SHM Converge Scientific Abstract ePoster Gallery-Neuroleptic Associated Myoclonus Without Rhabdomyolysis

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This poster presents a case of <strong>neuroleptic-associated myoclonus without rhabdomyolysis</strong> and emphasizes the diagnostic overlap between <strong>neuroleptic malignant syndrome (NMS)</strong> and <strong>malignant catatonia (MC)</strong>.

NMS is linked to antipsychotic use and classically causes altered mental status, muscular rigidity, high fever, and autonomic instability. MC is more often associated with schizophrenia and may present with catalepsy, stupor, mutism, waxy flexibility, negativism, posturing, rigidity, fever, and autonomic dysfunction. Because the two conditions share many features, they are often difficult to distinguish. Lead-pipe rigidity and recent antipsychotic exposure favor NMS, while catatonic signs support MC. Although elevated creatine phosphokinase (CPK) is commonly used to support NMS, normal or low CPK does not exclude it.

The case involves a <strong>58-year-old man with schizophrenia</strong> who was hospitalized for <strong>COVID pneumonia with respiratory failure</strong>. His home <strong>haloperidol 25 mg/day</strong> was continued. After initial improvement, he developed <strong>fever, tremors, mutism, muscular rigidity, and confusion</strong> on hospital day 9. The differential included seizures, sepsis, CNS infection, and intracranial hemorrhage. He was transferred to the ICU and underwent extensive workup, including <strong>MRI, EEG, and lumbar puncture</strong>, all of which were negative. Psychiatry was consulted, haloperidol was stopped, and benzodiazepines were given. He improved and was discharged to inpatient rehabilitation, with full recovery by day 13 after stopping haloperidol.

The authors conclude that <strong>NMS and MC both require inpatient medical management and can be missed, especially in medically complex patients</strong>. Clinicians should consider both diagnoses even when <strong>CPK is not elevated</strong>.

Asset Subtitle

Maxwell Miller

Meta Tag

Author List Maxwell Miller

Category Clinical Vignettes

Concept Neuroleptic Malignant Syndrome

Concept Malignant Catatonia

Concept Antipsychotic Exposure

Concept Dopaminergic Withdrawal

Concept Inpatient Medical Evaluation

Distinguished Non-Finalist

Presenter Organization East Carolina University Brody School of Medicine

Presenting Author Maxwell Miller

Track Adult

Keywords

neuroleptic malignant syndrome

malignant catatonia

haloperidol

myoclonus

schizophrenia

COVID pneumonia

muscular rigidity

altered mental status

creatine phosphokinase

benzodiazepines

Neuroleptic Malignant Syndrome

Malignant Catatonia

Antipsychotic Exposure

Dopaminergic Withdrawal

Inpatient Medical Evaluation