Progressive idiopathic axonal neuropathy

Abstract

Patients with a progressive disabling idiopathic axonal neuropathy could have a potentially treatable immune mediated neuropathy. To evaluate whether progressive idiopathic axonal neuropathy could be a pathologically difficult to prove vasculitic neuropathy pathologically difficult to prove or if it could be a separate clinical entity (i. e. with the axon as the primary immunological target), we performed a comparative clinical and histopathological study in 10 patients with progressive idiopathic axonal neuropathy, 10 patients with vasculitic neuropathy, and 12 patients with chronic idiopathic axonal polyneuropathy (CIAP). The clinical features and disease course in patients with progressive idiopathic axonal neuropathy and patients with vasculitic neuropathy were similar. Six patients with progressive idiopathic axonal neuropathy had been treated with prednisone and/or intravenous immunoglobulin. Disability decreased in all these six patients, but also in two of the four non-treated patients. Upon reviewing the sural nerve biopsy specimens, vasculitis was found in one patient with progressive idiopathic axonal neuropathy. Vasculitis-associated signs of ischemic injury or inflammation (most notably: large variation in fascicular axonal degeneration, perivascular inflammation, inflammation of the blood vessel wall without lumen obstruction) were found in four patients with progressive idiopathic axonal neuropathy, in all patients with vasculitic neuropathy, but were absent in patients with CIAP. The findings show that there is a small chance of finding sural nerve vasculitis upon scrutinising biopsy examination in progressive idiopathic axonal neuropathy. The presence of vasculitis-associated signs in progressive idiopathic axonal neuropathy suggests that some of these patients could have vasculitic neuropathy, even if vasculitic lesions cannot be demonstrated. However, if inflammatory changes cannot be demonstrated this does not preclude an immune-mediated origin.

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“…Cerebrospinal fluid was normal and intraepidermal nerve fiber density was reduced. Steroid treatment was inefficacious ( 18 ).…”

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“…In cases of progressive asymmetric or proximal deficits, nerve biopsy is indicated because vasculitic neuropathy and progressive idiopathic axonal neuropathy cannot be distinguished by clinical examination [21]. In our study half of the patients presented with asymmetric symptoms or signs.…”

“…The criteria for the diagnosis of vasculitis were very strict in our study. If we had taken into account vasculitis-associated signs of ischemic injury or inflammation like large variation in interfascicular axonal content, perivascular inflammation and inflammation of the blood vessel wall without lumen obstruction, more of our samples might have been categorized as vasculitic neuropathies – as this was the case in other studies [19,20,21]. …”

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