Extreme efficacy of intravenous immunoglobulin therapy for severe burning pain in a patient with small fiber neuropathy associated with primary Sjögren’s syndrome

Small fiber neuropathy

Small fiber neuropathy (SFN) is a peripheral nervous system disease due to affection of A-delta or C-fibers in a proximal, distal, or diffuse distribution. Selective SFN (without large fiber affection) manifests with pain, sensory disturbances, or autonomic dysfunction. Though uniform diagnostic criteria are unavailable, most of them request typical clinical features and reduced intra-epidermal nerve fiber density on proximal or distal skin biopsy. Little consensus has been reached about the treatment of SFN, why this narrative review aims at summarizing and discussing treatment options for SFN. Treatment of SFN can be classified as symptomatic, pathophysiologic, or causal. Prerequisites for treating SFN are an established diagnosis, knowledge about the symptoms and signs, and the etiology. Pain usually responds to oral/intravenous pain killers, antidepressants, anti-seizure drugs, or topical, transdermal specifications. Some of the autonomic disturbances respond favorably to symptomatic treatment. SFN related to Fabry disease or hATTR are accessible to pathogenesis-related therapy. Immune-mediated SFN responds to immunosuppression or immune-modulation. Several of the secondary SFNs respond to causal treatment of the underlying disorder. In conclusion, treatment of SFN relies on a multimodal concept and includes causative, pathophysiologic, and symptomatic measures. It strongly depends on the clinical presentation, diagnosis, and etiology, why it is crucial before initiation of treatment to fix the diagnosis and etiology. Due to the heterogeneous clinical presentation and multi-causality, treatment of SFN should be individualized with the goal of controlling the underlying cause, alleviating pain, and optimizing functionality.

Novel Autoantibodies in Idiopathic Small Fiber Neuropathy

Objective

Small fiber neuropathy (SFN) is clinically and etiologically heterogeneous. Although autoimmunity has been postulated to be pathophysiologically important in SFN, few autoantibodies have been described. We aimed to identify autoantibodies associated with idiopathic SFN (iSFN) by a novel high‐throughput protein microarray platform that captures autoantibodies expressed in the native conformational state.

Methods

Sera from 58 SFN patients and 20 age‐ and gender‐matched healthy controls (HCs) were screened against >1,600 immune‐related antigens. Fluorescent unit readout and postassay imaging were performed, followed by composite data normalization and protein fold change (pFC) analysis. Analysis of an independent validation cohort of 33 SFN patients against the same 20 HCs was conducted to identify reproducible proteins in both cohorts.

Results

Nine autoantibodies were screened with statistical significance and pFC criteria in both cohorts, with at least 50% change in serum levels. Three proteins showed consistently high fold changes in main and validation cohorts: MX1 (FC = 2.99 and 3.07, respectively, p = 0.003, q = 0.076), DBNL (FC = 2.11 and 2.16, respectively, p = 0.009, q < 0.003), and KRT8 (FC = 1.65 and 1.70, respectively, p = 0.043, q < 0.003). Further subgroup analysis into iSFN and SFN by secondary causes (secondary SFN) in the main cohort showed that MX1 is higher in iSFN compared to secondary SFN (FC = 1.61 vs 0.106, p = 0.009).

Interpretation

Novel autoantibodies MX1, DBNL, and KRT8 are found in iSFN. MX1 may allow diagnostic subtyping of iSFN patients. ANN NEUROL 2022;91:66–77

Combinatorial therapy with immunosuppressive, immunomodulatory and tear substitute eyedrops ("Triple Play") in Recalcitrant Immunological Ocular Surface Diseases

PURPOSE

The current paradigm for therapy of recalcitrant ocular surface diseases (OSD) consists of a sequential, step-up treatment approach. A combinatorial topical therapy (anti-inflammatory/immunosuppressive [steroid] with immunomodulatory [pooled human immune globulin] and tear substitute [serum]) that simultaneously targets several immunological pathways may be more efficacious. This report evaluates if the combinatorial therapy resulted in clinical benefit in patients with recalcitrant OSD.

METHODS

We performed a retrospective case study of patients receiving topical, preservative-free, compounded formulations of steroids, pooled human immune globulin, and serum tears. Outcome measures included visual acuity, ocular surface disease index (OSDI), ocular discomfort score, subjective global assessment (SGA), corneal staining, conjunctival redness, and slit lamp photographs.

RESULTS

Patients consisted of one male and 11 females ranging in age from 27 to 87 years old. Pathologies included ocular graft-versus-host disease (n = 4), Sjögren's syndrome (n = 3), ocular cicatricial pemphigoid (n = 1), pemphigus vulgaris (n = 1), peripheral ulcerative keratitis (n = 1), Stevens-Johnson syndrome (n = 1), and giant papillary conjunctivitis (n = 1). All patients were "improved" or "much improved" on SGA after combinatorial therapy. There was a clinically meaningful reduction in OSDI, ocular discomfort, corneal staining, and conjunctival injection. Additionally, three patients had improvement in their visual acuity (one from 20/400 to 20/20). Adverse effects included increased intraocular pressure in two patients, presumably due to topical steroid use.

