Clinical implications of collateral middle cerebral artery flow in acute ischaemic stroke with internal carotid artery occlusion

Abstract

The presence of collateral middle cerebral artery (MCA) flow via the primary collateral pathway is thought to protect against the progression of cerebral ischaemia. However, there have been few reports on early clinical outcomes according to the presence of collateral MCA flow in acute ischaemic stroke (AIS) with internal carotid artery (ICA) occlusion. Therefore, we sought to investigate the early clinical outcomes and lesion patterns according to the presence of collateral MCA flows in AIS with ICA occlusion. This is a retrospective study of patients with AIS with ICA occlusion consecutively admitted to our stroke center between October 2008 and March 2010. Patients were included if they were admitted within 12 h of symptom onset with AIS and symptomatic ICA occlusion. Collateral MCA flow was defined as the presence of MCA signals from proximal M1 to distal MCA branches ipsilateral to the ICA occlusion by magnetic resonance angiography. Early neurological deterioration (END) was defined as a 4-point increase in the National Institutes of Health Stroke Scale (NIHSS) score and persistent neurological deterioration for at least 24 h or newly developed neurological symptoms within 7 days. Sixty-five patients (42 men, 23 women) were finally included. Initial NIHSS scores were significantly lower, and favorable outcomes at 3 months were better in patients with collateral MCA flow than in those without (P < 0.001). Initial lesion patterns were different according to the collateral MCA flow. However, patients with mild AIS might more frequently deteriorate than those with moderate to severe AIS. In our study, collateral MCA flow reduced initial stroke severity and was associated with favorable outcomes at 3 months but did not seem to protect against END in mild AIS patients with ICA occlusion. Therefore, the results of this study suggest that mild AIS patients with ICA occlusion should be carefully managed because their conditions may deteriorate.