The suboccipital carrefour: cervical and vertebral arterial anastomosis

Our objective was to anatomically define the anastomoses between cervical and carotid arterial distributions (the carrefour) in the rabbit and to assess the contribution of these collaterals to cortical blood flow (CBF) during cerebral ischemia.

Angiography was carried out in six rabbits with basilar artery occlusion using selective contrast injection into the right subclavian, external carotid, and internal carotid arteries. Anastomoses were corroborated with methacrylate vascular casts prepared in five additional rabbits. CBF was measured in eight rabbits by H2 clearance after basilar artery occlusion and again after bilateral common carotid artery occlusion. Cortical DC potential was measured during ischemia in these rabbits and in another 19 rabbits after additional occlusion of the cervical collateral arteries.

A network of anastomoses between superficial and ascending cervical, superior intercostal, vertebral, and occipital arteries was found by angiography and corrosion casts. Additional communications in the ophthalmic, ethmoidal, and cerebellar arterial distributions are described. These pathways were found to supply a mean of 15 +/- 7 mL/100 g per minute residual CBF during three-vessel ischemia, or 24% of the preischemic CBF. Ischemic depolarization of DC potential occurred in seven of the eight rabbits with collateral CBF at a mean latency of 2.64 +/- 0.59 minutes and at 1.71 +/- 0.09 minutes in those without.

The suboccipital collateral network of the rabbit resembles that of humans and can contribute significantly to CBF during ischemia. The results suggest that this model may be useful for evaluating methods of optimizing hemodynamic control of the anastomoses in situations such as those encountered during endovascular therapy.