Affected nerves shows myelin sheath and axon degeneration. The large myelinated fibers are affected, demonstrating segmental demyelination and macrovacuolization. Both the motor and sensory fibers of the peripheral nerves demonstrate fatty degenerative changes and disintegration of the medullary sheaths due to demyel-ination by toxin. The anterior horn cells and posterior columns of the spinal canal can be involved, and the central nervous system may develop signs of hemorrhage, meningitis and encephalitis. Nonetheless, the polyneuro-pathy is reversable.

At autopsy, the heart is pale brown, soft and enlarged with a characteristic streaky appearance. Neutral fat accumulations are observed in approximately 50% of patients, with extensive hyaline degeneration and necrosis with inflammatory changes. EM demonstrates swollen disorganized mitochondria containing dense osmophilic granules.