Disappearing hyperdense middle cerebral artery sign is associated with striatocapsular infarcts on follow-up CT in ischemic stroke patients treated with intravenous thrombolysis.

Background: A striatocapsular infarct (SCI) is a subcortical infarct in the territory of the lenticulostriate arteries, most likely due to transient occlusion of the main stem of the middle cerebral artery (MCA). Presence of the hyperdense middle cerebral artery sign (HMCAS) is a reliable marker of occlusion of the MCA. We hypothesized that SCIs are related to HMCAS at baseline, which subsequently disappears (HMCAS-D) on follow-up CT in stroke patients treated with intravenous rtPA.

Methods: Baseline and 24-hour follow-up CTs were evaluated for HMCAS in acute ischemic stroke patients treated with intravenous rtPA and follow-up scans were also reviewed for the presence of isolated cortical (CIn), SCI, cortical and striatocapsular (CI-SCI) or lacunar infarct. We determined the incidence of SCI and the association between SCI and HMCAS on baseline and follow-up CT.

Results: Of the 247 patients, 43 had an SCI (17.4%; 95% CI: 13.1-22.5). The presence of HMCAS at baseline was related to the occurrence of infarction with involvement of the striatocapsular region (SCI or CI-SCI) on follow-up CT (OR: 11.6; 95% CI: 5.9-22.8). HMCAS-D on follow-up scans was significantly related to SCI on follow-up CT compared to CI-SCI (OR: 4.9; 95% CI: 3.7-6.1).

Conclusions: Occurrence of SCI and CI-SCI is associated with the presence of HMCAS on CT before thrombolysis, whereas HMCAS-D on follow-up CT is strongly related to the occurrence of SCI. Our findings support the causative role of transient occlusion of the MCA main stem in the pathogenesis of SCI.