Vasculitic Neuropathy and Other Connective Tissue Disorders Associated with Neuropathy: Fibrinoid Necrosis

Vasculitic neuropathies usually manifest with asymmetric nerve involvement, in a stepwise fashion often described as mononeuritis multiplex. They are often painful, in addition to clinically manifesting with signs of focal nerve dysfunction with weakness and sensory loss. In long-standing cases, many patients will appear to have a length-dependent symmetric peripheral neuropathy, if enough nerves are involved so that there is enough overlap for the process to appear diffuse. In systemic processes, fever and weight loss are often accompanying symptoms. In polyarteritis nodosa, there may also be vasculitic involvement of the skin, heart, and kidneys as well as other organ systems. The presence of asthma can be a clue for Churg-Strauss syndrome. Kidney involvement is common in microscopic polyangiitis.

A clinical examination that reveals significant asymmetry of neuropathic findings is a major clue to this diagnosis, as is a clinical history of stepwise involvement of different peripheral nerves, particularly when accompanied by pain. In DLRPN, there is typically lower limb pain and weakness with associated weight loss. Electrophysiologic studies show an asymmetric axonalpredominant neuropathy in most cases, although, as previously discussed, these findings can be symmetric, particularly in long-standing disease. Serologies including connective tissue markers, sedimentation rate, and C-reactive protein are often helpful diagnostically, as well as evidence of clinical involvement of other organ systems. In these cases, biopsy of a clinically affected nerve can be very useful, with findings of axonal degeneration and inflammatory changes, with prominent inflammatory changes involving and disrupting the layers of blood vessel walls. In some cases, necrotizing changes in blood vessel walls are noted, and these cases are referred to as necrotizing vasculitis. Treatment is generally with immunosuppressive agents. Some patients with isolated peripheral nerve microvasculitis are managed with corticosteroids. Patients with evidence of a more systemic condition or necrotizing vasculitis often need stronger degrees of immunosuppression for long-term management.

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