(Kiosk 4) Prolonged Ataxia, Tremor, and Dysarthria Following Serotonin Syndrome Secondary to Tramadol Overdose: A Case Report

Case Diagnosis: Serotonin syndrome following tramadol overdose can lead to persistent neurologic symptoms including ataxia, tremor, and dysarthria.

Case Description or Program Description: A 57-year-old female with bipolar disorder and generalized anxiety disorder presented after ingesting 300 tablets of tramadol 50 mg as a suicide attempt. She developed symptoms of serotonin syndrome - hyperthermia, tachycardia, and hyperreflexia. She was treated with active cooling, deep sedation, paralysis, and cyproheptadine. Course complicated by status epilepticus, rhabdomyolysis, and encephalopathy. Encephalopathy workup was negative including meningitis/encephalitis panel, CSF studies, and MRI brain. 17 days after overdose, she was admitted to inpatient rehabilitation for toxic encephalopathy. All serotonergic agents had been discontinued 2 weeks prior. Encephalopathy improved, however, the patient had continued hyperreflexia, ataxia, dysarthria, and tremor in her head and bilateral upper and lower limbs. MRI brain 1 month following the overdose showed no acute or chronic intracranial abnormalities to explain ongoing neurological changes.

Setting: Inpatient rehabilitation hospital

Assessment/Results: The patient was admitted to inpatient rehabilitation for 39 days. Multidisciplinary treatment team included PM&R, PT, OT, SLP, rehabilitation psychology, and psychiatry. She initially ambulated 10 feet with total assistance and at discharge, ambulated 300 feet with moderate assistance using a platform walker. Moderate cognitive deficits progressed to mild and severe dysarthria progressed to moderate.

Discussion (relevance): Tramadol is a centrally acting analgesic that acts through mu-opioid receptor agonism and serotonin and norepinephrine reuptake inhibition. Overdose can cause serotonin syndrome which can present as behavioral changes, neuromuscular excitability, and autonomic instability. Symptoms typically resolve within 24 hours to 1 week after discontinuation of the serotonergic agent. Here, we describe a case of prolonged symptoms following initial overdose and discontinuation of serotonergic agents.

Conclusions: Serotonin syndrome can lead to persistent neurologic symptoms including ataxia, tremor, and dysarthria, likely dependent on dose. To our knowledge, this is the first case reported of prolonged serotonin syndrome after tramadol overdose.