Serotonin syndrome

Question 1

Definition

Answer 1

Excess serotonin in synapse of CNS clinically manifests as NM excitation, autonomic effects, altered mental status

Question 2

Can commonly result from

Answer 2

Therapeutic use of medications
Drug overdose
Drug-drug interactions

Question 3

Medications causing SS

Answer 3

SSRI, SNRI, clomipramine, Opioids, MAOIs, amphetamines, ecstasy, bath salts, lithium, tryptophan, buspirone

Question 4

Key diagnostic factors

Answer 4

Risk factors
Clonus
Hyperreflexia
Anxiety
Agitation
Confusion
Tremor, shiver, muscle jerking
Sweating, headache, tachycardia
Hypertonia

Question 5

Investigations

Answer 5

FBC
Creatinine Phosphokinase- assess for rhabdomyolysis to exclude other causes
UDS- may be positive for illicit/other drugs
ECG- tachyC

Question 6

Management

Answer 6

Cessation of offending medications
ABCs
Rapid cooling
Sedate, intubate and ventilate early
Cyproheptadine
If unable to take oral medication- chlorpromazine for sedation
If severe- consider midazolam + morphine for sedation

Question 7

Differentials with key distinguishing features (7)

Answer 7

Acute baclofen w/d- hx of pump, respose to baclofen
Anticholinergic delirium- Xclonus, bowel sounds absent, dry skin
CNS infection- Xclonus, vomiting, neck stiffness
Malignant hyperthermia- Xclonuc, anesthetic exposure
NMS- Xclonus, bradykinesia
Nonconvulsive seizures- afebrile, epislepse, EEG features, response to benzodiazepines
Sympathomimetic toxicity- Xclonus, +CV features