Predictors of ICU Admission and Mechanical Ventilation in Neuroleptic Malignant Syndrome and Malignant Catatonia Presenting to the Emergency Department: A Systematic Review

Background. Neuroleptic malignant syndrome and malignant catatonia are uncommon emergencies in which altered consciousness, autonomic instability, and respiratory deterioration complicate disposition, in this systematic review study we aimed to identify factors measured during emergency department assessment that were associated with intensive care unit admission or invasive mechanical ventilation. Methods. PubMed and supplementary searches identified original reports published through 31 May 2026. Reports describing at least two affected patients were eligible when they documented intensive care admission, endotracheal intubation, or mechanical ventilation during the index illness. Findings were synthesized narratively by syndrome, recruitment setting, and outcome. Results. Fifteen original reports contributed data. In a Japanese inpatient cohort of 1,585 patients with neuroleptic malignant syndrome, 408 entered intensive care and 193 underwent intubation. Intensive care admission occurred in 31.4% of typical antipsychotic users and 21.0% of atypical antipsychotic users in a matched inpatient comparison. An Australian adverse-event study showed the opposite numerical pattern. In a treatment-selected series of eight patients with malignant catatonia associated with autoimmune encephalitis, seven received intensive care and four required mechanical ventilation. Conclusions. The evidence describes critical care use and provides limited inpatient associations. Prospective emergency department cohorts with timed baseline measurements and explicit indications for intubation are needed.