[Peripheral nerves in a case of lead neuropathy]

A patient developed lead neuropathy with an asymmetrical distal weakness of the four limbs and sensory signs. Tap water contained high amounts of lead and biopsy confirmed the intoxication. The electromyogram was altered from the onset of the disorder and was still abnormal one year after treatment with EDTA, which however brought frank improvement. Biopsies were taken from nerves of the upper and lower limbs. Examination of teased nerve fibers showed the predominance of fibers of small diameter and segmental demyelinization with signs of remyelination in the lower limbs. Semi-thin sections demonstrated depopulation of large myelinated fibers, regeneration clusters and Schwann cells with globular nuclei. Electron microscopy showed myelin sheath alterations and neuritic lesions, some hyperactive Schwann cells. Main alterations were seen in basal membranes of Schwann cells of unmyelinated fibers and endoneuronal capillaries. Such alterations to our knowledge have never been reported in human peripheral lead neuropathy, but have been described after experimental intoxication. These findings together with recent experimental studies allow a discussion about the site of entry of lead into the nerve and about its site of action on the various constituents of the peripheral nerve.