ENCEPHALOPATHIA HYPERCALCEMICA - A CLINICAL AND ELECTROENCEPHALOGRAPHIC STUDY IN MYELOMA AND OTHER DISORDERS

1. (1) The effect upon the central nervous system of a raised serum calcium level were studied clinically and by means of EEG in 37 patients suffering from hypercalcemia. Eighteen of them had multiple myeloma and 14 hyperparathyroidism. 2. (2) It was confirmed that many patients with high calcium levels, especially with myeloma, showed severe mental impairment and sometimes coma. These general symptoms disappeared when the calcium level became more normal. 3. (3) About one half of the patients with hypercalcemia also showed diffuse EEG abnormalities with slowing of the background rhythm and appearance of bilateral high voltage delta episodes. The EEG abnormalities were quantified by means of manual frequency analysis and the index of the mean frequency thus obtained, showed a gross negative correlation to the calcium level. 4. (4) In some patients, especially with hyperparathyroidism, hypercalcemia was observed without mental symptoms. In other cases EEG abnormalities were absent in spite of a considerable rise in the calcium level. Furthermore, marked but transient mental symptoms were occasionally observed at fairly low calcium levels. 5. (5) Several of the patients showed signs of impairment of renal function, which might have enchanced the cerebral effects of the hypercalcemia. Other factors which may have had a similar effect are discussed, including abnormalities of the serum albumin. It appears possible that both azotemia with acidosis, as well as a reduced serum albumin, may enhance the toxic effects of calcium upon the central nervous system by augmenting the ionization of the serum calcium. © 1969.