Cannabis as cause of stroke in younger patients
Most cannabis smokers are young, patients under 45 years of age presenting with symptoms of stroke should be asked about cannabis use and their urine tested for cannabinoids.
The relationship between cannabis and stroke is, however, complex, because other confounding factors have to be considered. These include potential triggering factors of sexual activity or concomitant alcohol consumption. There may also be genetic predisposition to susceptibility to stroke from cannabis use, but this needs more study.
Mechanism: Multifocal intracerebral stenosis
n terms of mechanism, cannabis appears to be associated with multifocal intracerebral stenosis, which can cause a stroke. “We have seen these stenoses in people who are regular cannabis smokers, and when they stop smoking the stenoses disappear. How cannabis causes the stenosis, we do not know.
The stenoses are caused by shrinkage of the blood vessels and can occur in several different areas of the brain. It appears that cannabis may cause the arteries to constrict. These stenoses can be difficult to see. They can be detected with magnetic resonance angiography, but careful scrutiny of the vessels is required.
To confirm the diagnosis, it is necessary to perform magnetic resonance angiography in the acute stage of stroke to search for intracranial stenosis. Thereafter, control vascular imaging is important to evaluate the reversibility of vascular abnormalities. However, when there is doubt between stenosis and arterial artifacts, conventional angiography with three-dimensional reconstructed images is needed to confirm diagnosis of stenosis.