The nonsystemic vasculitic neuropathies

Ways to think about vasculitic neuropathy

PURPOSE OF REVIEW

Vasculitis as a pathomechanism for neuropathy can be isolated to the peripheral nervous system, a part of a systemic autoimmune condition or a component of another syndrome. This review aims to discuss the broad range of diagnoses in which vasculitic neuropathy can be encountered, highlight the progress in imaging techniques in identifying vasculitis, and the new drugs developed for other autoimmune diseases that may be applied to neurological conditions.

RECENT FINDINGS

Advances in imaging modalities, ultrasound, MRI and FDG-PET scanning for neuromuscular applications has redefined many aspects of vasculitic neuropathies. The benefit of dividing vasculitides by vessel size is becoming less absolute as diagnostic approaches advance. MRI and FDG-PET are widely used in diagnosis, defining extent of involvement of disease and monitoring. In neuralgic amyotrophy, the identification of hourglass-like constrictions on imaging has changed the treatment paradigm to include surgical interventions. These diagnostic approaches are supported by new immunomodulating and immunosuppression techniques.

SUMMARY

Vasculitic neuropathies are a broad group of conditions with a range of causes and associations. Increased use of imaging techniques impacts our traditional definitions and classifications. The growth in treatment options for other autoimmune conditions are likely to infiltrate the neurological landscape.

Rituximab in non-systemic vasculitic neuropathy: a single-center experience

OBJECTIVES

This case series reports clinical features and outcome of four patients with non-systemic vasculitic neuropathy (NSVN) treated with the anti-CD20 agent rituximab.

METHODS

Clinical, electrophysiological and biopsy data were retrospectively obtained and evaluated. Only patients with pathological definite or probable NSVN were included. Extensive clinical and laboratory work-up excluded systemic vasculitis. Follow-up data for at least 12 months and up to five years is provided. Outcome of the patients was assessed using the MRC-Sum Score, Prineas Score and Neurological Symptom Score.

RESULTS

Two of four patients treated with rituximab achieved disease remission and one patient remained stable under anti-CD20 therapy after a required treatment switch due to toxic side effects of cyclophosphamide. One patient deteriorated under rituximab induction. Rituximab was well tolerated in all patients.

DISCUSSION

Anti-CD20 therapy might be an alternative in NSVN patients requiring further treatment escalation or treatment switch due to side effects of corticosteroids or cyclophosphamide.

Electrodiagnostic studies and new diagnostic modalities for evaluation of peripheral nerve disorders

Electrodiagnostic studies (EDx) are frequently performed in the diagnostic evaluation of peripheral nerve disorders. There is increasing interest in the use of newer, alternative diagnostic modalities, in particular imaging, either to complement or replace established EDx protocols. However, the evidence to support this approach has not been expansively reviewed. In this paper, diagnostic performance data from studies of EDx and other diagnostic modalities in common peripheral nerve disorders have been analyzed and described, with a focus on radiculopathy, plexopathy, compressive neuropathies, and the important neuropathy subtypes of Guillain-Barré syndrome, chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), vasculitic neuropathy and diabetic neuropathy. Overall EDx retains its place as a primary diagnostic modality in the evaluated peripheral nerve disorders. Magnetic resonance imaging and ultrasound have developed important complementary diagnostic roles in compressive and traumatic neuropathies and atypical CIDP, but their value is more limited in other neuropathy subtypes. Identification of hourglass constriction in nerves of patients with neuralgic amyotrophy may have therapeutic implications. Investigation of radiculopathy is confounded by poor correlation between clinical features and imaging findings and the lack of a diagnostic gold standard. There is a need to enhance the literature on the utility of these newer diagnostic modalities.

A, Feinstein D, Traisak P, Eid H, Karpoff M. An Unusual Case of Peripheral Nerve Vasculitis

Peripheral neuropathy is a common manifestation of systemic vasculitis. The etiology of vasculitic peripheral neuropathy is generally classified into two groups: systemic and nonsystemic. In systemic vasculitic neuropathy (SVN), neuropathy is a consequence of a systemic disease, most commonly involving medium and small vessels throughout the body. There are three main clinical presentations: multifocal neuropathy, distal symmetric polyneuropathy, and overlapping multifocal neuropathy. Specifically, distal symmetric polyneuropathy affects multiple somatic nerves diffusely in a symmetric and length-dependent pattern (also known as the classic stocking-glove pattern). This case represents an atypical presentation of SVN, presenting with widespread symmetric polyneuropathy.A 73-year-old woman presented with distal acute on chronic bilateral upper and lower extremity weakness, sensory changes, and widespread pain. Symptoms started about three months prior and gradually worsened with progressive difficulty with ambulation and required assistive devices. Elevated ESR is at 70 mm/hour, CRP at 25.66 mg/dL, elevated c-ANCA titers at 1 : 320 and PR3 at 5.0 AI, and elevated creatine kinase (CK) at 500-600 U/L. A muscle biopsy of the left vastus showed neurogenic atrophy without myositis. Initial improvement was with oral prednisone, but was stopped on discharge. Many purpuric and petechial lesions were developed on distal legs/feet and right fourth digit distal gangrene. EMG showed distal, symmetric, and axonal polyneuropathy affecting the upper and lower extremities and acute denervation in more distal muscles. The patient received pulse dose steroids and two doses of rituximab induction therapy and was discharged with an oral steroid taper. The patient's symptoms started as distal symmetric neuropathy at the onset and progressively worsened over the course of 3 months. Neuropathy, both on the exam and on EMG, seemed to have developed more rapidly than expected, regardless of its distribution. The EMG showed severe peripheral nerve damage and denervation, which is unusual for ANCA-associated systemic vasculitis.

[Mononeuropathy multiplex caused by cutaneous arteritis diagnosed by skin biopsies for emerging atypical erythema on upper limbs following neurological symptoms: a case report]

A 33-year-old female was admitted to our department complaining of multifocal paresthesia and weakness of the upper and lower extremities that had developed over the previous three months. She had also been undergoing treatment for atopic dermatitis with dupilumab, an anti-interleukin 4/13 receptor antibody. A nerve conduction study revealed multifocal axonal sensorimotor neuropathy of bilateral limbs. On admission, a small erythema appeared on her right forearm, but it was atypical for vasculitic skin lesions due to its location and time course. Nonetheless, a biopsy revealed medium-sized vessel vasculitis. The patient was therefore diagnosed with vasculitic neuropathy caused by cutaneous arteritis. Methylprednisolone pulse therapy with prednisolone and azathioprine markedly improved her symptoms. A skin biopsy is useful when mononeuropathy multiplex is suspected, even if the skin findings are atypical for vasculitic rash.

Focal inflammatory neuropathies

This chapter focuses on neuropathies that present with focal involvement of nerve roots, plexus, and/or peripheral nerves associated with autoimmune and inflammatory mechanisms that present with focal involvement of nerve roots, plexus and/or peripheral nerves. The clinical presentation, diagnosis, and treatment of focal autoimmune demyelinating neuropathies, focal nonsystemic vasculitic disorders (diabetic and nondiabetic radiculoplexus neuropathies, postsurgical inflammatory neuropathy, and neuralgic amyotrophy), and focal neuropathies associated with sarcoidosis and bacterial and viral infections are reviewed.

