[Clinical features of the peripheral nerve involvement in necrotizing angitis--characteristics in polyarteritis nodosa and allergic granulomatous angitis].

Thirteen patients with peripheral neuropathy caused by necrotizing vasculitis were clinico-pathologically analyzed. These patients consisted of nine classical periarteritis nodosa (PN), four allergic granulomatous angitis (Churg-Strauss syndrome, AGA). All of them were proven to have a necrotizing vasculitis by sural nerve biopsy. The characteristics of peripheral neuropathy of these patients were summarized as follows. 1) Mononeuritis multiplex was a principal features in all patients preferentially localized in common peroneal, sural, radial median and ulnar nerves, with all modality of sensory impairment. 2) Radiation or diffuse deep-pain was a major initial symptom. Since this pain occurs frequently in the manner of sudden onset, the patient can tell the day of onset. 3) Local edema on the skin of involved region was initially observed. 4) Muscular atrophy and weakness was distributed more widely than sensory impairment. 5) Morphometric and teased-fiber study of biopsied sural nerves revealed axonal degeneration as a major pathological process. As compared to myelinated fibers, unmyelinated fibers were likely to be well preserved in morphology and population, which suggests that unmyelinated fibers are relatively resistant to ischemia. 6) Motor and sensory conduction study showed greatly decreased sensory and motor action potentials frequently resulting in absent of recordings. Conduction velocity is almost within normal range or just below the normal. Routine EMG recordings showed active denervation potentials in the involved muscles. 7) Protein in CSF was rarely elevated which suggested involvement of the spinal roots is infrequent. 8) Hypereosinophilia, thrombocythemia, fever, increased erythrocyte sedimentation rate, positive CRP and RA, and polyclonal hypergammaglobulinemia (IgG, IgA) were observed in most cases.