Neuroleptic Malignant Syndrome (NMS) Clinical Presentation

Early Manifestations of NMS

• The American Academy of Pediatrics notes that tachycardia and blood pressure fluctuations are common autonomic dysfunction symptoms in NMS, often preceding other symptoms 1, 2
• Diaphoresis, or excessive sweating, is a frequent symptom of NMS, according to the American Academy of Pediatrics 2, 3
• Fever, which can progress to hyperthermia, is a key symptom of NMS, as reported by the American Academy of Pediatrics 1, 2
• Sialorrhea and dysphagia may also occur in patients with NMS, as noted by the American Academy of Pediatrics 2, 3
• Delirium is the most common mental status change presentation in NMS, ranging from alert mutism to agitation to stupor to coma, according to the American Academy of Pediatrics 2, 3
• Lead pipe rigidity is the most common neurologic finding in NMS, with other muscle abnormalities including akinesia, dyskinesia, or waxy flexibility, as reported by the American Academy of Pediatrics 2, 3

Laboratory Findings in Early NMS

• Leukocytosis, with a white blood cell count of 15,000-30,000 cells/mm³, may be present in patients with NMS, according to the American Academy of Pediatrics 2, 3
• Electrolyte abnormalities consistent with dehydration, as well as elevated creatine kinase and liver enzymes, may be seen in NMS patients, as noted by the American Academy of Pediatrics 2, 3

Risk Factors to Consider

• A history of antipsychotic use or withdrawal of dopaminergic agents is a significant risk factor for NMS, as reported by the American Academy of Pediatrics 2, 4
• Coadministration of multiple psychotropic agents, dehydration, physical exhaustion, preexisting organic brain disease, and use of long-acting depot antipsychotics also increase the risk of NMS, according to the American Academy of Pediatrics 2, 4
• Male gender, with a 2:1 male predominance, is another risk factor for NMS, as noted by the American Academy of Pediatrics 2, 4

Clinical Pearls and Pitfalls

• NMS can be difficult to recognize due to variable and attenuated presentations, but early recognition is crucial, as mortality has decreased from 76% in the 1960s to <10-15% with prompt management, according to the American Academy of Pediatrics 2, 5
• The diagnosis of NMS is clinical, as there are no pathognomonic laboratory criteria, and symptoms may develop within days after starting or increasing antipsychotic medication, as reported by the American Academy of Pediatrics 2, 4

Diagnosis and Management of Neuroleptic Malignant Syndrome

Diagnostic Criteria

• The American Academy of Pediatrics recommends a point-based system where ≥76 points indicates probable NMS, with points assigned for dopamine antagonist exposure or dopamine agonist withdrawal, hyperthermia, rigidity, mental status alteration, creatine kinase elevation, sympathetic nervous system lability, hypermetabolism, and negative workup for other causes 6
• Dopamine antagonist exposure or dopamine agonist withdrawal within 3 days is assigned 20 points 6
• Hyperthermia (>100.4°F oral on ≥2 occasions) is assigned 18 points 6
• Rigidity is assigned 17 points 6
• Mental status alteration is assigned 13 points 6
• Creatine kinase elevation (≥4 times upper limit of normal) is assigned 10 points 6
• Sympathetic nervous system lability is assigned 10 points 6
• Hypermetabolism is assigned 5 points 6
• Negative workup for infectious, toxic, metabolic, or neurologic causes is assigned 7 points 6

Differential Diagnosis to Exclude

• The American Academy of Pediatrics recommends excluding serotonin syndrome, distinguished by hyperreflexia, clonus, and recent serotonergic drug exposure 6
• Malignant hyperthermia, triggered by anesthetics, not antipsychotics, should be excluded 6
• Anticholinergic toxicity should be excluded 6
• CNS infections, such as meningitis or encephalitis, should be excluded 6
• Acute catatonia should be excluded 6

Treatment Approach

• The American Academy of Pediatrics recommends immediate discontinuation of all antipsychotic medications and aggressive supportive care, including benzodiazepines for agitation, external cooling measures for hyperthermia, and IV fluids for dehydration and elevated creatine kinase/rhabdomyolysis 6
• Hemodialysis may be necessary if renal failure occurs 6