Utilising clinical parameters to improve the selection of nerve biopsy candidates

BACKGROUND

Peripheral nerve biopsy is a valuable final diagnostic tool; however, histopathological results can be non-diagnostic.

AIMS

We aim to identify quality improvement measures by evaluating the pre-biopsy assessment and diagnostic yield of specific histopathological diagnosis.

METHODS

This was a retrospective study based on 10 years of experience with peripheral nerve biopsies at a single centre. Clinical data were obtained regarding pre-biopsy history, examination, serum and cerebrospinal fluid (CSF) investigations, neurophysiology and peripheral nerve imaging. Based upon a histopathological outcome, patients were grouped into vasculitis, granulomatous and infiltrative (diagnostic) group, or a comparison group of non-specific axonal neuropathy and normal (non-specific/normal) group.

RESULTS

From a cohort of 64 patients, 21 (32.8%) were included in the diagnostic group and 30 (46.9%) in the non-specific/normal group. Clinical parameters associated with the diagnostic group were shorter history (mean 10.2 months vs 38.1), stepwise progression (81% vs 20%), neuropathic pain (85.7% vs 56.7%), vasculitic rash (23.8% vs 0%), mononeuritis multiplex (57.1% vs 10%), asymmetry (90.5% vs 60%), raised white cell count (47.6% vs 16.7%), myeloperoxidase antibody (19.1% vs 0%) and abnormal peripheral nerve imaging (33.3% vs 10%).

CONCLUSION

Selection of patients undergoing nerve biopsy requires careful consideration of clinical parameters, including peripheral nerve imaging. Several quality improvement measures are proposed to improve yield of clinically actionable information from nerve biopsy.

Primary perineuritis, a rare but treatable neuropathy: Review of perineurial anatomy, clinicopathological features, and differential diagnosis

The perineurium surrounds each fascicle in peripheral nerves, forming part of the blood-nerve barrier. We describe its normal anatomy and function. "Perineuritis" refers to both a nonspecific histopathological finding and more specific clinicopathological entity, primary perineuritis (PP). Patients with PP are often assumed to have nonsystemic vasculitic neuropathy until nerve biopsy is performed. We systematically reviewed the literature on PP and developed a differential diagnosis for histopathologically defined perineuritis. We searched PubMed, Embase, Scopus, and Web of Science for "perineuritis." We identified 20 cases (11 M/9F) of PP: progressive, unexplained neuropathy with biopsy showing perineuritis without vasculitis or other known predisposing condition. Patients ranged in age from 18 to 75 (mean 53.7) y and had symptoms 2-24 (median 4.5) mo before diagnosis. Neuropathy was usually sensory-motor (15/20), painful (18/19), multifocal (16/20), and distal-predominant (16/17) with legs more affected than arms. Truncal numbness occurred in 6/17; 10/18 had elevated cerebrospinal fluid (CSF) protein. Electromyography (EMG) and nerve conduction studies (NCS) demonstrated primarily axonal changes. Nerve biopsies showed T-cell-predominant inflammation, widening, and fibrosis of perineurium; infiltrates in epineurium in 10/20 and endoneurium in 7/20; and non-uniform axonal degeneration. Six had epithelioid cells. 19/20 received corticosteroids, 8 with additional immunomodulators; 18/19 improved. Two patients did not respond to intravenous immunoglobulin (IVIg). At final follow-up, 13/16 patients had mild and 2/16 moderate disability; 1/16 died. Secondary causes of perineuritis include leprosy, vasculitis, neurosarcoidosis, neuroborreliosis, neurolymphomatosis, toxic oil syndrome, eosinophilia-myalgia syndrome, and rarer conditions. PP appears to be an immune-mediated, corticosteroid-responsive disorder. It mimics nonsystemic vasculitic neuropathy. Cases with epithelioid cells might represent peripheral nervous system (PNS)-restricted forms of sarcoidosis.

Application of a nerve stereoscopic reconstruction technique based on ultrasonic images in the diagnosis of neuralgic amyotrophy

Objective: To propose a nerve stereoscopic reconstruction technique based on ultrasound imaging for site diagnosis, intuitive reflection of disease severity, and classification of neuralgic amyotrophy (NA). Methods: We enrolled 44 patients with NA who underwent high-frequency ultrasonography examination. Multiple sites on the normal side and the affected side were scanned to calculate the ratio of the cross-section area (CSA) of the affected side to the normal side at each location measured, i.e., the cross-section area swelling ratio (CSASR). The CSASR of 44 patients and 30 normal controls was analyzed to determine their threshold value for the diagnosis of NA. Then, ultrasound images of the cross-section were used to reconstruct the stereoscopic model of the nerve on the affected side and the normal side. Using the CSASR values in each measurement location, a CSASR stereoscopic model was developed. Results: The threshold value of CSASR for ultrasound diagnosis of NA was 1.55. The average diseased segments per patient was 2.49 ± 1.97, with an average overall length of 10.03 ± 7.95 cm. Nerve stereoscopic reconstruction could be conducted for swelling, torsion, incomplete constriction, and complete constriction. Conclusion: The ultrasound image reconstruction method proposed in this study can accurately determine the site, range, and type of neuropathies in patients with NA, and simultaneously provide complete and accurate data information and intuitive morphological information.

Subclinical motor involvement in nonsystemic vasculitic neuropathy determined by the motor unit number estimation method MScanFit

INTRODUCTION/AIMS

Nonsystemic vasculitic neuropathy (NSVN) is characterized by a predominant lower limb involvement in many patients. Motor unit changes in upper extremity muscles have not been investigated in this subgroup but may be of interest for improving our understanding of the multifocal nature of the disease and counseling of patients about potential future symptoms. In this study we aimed to better understand subclinical motor involvement in the upper extremity muscles of patients with lower limb-predominant NSVN using the new motor unit number estimation (MUNE) method MScanFit.

METHODS

In this single-center, cross-sectional study, 14 patients with biopsy-proven NSVN, with no clinical signs of upper extremity motor involvement, were investigated and compared with 14 age-matched healthy controls. All participants were assessed clinically and by the MUNE method MScanFit to the abductor pollicis brevis muscle.

RESULTS

The number of motor units and peak CMAP amplitudes were significantly reduced in patients with NSVN (P = .003 and P = .004, respectively). Absolute median motor unit amplitudes and CMAP discontinuities were not significantly different (P = .246 and P = .1, respectively). CMAP discontinuities were not significantly correlated with motor unit loss (P = .15, rho = 0.4). The number of motor units did not correlate with clinical scores (P = .77, rho = 0.082).

DISCUSSION

Both MUNE and CMAP amplitudes showed motor involvement in upper extremity muscles in lower limb-predominant NSVN. Overall, there was no evidence of significant reinnervation. Investigations of the abductor pollicis brevis muscle did not show a correlation with overall functional disability of the patients.

