Polyarteritis nodosa and peripheral neuropathy. Ultrastructural study of 13 cases

Enlarging Ventriculus Terminalis in a Patient With Polyarteritis Nodosa

Ventriculus terminalis (VT) is a cystic embryological remnant within the conus medullaris that normally regresses after birth. In rare cases, it may persist into adulthood and give rise to neurologic symptoms. The pathogenesis remains unclear but is thought to be related to failed embryonic regression with other proposed possible etiologies including vascular disturbances. We present an intriguing case of a slow-growing VT in a woman with progressive neurologic symptoms who experiences symptomatic relief following thoracic laminectomy and fenestration. Our case is the first to present a unique association with polyarteritis nodosa and only the third to report a case of documented enlargement of the VT over time successfully treated with surgical fenestration.

Mitochondria and peripheral neuropathies

There has been considerable progress during the past 24 years in the molecular genetics of mitochondrial DNA and related nuclear DNA mutations, and more than 100 nerve biopsies from hereditary neuropathies related to mitochondrial cytopathy have been accurately examined. Neuropathies were first reported in diseases related to point mutations of mitochondrial DNA, but they proved to be a prominent feature of the phenotype in mitochondrial disorders caused by defects in nuclear DNA, particularly in 3 genes: polymerase gamma 1 (POLG1), mitofusin 2 (MFN2), and ganglioside-induced differentiation-associated protein 1 (GDAP1). Most patients have sensory-motor neuropathy, sometimes associated with ophthalmoplegia, ataxia, seizures, parkinsonism, myopathy, or visceral disorders. Some cases are caused by consanguinity, but most are sporadic with various phenotypes mimicking a wide range of other etiologies. Histochemistry on muscle biopsy, as well as identification of crystalloid inclusions at electron microscopy, may provide a diagnostic clue to mitochondriopathy, but nerve biopsy is often less informative. Nevertheless, enlarged mitochondria containing distorted or amputated cristae are highly suggestive, particularly when located in the Schwann cell cytoplasm. Also noticeable are clusters of regenerating myelinated fibers surrounded by concentric Schwann cell processes, and such onion bulb-like formations are frequently observed in neuropathies caused by GDAP1 mutations.

[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.

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%).

Skin denervation and cutaneous vasculitis in systemic lupus erythematosus

To understand the clinical significance and mechanisms of cutaneous denervation in systemic lupus erythematosus (SLE), we assessed intraepidermal nerve fibre (IENF) density of the distal leg in 45 SLE patients (4 males and 41 females, aged 38.4 +/- 13.6 years) and analysed its correlations with pathology, lupus activity, sensory thresholds and electrophysiological parameters. Compared with age- and gender-matched control subjects, SLE patients had lower IENF densities (3.08 +/- 2.17 versus 11.27 +/- 3.96 fibres/mm, P < 0.0001); IENF densities were reduced in 38 patients (82.2%). Pathologically, 11 patients (24.4%) were found to have definite cutaneous vasculitis; the severity and extent of cutaneous vasculitis were correlated with IENF densities. Patients with active lupus had even lower IENF densities than those with quiescent lupus (1.86 +/- 1.37 versus 4.15 +/- 2.20 fibres/mm, P = 0.0002). By linear regression analysis, IENF densities were negatively correlated with the SLE disease activity index (r = 0.527, P = 0.0002) and cumulative episodes of lupus flare-up within 2 years before the skin biopsy (r = 0.616, P = 0.0014). Clinically, skin denervation was present not only in the patients with sensory neuropathy but also in the patients with neuropsychiatric syndrome involving the CNS. SLE patients had significantly elevated warm threshold temperatures (P = 0.003) and reduced cold threshold temperatures (P = 0.048); elevated warm threshold temperatures were associated with the reduced IENF densities (P = 0.032). In conclusion, cutaneous vasculitis and lupus activities underlie skin denervation with associated elevation of thermal thresholds as a major manifestation of sensory nerve injury in SLE.

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.

Modifications des neurofilaments et des microtubules axonaux en fonction du mécanisme lésionnel : étude pathologique et expérimentale

INTRODUCTION

The consequences of axonal or demyelinating injuries on the axonal cytoskeleton have rarely been described.

METHODS

We have compared the density of fibers labeled by anti-neurofilaments (NF) and -beta tubulin (TUB) to the density of total fibers in nine patients with axonal neuropathies of undetermined etiology (AUE), six with necrotizing angeitis with neuropathy (NAN), seven with chronic inflammatory demyelinating neuropathy (CIDP) and in five controls, as well as in six patients with chronic multiple sclerosis (MS). We also studied demyelinated rat corpus callosum after lysophosphatidyl (LPC) microinjection.

