Vasculitic neuropathies

Numb Chin Syndrome in Sickle Cell Disease: A Systematic Review and Recommendations for Investigation and Management

Numb chin syndrome (NCS) is a rare sensory neuropathy resulting from inferior alveolar or mental nerve injury. It manifests as hypoesthesia, paraesthesia, or, rarely, as pain in the chin and lower lip. Several case reports suggest that sickle cell disease (SCD) could be a cause of NCS. However, information about NCS is scarce in this population. Our objectives were to synthesize all the available literature relevant to NCS in SCD and to propose recommendations for diagnosis and management based on the best available evidence. A systematic review was performed on several databases to identify all relevant publications on NCS in adults and children with SCD. We identified 73 publications; fourteen reports met the inclusion/exclusion criteria. These described 33 unique patients. Most episodes of NCS occurred in the context of typical veno-occlusive crises that involved the mandibular area. Radiological signs of bone infarction were found on some imaging, but not all. Neuropathy management was mostly directed toward the underlying cause. Overall, these observations suggest that vaso-occlusion and bone infarction could be important pathophysiological mechanisms of NCS. However, depending on the individual context, we recommend a careful evaluation to rule out differential causes, including infections, local tumors, metastatic disease, and stroke.

Polyarteritis Nodosa Neurologic Manifestations

Polyarteritis nodosa (PAN) is a necrotizing vasculitis affecting medium-sized vessels whose main manifestations are weight loss, fever, peripheral neuropathy, renal, musculoskeletal, gastrointestinal tract and/or cutaneous involvement(s), hypertension and/or cardiac failure. Peripheral neuropathy is one of the most frequent and earliest symptoms, affecting 50% to 75% of PAN patients. Central nervous system involvement affects only 2% to 10% of PAN patients, often late during the disease course. Treatment relies on combining corticosteroids and an immunosuppressant (mainly cyclophosphamide) in patients with poor prognoses. In patients with hepatitis B virus-related PAN, plasma exchanges and antiviral drugs should be combined with corticosteroids.

Treatment of Hepatitis B related Polyarteritis Nodosa presenting with mononeuritis multiplex

We describe the case of a male patient who presented with mononeuritis multiplex due to polyarteritis nodosa following recent hepatitis B infection. Despite immunomodulatory treatment, the condition progressed with renal and small bowel involvement and the patient died. This case illustrates the difficulty in treating this multisystem disorder and we review the literature on its pathogenesis and treatment.

Vasculitic neuropathy in elderly: A study from a tertiary care university hospital in South India

Objective:

To describe clinical, electrophysiological, and histopathological profile of vasculitic neuropathy in elderly subjects aged 65 years or more.

Design:

Retrospective chart review.

Setting:

Departments of Neurology and Neuropathology, National Institute of Mental Health and Neurosciences, Bengaluru, Karnataka, India.

Patients and Methods:

Elderly subjects, diagnosed vasculitic neuropathy by nerve biopsy over one decade, were studied.

Results:

The cohort consisted of 46 subjects. Symptom duration was 21.54 ± 33.53 months. Onset was chronic in majority (82.6%). Key features included paresthesias (89%), weakness (80%), sensory loss (70%), wasting (63%), and relapsing-remitting course (6.5%). Most Common clinico-electrophysiological patterns were distal symmetrical sensorimotor polyneuropathy - 19, mononeuritis multiplex - 9, and asymmetric sensorimotor neuropathy - 10. Diagnosis of vasculitis was not suspected before biopsy in 31 (67.3%). Nerve biopsy revealed definite vasculitis - 12, probable - 10, and possible - 24. Treatment included immunomodulatory agents (41), symptomatic medications only (9), and antiretroviral therapy (1). Twenty-four patients were followed up for mean period of 6.5 months. Outcome at last follow-up was improved (13), unchanged (8), and worsened (3).

Conclusion:

Vasculitis is an important, treatable cause of neuropathy in elderly. Nerve biopsy should be used judiciously for early diagnosis and appropriate treatment.

