The nonsystemic vasculitic neuropathies

Abstract

The vasculitides are a clinically diverse group of diseases with the histopathological signature of blood vessel-centred inflammation that results in vascular damage and ischaemic injury to the affected tissues 1 . Vasculitis can be caused by drugs, infections and cancers, but diagnostic workup reveals no trigger in most patients. Autoimmune mechanisms are active in all vasculitides, except those caused by direct infection of vessel walls. Most vasculitides are systemic and involve multiple organs and tissues. Those affecting small-to medium-sized vessels often manifest with a vasculitic neuropathy. For example, neuropathies occur in 60-70% of patients with polyarteritis nodosa, eosinophilic granulomatosis with polyangiitis and cryoglobulinaemic vasculitis, and 40-50% of those with microscopic polyangiitis and rheumatoid vasculitis 2 .Vasculitic neuropathy can also occur without systemic vasculitis. This single-organ vasculitis of the PNS has commonly been referred to as nonsystemic vasculitic neuropathy (NSVN), but other forms of clinically isolated PNS vasculitis are now recognized and can be considered variants of NSVN 3 . Although NSVN is classically an acute, relapsing, multifocal neuropathy, it can present as a slowly progressive neuropathy without distinct asymmetries. As such, it should be considered as a possible cause of any progressive axonal neur opathy. NSVN can be diagnosed only with a nerve biopsy, with or without a concomitant muscle or skin biopsy; as nerve biopsies are seldom performed, the condition is under-recognized. The disorder must be distinguished from many other causes of multifocal neuropathy, the definition of which is itself not standardized and requires clarification.A Peripheral Nerve Society guideline group reviewed the literature on vasculitic neuropathy and published consensus recommendations on the classification, diagnosis and immunosuppressive treatment of NSVN in 2010 (REF. 4) Abstract | Nonsystemic vasculitic neuropathy (NSVN) is an under-recognized single-organ vasculitis of peripheral nerves that can only be diagnosed with a nerve biopsy. A Peripheral Nerve Society guideline group published consensus recommendations on the classification, diagnosis and treatment of NSVN in 2010, and new diagnostic criteria for vasculitic neuropathy were developed by the Brighton Collaboration in 2015. In this Review, we provide an update on the classification, diagnosis and treatment of NSVN. NSVN subtypes include Wartenberg migratory sensory neuropathy and postsurgical inflammatory neuropathy. Variants include diabetic radiculoplexus neuropathy and -arguably -neuralgic amyotrophy. NSVN with proximal involvement is sometimes termed nondiabetic lumbosacral radiculoplexus neuropathy. Cutaneous polyarteritis nodosa and other skin-nerve vasculitides overlap with NSVN clinically. Three patterns of involvement in NSVN have been identified: multifocal neuropathy, distal symmetric polyneuropathy, and overlapping multifocal neuropathy (asymmetric polyneuropathy). These patterns lack standard defi...

Vasculitic neuropathy: Comparison of clinical predictors with histopathological outcome

“…In terms of other parameters, the mean age of 59.3 years in patients with pathologically confirmed vasculitis in the present series is similar to the mean age reported previously for patients with NSVN . Separately, it is unclear why patients with NSVN were overall younger than the rest of the cohort, and especially when compared to patients with systemic vasculitis.…”

“…When combined with an acute, subacute, or relapsing presentation, vasculitis yield on biopsy becomes more likely . Conversely, the presence of a chronic, symmetric phenotype would argue against the presence of vasculitis as demonstrated in our study …”

“…Another limitation relates to the type of NSVN patient who has prominent proximal involvement, termed radiculoplexus neuropathy (diabetic and nondiabetic). Compared with typical NSVN patients, these patients more frequently exhibit proximal limb weakness, weight loss, and raised CSF protein, and less frequently have necrotizing vasculitis on biopsy . Microvasculitis, when associated with vascular damage, is typically seen in the diabetic radiculoplexus neuropathies .…”

“…Vasculitic neuropathy occurring as part of a primary systemic vasculitis or considered to be secondary to systemic autoimmune conditions, infections, malignancy, and some drugs is termed systemic vasculitic neuropathy. Less common is nonsystemic vasculitic neuropathy (NSVN), where vasculitis is isolated to the peripheral nerves . Vasculitic neuropathy will hereafter be referred to as vasculitis.…”

“…Although considered a routine procedure, there remain 2 key concerns with nerve biopsies: first, the range of complications, such as sensory disturbance, pain, and wound infections; and second, previous studies have estimated the sensitivity of nerve biopsy to establish a diagnosis of vasculitis to be 50%–60% . Even for NSVN (where biopsy is essential to diagnosis), estimated sensitivity remains at 50% with sural nerve biopsy or combined superficial peroneal nerve and peroneus brevis muscle biopsy . Combined muscle–nerve biopsy increases diagnostic yield by only 5.1% …”