Vasculitic neuropathies.

Vasculitis typically affects the 50- to 400-micron vessels of the vasa nervorum, leading to randomly distributed ischemia along the course of the nerve. This, in turn, leads to a distinctive picture, multiple mononeuropathy, as a frequent but not invariant clinical consequence of vasculitis. The diagnosis of vasculitic neuropathy is usually made by biopsy histologic confirmation. The response to treatment varies among different vasculitides; vasculitis restricted to the peripheral nervous system is often especially responsive.