Clinical Neuropathology practice guide 3-2014: combined nerve and muscle biopsy in the diagnostic workup of neuropathy - the Bordeaux experience

Simultaneous combined superficial peroneal nerve and peroneous brevis muscle biopsy, via the same cutaneous incision, allows examination of several tissue specimens and significantly improves the diagnosis of systemic diseases with peripheral nerve involvement. Vasculitides are certainly the most frequently diagnosed on neuro-muscular biopsies, but this procedure is also well advised to asses a diagnosis of sarcoidosis or amyloidosis. More occasionally, combined nerve and muscle biopsy may reveal an unpredicted diagnosis of cholesterol embolism, intra-vascular lymphoma, or enables complementary diagnosis investigations on mitochondrial cytopathy or storage disease.

Differential gene expression in nerve biopsies of inflammatory neuropathies

DNA microarray analysis is a powerful tool for simultaneous analysis and comparison of gene products expressed in normal and diseased tissues. We used this technique to identify differentially expressed genes (DEGs) in nerve biopsy samples of chronic inflammatory demyelinating polyneuropathy (CIDP) and vasculitic neuropathy (VAS) patients. We found novel previously uncharacterized genes of relevance to CIDP or VAS pathogenesis. Of particular interest in CIDP were tachykinin precursor 1, which may be involved in pain mediation, stearoyl-co-enzyme A (CoA) desaturase, which may be a marker for remyelination, HLA-DQB1, CD69, an early T-cell activation gene, MSR1, a macrophage scavenger receptor, and PDZ and LIM domain 5 (PDLIM5), a factor regulating nuclear factor (NF)-kappa B activity. Genes upregulated in VAS included IGLJ3, IGHG3, IGKC, and IGL, which all function in B-cell selection or antigen recognition of B cells. Other upregulated genes included chemokines, such as CXCL9 and CCR2, as well as CPA3, a mast cell carboxypeptidase. Allograft inflammatory factor-1 (AIF-1), a modulator of immune response was upregulated both in CIDP and VAS. Microarray-based analysis of human sural nerve biopsies showed distinct gene expression patterns in CIDP and VAS. DEGs might provide clues to the pathogenesis of the diseases and be potential targets for therapeutics.

Homeostatic regulation of the endoneurial microenvironment during development, aging and in response to trauma, disease and toxic insult

The endoneurial microenvironment, delimited by the endothelium of endoneurial vessels and a multi-layered ensheathing perineurium, is a specialized milieu intérieur within which axons, associated Schwann cells and other resident cells of peripheral nerves function. The endothelium and perineurium restricts as well as regulates exchange of material between the endoneurial microenvironment and the surrounding extracellular space and thus is more appropriately described as a blood-nerve interface (BNI) rather than a blood-nerve barrier (BNB). Input to and output from the endoneurial microenvironment occurs via blood-nerve exchange and convective endoneurial fluid flow driven by a proximo-distal hydrostatic pressure gradient. The independent regulation of the endothelial and perineurial components of the BNI during development, aging and in response to trauma is consistent with homeostatic regulation of the endoneurial microenvironment. Pathophysiological alterations of the endoneurium in experimental allergic neuritis (EAN), and diabetic and lead neuropathy are considered to be perturbations of endoneurial homeostasis. The interactions of Schwann cells, axons, macrophages, and mast cells via cell-cell and cell-matrix signaling regulate the permeability of this interface. A greater knowledge of the dynamic nature of tight junctions and the factors that induce and/or modulate these key elements of the BNI will increase our understanding of peripheral nerve disorders as well as stimulate the development of therapeutic strategies to treat these disorders.

The blood-nerve barrier: structure and functional significance

The blood-nerve barrier (BNB) defines the physiological space within which the axons, Schwann cells, and other associated cells of a peripheral nerve function. The BNB consists of the endoneurial microvessels within the nerve fascicle and the investing perineurium. The restricted permeability of these two barriers protects the endoneurial microenvironment from drastic concentration changes in the vascular and other extracellular spaces. It is postulated that endoneurial homeostatic mechanisms regulate the milieu intérieur of peripheral axons and associated Schwann cells. These mechanisms are discussed in relation to nerve development, Wallerian degeneration and nerve regeneration, and lead neuropathy. Finally, the putative factors responsible for the cellular and molecular control of BNB permeability are discussed. Given the dynamic nature of the regulation of the permeability of the perineurium and endoneurial capillaries, it is suggested that the term blood-nerve interface (BNI) better reflects the functional significance of these structures in the maintenance of homeostasis within the endoneurial microenvironment.

