Transcranial Doppler for Risk Assessment in Subarachnoid Hemorrhage

Background and Purpose: Vasospasm is an important complication of subarachnoid hemorrhage (SAH) resulting in significant morbidity and mortality. Risk stratification attempts designed to identify patients most at risk of developing vasospasm have not led to significant practice changes. We sought to validate a prognostic utility criterion to identify patients at lowest risk of vasospasm. Methods: We conducted a single-centre retrospective observational study using transcranial doppler (TCD) readings of patients with SAH from 2018 to 2024. Through chart review, we extracted patient’s mean blood flow velocities in the bilateral middle cerebral artery (MCAs) throughout their admission. We defined patients at low-risk of vasospasm as: MCA velocities on TCD had to remain below 120 cm/s and velocities had to have peaked and started to decrease by the 7th day post SAH. Our primary outcome was to analyze the predictive ability of our low-risk criteria to identify patients less at risk of developing vasospasm, defined as the presence of moderate to severe vasospasm (mean velocity in the middle cerebral artery exceeding 160 cm/s). Results: We collected data on 210 consecutive patients, of whom 196 met inclusion criteria; 107 (55%) met our low-risk criteria. Only 3 (2.8%) patients meeting our low-risk criteria developed vasospasm (p < 0.001), while 46 (52%) patients not meeting our low-risk criteria developed vasospasms (RR 18.4). The Positive Predictive Value (PPV) for not developing vasospasm in our low-risk group was 97.2% (95% CI: 92.0% − 99.4%). Conclusion: Our low-risk criteria based on TCD patterns in the first 7 days since SAH can identify a cohort of patients at very low risk of moderate to severe vasospasm. Our low-risk criteria for vasospasm could be used in future prospective studies to evaluate the safety of early discharge from the intensive care unit.