloid material in and around the finer cerebral blood vessels, with subsequent calcification of this colloid (6). Eaton, Camp, and Love presented an excellent description of these histologic changes with photomicrographs. Such calcification, of a degree insufficient to be roentgenographically demonstrable, is evident histologically in about two-thirds of routine postmortem brain examinations (3, 48). In the cases described in this report the range in prominence was from massive calcifications to those that were barely discernible in routine skull films. Roentgen Demonstration of Basal Ganglia Calcification Basal ganglia calcifications appear as a cluster of irregular punctate densities located at a distance of 3 to 5 cm. above the sella turcica in the lateral projection of the skull, and 2 to 4 cm. lateral to the midline in the frontal and occipital projections (Fig. 2). These calcifications are almost invariably bilateral, and are usually symmetrical.