A case of severe peripheral nerve lesions in a patient with eosinophil
ia-myalgia syndrome induced by L-Tryptophan is reported. Both superfic
ial radial nerves were very tender on palpation. Biopsy of the radial
nerve showed myelin abnormalities of the type observed in experimental
chronic nerve entrapment Nerve lesions included assymmetrical distort
ion of the myelin sheath, segmental demyelination, axonal degeneration
and regeneration. Such abnormalities suggest that mechanical factors,
presumably due to proliferation of connective tissue, play a role in
the nerve lesions observed in this patient.