Electroencephalographic Criteria of Hypocalcemia and Hypercalcemia

Abstract

A patient presenting with delayed hypoparathyroidism following thyroidectomy had initial hypocalcemia and subsequent iatrogenic hypercalcemia. A series of electroencephalograms taken at various blood calcium levels was rated by two independent observers using previously agreed criteria. Characteristic changes in the EEG related to serum calcium levels emerged. Bursts of high voltage slow waves were characteristic of all degrees of hypercalcemia but were only present in severe hypocalcemia. Spikes occurred only in hypocalcemia whereas triphasic waves were seen only in hypercalcemia. Delayed recovery of the EEG and clinical findings was noted in both conditions. The method was tested on an additional series of patients with disturbed calcium metabolism and found to be valid.