Serotonin Syndrome

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Original Editors -HannahAnderson & Millie Ware from Bellarmine University's Pathophysiology of Complex Patient Problems project.

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Definition/Description

Serotonin syndrome occurs when you take medications that cause high levels of the chemical serotonin to accumulate in your body. Serotonin syndrome can occur when you increase the dose of such a drug or add a new drug to your regimen. Certain illicit drugs and dietary supplements are also associated with serotonin syndrome.

Serotonin is a chemical your body produces that's needed for your nerve cells and brain to function. But too much serotonin causes symptoms that can range from mild — shivering and diarrhea — to severe — muscle rigidity, fever and seizures. Severe serotonin syndrome can be fatal if not treated.

Milder forms of serotonin syndrome may go away within a day of stopping the medications causing symptoms and, sometimes, taking drugs that block serotonin.

Serotonin syndrome most often occurs when two drugs that affect the body's level of serotonin are taken together at the same time. The drugs cause too much serotonin to be released or to remain in the brain area.

Vomiting, sleep, temperature regulation, appetite, mood, regulation of blood pressure, and the perception of pain are functions that involve brain serotonergic neurons. Serotonin may also be associated or involved in conditions such as migraine headaches and anxiety. While correct serotonin concentrations can greatly improve quality of life, too much serotonin can have deleterious effects manifested as Serotonin Syndrome.

Prevalence

• Serotonin Syndrome is on the rise, however information on it is limited.
  
• According to an article in the New England Journal of Medicine, in 2002 there were over 7,000 cases of Serotonin Syndrome and of those 93 cases were fatal.
• Approximately 10% of the adult population in the U.S. reports having Depression.
• In 2011, the U.S. Center of Disease Control finished a study about the number of Americans taking Anti-depressants. The CDC found that one in every ten people over the age of 12 years old is taking an antidepressant.
• According to the Migraine Research Foundation, every one of four homes in the U.S. has someone who experiences migraines.
• The American Migraine Foundation states that 36 million Americans suffer from migraines.
  

Characteristics/Clinical Presentation

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Associated Co-morbidities

• Depression
• Migraine Headaches
  
• Cluster Headaches

Medications

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Diagnostic Tests/Lab Tests/Lab Values

Typically to diagnose Serotonin Syndrome, physicians will do various diagnostic tests to rule out other diseases and causes of the patient’s signs and symptoms. Tests may include:

• Blood cultures
• Complete blood count
• Drug screen
• Electrolyte levels
• Electrocardiogram
• Kidney and liver function tests
• Thyroid function tests
• Check body functions that may be affected by Serotonin Syndrome
  

Physician's will use either Hunter's Serotonin Toxicity Criteria: Decision Rules or Sternbach's Criteria to diagnose.

Etiology/Causes

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Systemic Involvement

Musculoskeletal System
o Clonus
o Muscle rigidity
o Hyperreflexia

Central Nervous System
o Altered mental status, delirium, agitation
o Akathisia (RLS)

Autonomic Nervous System
o Changes in blood pressure
o Tachycardia
o Increase in body Temperature
o Gastrointestinal System: diarrhea, nausea, vomiting

Medical Management (current best evidence)

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Physical Therapy Management (current best evidence)

o Inclusion of passive range of motion activities

• Progression to active-assist, active, and with resistance range of motion activities

o Walking program

• Treadmill training, over-ground training

o Strengthening: core and extremities

Alternative/Holistic Management (current best evidence)

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Differential Diagnosis

Serotonin Syndrome is unlikely to be the cause of the symptoms the patient is experiencing if they have not taken a Selective Serotonin Reuptake Inihibitor (SSRI), Serotonin-norepinephrine Reuptake Inihibitor (SNRI), or a Triptan within the last month.

Possible Diagnoses:

• Anticholinergic Overdose: This can be caused by use of insecticides. Symptoms include dry/hot skin, absent bowel sounds, and normal reflexes.
• Malignant Hyperthermia: This is related to the patient being under anesthesia and occurs acutely. Hyporeflexia is a common symptom.
• Neuroleptic Malignant Syndrome: NMS is a reaction to a dopamine antagonist drug. This is most commonly confused with Serotonin Syndrome because similar symptoms (ex. Hyperthermia, changes in mental status). However, symptoms of this syndrome that are different from Serotonin Syndrome are bradykinesia and muscle rigidity. Also, there is a gradual onset over a many days, whereas symptoms of Serotonin Syndrome quickly progress.
• Amphetamine, cocaine, or an MAOI drug overdose
• Some thyroid conditions
• Alcohol or heroin withdrawal
  
  

Case Reports/ Case Studies

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Resources

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Recent Related Research (from Pubmed)

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References

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