Introduction: Although it is a surrogate, detection of radiographic vasospasm is thought to aid in diagnosing clinical vasospasm following aneurysmal subarachnoid hemorrhage (aSAH). Digital subtraction angiography has been the gold standard radiographic vasospasm for several decades, but it is an invasive technique so a number of alternative techniques have been proposed; the most accessible of these are transcranial doppler ultrasonography (TCD, particularly effective for MCA vasospasm) and CT angiography (CTA). While these two have been validated individually, we review a series of patients to further refine the limitations of these techniques in conjunction.
Methods: 40 consecutive patients with aSAH were identified; 3 of these had no windows for TCD evaluation; 6 did not have angiography. Maximum vasospasm was compared between TCD, CTA, and angiography; correlation was rated as 0 - no correlation, 0.5 - underestimate, 1 - well correlated, 2 - overestimate. To further evaluate the temporal relationships, we evaluated early, middle, and late vasospasm period associations.
Results: Although the sensitivity of TCD and CTA in detecting vasospasm are 90% and 94% respectively, the degree of vasospasm is less accurate. In a global assessment of maximum spasm, CTA reflects angiographic vasospasm 40% of the time and overestimates vasospasm 40% of the time. On the other hand, TCD underestimates vasospasm 35% of the time and accurately reflects vasospasm 40% of the time. Most infarcts occured when TCD and CTA both accurately reflected the degree of vasospasm which occurred 20% of the time. In a two-factor Anova analysis, the CTA level of correlation neared statistical significance at p=0.06. Analyzing temporal dependence, both TCD and CTA have relatively similar accuracy during both the early and mid-vasospasm windows.
Conclusions: TCD and CTA serve as less invasive and less morbid screening techniques which can be used serially to determine patients who may benefit from interventional angiographic techniques.
Patient Care: This research will inform the use of non-invasive testing to optimize appropriate utilization and reduce exposure to risks and morbidity of non-invasive and invasive testing and treatments for vasospasm.
Learning Objectives: By the conclusion of this session, participants should be able to 1) Discuss limitations of TCDs and CTAs in identifying vasospasm following aneurysmal subarachnoid hemorrhage 2) Formulate a practice plan to utilize a combination of TCDs and CTAs based on sensitivity, specificity, positive and negative predictive values of these two tests 3) discuss with patients the likelihood of vasospasm given results of these two non-invasive testing modalities