Serotonin syndrome vs nms
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5,13,15,16 These abnormalities in vital physiologic homeostasis reflect adrenal gland stimulation of catecholamine release 12,14,18 and stimulation of the hypothalamus manifesting as fever. 5,13-15 The most important receptor in SS is 5-HT 2A, 12,16,17 which increases heart rate, elevates blood pressure and temperature, and has a role in neuromuscular excitement. As far as SS goes, the less important one is 5-HT 1A, which is thought to be responsible for myoclonus, hyperreflexia, and alterations on mental status. As a whole, this results in around 14 distinct serotonin receptors found throughout the body, though only two are thought to be involved in the mechanism of SS: 5-HT 1A and 5-HT 2A. There are 7 types of receptors, several of which have unique receptor subclasses. 7,12 The broad effects of serotonin are mediated by multiple receptors.
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5 In the CNS, serotonin functions by modulating core body temperature, wakefulness, analgesia, sexual behavior, mood, affect, perception, personality, emesis, and eating behavior (among other things). Once released, it will bind to post-synaptic receptors and remains viable until it is either degraded by monoamine oxidase (MAO) or removed from the synapse by reuptake pumps. 7 Serotonin in the CNS is mostly produced in the pons and upper brainstem. The overall level of serotonin in the CNS doesn’t matter as much as how much of it is stuck in the neuronal synapses, causing the effects of SS. While most of the total body serotonin is found in the periphery, 5 what we care about is the serotonin that causes SS, namely, the serotonin produced in the central nervous system (CNS). So now that we’re scared, how do we not miss this deadly disease? First, let us consider the mechanism for how SS occurs. 6 Work hour restrictions in the US were first established after a case of missed SS where an intern continued to give serotonergic medications for agitation in a patient with SS, likely resulting in her death. 8 The mortality rate of severe SS has been reported to be 2-12%. Unrecognized SS can quickly deteriorate into irreparable kidney damage, respiratory failure, or DIC. 4 Often when SS starts advancing from the mild into the moderate category, we may inadvertently treat the condition with more serotonergic medications, further precipitating decline. At least part of the reason why we miss this disease is due to the fact that mild cases can present with non-specific symptoms such as tremors, diarrhea, and tachycardia. 9 While that number is probably much better these days, SS still often goes unrecognized. In a previously published survey study, as many as 85% of physicians didn’t know what SS was. Why do we care about this disease? We care about this because the medical community often misses it.
Serotonin syndrome vs nms how to#
2-8 To get a better understanding of how to differentiate between the two, let’s look at each of these diseases a bit more in depth. They are both associated with psychiatric diseases and are often seen in the setting of polypharmacy, 1,2 which give the provider a broad differential to work through when these patients present in the emergency department (ED). Serotonin syndrome (SS) and neuroleptic malignant syndrome (NMS) are two types of pathologies that often give a very confusing picture. #3: 40yo F from nursing home w/ “stiffness” #2: 21yo F w/ “jitteriness” s/p a med change Authors: Jacob Avila, MD and Jonathan Bronner, MD (EM Attending Physicians, University of Kentucky) // Edited by: Alex Koyfman, MD (EM Attending Physician, UT Southwestern Medical Center / Parkland Memorial Hospital, and Brit Long, MD EM Chief Resident at SAUSHEC, USAF)