The laterality index in the evaluation of distal sensorimotor neuropathy

OBJECTIVE

Electrodiagnostic evaluation of distal sensorimotor neuropathy can be technically challenging. Conventional nerve conduction studies (NCS) often include unilateral upper and lower limb evaluation for patients with suspected sensorimotor peripheral neuropathy. For patients with predominantly lower extremity complaints, NCS of both lower limbs are performed occasionally. Side-to-side NCS parameters have not been adequately addressed.

METHODS

We performed NCS prospectively on 132 patients presenting with complaints of bilateral numbness or weakness in the extremities and 45 normal controls. The laterality index (LI) was defined as ratio of the smaller to the larger amplitude in a sensory or motor NCS, as a novel side-to-side comparison parameter.

RESULTS

Ten patients had at least 1 sensory or motor NCS with LIs exceeding that of normal controls. Patients 1-7 (group 1) had diagnoses of autoimmune or neoplasia-related conditions and all had 3 or more NCS with abnormal LIs. In contrast, patients 8-10 (group 2) had diabetes mellitus and all had 2 or less NCS with abnormal LIs (unpaired t test; P = 0.002). In group 1, patients 1-4, 6, and 7 all had both upper and lower limb LI abnormalities. In contrast, only 1 patient (patient 9) had upper limb LI abnormality in group 2.

CONCLUSIONS

Patients with abnormal LIs were uncommon in our cohort. Patients with diabetes mellitus had significantly less abnormal LIs than those with autoimmune or neoplasia-related etiologies. There is evidence of vasculitic inflammation documented in diabetic neuropathy. However, this process may be significantly less prominent compared with the former 2 conditions. Our findings of predominantly lower limb LI abnormalities suggest the presence of a length-dependent distal neuropathic process in diabetes mellitus. The LI is a simple and useful adjunct to detect asymmetrical NCS abnormalities. It may also provide helpful information regarding the underlying etiology.

Peripheral nerve vasculitis presenting as complex regional pain syndrome

OBJECTIVE

To report the clinical, electrodiagnostic, and pathologic findings in 3 patients who presented with complex regional pain syndrome as their primary manifestation of peripheral nerve vasculitis.

DESIGN

Case series.

SETTING

Outpatient clinic in a tertiary care academic medical center.

PATIENTS

Patient 1 was a 39-year-old woman with a 9-year history of non-length-dependent severe burning pain and swelling in her extremities. Patient 2 was a 67-year-old man with a 2-year history of severe burning pain and swelling in an extremity after a fall. Patient 3 was a 74-year-old man with a 6-month history of severe allodynic pain and atrophy of the right hand after a viral illness

RESULTS

In all 3 cases, clinical and electrodiagnostic testing were suggestive of multiple mononeuropathies. Nerve biopsy either confirmed vasculitis (patient 1) or was suggestive of angiopathy (patients 2 and 3). Immunomodulative therapy led to marked clinical improvement in all 3 cases.

CONCLUSIONS

To our knowledge, this is the first report demonstrating that the inflammatory nerve injury seen with peripheral nerve vasculitis can result in complex regional pain syndrome. Clinical and electrodiagnostic assessments can help in the identification and management of these patients.

Surgical treatment of superimposed nerve compressions in hepatitis C neuropathy

The plastic surgeon's usual involvement in patients with hepatitis C is most frequently limited to an inner city population with hand and forearm abscesses from intravenous drug use or to incidences of needle-stick injury in the operating room when the patient is hepatitis C positive. Hand surgeons and peripheral nerve surgeons often treat patients with underlying neuropathies who have superimposed overlying nerve compressions such as carpal tunnel syndrome. We have applied this experience to a patient with underlying peripheral neuropathy associated with Hepatitis C and clinical evidence of overlying lower extremity nerve compressions. We believe that she is the first successful surgical treatment of peripheral nerve compressions in a patient with hepatitis C-associated neuropathy, documented by noninvasive neurosensory testing.