CONCLUSIONS

Combinatorial therapy provides clinical benefit by reducing the symptoms and signs in recalcitrant OSD. Our study provides the rationale for performing prospective clinical trials to evaluate the efficacy of combinatorial therapy for treating recalcitrant OSD.

Autoimmune Neurologic Emergencies

Over the past decade, understanding of autoimmune neurologic disorders has exponentially increased. Many patients present as a neurologic emergency and require timely evaluation with rapid management and intensive care. However, the diagnosis is often either missed or delayed, which may lead to a significant burden of disabling morbidity and even mortality. A high level of suspicion in the at-risk population should be maintained to facilitate more rapid diagnosis and prompt treatment. At present, there is no all-encompassing algorithm specifically applicable to the management of fulminant autoimmune neurologic disorders. This article discusses manifestations and management of various autoimmune neurologic emergencies.

Peripheral nervous system manifestations of rheumatological diseases

Rheumatological diseases result in immune-mediated injury to not only connective tissue, but often components of the peripheral nervous system. These overlap conditions can be broadly categorized as peripheral neuropathies and overlap myositis. The peripheral neuropathies are distinctive as many have unusual presentations such as non-length-dependent, small fiber neuropathies and sensory neuronopathies (both due to dorsal root ganglia dysfunction), multiple mononeuropathies (e.g. vasculitic neuropathies), and even cranial neuropathies. Overlap myositis is increasingly recognized and is often associated with specific autoantibodies. Sarcoidosis also has widespread neurological manifestations and impacts both the peripheral nerves and muscle. Much work is needed to fully characterize the vast presentations of these overlap diseases. Given the rarity of these disorders, they are understudied, resulting in significant knowledge gaps with regards to their underlying pathophysiology and the best treatment approach. A basic knowledge of these disorders is mandatory for both practicing rheumatologists and neurologists as prompt recognition and early initiation of immunotherapy may prevent significant morbidity and permanent disability.

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.

Immunosuppressive treatment for peripheral neuropathies in Sjogren's syndrome - a systematic review

BACKGROUND

Sjogren's syndrome (SS) is among the most frequent autoimmune diseases and one of its most severe extraglandular manifestations is peripheral neuropathy. There is no consensus about peripheral neuropathy treatment in SS. Our aim is to identify studies proving the efficiency of immunosuppressive treatment on peripheral neuropathies in SS.

METHODS

The search was conducted on the PubMed (MEDLINE) database. Studies with patients diagnosed with SS and peripheral neuropathy were included. Treatment with one of the following was among inclusion criteria: glucocorticoids (GC), rituximab (RTX), azathioprine (AZA), mycophenolic acid (MMF), cyclophosphamide (CP), methotrexate (MTX), plasmapheresis or iv immunoglobulins (IV IG).

RESULTS

A total of 116 results were found and abstracts were examined. 103 papers were excluded, and the remaining 13 papers were analyzed. They were 3 case series and 10 case reports, retrospective, totalizing 62 patients of which 22 (35.5%) received IV IG, 8 (13%) received RTX, 7 (11%) CP, and 5 (8%) received only GC. Drug associations containing corticosteroids were frequent. Of those 22 treated with IV IG, 18 patients improved (82%), and 4 stabilized (18%). IV IG was useful in sensory, motor and sensorimotor neuropathies. CP had good results in mononeuritis multiplex, while autonomic neuropathies responded well to GC or RTX. AZA, RTX, MTX, MMF or plasmapheresis were not used alone. Follow-up periods were heterogenous and the evaluation of the neuropathy was not systematic.

CONCLUSION

There is only low level evidence (retrospective case reports and case series). In most cases, IV IG treatment in patients with peripheral neuropathies and SS resulted in clinical improvement, while other therapies, such as RTX, corticosteroids and CP proved to be useful in a handful of cases.

A Systematic Review of Pharmacologic and Rehabilitative Treatment of Small Fiber Neuropathies

The aim of this systematic review is to guide the physician in defining the pharmacologic and rehabilitative therapeutic approaches for adopting the best strategies described in the current literature. The search was conducted in PubMed, EMBASE, Cochrane Library and Web of Science to identify the treatment of small fiber neuropathies. Two reviewers independently reviewed and came to a consensus on which articles met inclusion/exclusion criteria. The authors excluded the duplicates, animal studies and included the English articles in which the treatment of patients with small fiber neuropathies was described. The search identified a total of 975 articles with the keywords “small fiber neuropathy” AND “rehabilitation” OR “therapy” OR “treatment”. Seventy-eight selected full-text were analyzed by the reviewers. Forty-two publications met the inclusion criteria and were included in the systematic review to describe the rehabilitative and pharmacologic treatment of small fiber neuropathies. Despite the range of different protocols of treatment for small fiber neuropathy, other robust trials are needed. In addition, always different therapeutic approaches are used; a unique protocol could be important for the clinicians. More research is needed to build evidence for the best strategy and to delineate a definitive therapeutic protocol.

