Hyperdense Sylvian fissure MCA "dot" sign - A CT marker of acute ischemia

Background and Purpose-The hyperdense appearance of the main middle cerebra l artery (HMCA) is now a familiar early warning of large cerebral infarctio n, brain edema, and poor prognosis. This article describes the hyperdensity associated with embolic occlusion of branches of the middle cerebral arter y in the sylvian fissure (MCA "dot" sign). We define it and determine its i ncidence, diagnostic value, and reliability. Methods-CT scans performed on patients with acute ischemic stroke within 3 hours of symptom onset were analyzed for signs of thromboembolic stroke and evidence of early CT ischemia. Two neuroradiologists and 2 stroke neurolog ists initially blinded to all clinical information and then with knowledge of the affected hemisphere evaluated scans for the presence of the MCA dot sign, the HMCA sign, and early MCA territory ischemic changes. Results-Of 100 consecutive patients who presented within 3 hours of symptom onset, 91 were considered at symptom onset to have anterior circulation st roke syndromes. Early CT ischemia was seen in 74% of these baseline CT scan s. The HMCA sign was seen in 5% of CT scans, whereas the MCA dot sign was s een in 16%. All patients then received intravenous tissue plasminogen activ ator. All 5 patients with an HMCA sign, including 2 with an associated MCA dot sign, were either dead or dependent at 3 months. The 14 patients with a n MCA dot sign alone were independent at 3 months in 64% of cases, compared with 50% without the sign (Fisher's exact test P=0.79). Balanced kappa sta tistics for both the HMCA and the MCA dot sign were in the model-ate to goo d range when the stroke symptom side was given. Conclusions-The MCA. dot sign is an early marker of thromboembolic occlusio n of the distal MCA branches seen in the sylvian fissure and is associated with better outcome than the HMCA sign.