From the Guidelines
Autonomic instability in serotonin syndrome is characterized by symptoms such as hyperthermia, tachycardia, hypertension, diaphoresis, flushing, mydriasis, and shivering, which can rapidly progress and become life-threatening, requiring immediate discontinuation of serotonergic medications and supportive care. The clinical presentation of serotonin syndrome is highly variable, but it typically includes a combination of mental status changes, autonomic hyperactivity, and neuromuscular abnormalities 1. The autonomic instability in serotonin syndrome can manifest as fluctuations in vital signs, including hyperthermia (often exceeding 38.5°C), tachycardia, hypertension, and sometimes rapid blood pressure fluctuations. Patients typically experience diaphoresis (excessive sweating), flushing, mydriasis (dilated pupils), and shivering. Gastrointestinal symptoms such as diarrhea, nausea, and vomiting are common. In severe cases, patients may develop metabolic acidosis, rhabdomyolysis, disseminated intravascular coagulation (DIC), and acute respiratory distress syndrome (ARDS) 1. These symptoms result from excessive serotonergic activity affecting the autonomic nervous system, particularly through 5-HT1A and 5-HT2A receptors. Benzodiazepines are often used for symptom control, while severe cases may require serotonin antagonists like cyproheptadine (initial dose 12mg orally, followed by 2mg every 2 hours until improvement, then 8mg every 6 hours) 1. Close monitoring of vital signs and aggressive cooling measures for hyperthermia are essential components of management. Some key points to consider in the management of autonomic instability in serotonin syndrome include:
- Discontinuation of serotonergic medications
- Supportive care, including benzodiazepines for symptom control
- Serotonin antagonists like cyproheptadine for severe cases
- Close monitoring of vital signs
- Aggressive cooling measures for hyperthermia
- Consideration of consultation with a toxicologist or poison control center.
From the Research
Autonomic Instability in Serotonin Syndrome
The symptoms of autonomic instability in serotonin syndrome include:
- Hypertension
- Hyperthermia
- Tachycardia
- Diaphoresis
- Shivering
Clinical Features
Autonomic instability is one of the key features of serotonin syndrome, along with mental status changes and neuromuscular hyperactivity 2, 3. The clinical manifestations of serotonin syndrome can range from mild to life-threatening, and the diagnosis is made using the Hunter Serotonin Toxicity Criteria 2.
Management
Management of serotonin syndrome involves withdrawal of the offending agent, supportive care, and occasionally the administration of serotonin antagonists such as cyproheptadine or chlorpromazine 3. In severe cases, patients may require hospitalization, neuromuscular paralysis, sedation, and intubation 2.
Treatment of Hypertension
In cases of severe hypertension associated with serotonin syndrome, classic antihypertensives may not be effective, and benzodiazepines, cyproheptadine, or propofol may be used to lower blood pressure 4.
Pathophysiology
Serotonin syndrome is caused by excessive serotonergic activity in the nervous system, which can be precipitated by the use of serotonergic drugs, including selective serotonin reuptake inhibitors, monoamine oxidase inhibitors, and other agents 5, 6.