Safety Study of Dantrolene in Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) is a devastating acute brain injury due to bleeding onto the brain surface from a ruptured aneurysm. Cerebral vasospasm (cVSP; critical narrowing of brain arteries) is a known complication after SAH and significantly increases disability and death after SAH. Vasospasm is difficult to treat and can lead to stroke. Animal studies have shown that the muscles in the artery wall play a role in cVSP. Dantrolene has been FDA approved and extensively used in clinical practice as a muscle relaxant for more than 30 years. It has been shown to provide some benefit in animal studies of cVSP, as well as in a small number of humans. However, the first human studies have only been observational and over a short period of time. This study will evaluate the safety and tolerability of intravenous dantrolene given every 6 hours over seven days to patients with or at risk for cVSP after SAH. The goal is to determine if future efficacy studies should be done to determine if treatment with Dantrolene may improve the outcome of patients with cVSP after SAH.