Acute intracranial hypertension-An experimental investigation

1. 1. Acute excessive elevation of the cerebrospinal fluid pressure (CSP) was 116 times produced by infusion of fluid under pressure into the lumbar or cisternal subarachnoid space in 19 dogs and 11 cats. 2. 2. An extreme vasopressor response could be elicited, followed by severe EKG changes, hypotension and increase of the venous pressure. When the excessive rise of the arterial pressure was presented by infusion of Arfonad, no such heart failure was observed. 3. 3. EEG alterations, ensuing in electrical silence, were registered, when the CSP surpassed the reactively raised systolic arterial pressure (absolute CSP). 4. 4. The electrical silence was the result of impairment of the cerebral circulation, as evidenced by angiography. 5. 5. In 17 experiments the CSP was elevated in the isolated spinal dural sac, as well as in the isolated cranial cavity. In the first case an excessive vasopressor reaction, without EEG changes were noticed, whereas in the latter the reverse was the case. 6. 6. By maintaining the absolute CSP during a prolonged time, the EEG silence proved to be irreversible. 7. 7. By damaging the brain in this manner it was possible to study an organism without a functioning central nervous system, imitating the state of deanimation in man. 8. 8. Neuropathological changes occurred after about 6 h, the most important being oedema and intravital necrosis of the brain. 9. 9. The mechanisms as evidenced by these experiments give an insight into the pathophysiology of acute increase of the cerebrospinal fluid pressure in man.