Neuropathy in eosinophilic granulomatosis with polyangiitis: a comparison study of 24 cases with or without prior leukotriene antagonist exposure.

Eosinophilic granulomatosis with polyangiitis (EGPA), also known as Churg-Strauss syndrome (CSS), is a systemic vasculitis affecting almost exclusively patients with asthma. Neuropathy is the presenting feature in 55-75 % of cases. An increased incidence of the syndrome has been reported in asthmatics treated with leukotriene antagonists (LTAs). The causal relation is still debated. We retrospectively examined clinical, biochemical, histological features, and outcome of patients referred between 1990 and 2006 for sural nerve biopsy affected by neuropathy related to EGPA. We identified 24 patients, 6 treated with LTA montelukast (T-group) and 18 not treated (NT-Group). All had chronic asthma; in T-group neuropathy developed from 1 to 150 days after starting montelukast. Demographic features as well as asthma duration and pre-onset treatment were remarkably similar, with the only exception of a statistically nonsignificant larger involvement of the nasal mucosa in T group. Nerve biopsy revealed in both group an axonal neuropathy. At follow-up, all within the T-group and most within the NT-group improved clinically; neurophysiological parameters remained stable, improved or worsened in the same proportion within the two groups. Only 2 NT and no T-patient had stopped steroid treatment before the appearance of the peripheral neuropathy, making withdrawal overall unlikely as a causative factor of the onset of neuropathy. In summary, the temporal relationship between montelukast administration and the onset of neuropathy, would make the latter more likely as an "adverse drug reaction". Despite this, no significant clinical neither neurophysiological differences were noted between the two groups.