Background Aneurysmal ruptures typically cause subarachnoid bleeding with intraparenchymal and intraventricular extension. However, rare instances of acute aneurysmal ruptures present with concomitant, non-traumatic subdural hemorrhage (SDH). We explored the incidence and difference in outcomes of SDH with aneurysmal subarachnoid hemorrhage (aSAH) as compared with aSAH alone.

Methods Retrospective cohort study from 2012 to 2015 from the National (Nationwide) Inpatient Sample (NIS) (20% stratified sample of all hospitals in the United States). NIS database (2012 to September 2015) queried to identify all patients presenting with aSAH. From this population, the patients with concomitant SDH were identified.

Results A total of 10 075 patients with both cerebral aneurysms and aSAH were included. Of these, 335 cases of concomitant SDH and aSAH were identified. There was no significant change in the rate of SDH in aSAH over time. SDH with aSAH patients had a mortality of 24% compared with 12% (p=0.003) in the SAH only group, and only 16% were discharged home vs 37% (p=0.003) in the SAH group.

Conclusions There is a 3.5% incidence of acute SDH in patients presenting with non-traumatic aSAH. Patients with SDH and aSAH have nearly double the mortality, higher rate of discharge to nursing home and rehabilitation, and a significantly lower rate of discharge to home and return to routine functioning. This information is useful in counseling and prognostication of patients with concomitant SDH and aSAH.