[Clinical, neurophysiologic and biopsy findings in neurotoxic amiodarone syndrome]

Three patients complained of proximal weakness and paraesthesia of the legs and difficulties in walking during amiodarone treatment. Examination showed signs of a predominantly distal sensory neuropathy, a proximal myopathy, and a cerebellar gait disorder. All had amiodarone dosages of 600 mg per day, amiodarone serum levels above 2.7 mg/l and a total amount of amiodarone ingestion of 300 to 500 g. The clinical symptoms subsided within six to eleven months after treatment was stopped.

The neurophysiologic investigations showed slowing of sensory and motor nerve conduction velocities with dissociation of the action potentials and delay of SEP latencies. With discontinuation of the drug these abnormalities were progressive in one patient. The biopsy (muscle, nerve and skin) in the most severely affected patient showed numerous intracellular lysosomal inclusions in cells of different tissues. It is supposed that the storage of amiodarone in muscle cells results in a predominantly proximal myopathy whereas storage in Schwann cells results in a secondary neuropathy. A similar storage in Purkinje cells may be responsible for the cerebellar gait disorder.

The clinical picture should be termed a neurotoxic amiodarone syndrome rather than amiodarone neuropathy.