Detection of nerve enlargement with ultrasound and correlation with skin biopsy findings in painful sensory neuropathy associated with Sjögren's syndrome

OBJECTIVES

We evaluated usefulness of peripheral nerve ultrasound (US) in detecting abnormality in painful sensory neuropathy (PSN) associated with primary Sjögren's syndrome (pSS), and associations among various clinical factors, US findings, and intraepidermal nerve fiber density (IENFD).

METHODS

We conducted a retrospective, single-center, observational study of patients with pSS-PSN. US image was obtained to measure cross sectional area (CSA) of peripheral nerves and compared with matched pSS control.

RESULTS

We included 11 patients with pSS-PSN (10 women; age 70.5 ± 5.66) and 17 pSS controls (15 women; age 62.5 ± 16.7). Sural nerve CSA were significantly increased in pSS-PSN group (3.48 ± 1.0 mm² vs 2.05 ± 0.65 mm², p = .001). US of sural nerve showed the area under the ROC curve of 0.872 (95% CI, 0.732 - 1). Sural nerve CSA and IENFD of lower leg showed positive correlation. Compared with pSS-PSN patients with abnormal IENFD, those with normal IENFD showed significantly larger sural nerve CSA, and trends toward less systemic disease activity and small fiber impairment with sparing of large fibers.

CONCLUSION

US was useful in discriminating pSS patients with PSN from those without. Additionally, US may disclose distinct subsets of pSS-PSN with different clinical findings and IENFD.

A Systematic Review of the Diagnostic Methods of Small Fiber Neuropathies in Rehabilitation

This systematic review describes the several methods to diagnose and measure the severity of small fiber neuropathies and aims to guide the physician to define all the diagnostic approaches for adopting the best strategies described in the current literature. The search was conducted in PubMed, EMBASE, Cochrane Library and Web of Science. Two reviewers independently reviewed and came to consensus on which articles met inclusion/exclusion criteria. The authors excluded all the duplicates, animals' studies, and included the English articles in which the diagnostic measures were finalized to assess the effectiveness of rehabilitation and pharmacologic treatment of patients with small fiber neuropathies. The search identified a total of 975 articles with the keywords "small fiber neuropathy" AND "rehabilitation" OR "therapy" OR "treatment". Seventy-eight selected full-text were analyzed by the reviewers. Forty-one publications met the inclusion criteria and were included in the systematic review. Despite the range of diagnostic tools for the assessment of small fiber neuropathy, other robust trials are needed. In addition, always different diagnostic approaches are used, a unique protocol could be important for the clinicians. More research is needed to build evidence for the best diagnostic methodologies and to delineate a definitive diagnostic protocol.

Neuro-Sjögren: Uncommon or underestimated problem?

OBJECTIVES

Sjögren's syndrome (SS) is a chronic inflammatory disease with an autoimmune background with possible complications from peripheral (PNS) and central nervous system (CNS). The aim of this study was to assess the prevalence and to describe the phenotype of peripheral neuropathies in patients with SS.

MATERIALS & METHODS

We studied fifty patients with primary Sjögren's syndrome for peripheral nervous system involvement. All patients underwent neurological and rheumatological examination followed by nerve conduction studies (NCS) of nine peripheral nerves.

RESULTS

Thirty-six patients (72%) fulfilled the criteria for the diagnosis of neuropathy. Carpal tunnel syndrome (54%) and axonal sensorimotor neuropathy (22%) were the most common. Neurological symptoms preceded the diagnosis of SS in eight patients.

CONCLUSIONS

Peripheral neuropathies are frequent in SS patients. Neurologists should be aware of possible autoimmune causes of neuropathies because clinical manifestations of neuropathy may precede the development of other symptoms of the autoimmune disease.

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.

Pathological consequences of anti-citrullinated protein antibodies in tear fluid and therapeutic potential of pooled human immune globulin-eye drops in dry eye disease

PURPOSE

To investigate the role of Anti-Citrullinated Protein autoantibodies (ACPAs) in the pathology of dry eye disease (DED) and the therapeutic potential of pooled human immune globulin-eye drops in these patients.

METHODS

We investigated the presence of citrullinated proteins and ACPAs in ocular surface wash (OSW) and conjunctival impressions from patients with DED and determined the pathological consequences of OSW with high ACPA using in vitro experiments and in vivo murine models. We performed a randomized, double-masked, pilot clinical trial to determine the safety, tolerability and preliminary efficacy of using pooled human immune globulin-eye drops to treat DED patients with ACPAs in OSW.

RESULTS

We found that neutrophils are a source of citrullinated proteins on the ocular surface of DED patients. We detected significantly higher immunoglobulin amount and presence of several species of ACPAs in OSW from DED patients. We also found that OSW with high ACPA contributes to production of NETs, and that ACPAs cause ocular surface disease in murine eyes, both of which are reduced with addition of Immune globulins. As compared to Vehicle treatment, pooled human immune globulin-eye drops (IVIG 4 mg/mL) twice a day for 8 weeks caused significant reduction in signs and symptoms of DED with no difference in tolerability or adverse events.

