Hypocalcemic Convulsions Research Articles

The Effect of Various Levels of Calcium, Phosphorus and Vitamin D in the Feed for Growing Pigs with Special Reference to Atrophic Rhinitis

Thirty-two pigs were divided into 8 groups in an experiment to study the effect of various levels of calcium, phosphorus and vitamin D in the feed on weight gain, feed conversion, calcium, inorganic phosphorus and alkaline phosphatase in serum, ash content of the bones and the health of the pigs. Deficiency of vitamin D caused various degrees of rickets, and some of the animals fed on a diet with a low calcium-phosphorus ratio died in hypocalcemic convulsions. Vitamin D deficiency caused a fall in serum calcium, followed by an increase in alkaline phosphatase. The animals on a diet deficient in vitamin D and with a low calcium-phosphorus ratio had a poorer weight gain, decreased feed conversion efficiency and lower ash content of the bones than the animals on diets with an optimal composition. Various degrees of bone resorption were observed by histological examination of the turbinates from animals on diets with an unfavourable calcium-phosphorus ratio or deficient in vitamin D. The bone resorption was caused by socalled pericytic osteolysis. Signs of osteodystrophia fibrosa were also found. Neither macroscopic nor histological signs of atrophic rhinitis were seen. In some cases of spontaneous atrophic rhinitis from pigs outside the experiment pericytic osteolysis of the turbinates was also shown. It is concluded that this form of bone resorption may occur simultaneously with atrophic rhinitis when the diet is deficient in vitamin D or when the calcium-phosphorus ratio is unfavorable.

The electroencephalogram and electromyogram in experimental hypocalcemia

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.