Vasculitic Neuropathies

BACKGROUND

Systemic vasculitis has been classically categorized as a primary disorder, such as polyarteritis nodosa, Churg-Strauss syndrome, and Wegener granulomatous, or as a secondary process, representing a complication from a connective tissue disorder (eg, rheumatoid vasculitis), infection, medication, or malignancy. Peripheral neuropathy is a well-recognized consequence of systemic vasculitis due to peripheral nerve infarction with Wallerian degeneration. Rarely, neuropathy is the sole manifestation of vasculitis, referred to as nonsystemic vasculitic neuropathy (NSVN). These conditions are defined pathologically by tissue biopsy demonstrating disruption or destruction of the vessel wall with inflammatory cell infiltrates.

REVIEW SUMMARY

The diagnosis of vasculitic neuropathy is straightforward in patients with an established diagnosis of systemic vasculitis and classic features of mononeuritis multiplex. Most patients have clinical features of a subacute, progressive, generalized but asymmetric, painful, sensorimotor polyneuropathy. Laboratory tests often indicate features of systemic inflammation, such as an elevated sedimentation rate or positive anti-neutrophil cytoplasmic antibody, and electrodiagnostic evaluation shows multiple mononeuropathies or a confluent, asymmetric axonal neuropathy. Nerve biopsy is necessary to establish the diagnosis in most cases, particularly in patients with NSVN. This review summarizes the current treatment of vasculitic neuropathy.

CONCLUSION

Long-term immunosuppressive therapy is required in most cases. High-dose prednisone combined with intravenous pulse or oral daily cyclophosphamide is standard initial therapy. In those with NSVN, cyclophosphamide also should be used if prednisone monotherapy is ineffective or the patient relapses with tapering. Other agents, such as azathioprine, methotrexate, intravenous immunoglobulin, mycophenolate mofetil, plasma exchange, and rituximab can be offered to patients who are intolerant or have a contraindication to cyclophosphamide. However, evidence for the benefit of these agents is limited to case reports and small case series.

[Neuromuscular biopsy and diagnosis of vasculitis]

One characteristic histological lesion on biopsy specimens is mandatory to establish the diagnosis of vasculitis. Combined nerve and muscle biopsies, by the same cutaneous incision, improve significantly the percentage of positive results. Nerve fragments should be taken in every patient presenting sensory manifestations. Such vasculitic lesions are present in medium-sized arterioles and/or small vessels, and correspond mainly to 4 necrotizing vasculitis: panarteritis nodosa (PAN), microscopic polyangiitis (MPA), Churg and Strauss syndrome and Wegener granulomatosis. Microvasculitis should be added to these classical entities, because it corresponds to small vessel wall infiltration by inflammatory cells, as observed in PAN and MPA, but without any necrosis. Microvasculitis has to be differentiated from the inflammatory cell infiltrates surrounding small vessels. However, such perivascular inflammatory cell infiltrates enable the diagnosis of probable vasculitis when associated with clusters of neo-vessels, hemosiderin deposits, or a focal damage of nerve fibers. Grossly, one third of vasculitis diagnosis is confirmed on muscle fragments, a second third on nerve fragments, and the last third on both nerve and muscle fragments. Moreover, in the search for vasculitis, an unpredicted diagnosis of lymphoma or amyloidosis is occasionally established on the neuro-muscular biopsy.

Multiplex neuritis in a patient with autoimmune hepatitis: A case report

A 37-year old woman presented with a 9-year history of hepatitis of unknown origin and aminotransferases within a 3-fold upper limit of normal. Autoimmune hepatitis (AIH) was diagnosed on the basis of elevated aminotransferases, soluble liver antigen/liver pancreas (SLA/LP) autoantibodies and characteristic histology. Immunosuppressive therapy led to rapid normalization of aminotransferases. Two years later, the patient developed left sided hemisensory deficits under maintenance therapy of prednisolone and azathioprine (AZT). Later she developed right foot drop and paraesthesia in the ulnar innervation territory on both sides. Magnetic resonance imaging (MRI) and cerebral panangiography suggested cerebral vasculitis. Neurological investigation and electromyography disclosed multiplex neuritis (MN) probably due to vasculitis. Consistent with this diagnosis, autoantibodies to extractable nuclear antigens were detectable in serum. Immunosuppression was changed to oral 150 mg cyclophosphamide (CPM0) per day. Prednisolone was increased to 40 mg/d and then gradually tapered to 5 mg. Oral CPM was administered up to a total dose of 40 g and then substituted by 6 times of an intervall infusion therapy of CPM (600 mg/m²). Almost complete motoric remission was achieved after 3 mo of CPM. Sensibility remained reduced in the right peroneal innervation territory. Follow-up of cranial MRI provided stable findings without any new or progressive lesions. This is the first report of multiplex neuritis in a patient with autoimmune hepatitis.