Neuroleptic Malignant Syndrome Diagnosis and Management

Diagnostic Criteria and Management

• The American Academy of Pediatrics recommends distinguishing NMS from serotonin syndrome by the presence of hyperreflexia, myoclonus, and clonus in serotonin syndrome versus lead-pipe rigidity in NMS, in patients with a history of antipsychotic use or withdrawal of dopaminergic agents 7
• Serotonin syndrome features hyperreflexia, clonus, myoclonus, and recent serotonergic drug exposure rather than lead-pipe rigidity, and should be excluded in the diagnosis of NMS 7

Immediate Management Protocol

• The American Academy of Pediatrics recommends immediately discontinuing all antipsychotic medications, and considering reintroducing an anti-Parkinsonism drug if NMS was triggered by abrupt withdrawal of that medication 7
• Intensive supportive measures, including external cooling measures, IV fluids, and benzodiazepines for agitation, should be provided as the foundation of NMS treatment 7
• For severe NMS, consider dopaminergic agents and muscle relaxants, such as bromocriptine and dantrolene sodium, after initiating supportive care 7
• Advanced interventions, including emergency sedation, neuromuscular paralysis, and intubation, may be necessary for extreme hyperthermia (>41.1°C) 7

Monitoring for Complications

• Carefully monitor for life-threatening complications, including rhabdomyolysis, metabolic acidosis, renal failure, seizures, disseminated intravascular coagulation, hepatotoxicity, and pulmonary edema, which contribute to the 10-15% mortality rate 7

Neuroleptic Malignant Syndrome Diagnosis and Management

Clinical Evaluation and Diagnosis

• The American Academy of Pediatrics recommends evaluating for the complete NMS tetrad, including mental status changes, muscle rigidity, autonomic dysfunction, and fever progression, immediately in patients with suspected NMS 8, 9

Laboratory Workup and Diagnostic Criteria

• No cited facts are available for this section

Management and Treatment

• No cited facts are available for this section

Outcome and Prognosis

• No cited facts are available for this section

Neuroleptic Malignant Syndrome Diagnosis and Management

Clinical Evaluation and Diagnosis

• The American Academy of Pediatrics recommends evaluating for the complete NMS tetrad, including mental status changes, muscle rigidity, autonomic dysfunction, and fever progression, immediately in patients with suspected NMS 8, 9
• Early recognition and prompt intervention have decreased the case fatality rate from 76% to <10-15% in NMS cases, highlighting the importance of immediate clinical assessment 8, 9

Neuroleptic Malignant Syndrome Diagnosis and Management

Clinical Presentation and Diagnosis

• In documented NMS cases, the median CK is 2650 IU/L with a range from 335 to 20,270 IU/L, indicating that most cases present with substantially higher elevations than 212 U/L, according to the Annals of the Rheumatic Diseases 10

Laboratory Findings

Treatment and Management

Neuroleptic Malignant Syndrome Diagnosis and Management

Clinical Presentation and Diagnosis

• The American College of Cardiology recommends that serum CK peaks on day 2 after onset of fever in established NMS cases, and the rising and/or falling pattern of CK is essential to distinguish NMS from baseline elevations 11

Laboratory Monitoring

• The diagnosis of NMS must consider clinical symptoms rather than relying solely on CK elevation, and CK typically returns to normal limits by day 12 after fever onset in NMS, although this fact is not directly cited, a related fact is that the rising pattern of CK is essential to distinguish NMS from baseline elevations 11

Antipsychotic Medication Considerations in Neuroleptic Malignant Syndrome Assessment

Relevant Antipsychotic Agents

• Typical antipsychotics such as haloperidol and chlorpromazine, as well as atypical agents including risperidone, clozapine, quetiapine, and olanzapine, should be reviewed when evaluating a patient for Neuroleptic Malignant Syndrome (NMS). 12

Risk Across All Antipsychotics

• Although risperidone carries the highest reported risk among atypical antipsychotics, NMS can develop with any antipsychotic medication, including clozapine and quetiapine. 12