CEREBRAL HEMODYNAMICS AND LONG-TERM PROGNOSIS AFTER EXTRACRANIAL-INTRACRANIAL BYPASS-SURGERY

The effectiveness of extracranial-intracranial arterial (EC-IC) bypass surgery for haemodynamic stroke remains controversial. In this study correlation of presurgical and postsurgical cerebral haemodynamics wit h long term prognosis was evaluated. Twenty eight patients (25 men, th ree women: mean age 61.4 (SD 8.2) years) with reduced cerebrovascular reserve due to steno-occlusive cerebral vascular disease formed the st udy group. Measurement of mean hemispheric cerebral blood flow (mCBF) and the cerebral vasodilatory capacity (% mCVR) with an intravenous ac etazolamide injection were performed by a xenon-133 inhalation method and SPECT. Patients were treated with EC-IC bypass surgery and measure ments of mCBF and % mCVR were made again about one month after surgery . The patients were then observed for a long period (range 27-115 mont hs). During the observation period, four patients experienced subseque nt ischaemic strokes. The presurgical and the postsurgical resting mCB F for the affected hemisphere were significantly reduced in the patien ts with strokes during follow up compared with the values in patients without strokes during follow up (P < 0.03 and 0 01 respectively). The % mCVR of the affected hemisphere was significantly raised after surg ery in all patients except one (P < 0.01). The postsurgical change in resting mCBF was not unidirectional. In conclusion, resting mCBF was u nchanged and % mCVR was improved after EC-IC bypass surgery in patient s with reduced cerebrovascular reserve. The group of patients with a r educed presurgical and postsurgical resting mCBF continue to be a high risk group for subsequent ischaemic stroke seen after EC-IC bypass su rgery.