CONCLUSIONS

This is the first report demonstrating ACPAs in OSW of DED patients and their contribution to ocular surface disease. The first-in-human clinical trial suggests that pooled immune globulin-eye drops are a potential new class of biologic therapies for Dry Eye patients.

Efficacy and Tolerability of Intravenous Immunoglobulin and Subcutaneous Immunoglobulin in Neurologic Diseases

PURPOSE

IV immunoglobulin (Ig) therapy has been widely used for the treatment of neurologic disorders, autoimmune diseases, immunodeficiency-related diseases, blood system diseases, and cancers. In this review, we summarize the efficacy and tolerability of IVIg and SCIg therapy in neurologic diseases.

METHODS

We summarized and analyzed the efficacy and tolerability of IVIg and SCIg in neurologic diseases, by analyzing the literature pertaining to the use of IVIg and SCIg to treat nervous system diseases.

FINDINGS

In clinical neurology practice, IVIg has been shown to be useful for the treatment of new-onset or recurrent immune diseases and for long-term maintenance treatment of chronic diseases. Moreover, IVIg may have applications in the management of intractable autoimmune epilepsy, paraneoplastic syndrome, autoimmune encephalitis, and neuromyelitis optica. SCIg is emerging as an alternative to IVIg treatment. Although SCIg has a composition similar to that of IVIg, the applications of this therapy are different. Notably, the bioavailability of SCIg is lower than that of IVIg, but the homeostasis level is more stable. Current studies have shown that these 2 therapies have pharmacodynamic equivalence.

IMPLICATIONS

In this review, we explored the efficacy of IVIg in the treatment of various neurologic disorders. IVIg administration still faces many challenges. Thus, it will be necessary to standardize the use of IVIg in the clinical setting. SCIg administration is a novel and feasible treatment option for neurologic and immune-related diseases, such as chronic inflammatory demyelinating polyradiculoneuropathy and idiopathic inflammatory myopathies. As our understanding of the mechanisms of action of IVIg improve, potential next-generation biologics can being developed.

Diagnosis and management of sensory polyneuropathy

Sensory polyneuropathies, which are caused by dysfunction of peripheral sensory nerve fibers, are a heterogeneous group of disorders that range from the common diabetic neuropathy to the rare sensory neuronopathies. The presenting symptoms, acuity, time course, severity, and subsequent morbidity vary and depend on the type of fiber that is affected and the underlying cause. Damage to small thinly myelinated and unmyelinated nerve fibers results in neuropathic pain, whereas damage to large myelinated sensory afferents results in proprioceptive deficits and ataxia. The causes of these disorders are diverse and include metabolic, toxic, infectious, inflammatory, autoimmune, and genetic conditions. Idiopathic sensory polyneuropathies are common although they should be considered a diagnosis of exclusion. The diagnostic evaluation involves electrophysiologic testing including nerve conduction studies, histopathologic analysis of nerve tissue, serum studies, and sometimes autonomic testing and cerebrospinal fluid analysis. The treatment of these diseases depends on the underlying cause and may include immunotherapy, mitigation of risk factors, symptomatic treatment, and gene therapy, such as the recently developed RNA interference and antisense oligonucleotide therapies for transthyretin familial amyloid polyneuropathy. Many of these disorders have no directed treatment, in which case management remains symptomatic and supportive. More research is needed into the underlying pathophysiology of nerve damage in these polyneuropathies to guide advances in treatment.

Small-fiber neuropathy definition, diagnosis, and treatment

In the last 30 years, improvement of diagnostic methods enabled routine evaluation of small A-delta and C nerve fibers impairment, which results with the clinical condition known as a small-fiber neuropathy (SFN). This syndrome develops as a result of metabolic, toxic, immune-mediated, or genetic factors. The main clinical features include neuropathic pain and autonomic disturbance, which are occasionally disclaimed due to outstanding fatigue, daily performance decline, anxiety, and depression. As clinical, neurological, nerve conduction, and electromyography studies are commonly normal, diagnosis often depends on the finding of decreased intra-epidermal density of nerve fibers, per skin biopsy. This review highlights the etiology, clinical, diagnostic aspects, and SFN treatment.

Pruritus in Autoimmune Connective Tissue Diseases

Pruritus in autoimmune connective tissue diseases is a common symptom that can be severe and affect the quality of life of patients. It can be related to disease activity and severity or occur independent of the disease. Appropriate therapy to control the itch depends on the etiology, and it is therefore essential to first work-up these patients for the underlying trigger.

IVIg for apparently autoimmune small-fiber polyneuropathy: first analysis of efficacy and safety

OBJECTIVES

Small-fiber polyneuropathy (SFPN) has various underlying causes, including associations with systemic autoimmune conditions. We have proposed a new cause; small-fiber-targeting autoimmune diseases akin to Guillain-Barré and chronic inflammatory demyelinating polyneuropathy (CIDP). There are no treatment studies yet for this 'apparently autoimmune SFPN' (aaSFPN), but intravenous immunoglobulin (IVIg), first-line for Guillain-Barré and CIDP, is prescribed off-label for aaSFPN despite very high cost. This project aimed to conduct the first systematic evaluation of IVIg's effectiveness for aaSFPN.

