2025 American Academy of Neurology Abstract Website

Objective:

Here we report a case of AAV presenting with unusual concurrent length-dependent axonal polyneuropathy and myositis along with literature review.

Background:

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) induces inflammation of small-to-medium vessels, predominantly affecting the respiratory tract and kidneys. Neurological involvement often manifests as peripheral neuropathy, while muscular involvement is a rare clinical presentation.

Design/Methods:

A woman in her 70s presented with numbness, pain and weakness. She first noticed numbness, pain, and weakness in feet. Symptoms progressed to thighs over several days and she became non-ambulatory. Later she developed numbness, pain, and weakness in hands, alongside achy pain in both thighs and upper arms. Physical examination showed diffuse areflexia, symmetric distal more than proximal weakness as well as glove-stocking distribution sensory loss. Lab was significant for elevated creatine kinase (CK), aldolase, creatinine, and positive anti-myeloperoxidase (MPO) antibodies.

Renal biopsy showed necrotizing arteritis consistent with AAV. The EDX testing confirmed severe length-dependent sensorimotor axonal polyneuropathy with superimposed non-irritable myopathy. Treatment with IVIG and steroids facilitated a gradual improvement in both strength and sensation.

Results:

To our knowledge, this is the first reported AAV case presenting with concurrent myositis and polyneuropathy. There were only eight AAV cases presenting with myopathy reported. Most cases had normal CK (except one). MRI universally showed muscle edema. Seven patients underwent muscle biopsy. Vascular pathology was identified in all, including fibrinoid necrosis in four. Myofiber pathology was uncommon, and only two had necrotic fibers. None presented with coexisting neuropathy.

Conclusions:

AAV could present with neuromyopathy and could have favorable response to IVIG, steroid and Rituximab.