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Centers for Disease Control and Prevention, 8 Nov. 2019, www.cdc.gov/tobacco/basic_ information/e-cigarettes/severe-lung-disease. html.
ABSTRACTS OF COMPETITION WINNERS: RESIDENTS
Vignette Abstract Winner
Consider Gabapentin Toxicity with Acute Movement Disorders by Dan Hurley, EMIM 4
Co-Authors: Esteban Mercado-Rodriguez, MD PGY2; John Donnelly, MD
Introduction: Gabapentin is reported
to have one of the highest rates of off- label medication use due to its relatively 5 The use of gabapentin to treat acute pain is increasing and clinicians may be less familiar
with potential toxicities associated with gabapentin.9 symptoms can help reduce morbidity and reduce the need for therapeutic dialysis.
Case Description: A 68-year-old
female with a past medical history of hypertension, diabetes, chronic pain, cervical fusion, and post-herpetic neuralgia presented with generalized weakness, slurred speech, myoclonic jerks, and ataxia worsening over seven days. She reported weakness with tremor, walking. Subsequently, she developed
two days of worsening slurred speech. She noticed intermittent diarrhea and weight loss the week prior to admission. Ten months prior to admission, the patient developed facial herpes zoster and was started and maintained on valacyclovir 1000mg BID and gabapentin 600 mg TID. On exam, she was anxious and restless. She had tongue fasciculations, slurring
of speech, resting tremors, and frequent involuntary myoclonic jerks occurring bilaterally in all extremities. There were no
neurological signs. CT of the head was
130, creatinine 4.62, and urinalysis with trace protein, leukocyte positive, and no blood. Retroperitoneal ultrasound showed increased echogenicity consistent with renal parenchymal disease. Concern
was raised for valacyclovir-induced nephrotoxicity with resultant gabapentin toxicity. Gabapentin and valacyclovir were discontinued. The patient was started on intravenous normal saline. Over the course of her hospitalization, creatinine Her myoclonus, fasciculations, and tremor slowly improved although she remained weakness, requiring transfer to rehab on discharge.
Discussion: Our patient’s symptoms
were consistent with gabapentin toxicity
in the setting of renal injury. Although a crystal-induced kidney injury has been described with acyclovir, this generally occurs in IV infusion and would be rare with oral medication.8 Our patient's rapid prerenal injury from the preceding diarrheal illness. Any patient with renal impairment should have appropriate dose adjustments made to their gabapentin.6 hours that can increase to 52 hours when Cr Cl falls to <30mL/min.10 There are isolated reports of symptoms related to gabapentin toxicity including fatigue, weakness, altered mentation, myoclonus, tremors, hyperkinesia, nystagmus,
and severe myopathy.1, 2, 3, 4,7 Treatment includes discontinuing the offending cases hemodialysis.4 Use caution when prescribing gabapentin to individuals with advanced age, polypharmacy, and chronic kidney disease. Heightened awareness
of acute movement disorders related to gabapentin toxicity can help prevent risk to our patients.
CONTRIBUTOR
■ Dan Hurley is a fourth-year resident
in the combined Emergency Medicine/ Internal Medicine Program at ChristianaCare. He received his medical degree from the Edward Via College of Osteopathic Medicine.
References
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4. Kaufman K., Parikh A., et al. Myoclonus in Renal Failure: Two Cases of Gabapentin Toxicity. Epilepsy & Behavior Case Report. 2013;2: 8-10.
5. Mack A. Examination of the Evidence for Off-Label Use of Gabapentin. J Manag Care Pharm. 2003;9(6):559-68.
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