METHODS

With IRB approval, we extracted all available paper and electronic medical records of qualifying patients. Inclusion required having objectively confirmed SFPN, autoimmune attribution and other potential causes excluded. IVIg needed to have been dosed at ⩾1 g/kg/4 weeks for ⩾3 months. We chose two primary outcomes - changes in composite autonomic function testing (AFT) reports of SFPN and in ratings of pain severity - to capture objective as well as patient-prioritized outcomes.

RESULTS

Among all 55 eligible patients, SFPN had been confirmed by 3/3 nerve biopsies, 62% of skin biopsies, and 89% of composite AFT. Evidence of autoimmunity included 27% of patients having systemic autoimmune disorders, 20% having prior organ-specific autoimmune illnesses and 80% having ⩾1/5 abnormal blood-test markers associated with autoimmunity. A total of 73% had apparent small-fiber-restricted autoimmunity. IVIg treatment duration averaged 28 ± 25 months. The proportion of AFTs interpreted as indicating SFPN dropped from 89% at baseline to 55% (p ⩽ 0.001). Sweat production normalized (p = 0.039) and the other four domains all trended toward improvement. Among patients with pre-treatment pain ⩾3/10, severity averaging 6.3 ± 1.7 dropped to 5.2 ± 2.1 (p = 0.007). Overall, 74% of patients rated themselves 'improved' and their neurologists labeled 77% as 'IVIg responders'; 16% entered remissions that were sustained after IVIg withdrawal. All adverse events were expected; most were typical infusion reactions. The two moderate complications (3.6%) were vein thromboses not requiring discontinuation. The one severe event (1.8%), hemolytic anemia, remitted after IVIg discontinuation.

CONCLUSION

These results provide Class IV, real-world, proof-of-concept evidence suggesting that IVIg is safe and effective for rigorously selected SFPN patients with apparent autoimmune causality. They provide rationale for prospective trials, inform trial design and indirectly support the discovery of small-fiber-targeting autoimmune/inflammatory illnesses.

Magnetic resonance imaging of the spinal cord in the evaluation of 3 patients with sensory neuronopathies: Diagnostic assessment, indications of treatment response, and impact of autoimmunity: A case report

RATIONALE

Sensory neuronopathy can be a devastating peripheral nervous system disorder. Profound loss in joint position is associated with sensory ataxia, and reflects degeneration of large-sized dorsal root ganglia. Prompt recognition of sensory neuronopathies may constitute a therapeutic window to intervene before there are irreversible deficits. However, nerve-conduction studies may be unrevealing early in the disease course. In such cases, the appearance of dorsal column lesions on spinal-cord MRI can help in the diagnosis. However, most studies have not defined whether such dorsal column lesions may occur within earlier as well as chronic stages of sensory neuronopathies, and whether serial MRI studies can be used to help assess treatment efficacy. In this case-series of three sensory neuronopathy patients, we report clinical characteristics, immunological markers, nerve-conduction and skin-biopsy studies, and neuroimaging features.

PATIENT CONCERNS

All three patients presented with characteristic features of sensory neuronopathy with abnormal spinal-cord MRI studies. Radiographic findings included non-enhancing lesions in the dorsal columns that were longitudinally extensive (spanning ≥ 3 vertebral segments).

DIAGNOSES

All patients had anti-Ro/SS-A and/or anti-La/SS-B antibodies, with patients one and two having Sjögren's syndrome. MRI findings were similar when performed in the earlier stages of a sensory neuronopathy (patient one, after four months) and chronic stages (patients two and three, after five and three years, respectively).

INTERVENTIONS

Patient one was treated with rituximab combined with intravenous immunoglobulin therapy.

OUTCOMES

Patient one was initially wheelchair-bound and had improved ambulation after treatment. In this patient, serial MRI studies revealed partial resolution of dorsal column lesions, associated with decreased sensory ataxia and improved nerve-conduction studies.

LESSONS

In addition to vitamin B12 and copper deficiency, it is important to include sensory neuronopathies in the differential diagnosis of dorsal column lesions. MRI spinal-cord lesions have similar appearances in the earlier as well as chronic phases of a sensory neuronopathy, and therefore suggest that such dorsal column lesions may reflect inflammatory as well as a gliotic burden of injury. MRI may also be a useful longitudinal indicator of treatment response.

Connective Tissue Disorder-Associated Vasculitis

Vasculitides secondary to connective tissue diseases are classified under the category of 'vasculitis associated with systemic disease' in the revised International Chapel Hill Consensus Conference (CHCC) nomenclature. These secondary vasculitides may affect any of the small, medium or large vessels and usually portend a poor prognosis. Any organ system can be involved and the presentation would vary depending upon that involvement. Treatment depends upon the type and severity of presentation. In this review, we describe secondary vasculitis associated with rheumatoid arthritis, systemic lupus erythematosus, sarcoidosis, relapsing polychondritis, systemic sclerosis, Sjogren's syndrome and idiopathic inflammatory myositis, focusing mainly on recent advances in the past 3 years.

