Diagnosing Serotonin Syndrome

 

This research article published in BMC Neurology tested the validity of following four hypothesis that have become widely accepted:-

  1. The Hunter classification performs clinically better than Sternbach and Radomski criteria.
  2. In contrast to neuroleptic malignant syndrome, onset of serotonin syndrome is usually rapid.
  3. Hyperthermia is a hallmark of severe serotonin syndrome.
  4. Serotonin syndrome can readily be distinguished from neuroleptic malignant syndrome on clinical grounds and on the basis of medication history.

 

RESULTS:

HYPOTHESIS 1: The Hunter classification performs clinically better than the Sternbach and Radomski criteria.

  • Confusion/consciousness impairment and agitation predominated as mental status changes.

  • For Neurological Symptoms: tremor and hyperreflexia were most frequently reported followed by muscle rigidity/hypertonia.

  • Myoclonus was more common than clonus.

  • Most common autonomic symptoms: Tachycardia, hypertension and fever

  • Important Differentiation: Rhabdomyolysis have more frequent muscle rigidity/hypertonicity, fever and hyperthermia.

  • Based on this review: Hunter Classification may clinically be less sensitive than hitherto assumed.

  • One concern regarding validity is that Hunter Classification was derived exclusively from SSRI overdoses.

  • Although frequently thought to be gold standard for diagnosis of serotonin syndrome, Hunter criteria did not perform better than Sternbach and Radomski criteria.

 

HYPOTHESIS 2: In contrast to neuroleptic malignant syndrome, the onset of serotonin syndrome is usually rapid.

  • This claim is based on one review of 41 cases with Serotonin Syndrome published between 1995 and 1999.

  • In this case collection, 61.5 % presented with 6 hours of ingestion of the causative agent and only 25.6 % later than 24 h. Thus, Serotonin Syndrome may develop quickly or slowly, depending on the context in which it occurs.

  • Although polypharmacy is an important etiological factor in the development of Serotonin Syndrome per se, dose and speed of distribution may determine its severity.

  • It remains also uncertain whether Serotonin Syndrome typically resolves much faster than NMS.

 

HYPOTHESIS 3: Hyperthermia is a hallmark of severe serotonin syndrome.

  • Fever (temperature > 41.1 °C) is considered a hallmark of Serotonin Syndrome and hyperthermia.

  • Mechanism: Elevated temperature is thought to arise from a loss of physiologic control of temperature regulation (leading to hyperthermia) rather than pyrogen mediated upregulation of the hypothalamic thermostat (pyrexia/hyperpyrexia).

  • Psychological and environmental factors (exercise, heating, apprehension and excitement) have shown to precipitate serotonin-mediated hyperthermia in susceptible patients.

 

HYPOTHESIS 4: Serotonin syndrome can readily be distinguished from neuroleptic malignant syndrome on clinical grounds and on the basis of medication history.

  • The distinction between NMS and SS is less clear-cut in agents which have both, antidopaminergic and serotonergic, properties.

  • Possibly, NMS and SS are part of the same pathology rather than two different pathological entities:-

– This could explain why rigidity/hypertonicity has emerged as a key symptom of SS.

– This could also explain why even severe SS is associated with rhabdomyolyis.

– Serotonin Syndrome and NMS are both associated with neuromuscular hyperexcitability.

 

Source: Werneke et al. BMC Neurology (2016) 16:97 

Full Article Available Here.



Dr. Harvinder Singh, M.D. (Admin and Course Instructor)


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