Background: Seventy percent of vasculitis are neurologically expressed as multiple mononeuropathy (MM) or asymmetrical neuropathy (AN). Concurrent nerve 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 neurophysiological findings, were studied at the Neurology Department of Hospital del Salvador. All underwent nerve and muscle biopsy (of the superficial peroneal nerve and the short peroneal muscle). Slices were stained with hematoxylin eosin, luxol fast blue and Gomori staining.
Results: Forty two patients, aged 52 +/- 15 years old (29 female) had a vasculitis. These subjects with MM or AN associated to vasculitis, corresponded to 22% of neuropathies subjected to nerve biopsy at the Department in the study period. Thirty two cases (76%) had necrotizing arteritis, characterized by wall fibrinoid necrosis and lumen occlusion in large vessels (> 100 microns), with lymphoplasmocytic and macrophage infiltration. Ten cases showed an inflammatory reaction and endothelial proliferation without wall necrosis, specially in small epineural arteries. Vascular recanalization was found in 33% of cases. Diagnostic vascular changes were found in 87% of nerve biopsies and 53% of muscle biopsies. No definitive relationship between the intensity of vascular and nerve 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 vasculitis. Nerve and muscle biopsies are complementary in the diagnostic work up.