Intravenous immunoglobulin therapy for small fiber neuropathy: study protocol for a randomized controlled trial

Background

Small fiber neuropathy is the most common cause of neuropathic pain in peripheral neuropathies, with a minimum prevalence of 53/100,000. Patients experience excruciating pain, and currently available anti-neuropathic and other pain drugs do not relieve the pain substantially. Several open-label studies have suggested an immunological basis in small fiber neuropathy and have reported efficacy of treatment with intravenous immunoglobulin. Therefore, immunological mechanisms conceivably may play a role in small fiber neuropathy. To date, no randomized controlled study with intravenous immunoglobulin in patients with small fiber neuropathy has been performed.

Methods/design

This study is a randomized, double-blind, placebo-controlled, clinical trial in patients with idiopathic small fiber neuropathy. The primary objective is to investigate the efficacy of intravenous immunoglobulin versus placebo on pain alleviation. A 1-point change in the PI-NRS compared to baseline is considered the minimum clinically important difference. In the IVIg-treated group, we assume a response rate of approximately 60 % based on the criteria composed by the IMMPACT group for measurement of pain. Based on this, a sample size of 60 patients is needed. Eligible patients fulfilling the inclusion/exclusion criteria will be randomized to receive either intravenous immunoglobulin or placebo (0.9 % saline). The treatment regimen will start with a loading dose of 2 g/kg body weight over 2–4 consecutive days, followed by a maintenance dose of 1 g/kg body weight over 1–2 consecutive days given three times at a 3-week interval. The primary endpoint is the comparison of the percentage of responder subjects between the two treatment groups from the first randomization during the 12 weeks of treatment. A responder is defined as ≥ 1-point Pain Intensity Numerical Rating Scale improvement on the mean weekly peak pain relative to baseline. The secondary outcomes are pain intensity, pain qualities, other small fiber neuropathy-related complaints, daily and social functioning, as well as quality of life. In addition, safety assessments will be performed for adverse events, vital signs, and laboratory values outside the normal range. Responders during the 12-week treatment period will be followed during a 3-month extension phase.

Discussion

This is the first randomized, double-blind, placebo-controlled clinical trial with intravenous immunoglobulin in patients with idiopathic small fiber neuropathy. Positive findings will result in a new treatment option for small fiber neuropathy and support an immunological role in this condition.

Trial registration

ClinicalTrials.gov, NCT02637700. Registered on 16 December 2015.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-016-1450-x) contains supplementary material, which is available to authorized users.

Immunotherapies for Neurological Manifestations in the Context of Systemic Autoimmunity

Neurological involvement is relatively common in the majority of systemic autoimmune diseases and may lead to severe morbidity and mortality, if not promptly treated. Treatment options vary greatly, depending on the underlying systemic pathophysiology and the associated neurological symptoms. Selecting the appropriate therapeutic scheme is further complicated by the lack of definite therapeutic guidelines, the necessity to differentiate primary neurological syndromes from those related to the underlying systemic disease, and to sort out adverse neurological manifestations caused by immunosuppressants or the biological agents used to treat the primary disease. Immunotherapy is a sine qua non for treating most, if not all, neurological conditions presenting in the context of systemic autoimmunity. Specific agents include classical immune modulators such as corticosteroids, cyclophosphamide, intravenous immunoglobulin, and plasma exchange, as well as numerous biological therapies, for example anti-tumor necrosis factor agents and monoclonal antibodies that target various immune pathways such as B cells, cytokines, and co-stimulatory molecules. However, experience regarding the use of these agents in neurological complications of systemic diseases is mainly empirical or based on small uncontrolled studies and case series. The aim of this review is to present the state-of-the-art therapies applied in various neurological manifestations encountered in the context of systemic autoimmune diseases; evaluate all treatment options on the basis of existing guidelines; and compliment these data with our personal experience derived from a large number of patients.

Facial Weakness, Otalgia, and Hemifacial Spasm: A Novel Neurological Syndrome in a Case-Series of 3 Patients With Rheumatic Disease

