A 46-year-old man presented to the emergency department with a three-day history of headache and vomiting, and one day of confusion and fevers. His medical history included an old spinal injury and his usual medications were methadone 70 mg daily, gabapentin 3.6 g daily and citalopram 40 mg daily. One week before admission he had a tooth extracted and two days later developed a 'head cold', from which he recovered.
At presentation the patient was febrile (39.1oC) and sweating. His pulse fluctuated between 80 and 140 beats/minute, and his blood pressure between 170/86 and 214/100 mm Hg. He had a score of 12 on the Glasgow Coma Scale and was unable to sustain conversation. His dental socket looked clean and there was no clinical evidence of infective endocarditis, but he had generalised abdominal tenderness. Neurological examination revealed dilated reactive pupils and no meningism, but he had increased tone in both legs, with brisk reflexes and clonus at both ankles. Investigations revealed a white cell count of 21.1 x 10, predominantly neutrophils, and a C-reactive protein of 15. Chest and abdominal X-rays and urine were normal.
The diagnosis was sepsis, probably from an intracerebral or abdominal source, so broad-spectrum antibiotics were started. However, the patient had a normal brain scan and the lumbar puncture found no evidence of infection. The patient's condition remained unchanged over the next 24 hours. An abdominal CT scan and an echocardiogram were ordered, but were normal.
On reviewing the history, the patient recounted taking 'Night and Day' capsules containing dextromethorphan as a cough suppressant for his head cold for two or three days before becoming unwell. A presumptive diagnosis of serotonin syndrome was made and the creatine kinase was found to be elevated (354 IU). After 48 hours without citalopram, the patient recovered fully.
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