To describe transcranial Doppler (TCD) findings in a population with clinical probable RCVS. Exploratory objectives included the study of clinical characteristics of probable RCVS patients with and without spasm detected by TCD.

Cross-sectional cohort study of patients with thunderclap headache (TCH) without subarachnoid hemorrhage (SAH) of our neurology and headache center between 2010 and 2019, selecting patients with clinical diagnosis of probable RCVS (negative angiography study) by ICHD-3 criteria and with at least two TCD studies.

From 114 TCH patients, 36/114 had probable RCVS by ICHD-3 criteria and had at least two TCD studies available. The mean age at RCVS onset was 42.9years (21–72years); 29/36 (80.6%) were female, 7/28 (25%) had cardiovascular risk factors and 20/36 (55.6%) had history of migraine. Most common triggers were stressful emotion, drugs, valsalva maneuvers and sexual activity. Five/36 (13.9%) had complications and 3/36 (8.3%) had late recurrence. Initial TCD was performed on average of 16 (6–26) days after headache onset. Twenty-nine had vasospasm on TCD, presenting mean flow velocity of MCA (VMCA) of 135.7±17.0cm/s and mean maximum VMCA of 138.3±17.2. Vasospasm was mild in 21/29 patients (72.4%) and moderate in 8/29 (27.6%). Complete VMCA normalization occurred on average 41 (30–70) days after headache onset and 24 (11–47) days after initial TCD. The group of patients with vasospasm detected by TCD had more female patients (26/29, 89.7% vs. 3/7, 42.8%, P=0.016), and more TCH attacks (mean of 3.6 vs. 2.14, P=0.049).

TCD may be a useful tool in the identification of vasospasm in patients with probable RCVS, supporting the diagnosis of RCVS in patients presenting with recurrent TCH without SAH.