Clinicopathological features of Churg–Strauss syndrome-associated neuropathy

We assessed the clinicopathological features of 28 patients with peripheral neuropathy associated with Churg–Strauss syndrome. Initial symptoms attributable to neuropathy were acute painful dysaesthesiae and oedema in the dysaesthetic portion of the distal limbs. Sensory and motor involvement mostly showed a pattern of mononeuritis multiplex in the initial phase, progressing into asymmetrical polyneuropathy, restricted to the limbs. Parallel loss of myelinated and unmyelinated fibres due to axonal degeneration was evident as decreased or absent amplitudes of sensory nerve action potentials and compound muscle action potentials, indicating acute massive axonal loss. Epineurial necrotizing vasculitis was seen in 54% of cases; infiltrates consisted mainly of CD8-positive suppressor/cytotoxic and CD4-positive helper T lymphocytes. Eosinophils were present in infiltrates, but in smaller numbers than lymphocytes. CD20-positive B lymphocytes were seen only occasionally. Deposits of IgG, C3d, IgE and major basic protein were scarce. The mean follow-up period was 4.2 years, with a range of 8 months to 10 years. Fatal outcome was seen only in a single patient, indicating a good survival rate. The patients who responded well to the initial corticosteroid therapy within 4 weeks regained self-controlled functional status in long-term follow-up (modified Rankin score was ≤2), while those not responding well to the initial corticosteroid therapy led a dependent existence (P < 0.01). In addition the patients with poor functional outcomes had significantly more systemic organ damage caused by vasculitis (P < 0.05). Necrotizing vasculitis mediated by cytotoxic T cells, leading to ischaemic changes, appears to be a major cause of Churg–Strauss syndrome-associated neuropathy. The initial clinical course and the extent of systemic vasculitic lesions may influence the long-term functional prognosis.