Axonal form of Guillain-Barré syndrome: evidence for macrophage-associated demyelination.

We report on the clinical, electrophysiological, and pathological findings in a patient with pure motor and axonal Guillain-Barré syndrome, who died 29 days after onset. There was marked reduction of compound motor action potential amplitudes and denervation potentials in the tibialis anterior muscle. Motor and sensory conduction velocities of median nerve were normal. Peroneal nerve was inexcitable at the ankle but its latency from knee to tibialis anterior was normal. F waves were absent or delayed. The major burden of pathological changes fell on ventral spinal roots. Fundamental lesions included segmental demyelination, axonal degeneration, widespread endoneurial lipid-laden macrophage infiltrates, remyelination, and clusters of small regenerating fibers. These findings suggest that axonal damage in the axonal form of Guillain-Barré syndrome is secondary to demyelination.