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(Stroke. 2000;31:2976.)
© 2000 American Heart Association, Inc.

Original Contributions

Perimesencephalic Hemorrhage and CT Angiography

A Decision Analysis

Ynte M. Ruigrok, MD; Gabriël J. E. Rinkel, MD; Erik Buskens, MD; Birgitta K. Velthuis, MD Jan van Gijn, MD, FRCP, FRCPE

From the Department of Neurology (Y.M.R., G.J.E.R., J. van G.); Julius Center for Patient Oriented Research (E.B.); and Department of Radiology (B.K.V.), University Medical Center Utrecht (Netherlands).

Correspondence to Y.M. Ruigrok, MD, Department of Neurology, University Medical Center Utrecht, PO Box 85500, 3500 GA Utrecht, Netherlands. E-mail ij.m.ruigrok{at}neuro.azu.nl

Background and Purpose—The method of choice for detecting or excluding a vertebrobasilar aneurysm still is a matter of debate in patients with a characteristically perimesencephalic pattern of subarachnoid hemorrhage (SAH) on CT. We used decision analysis to compare possible diagnostic strategies in these patients.

Methods—A decision analytic model was developed to evaluate the effect of 4 different diagnostic strategies following a perimesencephalic pattern of SAH on CT: 1, no further investigation; 2, digital subtraction angiography (DSA) by catheter; 3, CT angiography as initial modality, not followed by DSA if negative; and 4, CT angiography as initial modality, followed by DSA. We used a 4% prevalence of a vertebrobasilar aneurysm given a perimesencephalic pattern of hemorrhage, a 97% sensitivity and specificity of CT angiography, and a 99.5% sensitivity and 100% specificity of DSA. In a prospectively collected series, the complication rate from DSA in patients with a perimesencephalic pattern of hemorrhage was 2.6%. We calculated the expected utility of each of the 4 diagnostic options and used sensitivity analyses to examine the influence of the plausible ranges of the various estimates used.

Results—The expected utilities were 99.09 for CT angiography only, 98.96 for no further investigation, 98.22 for DSA, and 96.34 for CT angiography plus DSA. The results of the sensitivity analysis indicate that over a wide range of assumptions, CT angiography only is the most beneficial option. Only when the complication rate of catheter angiography is <0.2% is DSA the preferred strategy.

Conclusions—Our decision analysis shows that in patients with a perimesencephalic pattern of hemorrhage on CT, CT angiography only is the best diagnostic strategy. DSA can be omitted in patients with a perimesencephalic pattern of hemorrhage and a negative CT angiogram.

Key Words: angiography, computed tomographic • decision analysis • diagnosis • perimesencephalic hemorrhage

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