The serotonin syndrome: Definition and eause

Abstract

The serotonin syndrome (SS) is a toxic reaction to a (relative?) hyperserotonergic condition in the brainstern and tne spinal cord. The syndrome is characterized by motoric restlessness and anxiety, fever, diaphoresis, and myoclonus. An examination of the latest literature about SS and neuroleptic malignant syndrome (NMS) indicates that the two syndromes are of the same nature, induced by an imbalance between serotonin and dopamine in the brainstem; other neurotransmitters may also form part of the pathogenesis of the syndrome. The syndrome is probably an extreme form of well-known adverse effects. A particular high risk is seen at combination treatments with monoamine oxidase inhibitors (MAOI) and serotonergic agents. Owing to their slow elimination, special attention should be paid to the irreversible MAO inhibitors and fluoxetine (because the metabolite has a very long half-life in plasma). Finally, it should be noted that lithium may also be involved in the induction of SS. If there are signs of incipient serotonergic hyperstimulation, it is important to withdraw all relevant medication. In severe cases the patient should be referred to an intensive care unit for treatment, as paralysation and intubation may ensue. On the basis of this review a new definition of SS is proposed.

Key Words:

• Antidepressants
• Neuroleptic malignant syndrome
• Pathogenesis
• Serotonin syndrome
• Toxic reaction