Cannabis Use and Increased Nonaneurysmal Subarachnoid Hemorrhage in the Past Decade

Spontaneous subarachnoid hemorrhage is often due to rupture of an intracranial aneurysm, but some patients present with no identifiable source. Increased incidence of nonaneurysmal subarachnoid hemorrhage (naSAH) has been reported over time.

We performed a retrospective analysis of naSAH from 2008-2017 to determine the rate of naSAH change over time and its association with cannabis use. Univariable and multivariable regression analyses were performed to study the trend over time, radiographic patterns of hemorrhage, and clinical outcome at the time of discharge. In addition, we compared the rate of naSAH with the rate of aneurysmal SAH (aSAH) to adjust for changes in hospital volume and prevalence/reporting of cannabis use in the population over time.

A total of 86 naSAH and 328 aSAH patients were identified, with an increase in naSAH over time compared with aSAH (P = 0.0034). Increased cannabis use was associated with naSAH (odds ratio [OR] 2.1, 95% confidence interval 1.1, 4.1, P = 0.035) but not aSAH over time. Cannabis use was also associated with different subarachnoid hemorrhage patterns (P = 0.0065) in naSAH. Multivariable analysis demonstrated good neurologic outcome after naSAH to be inversely associated with cocaine use (OR 0.008 [0.002-0.4]), ventriculostomy placement (OR 0.004 [0.03-0.50]), and anticoagulant use (OR 0.016 [0.003-0.54]) but not with cannabis use.

As cannabis use becomes more prevalent with legalization, it is important to further investigate this association with spontaneous SAH.