Prediction Of Delayed Cerebral Ischemia After Subarachnoid Hemorrhage Using Variations Of Dynamic Cerebral Autoregulation

The risk of delayed cerebral ischemia (DCI) after cerebral aneurysm rupture is increased in patients with large cerebral artery vasospasm (VS). The predictive value of VS is, however, far to be optimal. Assessment of cerebral microcirculation impairment using dynamic cerebral autoregulation (DCA) measurement might improve our ability to predict DCI in these patients. Methods. We included consecutive patients with low-grade aneurysmal subarachnoid hemorrhage (SAH) (WFNS 1 to 3) within 4 days of aneurysm rupture. DCA was evaluated using the moving correlation coefficient Mx calculated from spontaneous fluctuations of cerebral blood flow velocities and arterial blood pressure. Impairment of DCA was defined as Mx ≥ 0.3. Transcranial colour-coded sonography was performed every 48 hours to look for VS. Diagnosis of VS was based on a Lindegaard ratio >3 (MCA), or mean flow velocities > 130 cm/s (ACA). DCI was defined as neurologic deterioration caused by brain ischemia confirmed by brain imaging. Results. Thirty patients (19 women; mean age ± SD: 44.7 ± 12.1 years) were included. Twenty (66.7%) patients had VS. DCI occurred in six (20%) patients after a median delay of 10 days (range 8 to 13 days). Mx (mean ± SD) was heightened at baseline (0.43 ± 0.2) and at day 7 (0.46 ± 0.2), then decreased at day 14 (0.37 ± 0.18 (p = 0.034). Isolated measures of VS and Mx were not associated with DCI. However, the elevation of Mx between baseline and day 7 in patients with VS was predictive of subsequent DCI (positive likelihood ratio=5.01; negative likelihood ratio=0.19; P=0.005). Conclusion. Findings suggest that DCA assessment may help to predict better the risk of DCI after cerebral aneurysm rupture than the simple recordings of mean flow velocities.