Paracentral strip infarcts of the middle cerebral artery: borderzone ischaemia or cortical artery occlusion?

Background And Purpose: We have noted the presence of small strip-like infarcts involving the cortex within the interdivisional territory of the middle cerebral artery (MCA) and sometimes extending to the periventricular region. The incidence in a stroke unit population, mechanisms, clinical expression and prognosis of patients with these cortical infarcts are unknown. To clarify these issues we retrospectively and prospectively identified these patients in our own stroke unit population.

Methods: Patients were identified retrospectively and prospectively from the Austin Hospital Stroke Unit from March 2001 to May 2007. All were selected on the basis of the recent onset of an acute neurological deficit with imaging showing strip infarction within the MCA territory. Clinical features were recorded and the mechanism of infarction was classified based on the TOAST criteria from standard investigations.

Results: From 4,274 acute stroke admissions, there were 24 patients (0.6%), 12 males and 12 females (mean age 75 years; range 44-92 years) with CT or MRI showing characteristic linear infarction in the middle cerebral territory. In most cases, infarction was adjacent to the central sulcus. Common clinical features included mild-to-moderate hemiparesis with cortical signs. The most common TOAST criterion mechanism categories were artery-to-artery or cardiac embolism. It is postulated that this resulted in either isolated small cortical artery branch occlusion or borderzone infarction between superior and inferior divisions of the MCA due to more proximal large-artery vessel occlusion. Prognosis was good.

Conclusions: We describe the phenotypic expression, postulated mechanisms and prognosis of strip-like infarcts between the superior and inferior MCA divisions. The likely artery-artery or cardio-embolic mechanisms should prompt clinicians to search for an embolic source. While the prognosis of the syndrome is generally good, its recognition may allow specific therapies to be developed to improve clinical outcomes further.