RESULTS

In AUE and NAN NF positive fibers decreased together with total fiber density, whereas TUB increased. In demyelinating lesions TUB was not altered (CIDP) or strongly decreased (MS, LPC); NF were strongly reduced in MS (where axon loss was prominent) and in LPC lesions (despite the lack of fiber degeneration) and for fiber densities<3900/mm2 in CIDP.

CONCLUSION

The initial mechanism of a disease, either axonal degeneration or demyelination, could result into a specific pattern of axonal cytoskeleton alterations.

Clinicopathological features of Churg-Strauss syndrome-associated neuropathy

We assessed the clinicopathological features of 28 patients with peripheral neuropathy associated with Churg-Strauss syndrome. Initial symptoms attributable to neuropathy were acute painful dysaesthesiae and oedema in the dysaesthetic portion of the distal limbs. Sensory and motor involvement mostly showed a pattern of mononeuritis multiplex in the initial phase, progressing into asymmetrical polyneuropathy, restricted to the limbs. Parallel loss of myelinated and unmyelinated fibres due to axonal degeneration was evident as decreased or absent amplitudes of sensory nerve action potentials and compound muscle action potentials, indicating acute massive axonal loss. Epineurial necrotizing vasculitis was seen in 54% of cases; infiltrates consisted mainly of CD8-positive suppressor/cytotoxic and CD4-positive helper T lymphocytes. Eosinophils were present in infiltrates, but in smaller numbers than lymphocytes. CD20-positive B lymphocytes were seen only occasionally. Deposits of IgG, C3d, IgE and major basic protein were scarce. The mean follow-up period was 4.2 years, with a range of 8 months to 10 years. Fatal outcome was seen only in a single patient, indicating a good survival rate. The patients who responded well to the initial corticosteroid therapy within 4 weeks regained self-controlled functional status in longterm follow-up (modified Rankin score was < or = 2), while those not responding well to the initial corticosteroid therapy led a dependent existence (P < 0.01). In addition the patients with poor functional outcomes had significantly more systemic organ damage caused by vasculitis (P < 0.05). Necrotizing vasculitis mediated by cytotoxic T cells, leading to ischaemic changes, appears to be a major cause of Churg-Strauss syndrome-associated neuropathy. The initial clinical course and the extent of systemic vasculitic lesions may influence the long-term functional prognosis.

AAEM minimonograph #38: neuropathies in connective tissue disease

Neuropathies are common in patients with known or suspected connective tissue disease. A vasculitic mononeuropathy multiplex is often seen in patients initially presenting with polyarteritis nodosa or developing arteritis as a complication of rheumatoid arthritis. However, vasculitic neuropathy may become confluent and present as as distal symmetrical polyneuropathy or occur without systemic necrotizing vasculitis. Distal symmetrical polyneuropathies without associated vasculitis are also common in many connective tissue diseases. Compression neuropathies, especially carpal tunnel syndrome, occur with increased frequency in rheumatoid arthritis. Finally, certain neuropathies may be the major presenting feature of particular connective tissue diseases. For example, trigeminal neuropathy often heralds the onset of systemic sclerosis or mixed connective tissue disease, and sensory neuronopathy may be the initial presenting feature of Sjögren's syndrome.

Peripheral neuropathy in hypereosinophilic syndrome with vasculitis

A 53-year-old woman with non-productive cough of unexplained aetiology for two years, developed a sub-acute symmetrical polyneuropathy involving all four limbs, accompanied by fever, cutaneous rash and myalgia in lower limbs. Laboratory studies revealed a leukocytosis with 70% eosinophils and excluded any cause for the hypereosinophilia. An echocardiogram showed increase in thickness of the atrial septum. Motor and sensory conduction velocity were reduced in ulnar and median nerve and unrecordable in peroneal and tibial nerves. A sural nerve biopsy showed an axonal degeneration involving myelinated and unmyelinated fibers as well as a vasculitis with fibrinoid necrosis and perivascular infiltration of eosinophils. There was considerable clinical and laboratory improvement with the use of steroids. The differential diagnosis between idiopathic hypereosinophilic syndrome and other disorders known to course with vasculitis and hypereosinophilia is discussed.

Significance of degenerating endoneurial cells in peripheral neuropathy

In 42 human sural nerve biopsies degeneration of endoneurial cells was evaluated semiquantitatively at the electronmicroscopic level. These cells were of non-Schwannian origin since they were not surrounded by a basement membrane. Most of the degenerating cells resembled endoneurial fibroblasts: their remaining cytoplasmic processes were quite extensive, not finger-like as in macrophages, and their cytoplasm did not contain conspicuous lysosomes or phagolysosomes that would identify them as degenerating macrophages. Criteria for regarding these cells as degenerating were defects of the cytoplasmic surface membrane with extracellularly situated organelles. The ratio between normal and degenerating endoneurial cells in five different groups of peripheral neuropathies was compared to a group of normal controls. No degenerating endoneurial cells were found in the latter. The largest proportion of degenerating endoneurial cells was noted in patients with panarteritis nodosa (30% of the endoneurial cells evaluated). Between 9% and 18% of the evaluated endoneurial cells were seen degenerating in hereditary motor and sensory neuropathies, in neuropathies associated with IgG or IgM gammopathy, and in chronic demyelinating inflammatory polyradiculoneuropathy. These findings suggest that degeneration of endoneurial cells is a nonspecific sign of peripheral neuropathy occurring in various types of neuropathy, although vasculitis represents the most frequent cause. Thus, degeneration of endoneurial cells can be added to the growing list of changes that possibly indicate an inflammatory disorder, even during the intervening stage when apparent inflammatory cell infiltrates are lacking.

