Myoclonus in renal failure: Two cases of gabapentin toxicity

Abstract

Gabapentin, an AED approved for the adjunctive treatment of partial seizures with/without secondary generalization and for the treatment of postherpetic neuralgia, is frequently used off-label for the treatment of both psychiatric and pain disorders. Since gabapentin is cleared solely by renal excretion, dosing requires consideration of the patient's renal function. Myoclonic activity may occur as a complication of gabapentin toxicity, especially with acute kidney injury or end-stage renal disease. We report 2 cases of myoclonic activity associated with gabapentin toxicity in the setting of renal disease which resolved with discontinuation of gabapentin and treatment with hemodialysis and peritoneal dialysis. As gabapentin has multiple indications and off-label uses, an understanding of myoclonus, neurotoxicity, and renal dosing is important to clinicians in multiple specialties.

A Patient with Multiple Myeloma who Developed Severe Myoclonus after Stem Cell Transplantation

“…The dystonia associated with myoclonus may affect a single part of the body, causing isolated problems such as a writer's cramp in the hand, or it may involve multiple areas of the body. High frequency myoclonus refers to twitches at more than one/minute [5]. Myoclonus is also reported in 0.1% to 12.5% of patients using Gabapentin [5,7] and also restless legs syndrome can be seen under Gabapentintreatment [5].…”

“…High frequency myoclonus refers to twitches at more than one/minute [5]. Myoclonus is also reported in 0.1% to 12.5% of patients using Gabapentin [5,7] and also restless legs syndrome can be seen under Gabapentintreatment [5]. Hypoglycaemia, and altered sensorium are also among the manifestations of Gabapentin toxicity [7,8].…”

“…Gabapentin provides a voltage-sensitive calcium channel modulation to protect the diabetic peripheral pain [5]. However the exact mechanisms of Gabapentin-induced myoclonus remain poorly understood.…”

“…However mental status of our patient was not affected. very rare with Gabapentin, only a report of a patient mentions the co-of and mental status changes [5].…”

“…Diabetic and Bortezomib associated sensory neuropathy are among the indications of Gabapentin treatment [2,3]. Gabapentin is primarily excreted from the kidneys and does not have hepatic clearance, and as expected its' clearance is altered in patients with deranged renal function [4,5]. Myoclonus, sudden brief, shock-like involuntary movement can be caused by anoxic brain injury, metabolic derangement, focal brain lesions, medications and viral infections [6].…”