Combined nerve and muscle biopsy in the diagnosis of vasculitic neuropathy. A 16-year retrospective study of 202 cases

We reviewed 202 biopsies performed on patients with suspected vasculitic neuropathy, of which 24 Churg-Strauss cases are studied separately. Specimens from the superficial peroneal nerve and peroneus brevis muscle were taken simultaneously by one incision. Without taking into account constitutional signs, systemic involvement was present in 131 patients, whereas the remaining 47 corresponded to non-systemic patients with lesions limited to peripheral nervous system and adjoining muscles. Diagnosis of panarteritis nodosa or microscopic polyangiitis, according to the size of involved vessels, was attested by an infiltration of vessel walls by inflammatory cells associated with fibrinoid necrosis or sclerosis. Microvasculitis was diagnosed when inflammatory infiltration concerned small vessels with few or no smooth-muscle fibers and without any necrosis. Microvasculitis was present in 11 of 46 non-systemic cases, and this predominance is statistically significant. Isolated perivascular cell infiltrates in the epineurium were considered not significant but allowed the diagnosis of 'probable vasculitis' if associated with at least one of the following features: regenerating small vessels, endoneurial purpura, asymmetric nerve fiber loss, and/or asymmetric acute axonal degeneration. Necrotizing vasculitis was visible in 60 cases: in nerve (16 cases), in muscle (19 cases), and both (25 cases). Microvasculitis was present in 25 cases: in nerve (19 cases), muscle (four cases), or both (two cases). Moreover, granulomatous vasculitis was found in the nerve of one non-systemic patient presenting also sarcoid granulomas in muscle. There were 24 'probable vasculitis' and 68 negative cases. Muscle biopsy improved the yield of definite vasculitis by 27%.

Neuro-muscular biopsy in Churg-Strauss syndrome: 24 cases

Churg-Strauss syndrome (CSS) is a distinctive clinical entity in which systemic vasculitis, associated with eosinophilia, occurs almost exclusively in individuals with adult-onset asthma. The major complications of the condition result from damage to the lungs, heart, and peripheral nerves. Necrotizing vasculitis with eosinophils in the cellular infiltrate, vascular or perivascular infiltration by eosinophils in absence of vessel wall necrosis, extra-vascular eosinophil infiltrates, and vascular or extra-vascular granuloma are histopathological features supportive of CSS. As the peripheral nerve disease often dominates the clinical picture, the peripheral nerve biopsy may be decisive in establishing the diagnosis. In this retrospective study of neuro-muscular biopsies in 24 CSS cases, the authors give an extensive description of neuropathological lesions associated with this disorder. Fifteen patients (62.5%) exhibited eosinophils either in extra-vascular infiltrates or in vessel walls, and 6 of them (25%) had an associated necrotizing vasculitis. Granulomas were found in only 3 cases (12.5%). The clinical diagnosis of CSS was supported in 15 out of the 24 patients (62.5%), in the nerve in 2 cases (8.3%), in the muscle in 8 cases (33.3%), and in both nerve and muscle in 5 others (20.8%).

