Serotonin syndrome in a patient with chronic pain taking analgesic drugs mistaken for psychogenic nonepileptic seizure: a case report

Serotonin syndrome (SS) is a potentially life-threatening condition that is caused by the administration of drugs that increase serotonergic activity in the central nervous system. We report a case of serotonin syndrome in a patient with chronic pain who was taking analgesic drugs. A 36-year-old female with chronic pain in the lower back and right buttock area had been taking tramadol hydrochloride 187.5 mg, acetaminophen 325 mg, pregabalin 150 mg, duloxetine 60 mg, and triazolam 0.25 mg daily for several months. After amitriptyline 10 mg was added to achieve better pain control, the patient developed SS, which was mistaken for psychogenic nonepileptic seizure. However, her symptoms completely disappeared after discontinuation of the drugs that were thought to trigger SS and subsequent hydration with normal saline. Various drugs that can increase serotonergic activity are being widely prescribed for patients with chronic pain. Clinicians should be aware of the potential for the occurrence of SS when prescribing pain medications to patients with chronic pain.