Oxygen-Glucose Deprivation Decreases the Motility and Length of Axonal Mitochondria in Cultured Dorsal Root Ganglion Cells of Rats

Controlling axonal mitochondria is important for maintaining normal function of the neural network. Oxygen-glucose deprivation (OGD), a model used for mimicking ischemia, eventually induces neuronal cell death similar to axonal degeneration. Axonal mitochondria are disrupted during OGD-induced neural degeneration; however, the mechanism underlying mitochondrial dysfunction has not been completely understood. We focused on the dynamics of mitochondria in axons exposed to OGD; we observed that the number of motile mitochondria significantly reduced in 1 h following OGD exposure. In our observation, the decreased length of stationary mitochondria was affected by the following factors: first, the halt of motile mitochondria; second, the fission of longer stationary mitochondria; and third, a transformation from tubular to spherical shape in OGD-exposed axons. Motile mitochondria reduction preceded stationary mitochondria fragmentation in OGD exposure; these conditions induced the decrease of stationary mitochondria in three different ways. Our results suggest that mitochondrial morphological changes precede the axonal degeneration while ischemia-induced neurodegeneration.

[Peripheral neuropathies during systemic diseases: Part II (vasculitis)]

Primary systemic vasculitides, mainly of the small and medium-sized vessels, are frequently associated with peripheral neuropathies. When the disease is already known, the appearance of a neuropathy should suggest a specific injury, especially when associated with other systemic manifestations. Conversely, when neuropathy is inaugural, close collaboration between neurologists and internists is necessary to reach a diagnosis. A standardized electro-clinical investigation specifying the topography, the evolution and the mechanism of the nerve damage enables the positive diagnosis of the neuropathy. Several elements orient the etiological diagnosis and allow to eliminate the main differential diagnosis: non systemic vasculitic neuropathy. The existence of associated systemic manifestations (glomerular or vascular nephropathy, interstitial lung disease, intra-alveolar hemorrhage, ENT involvement…), biological markers (ANCA, cryoglobulinemia, rheumatoid factor), and invasive examinations allowing histological analysis (neuromuscular biopsy) are all useful tools for.

Neuralgic amyotrophy detected by magnetic resonance neurography: subclinical, bilateral, and multifocal brachial plexus involvement

INTRODUCTION

Neuralgic amyotrophy (NA) is a painful non-traumatic peripheral nervous system condition affecting the brachial plexus. Signal abnormalities in nerves and muscles have been detected in these patients using magnetic resonance neurography (MRN).

METHODS

Electronic medical records and MRN images obtained in a 3 T scanner, in 14 adult patients diagnosed with NA at our Neurological institution (Neuromuscular Disorders Section), between December 2015 and December 2019 were retrospectively reviewed. The study was first approved by our Institutional Ethics Committee.

RESULTS

Subclinical, multifocal, and bilateral nerve signal anomalies were recorded in the brachial plexus of these patients. We identified four different types of nerve constriction without entrapment, which we categorized as follows: incomplete focal (type I), complete focal or hourglass (type II), multifocal or string of pearls (type III) and segmental (type IV).

CONCLUSIONS

Given that MRN is an accurate diagnostic tool to detect nerve damage, we believe abnormal findings could improve early detection of NA patients.

Central and Peripheral Nervous System Complications of Vasculitis Syndromes from Pathology to Bedside: Part 2-Peripheral Nervous System

PURPOSE OF REVIEW

Peripheral nervous system vasculitides (PNSV) are a heterogeneous group of disorders with a clinical subset that may differ in prognosis and therapy. We provide a comprehensive update on the clinical assessment, diagnosis, complications, treatment, and follow-up of PNSV.

RECENT FINDINGS

Progress in neuroimaging, molecular testing, and peripheral nerve biopsy has improved clinical assessment and decision-making of PNSV, also providing novel insights on how to prevent misdiagnosis and increase diagnostic certainty. Advances in imaging techniques, allowing to clearly display the vessel walls, have also enhanced the possibility to differentiate inflammatory from non-inflammatory vascular lesions, while recent histopathology data have identified the main morphological criteria for more accurate diagnosis and differential diagnoses. Overall, the identification of peculiar morphological findings tends to improve diagnostic accuracy by defining a clearer boundary between systemic and non-systemic neuropathies. Therefore, the definition of epineurium vessel wall damage, type of vascular lesion, characterization of lymphocyte populations, antibodies, and inflammatory factors, as well as the identification of direct nerve damage or degeneration, are the common goals for pathologists and clinicians, who will both benefit for data integration and findings translation. Nevertheless, to date, treatment is still largely empiric and, in some cases, unsatisfactory, thus often precluding precise prognostic prediction. In this context, new diagnostic techniques and multidisciplinary management will be essential in the proper diagnosis and prompt management of PNSV, as highlighted in the present review. Thirty to fifty percent of all patients with vasculitis have signs of polyneuropathy. Neuropathies associated with systemic vasculitis are best managed according to the guidelines of the underlying disease because appropriate workup and initiation of treatment can reduce morbidity. Steroids, or in severe or progressive cases, cyclophosphamide pulse therapy is the standard therapy in non-systemic vasculitic neuropathies. Some patients need long-term immunosuppression. The use of novel technologies for high-throughput genotyping will permit to determine the genetic influence of related phenotypes in patients with PNSV.

Role of tubulin post-translational modifications in peripheral neuropathy

Peripheral neuropathy is a common disorder that results from nerve damage in the periphery. The degeneration of sensory axon terminals leads to changes or loss of sensory functions, often manifesting as debilitating pain, weakness, numbness, tingling, and disability. The pathogenesis of most peripheral neuropathies remains to be fully elucidated. Cumulative evidence from both early and recent studies indicates that tubulin damage may provide a common underlying mechanism of axonal injury in various peripheral neuropathies. In particular, tubulin post-translational modifications have been recently implicated in both toxic and inherited forms of peripheral neuropathy through regulation of axonal transport and mitochondria dynamics. This knowledge forms a new area of investigation with the potential for developing therapeutic strategies to prevent or delay peripheral neuropathy by restoring tubulin homeostasis.

Repurposing MS immunotherapies for CIDP and other autoimmune neuropathies: unfulfilled promise or efficient strategy?

Despite advances in the treatment of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and other common autoimmune neuropathies (AN), still-many patients with these diseases do not respond satisfactorily to the available treatments. Repurposing of disease-modifying therapies (DMTs) from other autoimmune conditions, particularly multiple sclerosis (MS) and neuromyelitis optica spectrum disorders (NMOSD), is a promising strategy that may accelerate the establishment of novel treatment choices for AN. This approach appears attractive due to homologies in the pathogenesis of these diseases and the extensive post-marketing experience that has been gathered from treating MS and NMOSD patients. The idea is also strengthened by a number of studies that explored the efficacy of DMTs in animal models of AN but also in some CIDP patients. We here review the available preclinical and clinical data of approved MS therapeutics in terms of their applicability to AN, especially CIDP. Promising therapeutic approaches appear to be B cell-directed and complement-targeting strategies, such as anti-CD20/anti-CD19 agents, Bruton's tyrosine kinase inhibitors and anti-C5 agents, as they exert their effects in the periphery. This is a major advantage because, in contrast to MS, their action in the periphery is sufficient to exert significant immunomodulation.

