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Open Access Publications from the University of California

A Case Report of Opisthotonos Associated with Administration of Intramuscular Ketamine


Introduction: Ketamine, a commonly used medication to treat agitation, has known adverse effects such as emergence reactions, vomiting, and laryngospasm. Opisthotonos has not been a commonly reported adverse reaction.

Case Report: We report a case of opisthotonos brought on by administration of ketamine. A 24-year-old male with a history of schizophrenia was brought in by emergency medical services with opisthotonos shortly after treatment with 250 milligrams intramuscular ketamine by paramedics. He had become increasingly paranoid after being off his aripiprazole for a few weeks, and his family had become afraid for his and their safety. Paramedics administered ketamine to control his combative agitation, per protocol. The patient’s extreme neck and back extension rapidly resolved with the administration of midazolam. Further history and workup did not reveal another cause for opisthotonos.

Conclusion: This is the first reported case to our knowledge of ketamine-associated opisthotonos in the emergency setting. Emergency care providers should be aware of this potential side effect.

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