THE TIMING OF COMPUTED-TOMOGRAPHY IN ACUTE STROKE - A PRACTICE AUDIT

Objective: To compare the patterns of practice and diagnostic yields f or early and late computed tomography (CT) in patients with acute stro ke. Patients and methods: Among the 191 consecutive patients with acut e stroke admitted to a university teaching hospital from Sept. 1, 1989 , to Sept. 1, 1993, charts were available for review for 185. In addit ion to the timing and results of CT in these patients, data were colle cted on the demographic features of the patient group and the presence of any cardiovascular risk factors or other features suggestive of a nonstroke cause for the neurologic deficit. Results: Of the 185 patien ts for whom charts were available, 177 (95.7%) underwent CT. In 107 (6 0.4%) of the cases, scanning was performed early, within 24 hours of t he onset of neurologic deficit, and only 25 (23.4%) of these scans dem onstrated a lesion. Of the 70 initial scans obtained more than 24 hour s after the deficit onset (delayed scanning), 41 (58%) revealed a diag nostic lesion (relative probability of finding a lesion with early vs delayed scanning, 0.40; 95% confidence interval 0.27 to 0.59; p < 0.00 01, Fisher's exact test). Of the 107 patients who underwent early scan ning, 45 (42.0%) underwent repeat CT, and previously unrecognized lesi ons were seen in 28 (62%) of these. Scanning was repeated in only 17 ( 24%) of the 70 patients who underwent delayed initial scanning (p = 0. 02), and previously unrecognized lesions were seen in only 4 of these (24%). All lesions documented on repeat scans after initially nondiagn ostic scanning were ischemic. Patients presenting with features though t to justify early CT were no more likely to undergo this intervention than those without such features (68% and 56% respectively, p = 0.11) . Conclusions: Initial CT was often carried out within 24 hours of the onset of deficit in patients with suspected acute stroke at this inst itution. CT was a low-yield investigation, and scanning was frequently repeated. Although the literature suggests that clinical features can distinguish that subset of patients who should undergo urgent neuroim aging, prospective studies are needed to establish the indications for early CT in patients presenting with acute neurologic deficit.