[Diagnostic and clinical aspects of neuropathy of small nerve fibers].

Small fibre neuropathy, a phenomenon that neurologists have always been familiar with as an accidental or independent pattern of signs and symptoms in "sensitive" or "painful" neuropathy, has become interesting once again as a result of progress in diagnostic methods. The A-delta and C fibres as well as the B fibres (of the vegetative nervous system) are known as "small", i.e. thin, weak or non-myelinated nerve fibres of slow conductivity. More than 80% of the nerve fibre mass of the peripheral somatic nerve is accounted for by the small fibres; moreover, the small fibres make up the peripheral vegetative nervous system. However, their importance especially for the afferent functions has hardly been sufficiently appreciated to date. The present article surveys the forms of neuropathies and other lesions of the nerves where functional disturbance of the small nerve fibres is prominent, on the one hand for the peripheral somatic and on the other hand for the peripheral vegetative nervous system. A few methods of measurement for testing the function of the small fibres at the somatic nervous system (determination of temperature and pain threshold, specific pain measurement methods) and at the peripheric vegetative nervous system (autonomic function tests) are described.