Autoimmune polyneuropathies

The autoimmune peripheral neuropathies with prominent motor manifestations are a diverse collection of unusual peripheral neuropathies that are appreciated in vast clinical settings. This chapter highlights the most common immune-mediated, motor predominant neuropathies excluding acute, and chronic inflammatory demyelinating polyradiculoneuropathy (AIDP and CIDP, respectively). Other acquired demyelinating neuropathies such as distal CIDP and multifocal motor neuropathy will be covered. Additionally, the radiculoplexus neuropathies, resulting from microvasculitis-induced injury to nerve roots, plexuses, and nerves, including diabetic and nondiabetic lumbosacral radiculoplexus neuropathy and neuralgic amyotrophy (i.e., Parsonage-Turner syndrome), will be included. Finally, the motor predominant peripheral neuropathies encountered in association with rheumatological disease, particularly Sjögren's syndrome and rheumatoid arthritis, are covered. Early recognition of these distinct motor predominant autoimmune neuropathies and initiation of immunomodulatory and immunosuppressant treatment likely result in improved outcomes.

Adult and childhood vasculitis

Vasculitis refers to heterogeneous clinicopathologic disorders that share the histopathology of inflammation of blood vessels. Unrecognized and therefore untreated, vasculitis of the nervous system leads to pervasive injury and disability, making this a disorder of paramount importance to all clinicians. There has been remarkable progress in the pathogenesis, diagnosis, and treatment of primary CNS and PNS vasculitides, predicated on achievement in primary systemic forms. Primary neurological vasculitides can be diagnosed with assurance after intensive evaluation that incudes tissue confirmation whenever possible. Clinicians must choose from among the available immune modulating, suppressive, and targeted immunotherapies to induce and maintain remission status and prevent relapse, unfortunately without the benefit of RCTs, and tempered by the recognition of anticipated medication side effects. It may be said that efforts to define a disease are attempts to understand the very concept of the disease. This has been especially evident in systemic and neurological disorders associated with vasculitis. For the past 100 years, since the first description of granulomatous angiitis of the brain, the CNS vasculitides have captured the attention of generations of clinical investigators around the globe to reach a better understanding of vasculitides involving the central and peripheral nervous system. Since that time it has become increasingly evident that this will necessitate an international collaborative effort.

Diagnostic characteristics of nerve conduction study parameters for vasculitic neuropathy

INTRODUCTION/AIMS

In vasculitic neuropathy (VN), a 50% side-to-side difference in the amplitude of compound muscle action potentials and sensory nerve action potentials is considered meaningful, but unequivocal evidence is lacking. The aim of this study is to characterize electrodiagnostic features that best distinguish VN from other axonal polyneuropathies.

METHODS

We conducted a case-control study between January 2000 and April 2021. We reviewed the records of patients with VN who had bilateral nerve conduction studies (NCS) and evaluated different electrodiagnostic models to help distinguish VN from non-inflammatory axonal polyneuropathies.

RESULTS

We identified 82 cases, and 174 controls with non-inflammatory axonal neuropathies. The amplitude percent difference Z-score model showed the best discriminatory capability between cases and controls (area under the curve [AUC] 0.87; 95% confidence interval [CI] 0.82, 0.93), and the number of nerves tested did not significantly influence the model. Individually, the ulnar motor nerve (AUC 0.86; 95% CI 0.77, 0.94) and median motor nerve (AUC 0.85; 95% CI 0.77, 0.94) showed the best discriminatory capability. A 50% amplitude difference between at least two bilateral nerves, either in the upper (AUC 0.85; 95% CI 0.77, 0.93) or lower (AUC 0.79; 95% CI 0.71, 0.87) extremity showed good discriminatory threshold for detecting VN.

DISCUSSION

The best electrodiagnostic criteria for VN utilizes z-scores of percent differences in nerve amplitudes, but this approach may be difficult to implement at the bedside. Alternately, a 50% amplitude difference in at least two nerves is a reasonable approximation.

Single-center experience of induction therapy in non-systemic vasculitic neuropathy

Background

No controlled studies for non-systemic vasculitic neuropathy treatment exist (NSVN). We compared the treatment response to induction therapy commonly used in clinical practice in NSVN.

Methods

In this retrospective single-center study, 43 patients with biopsy-proven NSVN were analyzed. Patients were subdivided into groups depending on their initial treatment. Relapse rates, changes of motor and sensory symptoms, adverse events, predictors of relapses, and second-line treatment were compared.

Results

Initial treatment regimens were corticosteroid monotherapy, cyclophosphamide monotherapy, pulsed corticosteroid therapy, and combination therapy. Discontinuation due to adverse events occurred in 6 of 43 patients. Clinical data did not differ between treatment groups. Within 12 months, 24.3% of patients relapsed. The median time to relapse was 4 (1.5, 6) months. No relapse occurred in the combination therapy group. However, there was no statistically significant difference in relapse-free survival between treatment groups (p = 0.58). Neither clinical data nor biopsy analysis predicted relapses sufficiently. As a second-line treatment, cyclophosphamide as mono- or combination therapy was used (7 of 9 patients) most frequently. One patient was treated with methotrexate, and one with IVIG.

Conclusions

Induction therapy used in clinical practice is effective and mainly well-tolerated in NSVN. Our data do not support an overall advantage of cyclophosphamide over corticosteroid monotherapy. Controlled trials comparing the effectiveness of induction and maintenance therapy in NSVN are warranted.

Supplementary Information

The online version contains supplementary material available at 10.1186/s42466-022-00198-5.

Patterns of myelinated nerve fibers loss in transthyretin amyloid polyneuropathy and mimics

Objective

The present study was intended to analyze the characteristics of myelinated nerve fibers density (MFD) of transthyretin amyloid polyneuropathy (ATTR‐PN) and other similar neuropathies.

Methods

A total of 41 patients with ATTR‐PN, 58 patients of other common peripheral neuropathies, and 17 age‐and gender‐matched controls who visited the First Hospital of Peking University and performed sural nerve biopsy between June 2007 and August 2021 were included for analysis of MFD.

Results

Except the vasculitic neuropathy group, the total and small MFD of patients in the ATTR‐PN group were significantly lower than those of other disease groups. There was an obvious negative correlation between the total MFD and the disease course in the ATTR‐PN group. The disease course of early‐onset and late‐onset symptoms was similar, but the loss of large myelinated nerve fibers (MF) was more severe for the latter. In addition, all late‐onset and most early‐onset patients had severely reduced MFD after a 2 years' disease course. The MFD in ATTR‐PN patients was negatively correlated with Neuropathy Impairment Score (NIS) and Norfolk Quality of life‐diabetic neuropathy (Norfolk QOL‐DN) score.

Conclusion

MF is lost differently in ATTR‐PN and in other common peripheral neuropathies. The late‐onset and early‐onset ATTR‐PN patients have different patterns of loss of large and small MF.

