Abstract T P354: The Role of Lindegaard Ratio on TCD for Predicting Angiographic Vasospasm Following Aneurysmal Subarachnoid Haemorrhage

Abstract

Background and objective: Middle cerebral artery (MCA) Lindegaard ratio (LR) has been used as indicator of moderate to severe vasospasm (VSP) following subarachnoid hemorrhage (SAH). However there have been many criticisms about the ability to detect impending vasospasm using Transcranial Doppler (TCD). The purpose of this study was to determine the correlation between TCD Mean Flow Velocities (MFV) and angiographic VSP after aneurysmal SAH using LR of several anterior circulation vessels. Methods: The study population included prospective collected data of 134 patients with aneurysmal SAH admitted to University of Alberta hospital from January 2006 to December 2008. Complete TCD was performed daily from day 2 to 14 from symptoms onset. All patients underwent cerebral angiography on admission and within 7 days following onset of symptoms. The M1, M2 MCA, ACA and intracranial ICA/ipsilateral extra cranial ICA velocity ratios (LR) were calculated and correlation was made with the presence of angiographic vasospasm (defined as more than one-third luminal narrowing). Then, anterior circulation LR was defined as the highest LR in the ipsilateral anterior circulation arteries. Moderate to severe VSP was defined as LR > 3. Results: Results are shown in table. The probability of VSP in the presence of one anterior circulation vessel LR > 3 is 14 % (2/14), 2 vessels LR >3 (4/16. 16 %), 3 vessels LR > 3 (3/6, 50 %) and 4 vessels LR >3 (5/5 = 100 %). (P< 0.001) Conclusion: LR of M2 MCA has higher sensitivity compared to other vessels and ACA LR has less sensitivity but more specificity whereas the rest of anterior circulation LR had modest predictive value. The likelihood of VSP increases as more number of vessels in anterior circulation shows LR>3. LR should not be interpreted in a blind fashion to the rest of TCD MFV numbers.