Case Presentation: A 54-year-old man with congestive heart failure, chronic kidney disease and atrial fibrillation (on digoxin 0.125 mg daily for 3 years) presented to the emergency department with fatigue, weakness, vomiting, poor oral intake and whole body “involuntary sudden movements.” Neurological exam revealed generalized symmetrical choreiform movements more pronounced in the head, upper torso and arms; otherwise, normal cognition, cranial nerve function, strength, sensation and reflexes. Careful history revealed that the patient may have inadvertently taken more digoxin pills than prescribed. Pertinent labs revealed acute on chronic kidney injury with a creatinine level of 2.7 mg/dL (baseline 1.6 mg/dL), hyponatremia at 127 mMol/L, hyperammonemia at 65 mMol/L. Digoxin levels were >5.0 ng/ml (reference range 0.9-2.0 ng/ml). Computed tomography of head showed a subacute infarct in the right temporal cortex, otherwise no apparent basal ganglia lesions to explain central cause of chorea. Digoxin was discontinued and 2 doses of DIGIFab 80 mg IV were administered. On day 2 of admission, digoxin levels were 3.3 ng/ml, chorea became less pronounced in the head and upper extremities and resolved in lower extremities. By day 3, chorea had completely resolved, and digoxin levels normalized at 1ng/ml. Neuroleptic home medications including Sertraline and Mirtazapine were continued throughout his admission and on discharge.
Discussion: Transient bilateral chorea due to digoxin toxicity in a setting of renal dysfunction is an extremely rare presentation. Four prior cases have been reported with variable success after drug discontinuation (Wedzicha et al. 1984; Mulder et al. 1988; Sekul et al. 1999; Mannion et al. 2021). Chorea has several potential etiologies, requiring a comprehensive neurological workup including neuroimaging, serologic workup for potential autoimmune, inflammatory, infectious, and neoplastic causes. A thorough history and review of medications is crucial as, in some cases, a simple drug discontinuation can lead to complete resolution of symptoms, obviating the need for unnecessary and expensive testing. Mechanistic association between use of digoxin and chorea remains largely unknown, alteration of dopamine signaling by the drug has been proposed.
Conclusions: Considering the wide and long-term use of digoxin, it is crucial to educate ourselves and our patients about digoxin-induced chorea and our case contributes to the limited but growing evidence of this important iatrogenic condition. More importantly, in our patient’s case, symptoms appeared after 3 years of use. When necessary, discontinuing the suspected drugs should be trialed to confirm the diagnosis, instead of symptomatic treatment. Larger epidemiological studies are required to establish true prevalence and to elucidate the underlying mechanisms and optimal management strategies for this manifestation.