Unusual neurotoxicity associated with amiodarone therapy

Area of Science:

• Cardiology
• Neurology
• Pharmacology

Background:

• Recurrent, drug-refractory tachyarrhythmias pose significant treatment challenges.
• Amiodarone is a widely used antiarrhythmic agent.
• Neurotoxicity is a known adverse effect of amiodarone.

Purpose of the Study:

• To investigate the spectrum and characteristics of amiodarone-induced neurotoxicity.
• To determine the extent of central nervous system involvement in amiodarone neurotoxicity.
• To identify potential risk factors for amiodarone neurotoxicity.

Main Methods:

• Retrospective analysis of 102 patients treated with amiodarone for tachyarrhythmias.
• Clinical assessment of neurotoxic reactions, including frequency and severity.
• Neurophysiologic studies to evaluate peripheral nerve involvement.
• Analysis of patient age and cumulative amiodarone dose as potential risk factors.

Main Results:

• Forty-five patients (44%) experienced neurotoxic reactions, with nine requiring dose adjustment or discontinuation.
• Most common neurotoxic findings included tremor (44%), peripheral neuropathy (10%), and ataxia (7%).
• Unusual manifestations involved brainstem dysfunction, dyskinesia, and myopathy; neurophysiologic studies indicated demyelinating peripheral neuropathy.
• Neurotoxic symptoms improved upon amiodarone dose reduction or cessation.
• Neither patient age nor cumulative dose correlated with neurotoxicity development.

Conclusions:

• Amiodarone-induced neurotoxicity affects both peripheral and central nervous systems, including the brainstem and basal ganglia.
• The spectrum of amiodarone neurotoxicity is broader than previously recognized.
• Early recognition and dose modification are crucial for managing amiodarone neurotoxicity.