A decade has passed since systematic studies were initiated in the USA in an attempt at establishing the experimental basis for a surgical technique which was to prove an effective tool in combatting one of the most common diseases, i.e. cerebrovascular accidents. The development of such intricate vasculosurgical techniques as are required for extra- intracranial arterial bypass operations would not have been possible without the aid of the surgical microscope, which had been designed some years earlier. In the past few years increasing emphasis has been placed on establishing clear-cut...