In the 5-year period from 1978 to 1983, 1076 patients with ruptured intracranial aneurysms were admitted to the six neurosurgical departments in Denmark and were entered in a prospective consecutive study conducted by the Danish Aneurysm Study Group. The patients were followed with 3-month and 2-year examinations or to death. A total of 133 patients suffered at least one rebleed after their initial hemorrhage during their first stay in the neurosurgical department; these patients had a mortality rate of 80% compared to 41% for patients without a rebleed (p less than 0.0001). During the first 2 weeks after the initial insult, 102 rebleeds were registered. The daily rate of rebleeds during these 2 weeks, calculated using a life-table method, varied from 0.2% to 2.1%. The rebleed rate during the first 24 hours (Day 0) was 0.8%, and the maximum risk of rebleeding was observed between Day 4 and Day 9. Significantly fewer rebleeds were reported in patients with good clinical grades (Grades 1 to 3, Hunt Grades I and II) compared to those with poor clinical grades (Grades 4 to 9, Hunt Grades III to V: p less than 0.001).

A prospective randomized study to compare discectomy without (DE) and with fusion (DEF) included 63 patients operated on with DE returned to work during the first 9 weeks postoperatively than patients operated on with DEF (p less than 0.005 to 0.05). The prognosis is significantly better for men than for women after DEF (p less than 0.005), while no difference can be shown after DE.

We have studied the effect of 1 or 2 MAC isoflurane with or without ketanserin on cerebral blood flow (CBF), cerebral oxygen metabolism (CMRO2) and CBF autoregulation in 20 adult patients undergoing lumbar disc surgery. Ten patients received ketanserin and 10 isotonic saline. CBF measurements were started after 1 h of infusion of saline or ketanserin. The patients were anaesthetized with thiopentone 5 mg kg-1 followed by isoflurane. During 1 MAC of isoflurane, baseline values were recorded and then CBF autoregulation was examined (mean arterial pressure increased by about 30% with angiotensin). The sequence was repeated with 2 MAC of isoflurane. CBF was measured by the i.v. xenon-133 technique. CMRO2 was calculated as the product of CBF and the cerebral arterio-venous oxygen content difference. Ketanserin had no effect on CBF, CMRO2 or CBF autoregulation during isoflurane anaesthesia, therefore all patients were pooled for evaluation of the effect of isoflurane. Increasing isoflurane anaesthesia from 1 to 2 MAC increased mean CBF from 41 to 49 ml/100 g min-1 (P < 0.01) and decreased mean CMRO2 from 1.5 to 1.1 ml/100 g min-1 (P < 0.001) and thus abolished the coupling between flow and metabolism. The CBF autoregulation test indicated that autoregulation was disrupted at 2 MAC, but not during 1 MAC isoflurane anaesthesia.

In a well-defined area, The Kingdom of Denmark, 1076 patients with ruptured intracranial aneurysms were admitted to the six Danish neurosurgical departments in a prospective consecutive study in the 5-year period 1978-1983. Follow-up examinations were accomplished 3 months and 2 years after the admission. A total of 674 women and 402 men with a median age of 49 years were included in the study. The localisation of the ruptured aneurysms were: internal carotid artery 285, anterior communicating artery and horizontal part of anterior cerebral artery 383, middle cerebral artery 291, basilar and vertebral arteries 83 and peripheral or other localisation 34. A significantly better outcome was seen in cases with internal carotid aneurysms compared to other localisations. 670 patients underwent operation. A highly significantly better outcome was found in operated versus non-operated patients in comparable clinical conditions. The advantage of microneurosurgery was well documented. Patients with vasospasm had a significantly worse outcome. Within the first 2 weeks a daily rebleeding rate from 0.2% to 2.1% was observed, and patients who rebled had a significantly worse outcome compared to patients, who did not rebleed. The overall outcome at 2-year follow-up was: normal 27.5%, mild dementia 15.8%, severe dementia 9.9%, vegetative 1.3% and mortality 45.5%.