Deep venous drainage variant rate and degree may be higher in patients with perimesencephalic than in non-perimesencephalic angiogram-negative subarachnoid hemorrhage.

Objectives: The basal vein of Rosenthal (BVR) variant is a potential origin of bleeding in angiogram-negative subarachnoid hemorrhage (AN-SAH). We compared the rate and degree of BVR variants in patients with perimesencephalic AN-SAH (PAN-SAH) and non-perimesencephalic AN-SAH (NPAN-SAH).

Methods: We retrospectively reviewed the records of AN-SAH patients admitted to our hospital between 2013 and 2018. The associations between variables (baseline characteristics, clinical and radiological data, and outcome) with bleeding patterns and degree of BVR variants were analyzed. Additionally, potential predictors of positive findings on repeated digital-subtracted angiogram (DSA), rebleeding, delayed cerebral infarction (DCI), and poor outcome were further studied.

Results: A total of 273 patients with AN-SAH were included. The incidence rate and degree of BVR variants were significantly higher in PAN-SAH patients compared with those in NPAN-SAH patients (p < 0.001). Patients with normal bilateral BVRs are more likely to have a severe prognosis and diffused blood distribution (p < 0.05). We found an increased rate of positive findings on repeated DSA, DCI, rebleeding, and poor outcome at 3 months and 1 year after discharge (all p < 0.05) in patients with bilateral normal BVRs. Bilateral normal BVRs were considered a risk factor (predictor) of positive findings on repeated DSA, rebleeding, and poor outcome (all p < 0.05).

Conclusions: PAN-SAH patients have a higher rate and degree of BVR variants compared with patients with NPAN-SAH. Those AN-SAH patients with bilateral normal BVRs are more likely to be of arterial origin and are at risk of suffering from rebleeding and a poor outcome.

Key Points: • Patients with PAN-SAH have a higher rate and degree of BVR variants compared with patients with NPAN-SAH, which suggested that AN-SAH patients with normal BVRs are more likely to originate from arterial bleeding. • AN-SAH patients with normal BVRs are more likely to have positive findings on repeated DSA examinations, as well as an increased incidence of rebleeding and poor outcome, which may assist and guide neurologists in selecting treatment.