The use of TCD velocities, Lindegaard ratio, and spasm index independently is of limited value for the diagnosis of clinical and angiographic vasospasm. The VPI achieved a global accuracy of 89.9% for angiographic vasospasm detection. For diagnosis of angiographic vasospasm, the model included Fisher grade, Hunt and Hess grade, and Lindegaard ratio. The VPI had a global accuracy of 92.9% for clinical vasospasm detection. The selected model for estimation of clinical vasospasm included Fisher grade, Hunt and Hess grade, and spasm index. A spasm index higher than 3.5 had an accuracy of 82.0% for the diagnosis of clinical vasospasm and 81.6% for angiographic vasospasm. For a Lindegaard ratio higher than 3.0, the accuracy was 85% for clinical vasospasm and 83.2% for angiographic vasospasm. For TCD velocities above 120 cm/second at the middle cerebral artery, the global accuracy was 81.1% for the diagnosis of clinical vasospasm and 77.2% for angiographic vasospasm. In 18 patients (26.5%) symptomatic vasospasm was diagnosed, and 33 (48.5%) had angiographic evidence of vasospasm. Logistic regression was used to evaluate the possible predictive factors, and the coefficients of the logistic regression were integrated to create the VPI. Sensitivity, specificity, predictive values, and global accuracy of the different tests were calculated. Digital subtraction angiography images were measured at specific points of interest. Lindegaard ratios and spasm indexes (TCD velocities/hemispheric CBF) were calculated bilaterally. Clinical characteristics analyzed included age, sex, Hunt and Hess grade, Fisher grade, days after SAH, day of treatment, type of treatment (coil embolization, surgical clip occlusion, or conservative treatment), smoking history, and hypertension history. Forty-one women (60.3%) and 27 men (39.7%) between the ages of 35 and 84 years (58.0 +/- 13.2 years ) were included. Seven cases were excluded because of a limited sonographic window. In 154 patients angiography was performed within 24 hours of the TCD examination, and in 75 133Xe cerebral blood flow (CBF) studies were obtained the same day. Seven hundred ninety-five patients in whom aneurysmal SAH was demonstrated by computed tomography, and in whom one or more intracranial aneurysms had been diagnosed, underwent transcranial Doppler (TCD) studies between April 1998 and January 2000. The goal in this study was to create an index (vasospasm probability index ) to improve diagnostic accuracy for vasospasm after subarachnoid hemorrhage (SAH).
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