Intracranial pressure during prolonged experimental convulsions in cats.

Experiments were carried out in cats to examine the relationship between prolonged convulsions and intracranial pressure. The convulsions were induced by pentylenetetrazole or bicuculline. Blood pressure, intracranial pressure and electroencephalogram were continuously monitored. Generalized tonic-clonic convulsions appeared with typical changes in the electroencephalogram 7-35 s after administration of the epileptogenic drugs. These convulsions persisted for 1-2 h. Concomitant with the clinical convulsions, intracranial pressure increased three- to fivefold, reaching maximal pressures of 20-94 mm Hg after 20-420s. The intracranial pressure remained high for between 47 s and 10 min, then began to fall gradually, reaching preictal levels after 2-30 min despite the continuation of convulsions. The variations in intracranial pressure were found to be independent of changes in blood pressure. The intracranial pressure, after dropping to preictal values, remained unchanged for up to 6 h after the induction of convulsions.