To determine the association of asymptomatic cerebral vasospasm with hospital length of stay (LOS), duration of external ventricular drain (EVD), and functional outcome in patients with aneurysmal subarachnoid hemorrhage (aSAH).

Delayed cerebral ischemia (DCI) from cerebral vasospasm commonly complicates recovery following aneurysmal subarachnoid hemorrhage (aSAH). Patients with asymptomatic vasospasm are less likely to be treated with vasopressors than those with DCI. The impact of asymptomatic vasospasm is unclear. We sought to identify the association of asymptomatic vasospasm with outcomes.

We retrospectively analyzed consecutive aSAH patients at an academic referral center from 2016-2021. We defined vasospasm as a transcranial Doppler (TCD) reading ≥120 cm/s and Lindegaard ratio ≥3 in the anterior circulation. Symptomatic vasospasm included vasospasm with a new focal deficit or change in level of consciousness after excluding other causes. Asymptomatic vasospasm included subclinical TCD vasospasm. Multiple linear regression analysis and binary logistic regression analysis were used to determine association with ICU length of stay, external ventricular drain [EVD] duration, and functional outcome (3-month modified Rankin scale).

The cohort included 201 aSAH patients with a mean age 54.9 years (SD 13.6). 109 patients had vasospasm on TCD and 92 patients had no vasospasm on TCD. Among patients with vasospasm, 40% were asymptomatic and 60% were symptomatic. Only symptomatic vasospasm (beta=8.78, p<0.001), Modified Fisher scale (beta=2.17, p=0.003), and Hunt and Hess grade (beta=1.92, p=0.011) predicted hospital length of stay (LOS). Only Hunt and Hess grade independently predicted poor outcomes (OR 1.73, 95% CI 1.13–2.64; p=0.011).

Most patients with mild vasospasm on TCD were asymptomatic but most patients with moderate or severe vasospasm on TCD were symptomatic. Symptomatic vasospasm, Modified Fisher score, and Hunt & Hess grade were associated with increased hospital LOS in aSAH patients. Asymptomatic vasospasm was neither associated with worse functional outcome at 3 months nor hospital LOS.