Middle cerebral artery occlusion: correlation of computed tomography and angiography with clinical outcome.

The clinical outcome of 40 cases with middle cerebral artery (MCA) occlusion was examined in relation to the site of occlusion and the findings on computed tomography (CT). Patients were treated conservatively without surgery. A few had decompressive craniotomy when necessary. Outcome in 7 (18%) was good, in 6 (15%) moderate, and in 15 (38%) severe; 12 (30%) died by the follow-up at 3 months. In cases with occlusion at the origin of the MCA, hypodensity on CT scan was usually localized to the basal ganglia, presumably because of collateral circulation through the anterior cerebral arteries; the outcome in these patients was not always favorable. Cases with occlusion of the trunk or branch vessels always showed marked CT hypodensity, and clinical outcome was poor. To assess quantitatively the extent of collateral circulation, the conduction time of contrast medium from the intracranial siphon (IC) to the insular portion of the MCA (M2) through the anterior cerebral arteries was calculated on serial carotid angiograms obtained within 24 hours after stroke onset. An IC-M2 time of 5 seconds was a critical indicator of whether extensive CT hypodensity would develop (the rule of 5 seconds). Furthermore, this method predicted the appearance and extent of infarction before CT revealed hypodensity. The significance of acute reconstructive surgery is also discussed.