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Differentiating serotonin syndrome and neuroleptic malignant syndrome
| NMS | Serotonin Syndrome |
| within 7 days of neuroleptic/increased dose | within 24 hours of starting med |
| dysphagia/hypersalivation/incontinence | agitation/diarrhea |
| hyperthermia/rigidity/rhabdo/akinesia | dilated pupils/myoclonus/hyperreflexia |
NMS
- have on radar if being treated with neuroleptics + change in mental status/EPS symptoms (nonresponsive to meds)/autonomic dysfunction
- classic – hyperthermia, “lead-pipe” rigidity, delirium/catatonia
- Labs may show: leukocytosis, elevated CK (>4x upper limit), low serum iron, metabolic acidosis (all nonspecific)
- Always consider: CNS infection, trauma and status epilepticus (neuroleptics also lower seizure thresholds), subcortical lesions, thyrotoxicosis, tetanus, malignant hyperthermia, and others
Criteria for NMS
MAJOR CRITERIA
- T> 38C (confirmed)
- Muscle rigidity
- CPK elevation (5x normal)
MINOR CRITERIA
- Altered mental status
- Tachycardia
- Labile BPs
- Diaphoresis
- Tremor
- Incontinence
- Leukocytosis
- Metabolic acidosis
Treatment:
- Often self-limited with discontinuation of neuroleptics
- Consider BZDs
- Consider dantrolene (1-10mg/kg/day in divided doses)
- risks: hepatic, respiratory compromise
- Consider Bromocriptine 2-15mg TID
- Consider Amantadine 200-400mg/day
- Consider psychiatry consult, particularly for rechallenge
*Mild – supportive care and BZDs
*Mod (rigidity and temps 38-40) – supportive care, BZDs, then Dopamine agonist
*Severe (above + hyper metabolism, temps >40) – above + dantrolene
SS
- Have this on your radar if > 1 serotonergic agent – SSRI, TCA, MAOIs, linezolid, tramadol
- severe cases can progress to DIC, ARDS, renal failure
- if neuroleptic started at this time as well, consider NM
- Evaluation
- cognitive/behavioral changes, autonomic instability, neuromuscular abnormalities
- Labs (all nonspecific, no utility in serum serotonin level): elevated WBC, transaminases, decreased serum bicarb
- Always consider: infections, metabolic, endocrine, tox
- Hunter Serotonin Toxicity Criteria:\In presence of serotonergic agent
- spontaneous clonus = serotonin toxicity
- inducible clonus AND agitation/diaphoresis = serotonin toxicity
- ocular clonus AND agitation/diaphoresis = serotonin toxicity
- tremor AND hyperreflexia = serotonin toxicity
- hypertonic AND temp > 38 AND ocular/inducible clonus = serotonin toxicity
- Tx
- Early recognition, supportive care
- discontinue offending agents
- hydrate and cool
- consider benzodiazepines, cyproheptadine, propranolol, chlorpromazine
- Consider Psychiatry consults
- Unlike NMS, need to rechallenge is usually less urgent and can usually be deferred outpatient provider