[Neuropathology of polyneuropathies]

The concept of polyneuropathies is defined; some basic anatomical data about the peripheral nerve are reviewed. The structural substrates of the 3 main types of polyneuropathies are demonstrated: 1. demyelination, i.e. elective loss of myelin sheaths; 2. axonal degeneration which can appear in a) desintegrative form or in b) dystrophic form, especially as "dying back", 3. peripheral neuroaxonal dystrophy. The pathogenetic conditions and respective etiologies are discussed, clinical manifestations are described.