Wernicke's Encephalopathy and Serotonin Syndrome: A Case Report of Overlapping Pathologies.

Acute encephalopathy is a common symptom encountered in critically ill patients and may be associated with Wernicke's encephalopathy (WE) or serotonin syndrome (SS). We describe a patient who presented with clinical manifestations of both WE and SS and who responded to treatment for both pathologies. A 56-year-old male presented after being found unresponsive and in a questionable tonic-clonic state. Past medical history was significant for depression managed with fluoxetine 20 mg by mouth daily and alcohol use disorder. A physical exam revealed severe clonus in the bilateral lower extremities; diffuse hyperreflexia along with akinesia on the left upper extremity; ophthalmoplegia; and persistent tachycardia despite pharmacologic interventions. It was learned that the patient had been taking his fluoxetine 3 times per day rather than daily as prescribed. Oral cyproheptadine was administered at a 12 mg initial dose followed by 4 mg every 6 hours. A thiamine regimen of 500 mg intravenous (IV) every 8 hours in addition to folic acid 1 mg IV every 24 hours was initiated to treat WE. Physical symptoms of both WE and SS resolved within 48 hours, and the patient was ultimately discharged to home in stable condition. The clinical diagnosis of both WE and SS in this case is supported by the Caine and Hunter criteria, respectively, as well as the resolution of symptoms with accepted treatment modalities for each. It is important for clinicians to be cognizant of potential overlapping pathologies when patients present with nonspecific symptoms, especially acute encephalopathy, in the intensive care unit.