Atypical Presentations of Neuroleptic Malignant Syndrome: Toward a Redefinition of Diagnostic Criteria?
I. Bouamoud, S. Belbachir, A. OuanassIntroduction
Neuroleptic Malignant Syndrome (NMS) is a rare but severe reaction to dopamine antagonists, typically characterized by hyperthermia, muscle rigidity, altered mental status, and autonomic instability. However, increasing reports of atypical or incomplete presentations, especially with second-generation antipsychotics, challenge the applicability of traditional diagnostic criteria.
Objectives
To describe the atypical clinical presentations of NMS observed in a recent cohort.
To evaluate the sensitivity of different diagnostic criteria (DSM-5, Levenson, Pope, Caroff ).
To propose the need for a more inclusive and flexible diagnostic framework for NMS.
Methods
We conducted a retrospective case-control study at Arrazi University Psychiatric Hospital (Salé, Morocco) from 2020 to 2023.
Cases:
43 patients diagnosed with NMS based on DSM-5 criteria.
Controls:
86 hospitalized patients receiving neuroleptics but without NMS.
Data collection included sociodemographic, clinical, biological, and therapeutic variables. Diagnostic compatibility with various international criteria was assessed.
Results
Among the 43 confirmed NMS cases, only DSM-5 criteria identified all patients (100%), while older criteria were less sensitive: Levenson (19%) , Pope (11.6%) , and Caroff (4.7%) .
Muscle rigidity (79.1%) and altered mental status (51.2%) were the most frequent symptoms, while hyperthermia appeared in only 18.6% of cases.
CPK elevation was found in 97.7% of patients. Multivariate analysis revealed two significant risk factors: haloperidol use (OR = 16.46) and prior NMS history (OR = 62.07).
These findings highlight the frequent atypical presentations of NMS and the limitations of traditional diagnostic criteria .
Conclusions
Our findings confirm a growing trend of atypical or incomplete forms of NMS , which are frequently underdiagnosed using classical criteria. The DSM-5 criteria proved to be the most inclusive, but even they may overlook subtle early presentations. These results support the urgent need to revise and modernize diagnostic approaches to NMS, especially in psychiatric settings where early intervention can prevent serious complications.
Disclosure of Interest
None Declared