Cerebral circulatory and metabolic changes following EC/IC bypass surgery in cerebral occlusive diseases

Area of Science:

• Neurology
• Neurosurgery
• Medical Imaging

Background:

• Ischemic cerebrovascular disease poses significant risks due to reduced cerebral blood flow (CBF).
• Extracranial-intracranial (EC/IC) bypass surgery aims to restore blood supply to the brain.
• Assessing the efficacy of EC/IC bypass requires objective measures of cerebral perfusion and metabolism.

Purpose of the Study:

• To evaluate the impact of EC/IC bypass surgery on CBF, oxygen extraction fraction (OEF), and cerebral metabolic rate of oxygen (CMRO2).
• To determine the utility of Positron Emission Tomography (PET) in patient selection for EC/IC bypass.

Main Methods:

• Utilized Positron Emission Tomography (PET) with the 15O steady-state technique.
• Measured CBF, OEF, and CMRO2 in 14 patients before and after EC/IC bypass.
• Included patients with carotid lesions (superficial temporal artery-middle cerebral artery anastomosis) and vertebro-basilar lesions (STA-superior cerebellar artery anastomosis).

Main Results:

• Significant increases in CBF and decreases in OEF were observed post-surgery in both patient groups.
• Patients with vertebro-basilar lesions showed notable improvements in both the cerebellum and cerebral cortex.
• Preoperative higher OEF correlated with marked increases in CBF and decreases in OEF post-bypass.
• EC/IC bypass demonstrated effectiveness, particularly when preoperative uncoupling of cerebral circulation and metabolism was pronounced.

Conclusions:

• EC/IC bypass surgery is an effective treatment for selected patients with ischemic cerebrovascular disease.
• PET imaging is valuable for identifying patients who would benefit most from EC/IC bypass.
• The study highlights the importance of addressing marked preoperative uncoupling between cerebral circulation and metabolism.