511 - Baclofen Toxicity in End-Stage Renal Disease: A Case Report and Clinical Lessons

Case Diagnosis: Baclofen-Induced Toxic Encephalopathy

Case Description: A 87-year-old female with history of end-stage renal disease (ESRD) on peritoneal dialysis (PD) presented to the emergency department with acute altered mental status (AMS). The patient's presentation occurred in the context of a recent primary care visit to address cervical muscle spasms. The patient was prescribed 10mg of oral baclofen twice daily and took two doses in the 24 hours prior to hospital presentation. Initial clinical examination was notable for lethargy, profound disorientation, nystagmus, and low-frequency tremor. Initial diagnostic evaluation demonstrated no severe metabolic derangements, signs of infection, or acute cerebrovascular event underlying the patient's symptoms. Without a clear alternate etiology for her AMS, the patient was diagnosed with baclofen-induced toxic encephalopathy, underwent placement of temporary hemodialysis (HD) catheter, and received HD twice over the next 48 hours. Subsequently, her mentation returned to baseline, and she was ultimately discharged without any residual neurologic deficits.

Discussions: Baclofen is a commonly prescribed muscle relaxant that is almost entirely renally excreted in unchanged form. While the only absolute contraindication to prescribing baclofen is prior hypersensitivity reaction, it is widely known that baclofen should be avoided in patient's with ESRD due to its predominant renal excretion. Further, PD is inadequate in its elimination of small, water-soluble, and low protein-bound molecules like baclofen. This case demonstrates that even low-dose oral baclofen can precipitate severe neurotoxicity in elderly patients with ESRD.

Conclusions: In this case, a well-intentioned baclofen prescription from a primary care provider resulted in hospitalization and emergent HD. Earlier involvement of a physiatrist — more familiar with baclofen dosing precautions — might have prevented this adverse event. Iatrogenic causes of encephalopathy must remain high on the differential when encountered in the acute or post-acute care settings, particularly in patients with complicated medical histories.