Therapy for vasculitic neuropathies

The term vasculitis refers to a pathologic condition defined by inflammatory cell infiltration and destruction of blood vessels. Systemic vasculitis is classified as primary (eg, polyarteritis nodosa, Churg-Strauss syndrome) or secondary, the latter associated with connective tissue disorders, infections, medications, and rarely, as a paraneoplastic phenomenon. Neuropathy is a common complication of systemic vasculitis and is related to ischemic nerve fiber damage with axon loss. Peripheral neuropathy may be the sole manifestation of vasculitis, a condition termed nonsystemic vasculitic neuropathy (NSVN). Treatment of vasculitic neuropathy requires long-term immunosuppressive therapies with potential side effects. The diagnosis of vasculitis should be established by tissue (preferably nerve) biopsy. High-dose prednisone is the standard platform therapy for patients with systemic and NSVN; for those with systemic vasculitis, at least 3 to 12 months of treatment with cyclophosphamide (monthly intravenous pulse or daily oral therapy) is also necessary to sustain remission and allow successful prednisone tapering. The use of cyclophosphamide in patients with NSVN is controversial, but recent retrospective data suggest that those treated with prednisone and cyclophosphamide from the outset fare better than those initially treated only with prednisone. If prednisone is administered as monotherapy, cyclophosphamide should be added after several months if there is no improvement or relapse occurs with tapering of prednisone. Intravenous pulse and daily oral cyclophosphamide probably offer similar efficacy, although the risk of complications is greater with oral therapy. Azathioprine can be safely substituted for cyclophosphamide after 3 months without an increased relapse rate. Azathioprine, methotrexate, intravenous immune globulin, mycophenolate mofetil, plasma exchange, and rituximab can be offered to patients who are intolerant or have a contraindication to cyclophosphamide. However, efficacy is unproven for any of these therapies. Interferon-alpha, sometimes combined with plasma exchange, is used to treat vasculitis associated with hepatitis B infection. Some patients also may improve with corticosteroids. The classification of diabetic lumbosacral radiculoplexus neuropathy as a vasculitic disorder remains controversial. However, there is compelling pathological evidence that this condition represents a T-cell-mediated microvasculitis. Some patients treated with intravenous corticosteroids may have greater recovery and improved pain control.

Non-systemic vasculitic neuropathy

PURPOSE OF REVIEW

This article reviews the literature on non-systemic vasculitic neuropathy, with emphasis on recent advances, summarizing the clinical presentation, diagnosis, pathology, treatment, and outcome of this condition, and speculating on its nosological status vis-à-vis the systemic vasculitides.

RECENT FINDINGS

A new cohort of non-systemic vasculitic neuropathy patients was recently reported. Analysis of the clinical characteristics of this cohort demonstrated a higher incidence of painful, asymmetric, overlapping deficits than in previous studies. Extended follow-up revealed a high relapse rate, low risk of systemic spread, high incidence of chronic pain, relatively good neurological outcome, and low mortality rate. Analysis of therapeutic responses showed better outcomes with combination therapy than corticosteroid monotherapy. Another recent report proposed a role for magnetic resonance angiography in the diagnosis and follow-up of non-systemic vasculitic neuropathy. Recent pathological studies implicated proinflammatory cytokines and matrix metalloproteinase-9 in the mediation of vascular and axonal damage in non-systemic vasculitic neuropathy.

SUMMARY

Non-systemic vasculitic neuropathy is one of many localized vasculitides, with involvement restricted to nerves and (possibly) muscles. Inclusion and exclusion criteria differ between reported cohorts. All require a nerve biopsy diagnostic of or suspicious for vasculitis and no extra-neuromuscular involvement. Patients typically present subacutely with a painful, multifocal/asymmetric, distal-predominant neuropathy. In the absence of clinical or laboratory evidence of systemic vasculitis or a condition predisposing to such, prognosis with treatment is good. Pathological data are supportive of a primary T-cell-mediated immunopathogenesis. Some patients classified as having non-systemic vasculitic neuropathy have a systemic vasculitis presenting with neuropathy; in others, the disease is organ-specific.

Response of Vasculitic Peripheral Neuropathy to Intravenous Immunoglobulin

Peripheral neuropathy is a prominent feature of the systemic and secondary vasculitides. Usually, it responds to corticosteroids therapy, but in certain cases it may resist corticosteroid or immunosuppressive treatment, or both. The objective of this study is to present case reports of patients who exhibited various inflammatory diseases, accompanied with vasculitic peripheral neuropathies, for which intravenous immunoglobulin (IVIg) was used for treatment. The study included 10 patients with the following: Sjögren's syndrome (1), systemic lupus erythematosus (2), vaccination-induced vasculitis (1), Churg-Strauss vasculitis (1), mixed cryoglobulinemia (2), polyarteritis nodosa (1), sarcoidosis (1), and scleroderma (1). All developed vasculitic peripheral neuropathy and were treated with 1-13 cycles of high-dose IVIg (2 g/kg body weight). The patients were followed up for 1-5 years after this treatment. Results showed that in all but two patients (mixed cryoglobulinemia associated with hepatitis C and sarcoidosis), neuropathy improved or completely resolved after IVIg treatment. In conclusion, IVIg may be beneficial in cases of resistant vasculitic peripheral neuropathy. IVIg should probably be considered as a sole or adjuvant treatment in patients for whom conventional treatment is contraindicated, or for patients in whom conventional treatment has failed.

