*8.5.1 Direct revascularization*

Anastomosis is formed between the superficial temporal artery and cortical branches of middle cerebral arteries in this procedure. For posterior circulation, the occipital artery is used as a donor for nteroposterior cerebral arteries' cortical branches. The transdural or transcalvarial collateral channels should be preserved during the surgery.

The advantage of this procedure is an immediate improvement in the cerebral blood flow after surgery. However, the successful restoration of cerebral blood flow is operator dependant as it is challenging to perform. Moreover, postoperative hyperperfusion syndrome may develop after surgery leading to neurological deterioration. Patency and amount of bypass flow may be assessed postoperatively by digital subtraction angiography or quantitative magnetic resonance angiography.

The annual stroke rate after direct revascularization was reportedly 0–1.6% [40].
