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Cannabis Use Tied to Delayed Cerebral Ischemia After Aneurysm Rupture

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Cannabis use is significantly associated with delayed cerebral ischemia (DCI) in patients with aneurysmal subarachnoid hemorrhage (aSAH), according to a study published in Stroke.

Previous research has linked cannabis use to cerebrovascular disease, including aSAH, with the likelihood of aSAH being twice as high in patients who use cannabis compared to nonusers in a young age group. The pathophysiology that drives this relationship is unclear, but research suggests multifocal intracranial stenosis, oxidative stress, and cerebral mitochondrial dysfunction are key factors, the researchers explained. The objective of the current study was to evaluate the effects of cannabis on DCI and other outcomes of patients with aSAH.

The researchers reviewed records of all aSAH patients treated at a neurological institute from August 1, 2007, to July 31, 2019. Cannabis use was the primary exposure and was detected with routine urine toxicology screening. Participants were also screened for other vasoactive substances such as cocaine, amphetamines, and tobacco, which were adjusted for in the propensity analysis.

DCI was the primary outcome and was defined as “cerebral infarction identified on computed tomography or magnetic resonance imaging or proven on autopsy, after exclusion of procedure-related infarctions.”

A total of 1014 patients were hospitalized and treated for aSAH in the 12-year study period. Of this group, 968 (mean [SD] age, 56.1 [14.2] years; 70.7% female) did not have a positive urine drug screen for cannabis, and 46 (4.5%) did have a positive urine drug screen for cannabis (mean age 46.5 [10.7] years; 41.3% female).

The rate of DCI in the cohort was 36.2% (n = 367), the rate of poor functional outcome (modified Rankin Scale score >2) was 50.2% (n = 509), and the mortality rate was 13.5% (n = 137). The DCI rate was significantly higher among patients with a urine drug screen positive for cannabis compared with those without a positive test result (52.2% [24/46] vs 35.4% [343/968], respectively; P = .03).

DCI was not associated with cocaine, methamphetamine, and tobacco use (P ≥.29). Hunt and Hess and Fisher grades were significantly associated with DCI (both P <.001).

Radiographic vasospasm occurred significantly more frequently among cannabis users compared with nonusers (40/45 [88.9%] vs 675/958 [70.5%], respectively; P =.008). In a subset of patients with radiographic vasospasm (n=715), 50.0% (20/40) of cannabis users, and 39.0% (263/675) of nonusers had DCI (P =.17).

Cannabis use was independently associated with an increased likelihood of DCI (odds ratio, 2.7 [95% CI, 1.4-5.2], P =.003), according to propensity score-adjusted binary logistic regression analysis.

Study limitations include the retrospective, single-center design and lack of cannabis-specific details such as timing, route, frequency, and quantity. In addition, the positive screening rate for cannabis was lower than expected, which limited the power of the study.

“We found a higher rate of angiographic spasm in cannabis users, which supports vasospasm as a potential reason for increased DCI,” the researchers concluded. “However, we cannot exclude the possibility that cannabis users have a lower threshold for DCI.”


Catapano JS, Rumalla K, Srinivasan VM, et al. Cannabis use and delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage. Stroke. Published online January 5, 2022. doi:10.1161/STROKEAHA.121.035650

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Schedule10 Jun 2023