Vasculitic Neuropathies

Vasculitic neuropathies are disorders that result from inflammation in the peripheral nerves' vascular supply, resulting in ischemic injury. These disorders may be a result of systemic inflammation or may be confined to the peripheral nervous system. Causative etiologies include primary systemic vasculitis, vasculitis secondary to other conditions such as primary connective tissue disorders, infectious, paraneoplastic, and drug-induced conditions, and nonsystemic vasculitic neuropathy. Early recognition and treatment of these conditions is imperative to prevent substantial morbidity and mortality. The goal of this review is to provide an organization of the vasculitic neuropathies and an overview of principles of diagnosis and treatment for the clinical neurologist.

Case 27

Mononeuropathy multiplex is a disorder which distinguishes itself from peripheral polyneuropathy by involvement of specific individual peripheral nerves. Mononeuropathy multiplex is often asymmetrical and is classified, based on electrophysiologic and pathologic findings, into axonal and demyelinating types. Mononeuritis multiplex is a term that is used exclusively for cases of axonal multiple mononeuropathies due to peripheral nerve vasculitis. This may be associated with connective tissue disease or hepatitis B and C infection. This case outlines the clinical and electrophysiological findings in mononeuritis multiplex and discusses the differential diagnosis of systemic and nonsystemic vasculitic neuropathy. The causes and pathological findings that characterize vasculitic neuropathy are highlighted.

Distinct pathogenesis in nonsystemic vasculitic neuropathy and microscopic polyangiitis

Objective:To investigate the mechanisms of vasculitis in nonsystemic vasculitic neuropathy (NSVN) and microscopic polyangiitis (MPA), focusing on complement- and antineutrophil cytoplasmic antibody (ANCA)-associated pathogenesis.Methods:Sural nerve biopsy specimens taken from twenty-four patients with NSVN and 37 with MPA-associated neuropathy (MPAN) were examined. Twenty-two patients in the MPAN group tested positive for ANCA.Results:Immunostaining for complement component C3d deposition showed more frequent positive staining of epineurial small vessels in NSVN than in MPAN (p = 0.002). The percentages of C3d-positive blood vessels were higher in the NSVN group than those in the ANCA-positive MPAN and ANCA-negative MPAN groups (p = 0.002 and p = 0.009, respectively). Attachment of neutrophils to the endothelial cells of epineurial small vessels was frequently observed in the MPAN groups, irrespective of the presence or absence of ANCA, but was scarce in the NSVN group. Immunohistochemistry using antimyeloperoxidase (MPO) antibodies revealed that the number of MPO-positive cells attached to the endothelial cells of epineurial vessels was lower in the NSVN group than that in the ANCA-positive MPAN and ANCA-negative MPAN groups (p < 0.001 and p = 0.011, respectively).Conclusions:NSVN and MPA have distinct mechanisms of vasculitis. In MPA, the attachment of neutrophils to vascular endothelial cells seems to be an initial lesion of vasculitis, regardless of the presence or absence of ANCA. Complement participated in the pathogenesis of vasculitis in NSVN.

Nerve Ultrasound as a Decisive Tool in Nonsystemic Vasculitic Neuropathy: A Case Report

Introduction: The additional value of peripheral nerve ultrasound in acquired immune-mediated neuropathies has recently been reported. Its impact in vasculitic neuropathy is yet to be defined. We report electrophysiological and nerve ultrasound studies in a patient with nonsystemic vasculitic neuropathy at first diagnosis and in response to immunosuppression. Case Report: A 44-year-old female presented with painful neuropathy and weakness of the intrinsic hand muscles. Electrodiagnostic studies revealed severe axonal neuropathy of the nerves of the left arm. On nerve ultrasound, massive and patchy swelling of these nerves was detected. Clinical, laboratory, and radiological evidence of nonneuromuscular involvement and systemic vasculitic diseases was absent. Hence, nonsystemic vasculitic neuropathy was diagnosed without the possibility of histological verification. After 6 months of systemic immunosuppression with steroids and cyclophosphamide, clinical symptoms improved in parallel with neurosonography. In contrast, electrophysiological studies remained pathological despite clinical improvement. Conclusions: Neurosonography studies in nonsystemic vasculitic neuropathy are rare but might be an ancillary technique to guide noninvasive diagnosis and therapeutic monitoring. Morphological analysis of nerves and changes in response to treatment could be well visualized. Additionally, neurosonography might be useful to target nerve biopsy.