Mean hemispheral cerebral blood flow changes after craniotomy. Significance and prognostic value

The effects of craniotomy on cerebral haemodynamics remains controversial from a study of the literature. This report represents our experience with respect to CBF changes within 10 days of surgery. Our objective was twofold, first to study the effect of craniotomy on the cerebral circulation and second to determine whether the CBF pattern at different post-operative intervals could provide useful prognostic information. A total of 135 CBF measurements were performed at the bedside of 36 patients; 19 patients with an assortment of intracranial tumours and 17 patients with intracranial aneurysm in different clinical grades. Our results indicate a significant rise in CBF in the immediate post-operative period averaging 18% of the pre-operative value. We believe this reflects a normal reaction of the cerebral vasculature to the inevitable disturbance of surgery. Furthermore, this hyperaemia may be of prognostic value as it was observed in 85% of the patients with tumour discharged without post-operative deficit and in 80% of the patients with aneurysms discharged in clinical grade 1 or 2. This is in sharp contrast with its development in only 16% of the patients with tumour discharged with post-operative deficit and 16% of the patients with aneurysm discharged in grade 3 or 4. The study adds to the direct clinical utility of CBF determination as a prognostic tool.