Serotonin Syndrome Following Combined Administration of Dopaminergic and Noradrenergic Agents in a Patient With Akinetic Mutism After Frontal Intracerebral Hemorrhage: A Case Report.

BACKGROUND: Serotonin syndrome (SS) is a potentially life-threatening condition that can be caused by use of proserotonergic drugs. Several studies have reported that combined administration of various medications may induce SS. We report a case of SS in a patient who was being treated with dopaminergic and noradrenergic drugs. CASE PRESENTATION: A 55-year-old man with a right frontal intracerebral hemorrhage extending to the left cerebral hemisphere presented with clinical features of akinetic mutism. Three months after onset, dopaminergic (methylphenidate, levodopa/benserazide) and noradrenergic (atomoxetine) drugs were administered to enhance his cognitive function. His cognitive function gradually improved during 8 weeks of dose escalation. One day after the dose of atomoxetine was increased from 40 mg/d to 60 mg/d, the patient developed inducible clonus, rigidity, diarrhea, tachycardia, and hyperthermia, in keeping with a diagnosis of SS. The symptoms and signs suggestive of SS resolved on the day following cessation of all dopaminergic and noradrenergic drugs. CONCLUSIONS: This case demonstrates that medications generally known as dopaminergic or noradrenergic agents could have serotonergic effects via a mechanism that is yet to be fully elucidated. The clinical manifestations of SS can be diverse, ranging from mild to severe and potentially fatal symptoms. When administering a combination of catecholaminergic agents, clinicians should carefully monitor the patient's neurologic status for unexpected adverse reactions.

Methylene blue-associated serotonin syndrome: a 'green' encephalopathy after parathyroidectomy.

INTRODUCTION: Methylene blue (MB) infusion is frequently used to localize the parathyroid glands during parathyroidectomy and generally considered safe. Several recent reports suggest neurological toxicity and post-operative altered mental state typically after large dose infusions. The mechanism by which MB has neurotoxic effects in some patients remains uncertain. CASE REPORT: A 67-year-old male underwent lumbar laminectomy followed by parathyroidectomy. Postoperatively, he was comatose (Glasgow Coma Scale of 7) and underwent extensive neurological evaluation. Brain computed tomography (CT) imaging and CT angiography revealed no ischemia, vessel occlusion, or hemorrhage. Electroencephalogram (EEG) showed only slowing of cerebral hemispheric activity bilaterally. Over the next 48 h, his mental status slowly improved and the patient made a full neurological recovery (Glasgow Coma Scale 15). CONCLUSION: Methylene blue, when used in patients on antidepressant drugs, may be associated with a transient encephalopathic state and serotonin syndrome. Patients on antidepressants undergoing parathyroidectomy who may receive MB infusion should be considered for alternative parathyroid gland identification or discontinuation of the antidepressants before surgery. MB-associated serotonin syndrome is an increasing and under recognized ('green') post-operative encephalopathy that warrants education to critical care neurologists and other physicians.