The collateral circulation plays an important protective role in different pathophysiological mechanisms, such as improving blood perfusion in the ischemic area or promoting the lysis of distal arterial embolic and increasing recanalization rates. There is growing evidence that collateral circulation is also essential in preventing the risk of secondary stroke in patients with sICAS. The cerebral collateral circulation is a compensatory endogenous anastomotic pathway for intracranial arterial stenosis or occlusion. It is effective in maintaining the nutritional requirements of the neurovascular unit for a specific time after complete arterial occlusion. It effectively maintains the nutritional requirements of the ischemia brain tissue in the neurovascular unit for a specific period time; symptoms of ischemia only occur in the presence of collateral circulation failure, and the degree of stenosis does not fully reflect the risk of cerebral ischemia. Studies have shown that patients with severe intracranial arterial stenosis or occlusion have relatively abundant collateral circulation. Early cerebral atherogenesis is characterized by a positively regulated response of genes associated with an inflammatory response [9]. Thus, the collateral circulation in patients with severe intracranial arterial stenosis or occlusion is also regulated by inflammatory processes.

However, the relationship between NLR, atherosclerosis, and collateral circulation remains unclear. This study investigated the correlation between peripheral blood NLR levels and collateral circulation by grading the cerebral collateral circulation in patients with severe stenosis or occlusion of intracranial arteries (including TIA and cerebral infarction).

With Regards,
Sara Giselle
Associate Managing Editor
Journal of Stroke Research & Therapy