The role of sural nerve biopsy in diagnosis of vasculitis

OBJECTIVE

The diagnostic yield of sural nerve biopsy (SNB) in vasculitis is uncertain. Our aim was to document relevant characteristics of patients undergoing sural nerve biopsy in the investigation of vasculitis; determine the diagnostic yield; relate positive biopsy findings to patient demographic, laboratory, and clinical parameters; and to calculate the rate of surgical complications.

METHODS

Patients with suspected vasculitis that underwent SNB as part of diagnostic evaluation at academic medical centres in Sweden and the United Kingdom were identified by searching local pathology databases and clinic registers. A structured review of medical case records and pathology reports was conducted. Histological findings were categorized as definite, probable, or no vasculitis in accordance with the 2015 Brighton Collaboration reinterpretation and update of the Peripheral Nerve Society Guidelines for Vasculitic Neuropathy. Definite and probable findings were considered positive for vasculitis.

RESULTS

Ninety-one patients that underwent SNB were identified (45% female). Forty (44%) showed histological evidence of vasculitis: 14 definite and 26 probable. A concomitant muscle biopsy conducted in 10 patients did not contribute to the diagnostic yield. Positive antineutrophil cytoplasmic antibody test, organ involvement other than the nervous system, and a longer biopsy sample were associated with a positive biopsy. The reported surgical complication rate was 15%.

CONCLUSION

Sural nerve biopsy of sufficient length is an expedient procedure to confirm a diagnosis of vasculitis.

Adalimumab-induced sensory vasculitic neuropathy

Vasculitis and other autoimmune conditions are known complications of tumour necrosis factor alpha (TNF-α) inhibitor use. By definition, TNF-α inhibitor induced vasculitis is a secondary systemic vasculitis. However, its phenotype is varied and can present as an isolated vasculitic neuropathy. This presents a diagnostic challenge as the gold standard for diagnosis of a vasculitic neuropathy is a peripheral nerve biopsy that meets predefined histopathological criteria. Given the poor sensitivity of the peripheral nerve biopsy, it is important that clinicians take a good history and maintain a high index of suspicion, as this is a treatable iatrogenic condition. Here we present a case of adalimumab-induced sensory vasculitic neuropathy, treated according to the Peripheral Nerve Society guideline for non-systemic vasculitic neuropathy, given her disease phenotype.

Risk factors for Lumbosacral Radiculoplexus Neuropathy

INTRODUCTION/AIMS

Recently, our group found an association between diabetes mellitus (DM) and lumbosacral radiculoplexus neuropathy (LRPN) in Olmsted County, Minnesota; we found a higher risk (OR: 7.91) for developing LRPN in diabetic compared to non-diabetic patients. However, the influence of other comorbidities and anthropomorphic variables was not studied.

METHODS

Demographic and clinical data from 59 LRPN patients and 177 age-sex matched controls were extracted using the Rochester LRPN epidemiological study. Differences between groups were compared by Chi-square/Fisher's exact test or Wilcox sum rank. Univariate and multivariate logistic regression analysis were performed.

RESULTS

Factors predictive of LRPN on univariate analysis were DM (OR 7.91; CI 4.11-15.21), dementia (OR 6.36; CI 1.13-35.67), stroke (OR 3.81; CI 1.32-11.01), dyslipidemia (OR 2.844; CI 1.53-5.27), comorbid autoimmune disorders (OR 2.72; CI 1.07-6.93), hypertension (OR 2.25; CI 1.2-4.13), obesity (OR 2.05; CI 1.11-3.8), BMI (OR 1.1; CI 1.04-1.15), and weight (OR 1.02; CI 1.009-1.037). On multivariate logistic regression analysis only DM (OR 8.03; CI 3.86-16.7), comorbid autoimmune disorders (OR 4.58; CI 1.45-14.7), stroke (OR 4.13; CI 1.2-14.25) and BMI (OR 1.07; CI 1.01-1.13) were risk factors for LRPN.

DISCUSSION

DM is the strongest risk factor for the development of LRPN, followed by comorbid auto-immune disorders, stroke and higher BMI. Altered metabolism and immune dysfunction seem to be the most influential factors in the development of LRPN. This article is protected by copyright. All rights reserved.

Common Focal Neuropathies in the Hospitalized Patient

Neuropathies are a common problem encountered by neurologist in the hospitalized setting. Nerve injury may occur secondary to compression, stretch, and direct trauma, among other causes. Common focal neuropathies include the ulnar, median, and radial nerve in the upper extremities and sciatic, peroneal, and femoral nerve in the lower extremities. Surgical and obstetric risk factors are especially important considerations in evaluation of patients with focal neuropathies. Treatment is either conservative therapy or surgery depending on the mechanism of injury and extent of recovery.

Immune mechanisms, the role of complement, and related therapies in autoimmune neuropathies

INTRODUCTION

Autoimmune neuropathies have diverse presentations and underlying immune mechanisms. Demonstration of efficacy of therapeutic agents that inhibit the complement cascade would confirm the role of complement activation.

AREAS COVERED

A review of the pathophysiology of the autoimmune neuropathies, to identify those that are likely to be complement mediated.

EXPERT OPINION

Complement mediated mechanisms are implicated in the acute and chronic neuropathies associated with IgG or IgM antibodies that target the Myelin Associated Glycoprotein (MAG) or gangliosides in the peripheral nerves. Antibody and complement mechanisms are also suspected in the Guillain-Barré syndrome and chronic inflammatory demyelinating neuropathy, given the therapeutic response to plasmapheresis or intravenous immunoglobulins, even in the absence of an identifiable target antigen. Complement is unlikely to play a role in paraneoplastic sensory neuropathy associated with antibodies to HU/ANNA-1 given its intracellular localization. In chronic demyelinating neuropathy with anti-nodal/paranodal CNTN1, NFS-155, and CASPR1 antibodies, myotonia with anti-VGKC LGI1 or CASPR2 antibodies, or autoimmune autonomic neuropathy with anti-gAChR antibodies, the response to complement inhibitory agents would depend on the extent to which the antibodies exert their effects through complement dependent or independent mechanisms. Complement is also likely to play a role in Sjogren's, vasculitic, and cryoglobulinemic neuropathies.

To be, or not to be… Guillain-Barré Syndrome

Guillain-Barré Syndrome (GBS) is currently the most frequent cause of acute flaccid paralysis on a global scale, being an autoimmune disorder wherein demyelination of the peripheral nerves occurs. Its main clinical features are a symmetrical ascending muscle weakness with reduced osteotendinous reflexes and variable sensory involvement. GBS most commonly occurs after an infection, especially viral (including COVID-19), but may also transpire after immunization with certain vaccines or in the development of specific malignancies. Immunoglobulins, plasmapheresis, and glucocorticoids represent the principal treatment modalities, however patients with severe disease progression may require supportive therapy in an intensive care unit. Due to its symptomology, which overlaps with numerous neurological and infectious illnesses, the diagnosis of GBS may often be misattributed to pathologies that are essentially different from this syndrome. Moreover, many of these require specific treatment methods distinct to those recommended for GBS, in lack of which the prognosis of the patient is drastically affected. Such diseases include exposure to toxins either environmental or foodborne, central nervous system infections, metabolic or serum ion alterations, demyelinating pathologies, or even conditions amenable to neurosurgical intervention. This extensive narrative review aims to systematically and comprehensively tackle the most notable and challenging differential diagnoses of GBS, emphasizing on the clinical discrepancies between the diseases, the appropriate paraclinical investigations, and suitable management indications.

