B48-09 When Sedation Fails: A Case of Anti-NMDAR Encephalitis, Autonomic Dysregulation and Refractory Agitation

Introduction Anti-N-methyl-D-Aspartate Receptor (anti-NMDAR) encephalitis is a neuropsychiatric illness that is often associated with teratoma tumors. Symptoms manifest as acute onset of psychosis, seizures, autonomic instability, movement disorders, hypoventilation and coma. Many patients may require ventilatory support and intensive care management. Approximately 80% of patients experience disease improvement after treatment with first- and/or second-line therapies. Critical care providers should be aware of the difficulties associated with management of neuropsychiatric complications and autonomic instability in patients with anti-NMDAR encephalitis. Description A 32-year-old patient at 5 weeks of gestation, without previous psychiatric or relevant medical history, was admitted to an outside psychiatric unit for bizarre behavior. She displayed medication-resistant violent behaviors. Due to periods of sinus tachycardia and status epilepticus, she was intubated and transferred to our intensive care unit. On arrival, she remained intubated, mildly tachycardic but otherwise hemodynamically stable. Her workup was positive for Glu-N1 NMDA-R antibodies (1:20 titer) and an ovarian teratoma. She was treated with pulse-dose steroids, IVIG and oophorectomy. Her course was complicated by excitatory agitation, which was refractory to multiple high dose sedatives including dexmedetomidine and ketamine infusions. She developed evidence of a non-ST-segment elevation myocardial infarction (NSTEMI) and cardiomyopathy, which improved after ketamine cessation. Second-line treatment with rituximab was delayed due to obstetric concerns but was ultimately initiated after elective medical abortion. Thereafter, the patient’s clinical condition improved to baseline and she was discharged home. Discussion Our patient presented with sinus tachycardia, which has been described as one of the most common features of autonomic dysregulation amongst patients with anti-NMDAR encephalitis. Autonomic dysfunction is an important complication to recognize as it portends worse outcomes and need for more anti-NMDAR immunosuppressants. Furthermore, paradoxical phenomenon to antipsychotics has been described amongst patients with anti-NMDAR encephalitis. Effects may range from disproportionate drowsiness, movement disorders to worsening agitation. Ketamine, in particular, should be used with caution. Although it can be useful for refractory status epilepticus, it can paradoxically worsen psychosis and autonomic instability via its action on NMDA receptors. Simultaneously, it can contribute towards a negative inotropic effect and sympathomimetic effect in those patients with autonomic dysfunction. We report a critically ill patient with anti-NMDAR encephalitis presenting with difficult-to-control neuropsychiatric symptoms and autonomic instability. Our case highlights the importance of maintaining of a high index of suspicion for autonomic instability and paradoxical responses to antipsychotics. This abstract is funded by: None