Acute Hippocampal Encephalopathy in Heavy Cannabis Users: About 2 Cases

Background Cannabis use is increasing worldwide despite the various health effects of this substance. Methods We report 2 cases of acute hippocampal encephalopathy in heavy cannabis users (>10 joints/d). Results In both male patients, acute encephalitis was suspected. Brain magnetic resonance imaging (MRI) diffusion-weighted sequences showed bilateral high signal abnormalities in hippocampal regions. Patients had renal dysfunction, rhabdomyolysis, and inflammatory syndrome. Investigations showed no evidence of infectious or autoimmune encephalitides. Repeated electroencephalograms revealed no epileptic activity. Clinical, biological, and magnetic resonance imaging acute abnormalities improved within weeks. New exposure to cannabis yielded a new episode of encephalopathy. In both patients, severe long-lasting episodic memory impairment associated with hippocampal atrophy were observed several months later. Conclusions Health professionals should be aware of this cannabis-related syndrome given its severe and long-lasting effects.