Multiple mononeuropathy and vasculitis

Background: Seventy percent of vasculitis are neurologically expressed as m ultiple mononeuropathy (MM) or asymmetrical neuropathy (AN). Concurrent ner ve and muscle biopsy increases the diagnostic accuracy of the disease. Aim: To define the pathological features of vascular damage in nerve and muscle in patients with MM or AN. Patients and methods: Between 1980 and 1997, 50 patients with a MM or AN diagnosis, based on neurological and neurophysiol ogical findings, were studied at the Neurology Department of Hospital del S alvador. All underwent nerve and muscle biopsy (of the superficial peroneal nerve and the short peroneal muscle). Slices were stained with bematoxylin eosin, luxol fast blue and Gomori staining. Results: Forty two patients, a ged 52 +/- 15 years old (29 female) had a vasculitis. These subjects with M M or AN associated to vasculitis, corresponded to 22% of neuropathies subje cted to nerve biopsy at the Department in the study period. Thirty two case s (76%) had necrotizing arteritis, characterized by wall fibrinoid necrosis and lumen occlusion in large vessels (>100 microns) with lymphobplasmocyti c and macrophage infiltration. Ten cases showed an inflammatory reaction an d endothelial proliferation without wall necrosis, specially in small epine ural arteries. Vascular recanalization was found in 33% of cases. Diagnosti c vascular changes were found in 87% of nerve biopsies and 53% of muscle bi opsies. No definitive relationship between the intensity of vascular and ne rve lesions was found. All muscle biopsies showed some degree of neurogenic atrophy and 5 had micro infarcts. Conclusions: Superficial peroneal nerve biopsy is diagnostic in most patients with MM or AN associated with vasculi tis. Nerve and muscle biopsies are complementary in the diagnostic work up.