Bell palsy occurs in different rheumatic diseases, causes hemifacial weakness, and targets the motor branch of the 7th cranial nerve. Severe, persistent, and refractory otalgia having features of neuropathic pain (ie, burning and allodynic) does not characteristically occur with Bell palsy. Whereas aberrant regeneration of the 7th cranial nerve occurring after a Bell palsy may lead to a variety of clinical findings, hemifacial spasm only rarely occurs. We identified in 3 rheumatic disease patients (2 with Sjögren syndrome, 1 with rheumatoid arthritis) a previously unreported neurological syndrome of facial weakness, otalgia with neuropathic pain features, and hemifacial spasm. We characterized symptoms, examination findings, and response to therapy. All 3 patients experienced vertigo, as well as severe otalgia which persisted after mild facial weakness had completely resolved within 1 to 4 weeks. The allodynic nature of otalgia was striking. Two patients were rendered homebound, as even the barest graze of outdoor breezes caused intolerable ear pain. Patients developed hemifacial spasm either at the time of or within 3 months of facial weakness. Two patients had a polyphasic course, with recurrent episodes of facial weakness and increased otalgia. In all cases, otalgia and hemifacial spasm were unresponsive to neuropathic pain regimens, but responded in 1 case to intravenous immunoglobulin therapy. No patients had vesicles or varicella zoster virus in spinal-fluid studies. We have defined a novel neurological syndrome in 3 rheumatic disease patients, characterized by facial weakness, otalgia, and hemifacial spasm. As described in infectious disorders, the combination of otalgia, facial weakness, and 8th cranial nerve deficits suggests damage to the geniculate ganglia (ie, the sensory ganglia of the 7th cranial nerve), with contiguous involvement of other cranial nerves causing facial weakness and vertigo. However, the relapsing nature and association with hemifacial spasm constitute a unique part of this neurological syndrome.

Movement and Other Neurodegenerative Syndromes in Patients with Systemic Rheumatic Diseases: A Case Series of 8 Patients and Review of the Literature

Patients with rheumatic diseases can present with movement and other neurodegenerative disorders. It may be underappreciated that movement and other neurodegenerative disorders can encompass a wide variety of disease entities. Such disorders are strikingly heterogeneous and lead to a wider spectrum of clinical injury than seen in Parkinson's disease. Therefore, we sought to stringently phenotype movement and other neurodegenerative disorders presenting in a case series of rheumatic disease patients. We integrated our findings with a review of the literature to understand mechanisms which may account for such a ubiquitous pattern of clinical injury.Seven rheumatic disease patients (5 Sjögren's syndrome patients, 2 undifferentiated connective tissue disease patients) were referred and could be misdiagnosed as having Parkinson's disease. However, all of these patients were ultimately diagnosed as having other movement or neurodegenerative disorders. Findings inconsistent with and more expansive than Parkinson's disease included cerebellar degeneration, dystonia with an alien-limb phenomenon, and nonfluent aphasias.A notable finding was that individual patients could be affected by cooccurring movement and other neurodegenerative disorders, each of which could be exceptionally rare (ie, prevalence of ∼1:1000), and therefore with the collective probability that such disorders were merely coincidental and causally unrelated being as low as ∼1-per-billion. Whereas our review of the literature revealed that ubiquitous patterns of clinical injury were frequently associated with magnetic resonance imaging (MRI) findings suggestive of a widespread vasculopathy, our patients did not have such neuroimaging findings. Instead, our patients could have syndromes which phenotypically resembled paraneoplastic and other inflammatory disorders which are known to be associated with antineuronal antibodies. We similarly identified immune-mediated and inflammatory markers of injury in a psoriatic arthritis patient who developed an amyotrophic lateral sclerosis (ALS)-plus syndrome after tumor necrosis factor (TNF)-inhibitor therapy.We have described a diverse spectrum of movement and other neurodegenerative disorders in our rheumatic disease patients. The widespread pattern of clinical injury, the propensity of our patients to present with co-occurring movement disorders, and the lack of MRI neuroimaging findings suggestive of a vasculopathy collectively suggest unique patterns of immune-mediated injury.

[Case report of effective intravenous immunoglobulin for lower limbs pain in steroid-resistant eosinophilic granulomatosis with polyangiitis]

We report a 58-year-old woman with bronchial asthma. The onset of the disease was marked by numbness in the right lower extremity, for which she was hospitalized 10 days later. The patient presented with sensory impairment and muscle weakness in the distal regions of both lower limbs, acute pain, purpura, and a leukocyte count of 2.4 × 10(4)/μl (59.2% eosinophils). Nerve conduction tests revealed a decrease in the amplitude of the compound muscle action potential in all 4 extremities. Skin biopsy results led to the diagnosis of eosinophilic granulomatosis with polyangiitis (EGPA). Steroid pulse therapy and oral steroid therapy were initiated but did not resolve the acute pain or numbness. However, intravenous immunoglobulin (IVIg) was administered at day 28 after the beginning of the steroid treatment, and the pain started to improve immediately afterward. In some cases, IVIg can be effective in the treatment of intense pain in peripheral neuropathy associated with steroid-resistant EGPA.

Use of a novel high-resolution magnetic resonance neurography protocol to detect abnormal dorsal root Ganglia in Sjögren patients with neuropathic pain: case series of 10 patients and review of the literature