Conduction block in neuropathies with necrotizing vasculitis

Thirty-two patients with a mononeuropathy multiplex associated with a systemic necrotizing vasculitis were studied. The main abnormality was a loss of motor and sensory axons confirmed by electrophysiological and histological methods. A conduction block was observed in five patients, but only one was at a usual site of compression. Based on previous pathological studies and the experimental data in human and animals, the mechanism of the block is proposed to be ischemic. It is suggested that a conduction block in one nerve in a neuropathy with two or more individual nerves affected and with electrophysiological features of axonal degeneration may be due to a vasculitis.

Course of cerebral lesions in a patient with periarteritis nodosa studied by magnetic resonance imaging

The course is reported of a patient with periarteritis nodosa who initially presented with neurological symptoms. Multiple cerebral lesions were documented by the first magnetic resonance imaging (MRI) investigation. The majority of these had disappeared completely in the follow-up MRI studies. In contrast to neurological improvement the patient eventually died due to multiorgan failure. Postmortem histological examination revealed no pathological findings in the brain except one single necrotic area already known from MRI. Remissions of histological and angiographic alterations in periarteritis nodosa have been described as "local healing" leading to fibrosis and scarring. Our findings suggest that restitutio ad integrum may occur, at least in cerebral lesions.

Peripheral neuropathy with essential mixed cryoglobulinemia: biopsies from 5 cases

Essential mixed cryoglobulinemia, which can cause hypersensitivity vasculitis, was observed in five patients with peripheral neuropathy. Three cases presented with multifocal neuropathies and two cases with symmetrical polyneuropathy. One had cryoglobulinemia with IgM monoclonal gammopathy IgG polyclonal gammopathy, and the other four had cryoglobulinemia with polyclonal gammopathy. Biopsies showed perivascular infiltration by mononuclear cells around medium, and mainly small-sized blood vessels. This was observed in the epineurium (five cases) and muscular fragments (three cases). At ultrastructural examination two cases showed severe damage of most myelinated fibers, which presented acute stages of Wallerian-like degeneration, and the three other cases showed a less widespread destruction of myelinated fibers. Most endoneurial capillaries showed swollen endoneurial cells. Myelino-axonal degeneration of myelinated fibers is probably due mainly to the vasculitis always present in the epineurium. This damage was probably worsened by the modifications of endoneurial capillaries. These lesions and their mechanisms are quite different from those observed in cases of cryoglobulinemia with an isolated monoclonal gammopathy.

Acute ischemia causes axonal stasis, swelling, attenuation, and secondary demyelination

Microsphere embolization of rat sciatic nerve capillaries results in a central fascicular ischemic core. Twenty-four hours after microembolization, the pathological alterations along the length of 55 myelinated fibers were reconstructed by computer imaging of 2,000 serial semi-thin epoxy sections of a tissue block that extended from just above and into an ischemic core. From proximal to distal, the typical sequence of pathological alterations was: normal----swollen dark axons + thin myelin or demyelination----attenuated axons----axon cytolysis (46 fibers) or normal axons (9 fibers). Because organelle accumulation and axonal swelling were the earliest and most proximal pathological lesions, we infer that regional hypoxia causes axonal stasis as a primary event. Demyelination was found in fibers showing swollen dark and attenuated axons. These findings suggest that axons are selectively vulnerable to acute ischemia and that, depending on severity, the fibers either undergo axonal degeneration or transitory structural alterations without axonal degeneration, the latter consisting of axonal changes and secondary demyelination.

Acute inflammatory demyelinating polyneuropathy in a diabetic patient: predominance of vesicular disruption in myelin sheaths

A diabetic woman underwent an incision of the right big toe for an abscess and developed a typical Guillain-Barré syndrome 48 h later. A biopsy of a peripheral nerve, performed 10 days later, showed modifications usually seen in diabetic patients, as well as the characteristic ultrastructural modifications of the Guillain-Barré syndrome (GBS). Moreover, 22% of myelinated fibers exhibited vesicular disruption of the myelin sheaths. This lesion is rarely encountered on the biopsies of peripheral nerve in GBS and concerns only a few myelinated fibers. Such a prominence of myelinic vesicular disruption and its occurrence in a diabetic patient are discussed.