Combination rituximab and intravenous immunoglobulin for treatment of refractory vasculitic neuropathy: a case series

OBJECTIVE

Limited evidence exists to guide treatment of refractory vasculitic neuropathy. While rituximab (RTX) and IVIG have both been proposed as individual treatment options for these patients, combination therapy has never been reported.

METHODS

Written informed consent was obtained from three patients with refractory vasculitic neuropathy who were treated with combination RTX and IVIG. Their electronic medical records were reviewed and clinical and functional outcomes were reported.

RESULTS

Two male patients with non-systemic vasculitic neuropathy and one male patient with granulomatosis with polyangiitis were treated with combination RTX and IVIG therapy. All three patients demonstrated clinical improvement with at least partial functional recovery and a reduction in corticosteroid dose. This combination was generally well tolerated.

CONCLUSIONS

Combination RTX and IVIG therapy may be a safe and effective treatment option for patients with refractory vasculitic neuropathy. Further studies are needed to better characterize the risks and benefits of this combination.

Mononeuropathy Multiplex After COVID-19

OBJECTIVES

COVID-19 is a novel coronavirus that emerged in 2019 and is responsible for a global pandemic. Numerous neurologic manifestations have been described in the literature regarding COVID-19, but most studies are focused on the central nervous system. The authors have noted an association between prior COVID-19 infection and the development of a systemic neuropathy that manifests with asymmetric sensorimotor loss in the peripheral nervous system. We describe 4 cases of mononeuropathy multiplex that were diagnosed after COVID-19 infection.

METHODS

All patients included were treated for severe COVID-19 infection at New York Presbyterian Hospital and subsequently referred to the Columbia Peripheral Neuropathy Center for persistent neuropathy.

RESULTS

Patient history, COVID-19 disease course, and mononeuropathy multiplex diagnostic evaluation of the 4 patients are recounted.

CONCLUSIONS

We postulate a connection between COVID-19 and the development of mononeuropathy multiplex with implications in prognostication, rehabilitation strategies, and future treatments.

Nerve biopsy: Current indications and decision tools

After initial investigation of patients presenting with symptoms suggestive of neuropathy, a clinical decision is made for a minority of patients to undergo further assessment with nerve biopsy. Many nerve biopsies do not demonstrate a definitive pathological diagnosis and there is considerable cost and morbidity associated with the procedure. This highlights the need for appropriate selection of patients, nerves and neuropathology techniques. Additionally, concomitant muscle and skin biopsies may improve the diagnostic yield in some cases. Several advances have been made in diagnostics in recent years, particularly in genomics. The indications for nerve biopsy have consequently changed over time. This review explores the current indications for nerve biopsies and some of the issues surrounding its use. Also included are comments on alternative diagnostic modalities that may help to supplant or reduce the use of nerve biopsy as a diagnostic test. These primarily include extraneural biopsy and neuroimaging techniques such as magnetic resonance neurography and nerve ultrasound. Finally, we propose an algorithm to assist in deciding when to perform nerve biopsies.

A Structured Approach to the Diagnosis of Peripheral Nervous System Disorders

PURPOSE OF REVIEW

Neuroanatomic localization and pattern recognition can be used to diagnose both focal lesions and generalized disorders of the peripheral nervous system. This article describes the nature and pattern of sensory and motor deficits associated with lesions of specific spinal nerve roots, plexus, or peripheral nerves. It also describes the patterns of sensory and motor deficits that suggest multifocal or generalized disorders of the motor neurons, sensory neurons, and peripheral nerves.

RECENT FINDINGS

The pattern of sensory and motor deficits may be used to distinguish lesions of the peripheral nervous system from those of the central nervous system. The spinal roots, nerve plexus, and peripheral nerves supply specific muscles and receive sensory input from distinctive cutaneous regions. Focal lesions of these structures therefore produce characteristic patterns of sensory and motor deficits. Multifocal or generalized disorders of the peripheral nervous system may be distinguished by categorizing their sensory and motor involvement, proximal and distal predominance, and degree of symmetry. Serum tests, CSF analysis, electrodiagnostic studies, MRI, ultrasound, nerve biopsy, and skin biopsy have unique roles in the diagnosis of suspected neuromuscular disorders.

SUMMARY

A structured approach to the diagnosis of nerve and motor neuron disorders can lead to hypothesis-driven diagnostic testing. Ancillary tests should be reserved for cases in which confirming or refuting a diagnosis will change patient management.

Localized Forms of Vasculitis

Purpose of Review

To provide an updated review on epidemiology, clinical manifestations, diagnostic assessment, treatment, and prognosis of localized vasculitis, following the 2012 Revised International Chapel Hill Consensus Conference Nomenclature on single-organ vasculitis.

Recent Findings

Localized, single-organ vasculitides encompass a group of rare conditions in which there is no evidence of concomitant systemic vasculitis. Most data on this topic derives from case reports and small case series. Although some aspects of these diseases, such as clinical manifestations and histologic findings, have already been extensively investigated, there is still a lack of robust data concerning the pathogenesis, epidemiology, and treatment.

Summary

Localized vasculitides may have a wide range of clinical features depending on the organ affected. The inflammatory process may have a multifocal/diffuse or unifocal distribution. Diagnosis is usually based on histopathology findings and exclusion of systemic vasculitis, which may frequently pose a challenge. Further research on treatment is warranted.

The evaluation and management of monoclonal gammopathy of renal significance and monoclonal gammopathy of neurological significance

Despite the benign nature of monoclonal gammopathy of undetermined significance (MGUS), mounting data are associating MGUS with the development of organ dysfunction, specifically monoclonal gammopathy of renal significance (MGRS) and monoclonal gammopathy of neurological significance (MGNS), which could be associated with substantial morbidity. Emerging evidence suggests that patients with MGRS and MGNS could benefit from treatments used for myeloma, Waldenström macroglobulinemia, or chronic lymphocytic leukemia, depending on the underlying pathology. However, the treatment of MGRS and MGNS is not standardized, and potentially effective therapies might not be reimbursed because these conditions do not formally meet the criteria for malignant processes. The present review aims at establishing standards for the evaluation and management of MGRS and MGNS, which can facilitate the diagnosis of and provide therapeutic options for treating practitioners and patients affected by these conditions. The careful design and execution of clinical trials for patients with MGRS and MGNS are positively encouraged.

