Noncontrast CT assessment of early cerebral ischaemia.

PURPOSE: To assess the diagnostic value of early signs of ischaemic cerebral infarction detected by unenhanced CT in the first 6-10 hours. MATERIAL AND METHODS: We reviewed the CT examinations of 42 patients (mean age: 61 years, range: 35-79) with suspected ischaemic stroke. We assessed CT findings at 6-10 hours of the onset of stroke for hemilateral evidence of main cerebral artery hyperdensity, sulcal effacement, liquoral space asymmetry, hypodensity of grey matter. The CT scans were performed without contrast medium. RESULTS: The topographic pattern of cerebral infarctions was: middle cerebral artery territory in 25 patients, anterior cerebral in 9, striatal lacunar infarction in 2, posterior junctional infarction in 5, anterior junctional infarction in 1. Early signs of infarction were present in 24 patients (57%). CT scans showed early signs in 20 cases (80%) of middle cerebral infarctions; 8 (32%) had middle cerebral artery hyperdensity; 3 (12%) had middle cerebral artery hyperdensity and sulcal effacement; 4 (16%) had sulcal effacement; 2 (8%) had liquoral space asymmetry; 3 (12%) had hypodensity of grey matter and liquoral space asymmetry. CT scans showed early signs in 4/9 (44%) of anterior cerebral infarctions. Sensitivity and specificity of early CT to cerebral infarction was 57% and 100%. The three cases with both hyperdense middle cerebral artery and sulcal effacement died of transtentorial herniation within the 10th day. The seven other deaths occurred in patients without early signs or particular patterns appearing in subsequent CT. DISCUSSION: In the management of ischaemic stroke the aim of neuroradiologic methods is to provide exact direction to immediate therapy by early diagnosis. In such cases the use of CT scanning aims at detecting signs of two main alterations of infarction: vascular occlusion and brain oedema. Middle cerebral artery hyperdensity, showing steady correspondence to infarction site and frequent disappearance on the follow-up CT, is indicative of embolic occlusion. Signs of "mass effect" are evident from the early stages in relation to the substantial concomitance of various types of brain oedema. The semeiology discussed in this study is more clearly detectable in middle cerebral artery infarction because this territory is the main site of embolic occlusion, and its larger size increases the "mass effect" due to oedema. The sensitivity obtained in this study is among the lowest values reported, which likely relates to our choice to use short scan times.