Denervation of the sympathetic supply of the limb produces vasodilatation and loss of sweating. Initially there is rosy colouring of the digits, due to capillary dilatation, but this may progress to mottling, edema and lowering of the temperature. Degenerative (trophic) changes may develop, giving smooth skin and some spindling, due to pulp atrophy. Hyperkeratinisation may develop on traumatised areas, together with loss of hair, trauma lines across the nails and clubbing.
Abnormalities of the sacral parasympathetic innervation include altered tone in the anal and urinary sphincters, and impotence. Changes associated with cranial nerve lesions are considered on page 60.