Neuroleptic Malignant Syndrome Status Post Anoxic Brain Injury: A Case Presentation of Heightened Susceptibility in the Brain Injury Population

Neuroleptic malignant syndrome (NMS), a potentially life-threatening neurological emergency characterized by muscle rigidity, altered mental status (AMS), autonomic instability, and hyperthermia, is most commonly precipitated by high-potency first-generation antipsychotics due to central dopamine receptor blockade. There is a heightened risk of NMS in animals with ischemic brain injury (IBI) or traumatic brain injury (TBI) due to the resulting death of dopaminergic neurons from injury and the dopamine receptor blockade elicited upon recovery. To the best of our knowledge, this will be the first documented case of a critically ill patient, with a history of prior exposure to antipsychotics, who suffered an anoxic brain injury with subsequent development of NMS after the initiation of haloperidol for the treatment of acute agitation. Further investigation is necessary to expand upon the existing literature suggesting the role of alternative agents, including amantadine, due to its impact on dopaminergic transmission, as well as dopamine and glutamine release. Furthermore, NMS can be difficult to diagnose due to variable clinical presentation and lack of absolute diagnostic criteria, which is further compounded with central nervous system (CNS) injury, where neurological abnormalities and AMS may be attributed to the injury, rather than a medication effect, especially in the early period. This case highlights the significance of prompt recognition with appropriate treatment of NMS in vulnerable and susceptible patients suffering from brain injury.