Vasculitis, Autoimmunity, and Cytokines: How the Immune System Can Harm the Brain

More and more findings suggest that neurological disorders could have an immunopathological cause. Thus, immune-targeted therapies are increasingly proposed in neurology (even if often controversial), as anakinra, inhibiting IL-1 for febrile inflammatory illnesses, and JAK inhibitors for anti-interferons treatment. Precision medicine in neurology could be fostered by a better understanding of the disease machinery, to develop a rational use of immuno-modulators in clinical trials. In this review, we focus on monogenic disorders with neurological hyper-inflammation/autoimmunity as simplified “models” to correlate immune pathology and targeted treatments. The study of monogenic models yields great advantages for the elucidation of the pathogenic mechanisms that can be reproduced in cellular/animal models, overcoming the limitations of biological samples to study. Moreover, monogenic disorders provide a unique tool to study the mechanisms of neuroinflammatory and autoimmune brain damage, in all their manifestations. The insight of clinical, pathological, and therapeutic aspects of the considered monogenic models can impact knowledge about brain inflammation and can provide useful hints to better understand and cure some neurologic multifactorial disorders.

Vasculitic peripheral neuropathy in deficiency of adenosine deaminase 2

Deficiency of adenosine deaminase 2 (DADA2) is an autosomal recessive inflammatory vasculopathy characterized by systemic vasculitis, early-onset stroke and livedo racemosa. We report a family cohort of 3 patients with ADA2 compound heterozygous mutation p.[Thr360Ala] and [Gly383Ser]. Two of them had progressive involvement of the peripheral nervous system in the fourth decade, both after stroke. In one patient, clinical and neurophysiological studies showed progression of mononeuritis multiplex to chronic axonal sensorimotor polyneuropathy, nerve biopsy had features of small vessel vasculitic neuropathy, and muscle biopsy disclosed neurogenic atrophy with reinnervation. The second patient presented with progressive sensory symptoms of the lower limbs and chronic axonal sensorimotor polyneuropathy in nerve conduction studies. These two patients had absent plasma ADA2 activity. The third patient had no neurological affection despite low, but not absent, plasma ADA2 activity. Patients were started on a tumor necrosis factor (TNF) inhibitor, which has presumed benefits for the vasculitic phenotype of DADA2.

COVID-19 Related Acro-Ischemic Neuropathic-like Painful Lesions in Pediatric Patients: A Case Series

BACKGROUND

A variety of skin manifestations have been associated with COVID-19 infection. Acral lesions on hands and feet, closely resembling chilblains, have been reported in association with COVID-19, which are nonspecific. These acro-ischemic painful lesions have been described mainly in asymptomatic and mildly symptomatic pediatric COVID-19 positive patients, without a precise pathogenetic mechanism. COVID-19-induced chilblains may portend an indolent course and a good outcome. In young patients, the IFN-1 response induces microangiopathic changes and produces a chilblain lupus erythematosus-like eruption with vasculitic neuropathic pain features.

OBJECTIVES

This paper presented a case series of pediatric patients with COVID-19-related skin lesions and neuropathic-like pain.

METHODS

Clinical outcomes were collected from 11 patients diagnosed with painful erythematous skin lesions with neuropathic-like pain and positive IgG for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

RESULTS

It is a mildly symptomatic condition not related to severe pain rates, and it is treated with paracetamol due to the transitory nature of the problem, which provides good results.

CONCLUSIONS

A particular point of interest is skin lesion manifestation as a further indirect sign of SARS-CoV-2 infection. Due to the initial manifestation of chilblains in pauci-symptomatic pediatric patients, they need to be immediately tested and isolated. Chilblains can be considered a clinical clue to suspect SARS-CoV-2 infection and help in early diagnosis, patient triage, and infection control.

Chronic Immune-Mediated Polyneuropathies

This article discusses the chronic immune-mediated polyneuropathies, a broad category of acquired polyneuropathies that encompasses chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), the most common immune-mediated neuropathy, the CIDP variants, and the vasculitic neuropathies. Polyneuropathies associated with rheumatological diseases and systemic inflammatory diseases, such as sarcoidosis, will also be briefly covered. These patients' history, examination, serum studies, and electrodiagnostic studies, as well as histopathological findings in the case of vasculitis, confirm the diagnosis and differentiate them from the more common length-dependent polyneuropathies. Prompt identification and initiation of treatment is imperative for these chronic immune-mediated polyneuropathies to prevent disability and even death.

Treatable, motor-sensory, axonal neuropathies with C5b-9 complement on endoneurial microvessels

INTRODUCTION

Identification and treatment of immune-mediated polyneuropathies may lead to improved strength and function. We studied the clinical and laboratory features, and treatment response, in patients with motor-sensory axonal polyneuropathies who were found to have C5b-9 complement staining on endoneurial microvessels.

METHODS

Retrospective review of 16 consecutive adults with motor-sensory axonal polyneuropathies who were then found to have C5b-9 staining of endoneurial microvessels on nerve biopsy, and subsequently treated with intravenous corticosteroids (1 g methylprednisolone for 5 consecutive days, and then weekly). Strength measurements were done using quantitative handheld dynamometry. Nerve biopsy analysis included frozen and fixed tissue.

RESULTS

Patients (mean onset age, 59 ± 4 years; range, 34-83 years; 12 of 16 were males; 9 of 16 had diabetes) had progressive (median duration, 2 years), asymmetric, distal weakness, in the lower extremities (16 of 16) and/or upper extremities (7 of 16), and panmodal sensory loss. Electrodiagnostic studies showed axon loss. Nerve pathology showed abnormal C5b-9 staining on endoneurial microvessels. Axon loss was present in all nerves, often varied among fascicles. Inflammation was uncommon. Distal strength usually improved (mean improvement of 34 ± 6% of normal strength; P = .0003) with corticosteroid treatment.

DISCUSSION

Motor-sensory axonal polyneuropathies having noninflammatory, humoral immune pathology with C5b-9 staining of endoneurial microvessels (HIEM) frequently manifest progressive asymmetric, distal, lower extremity with or without upper extremity weakness that improves rapidly during corticosteroid treatment. HIEM may represent a new class of noninflammatory-vasculopathic, treatable axonal motor-sensory neuropathies.

Orphan Peripheral Neuropathies

Objectives:

Generally, neuropathies of peripheral nerves are a frequent condition (prevalence 2–3%) and most frequently due to alcoholism, diabetes, renal insufficiency, malignancy, toxins, or drugs. However, the vast majority of neuropathies has orphan status. This review focuses on the etiology, frequency, diagnosis, and treatment of orphan neuropathies.

Methods:

Literature review

Results:

Rareness of diseases is not uniformly defined but in the US an orphan disease is diagnosed if the prevalence is <1:200000, in Europe if <5:10000. Most acquired and hereditary neuropathies are orphan diseases. Often the causative variant has been reported only in a single patient or family, particularly the ones that are newly detected (e.g. SEPT9, SORD). Among the complex neuropathies (hereditary multisystem disorders with concomitant neuropathies) orphan forms have been reported among mitochondrial disorders (e.g. NARP, MNGIE, SANDO), spinocerebellar ataxias (e.g. TMEM240), hereditary spastic paraplegias (e.g UBAP1), lysosomal storage disease (e.g. Schindler disease), peroxisomal disorders, porphyrias, and other types (e.g. giant axonal neuropathy, Tangier disease). Orphan acquired neuropathies include the metabolic neuropathies (e.g. vitamin-B1, folic acid), toxic neuropathies (e.g. copper, lithium, lead, arsenic, thallium, mercury), infectious neuropathies, immune-mediated (e.g. Bruns-Garland syndrome), and neoplastic/paraneoplastic neuropathies.

