The value of cerebral blood flow measurement in carotid surgery.

The considerable risks and high costs associated with carotid surgery have raised the discussion of its expediency. Carotid surgery is only indicated if a source of embolism in the region of the carotid bifurcation has been demonstrated or an endangerment of the blood supply to the brain is certain. Methods to detect a source of embolism with some reliability were not available until the advent of high-resolution Doppler ultrasound and transcranial techniques. The demonstration of an endangerment of the blood supply to the brain requires measurement of the regional cerebral blood flow assessment of the collateral circulations, and determination of the reserve capacity of the cerebral blood system. Diagnostic procedures available for this and their clinical relevance are discussed. Reliable assessment, however, requires functional criteria which still have to be developed.