"Is this serotonin syndrome or NMS?"
In a patient with hyperthermia, altered mental status and neuromuscular abnormalities, evaluating 3 factors makes the distinction easier
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In a patient with hyperthermia, altered mental status and neuromuscular abnormalities, evaluating 3 factors makes the distinction easier
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#1: The drugs
SS: 5-HT agonists, either in large amounts (OD) or in combination - SSRIs, some TCAs, MAOIs (incl. linezolid), opioids, St. John's wort, MDMA, LiβΊ, others
NMS: D2 blockers - antipsychotics, metoclopramide; also, withdrawal of dopamine agonists (eg. L-dopa)
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SS: 5-HT agonists, either in large amounts (OD) or in combination - SSRIs, some TCAs, MAOIs (incl. linezolid), opioids, St. John's wort, MDMA, LiβΊ, others
NMS: D2 blockers - antipsychotics, metoclopramide; also, withdrawal of dopamine agonists (eg. L-dopa)
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#2: The time course
Serotonin syndrome: Rapid onset, typically escalating over hours
NMS: Evolves gradually over days or even weeks. Can fluctuate dramatically over the course of the day (eg. mute, withdrawn and rigid in the morning; speaking and moving in the afternoon)
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Serotonin syndrome: Rapid onset, typically escalating over hours
NMS: Evolves gradually over days or even weeks. Can fluctuate dramatically over the course of the day (eg. mute, withdrawn and rigid in the morning; speaking and moving in the afternoon)
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#3: The neuromuscular features
SS - clonus (spontaneous or inducible) and hyperreflexia are the hallmarks
NMS - rigidity ("lead pipe") is classic
Serotonin syndrome is hyperkinetic, NMS is bradykinetic
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SS - clonus (spontaneous or inducible) and hyperreflexia are the hallmarks
NMS - rigidity ("lead pipe") is classic
Serotonin syndrome is hyperkinetic, NMS is bradykinetic
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If you need a reflex hammer, it probably isn't serotonin syndrome
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Final point: SS and NMS exist on a spectrum. No patient is obliged to have the full house.
NMS is especially easy to miss
Normal temp? Could still be NMS
Not rigid? Maybe you're catching them in a lull
Sick patient on an antipsychotic? Just put NMS on the differential
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NMS is especially easy to miss
Normal temp? Could still be NMS
Not rigid? Maybe you're catching them in a lull
Sick patient on an antipsychotic? Just put NMS on the differential
/ end
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