The electroencephalogram and electromyogram in experimental hypocalcemia

Abstract

The characteristics of the electroencephalographic and electromyographic changes occurring during and after hypocalcemic convulsions were investigated in cats after parathyroidectomy. 1. 1. In the awake intact cat the EEG characteristically exhibited lower voltage and higher frequency potentials with the onset of hypocalcemic convulsions. In some animals no changes in the EEG could be detected. Paroxysmal spikes or spikes and waves were never observed. 2. 2. In six out of seven encéphale isolé preparations there were no changes in the EEG, although severe convulsions involving the entire cat occurred. 3. 3. It is concluded that the arousal reactions observed in the EEG of intact cats were the result, at least in part, of the excitation of peripheral skin and muscle receptors occurring during the tetanic convulsions. 4. 4. Epileptiform seizure patterns occasioned by mechanical damage to the cerebral cortex of two of the hypocalcemic cats were abolished by intravenous injections of calcium gluconate. 5. 5. It is suggested that the epileptiform seizures occurring in chronic hypocalcemia of man are of a different pathophysiological origin from those of acute hypocalcemia, and are possibly a manifestation of degenerative changes in this condition. 6. 6. The convulsions of rachitic hypocalcemic babies are not a single entity. Typical tetanic spasms are the predominant manifestations only in some cases; in others, real cortical seizures occur.