Cerebral calcinosis with late onset encephalopathy. Unusual type of pseudo-pseudohypoparathyreoidism

A family from Western Norway is described in which 5 out of 9 members in one generation developed a progressive encephalopathy in middle life. Massive, symmetrical calcifications located in basal ganglia, dentate nuclei and cerebral sulci of the brain were seen on roentgenograms of the skull. All affected members exhibited a clinical syndrome which included mental deterioration, extrapyramidal motor deficit, cerebellar ataxia and tremor. The biochemical investigation showed normal serum calcium and phosphorous and concentration of immunoreactive parathyroid hormone was normal. The Ellsworth-Howard test with exogenously administered parathyroid extract revealed a subnormal phosphorous diuresis while urinary excretion of cyclic AMP was normal. Thus, the defect appears to be an insufficient intracellular response to cyclic AMP. The late onset of symptoms is compatible with the slight disturbance in calcium-phosphorous metabolism we have demonstrated. The family probably represents an unusual type of pseudo-pseudohypoparathyroidism of which only one other family has been reported earlier. The investigations and pedigree analysis of the present kindred is suggestive of an autosomal recessive inheritance of the disorder.