Conclusions:

Though orphan neuropathies are rare per definition they constitute the majority of neuropathies and should be considered as some of them are easy to identify and potentially treatable, as clarification of the underlying cause may contribute to the knowledge about etiology and pathophysiology of these conditions, and as the true prevalence may become obvious only if all ever diagnosed cases are reported.

What Every Neuropathologist Needs to Know: Peripheral Nerve Biopsy

Peripheral neuropathy is a common disorder with many possible etiologies including metabolic diseases, inflammatory conditions, infections, malignancy, inherited diseases, drugs, and toxins. In most instances, diagnosis and treatment plan can be established based on clinical presentation, family history, laboratory results, genetic testing, and electrophysiological studies. But in some situations, a peripheral nerve biopsy remains a valuable tool. This is especially true in patients with rapidly progressive disease, with atypical presentation or for whom other approaches fail to yield a definitive diagnosis. The pathologic examination starts with basic decisions about specimen triage. A few basic questions help to provide an initial framework for the assessment of a nerve biopsy-is the specimen adequate; are there inflammatory changes; are there vascular changes; is there amyloid; are there changes to axonal density and the Schwann cell-myelin-axon unit. In the appropriate context and with such an approach peripheral nerve biopsies can still represent a clinically helpful test.

Vasculitic Peripheral Neuropathy, Differences Between Systemic and Non-Systemic Etiologies: A Case Series and Biopsy Report

BACKGROUND

Vasculitic peripheral neuropathy (VPN) is caused by vessel inflammation leading to peripheral nerve injury of acute-to-subacute onset. When VPN occurs in the context of systemic disease it is classified as Systemic Vasculitic Neuropathy (SVN) and as Non-Systemic Vasculitic Neuropathy (NSVN) when restricted to the nerves.

OBJECTIVE

This study aimed to compare the clinical characteristics, biopsy findings and disease outcome in patients with VPN.

METHODS

Clinical records of adult patients with VPN diagnosed at our institution between June-2002 and June-2019 were retrospectively reviewed. Demographic characteristics, clinical manifestations, nerve conduction studies, nerve biopsies, treatment and clinical evolution were analyzed in all patients with at least 6 months follow-up.

RESULTS

Twenty-five patients with VPN were included (SVN, n = 10; NSVN, n = 15). No significant differences in demographic or clinical features were found between groups. The median delay between symptom onset and nerve biopsy was significantly longer in NSVN patients (10 vs 5.5 months, p = 0.009). Erythrocyte sedimentation rate (ESR) values over 20 mm/h were significantly more common in SVN patients (100% vs. 60%, p = 0.024). Nerve biopsies showed active lesions more frequently in treatment-naive patients compared to those who had received at least 2 weeks of corticosteroids (92% vs 38%; p = 0.03), with a higher proportion of definite VPN cases (92 vs 46%; p = 0.04).

CONCLUSIONS

Although the clinical manifestations are similar, ESR is an important tool to help distinguish between both conditions. Early nerve biopsy in untreated patients increases diagnostic accuracy, avoiding misdiagnosis.

Peripheral neuropathy in systemic vasculitis and other autoimmune diseases - a report of five cases emphasizing the importance of etiologic characterization

Introduction

Peripheral neuropathies may present in the context of systemic vasculitis and other autoimmune diseases. The etiologic characterization is crucial to define the treatment and prognosis in secondary vasculitis. The purpose of this study is to describe the pathway of etiologic investigation including the role of nerve biopsy.

Methods

Retrospective analysis of patients seen in the neuromuscular outpatient clinic during the last four years with peripheral neuropathy in the context of systemic vasculitis or other autoimmune diseases.

Results

We present five patients with stepwise progressive sensorimotor deficits of upper and lower limbs. All patients presented with systemic features and one of them had an established diagnosis of systemic vasculitis. They underwent an extended blood panel, including autoimmune and serologic tests. Electromyography and nerve conduction studies revealed asymmetric axonal sensorimotor polyneuropathies in four patients, and an axonal sensorimotor multiple mononeuropathy in one. Four patients underwent nerve biopsy and the other performed a skin biopsy, with findings suggestive of possible vasculitic processes. The etiologies identified included microscopic polyangiitis, HBV-related polyarteritis nodosa and two eosinophilic granulomatosis with polyangiitis. In the last patient a specific etiology could not be established.

Conclusion

This series reveals the etiologic and phenotypic diversity of peripheral neuropathies related with systemic vasculitis. The therapeutic approach and prognosis were distinct in each patient, emphasizing the importance of a prompt diagnosis and appropriate treatment.

Neuralgic amyotrophy: a paradigm shift in diagnosis and treatment

Neuralgic amyotrophy (NA), also known as Parsonage-Turner syndrome, is characterised by sudden pain attacks, followed by patchy muscle paresis in the upper extremity. Recent reports have shown that incidence is much higher than previously assumed and that the majority of patients never achieve full recovery. Traditionally, the diagnosis was mainly based on clinical observations and treatment options were confined to application of corticosteroids and symptomatic management, without proven positive effects on long-term outcomes. These views, however, have been challenged in the last years. Improved imaging methods in MRI and high-resolution ultrasound have led to the identification of structural peripheral nerve pathologies in NA, most notably hourglass-like constrictions. These pathognomonic findings have paved the way for more accurate diagnosis through high-resolution imaging. Furthermore, surgery has shown to improve clinical outcomes in such cases, indicating the viability of peripheral nerve surgery as a valuable treatment option in NA. In this review, we present an update on the current knowledge on this disease, including pathophysiology and clinical presentation, moving on to diagnostic and treatment paradigms with a focus on recent radiological findings and surgical reports. Finally, we present a surgical treatment algorithm to support clinical decision making, with the aim to encourage translation into day-to-day practice.

Clinical diagnosis and management of small fiber neuropathy: an update on best practice

INTRODUCTION

Small fiber neuropathy (SFN) is a heterogeneous group of disorders affecting thin myelinated Aδ and unmyelinated C fibers. Common symptoms include neuropathic pain and autonomic disturbances, and the typical clinical presentation is that of a length-dependent polyneuropathy, although other distributions could be present.

AREA COVERED

This review focuses on several aspects of SFN including etiology, clinical presentation, diagnostic criteria and tests, management, and future perspectives. Diagnostic challenges are discussed, encompassing the role of accurate and standardized assessment of symptoms and signs and providing clues for the clinical practice. The authors discuss the evidence in support of skin biopsy and quantitative sensory testing as diagnostic tests and present an overview of other diagnostic techniques to assess sensory and autonomic fibers dysfunction. The authors also suggest a systematic approach to the etiology including a set of laboratory tests and genetic examinations of sodium channelopathies and other rare conditions that might drive the therapeutic approach based on underlying cause or symptoms treatment.

EXPERT OPINION

SFN provides a useful model for neuropathic pain whose known mechanisms and cause could pave the way toward personalized treatments.