Clinicopathological features of neuropathy in anti-neutrophil cytoplasmic antibody-associated vasculitis

Microscopic polyangiitis (MPA), Churg–Strauss syndrome (CSS), and Wegener’s granulomatosis are anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitides that may affect both the central and peripheral nervous systems. In these diseases, the frequency of concomitant peripheral neuropathy is particularly high in MPA and CSS. As opposed to kidney and lung involvement, which may be life threatening, peripheral neuropathy due to vasculitis alone does not significantly affect survival, although it can disturb day-to-day functioning and quality of life of patients. In this article, we describe clinical and pathological features of neuropathy in ANCA-associated vasculitides, focusing on MPA and CSS. A mononeuritis multiplex pattern instead of a symmetric polyneuropathy pattern characterizes the neuropathic features of MPA and CSS. Pathological findings of vasculitic neuropathy are characterized by axonal degeneration of nerve fibers caused by vasculitis-induced ischemia in both MPA and CSS. Hence, CSS- and MPA-associated neuropathies share common neuropathic features, but the extent of systemic organ involvement is significantly higher in MPA cases, resulting in poorer survival rates.