Peripheral neuropathy in systemic vasculitides

PURPOSE OF REVIEW

Peripheral nervous system (PNS) involvement is of great diagnostic value in systemic vasculitides, because it occurs frequently and often early during the course of these diseases, despite the supposed blood-nerve barrier that should prevent or at least minimize PNS damage. However, it carries no poor prognostic value in vasculitides. Recent advances have been made in understanding the pathogenetic mechanisms of PNS involvement.

RECENT FINDINGS

Vasculitic neuropathy may result from primary or secondary systemic vasculitides, or may be restricted to the PNS, in a form that is now also considered to be a systemic vasculitis. The blood-nerve barrier is not as efficient as the blood-brain barrier. Inflammatory cell infiltration into the vasa nervorum and epineurial arteries leads to ischemic axonal nerve injury and is facilitated by additional breaches in the blood-nerve barrier, induced by proinflammatory cytokines, oxidative stress-derived molecules, and matrix metalloproteinases. Although animal models of myeloperoxidase or, now, proteinase 3-antineutrophil cytoplasmic autoantibody-inducing vasculitis have been developed, they do not support a role for antineutrophil cytoplasmic autoantibodies in PNS involvement. Treatment should be chosen based on the other organ involvement and the patient's general condition. When PNS involvement is isolated, corticosteroids alone should be used as first-line treatment.

SUMMARY

Apart from the so-called nonsystemic nerve vasculitis, PNS involvement is rarely the sole clinical sign of systemic necrotizing vasculitis, and its association with other typical manifestations is often suggestive of the diagnosis of vasculitis. Herein are summarized recent advances that have clarified but not yet fully elucidated the pathogenesis of peripheral neuropathy in systemic vasculitides, together with the latest clinical findings and therapeutic strategies.

Vasculitis in systemic lupus erythematosis

Vasculitis in connective tissue diseases is not an uncommon complication. Vasculitis complicates both rheumatoid arthritis and systemic lupus erythematosis (SLE) in about 4% of cases. Cutaneous lesions, representing small-vessel involvement, are most common; however, widespread, necrotizing visceral medium-and large-vessel involvement, mimicking primary vasculitic syndromes, may also occur. Connective tissue disease-associated vasculitis is separated from primary vasculitis syndromes in classification schemes. Granulomatous large-vessel disease does not occur in connective tissue diseases, suggesting a different pathogenesis. In most disorders, the etiology of vascular inflammation in not completely understood, but basic pathogenic mechanisms can often be distinguished. The role of immune complexes in the inflammatory manifestations of SLE is recognized, and other pathogenic factors such as antineutrophil cytoplasmic antibodies, common in other vasculitides, are infrequent. A diverse spectrum of clinical features, due to inflammatory involvement of arterial and venous vessels of all sizes, characterize several connective tissue diseases including Behçet's disease and SLE. The recognition of disease manifestations due to vasculitis in these disorders has important implications for treatment and may be critical to reduce morbidity and mortality.

Advances in understanding and treatment of immune-mediated disorders of the peripheral nervous system

During recent years, novel insights in basic immunology and advances in biotechnology have contributed to an increased understanding of the pathogenetic mechanisms of immune-mediated disorders of the peripheral nervous system. This increased knowledge has an impact on the management of patients with this class of disorders. Current advances are outlined and their implication for therapeutic approaches addressed. As a prototypic immune-mediated neuropathy, special emphasis is placed on the pathogenesis and treatment of the Guillain-Barré syndrome and its variants. Moreover, neuropathies of the chronic inflammatory demyelinating, multifocal motor, and nonsystemic vasculitic types are discussed. This review summarizes recent progress with currently available therapies and--on the basis of present immunopathogenetic concepts--outlines future treatment strategies.