The diagnosis and treatment of patients with Sjögren syndrome (SS) with neuropathic pain pose several challenges. Patients with SS may experience unorthodox patterns of burning pain not conforming to a traditional "stocking-and-glove" distribution, which can affect the face, torso, and proximal extremities. This distribution of neuropathic pain may reflect mechanisms targeting the proximal-most element of the peripheral nervous system-the dorsal root ganglia (DRG). Skin biopsy can diagnose such a small-fiber neuropathy and is a surrogate marker of DRG neuronal cell loss. However, SS patients have been reported who have similar patterns of proximal neuropathic pain, despite having normal skin biopsy studies. In such cases, DRGs may be targeted by mechanisms not associated with neuronal cell loss. Therefore, alternative approaches are warranted to help characterize abnormal DRGs in SS patients with proximal neuropathic pain.We performed a systematic review of the literature to define the frequency and spectrum of SS peripheral neuropathies, and to better understand the attribution of SS neuropathic pain to peripheral neuropathies. We found that the frequency of SS neuropathic pain exceeded the prevalence of peripheral neuropathies, and that painful peripheral neuropathies occurred less frequently than neuropathies not always associated with pain. We developed a novel magnetic resonance neurography (MRN) protocol to evaluate DRG abnormalities. Ten SS patients with proximal neuropathic pain were evaluated by this MRN protocol, as well as by punch skin biopsies evaluating for intraepidermal nerve fiber density (IENFD) of unmyelinated nerves. Five patients had radiographic evidence of DRG abnormalities. Patients with MRN DRG abnormalities had increased IENFD of unmyelinated nerves compared to patients without MRN DRG abnormalities (30.2 [interquartile range, 4.4] fibers/mm vs. 11.0 [4.1] fibers/mm, respectively; p = 0.03). Two of these 5 SS patients whose neuropathic pain resolved with intravenous immunoglobulin (IVIg) therapy had improvement of MRN DRG abnormalities.We have developed a novel MRN protocol that can detect DRG abnormalities in SS patients with neuropathic pain who do not have markers of peripheral neuropathy. We found that SS patients with MRN DRG abnormalities had statistically significant, increased IENFD on skin biopsy studies, which may suggest a relationship between trophic mediators and neuropathic pain. Given that our literature review has demonstrated that many SS neuropathic pain patients do not have a neuropathy, our findings suggest an important niche for this MRN DRG technique in the evaluation of broader subsets of SS neuropathic pain patients who may not have underlying neuropathies. The improvement of MRN DRG abnormalities in patients with IVIg-induced remission of neuropathic pain suggests that our MRN protocol may be capturing reversible, immune-mediated mechanisms targeting the DRG.

Sjögren Syndrome-Associated Small Fiber Neuropathy: Characterization From a Prospective Series of 40 Cases

We conducted the current study to analyze the clinical, immunologic, and neurophysiologic features of primary Sjögren syndrome (pSS)-associated sensory small fiber neuropathies (SFNs). Forty consecutive pSS patients with SFN were included. SFN was defined by the presence of suggestive sensory painful symptoms with normal nerve conduction studies and abnormal neurophysiologic tests for small nerve fibers or a low intraepidermal nerve fiber density at skin biopsy. Included patients were compared to 100 pSS patients without peripheral neuropathy.SFN patients were mainly female (92.5%). Age at pSS diagnosis was 55.3 ± 13.1 years, and at SFN diagnosis, 58.9 ± 11.8 years, with a median time to SFN diagnosis after symptom onset of 3.4 years. Clinical symptoms included burning pains (90%), numbness (87.5%), tingling (82.5%), pins and needles (72.5%), electric discharges (70%), and allodynia (55%). Dysautonomia included vasomotor symptoms (66%) and hyperhidrosis (47%). Abnormal neurophysiologic tests included laser evoked potentials (97.5%), thermal quantitative sensory testing (67.5%), and sympathetic skin reflex (40%). A skin biopsy revealed low intraepidermal nerve fiber density in 76% of the 17 tested patients.Compared to the 100 pSS patients without peripheral neuropathy, the 40 pSS-SFN patients were older at pSS diagnosis (55.3 ± 13.1 vs. 49.5 ± 14.9 yr; p = 0.03), and more often had xerostomia (97.5% vs. 81%; p = 0.01) and arthralgia (82.5% vs. 65.0%; p = 0.04). Immunologically, they were characterized by a lower prevalence of serum B-cell activation markers, that is, antinuclear antibodies (65% vs. 85%; p = 0.01), anti-SSA (42.5% vs. 71%; p = 0.002), and anti-SSB (17.5% vs. 39%; p = 0.017); rheumatoid factor (32.5% vs. 66%; p = 0.0005); and hypergammaglobulinemia (35% vs. 62%; p = 0.005).In conclusion, we report the main features of SFN in patients with pSS, the first such study to our knowledge. Our results show that patients with pSS-associated SFN are characterized by an older age at pSS diagnosis and a distinctive immunologic profile hallmarked by a lower frequency of serum B-cell activation markers.

Safety and efficacy of ARA 290 in sarcoidosis patients with symptoms of small fiber neuropathy: a randomized, double-blind pilot study

ARA 290 (a peptide designed to activate the innate repair receptor that arrests injury and initiates cytoprotection, antiinflammation and healing) reduces allodynia in preclinical neuropathy models. We studied the safety and efficacy of ARA 290 to reduce symptoms of small fiber neuropathy (SFN) in patients with sarcoidosis. A total of 22 patients diagnosed with sarcoidosis and symptoms of SFN were enrolled in a double-blind, placebo-controlled exploratory trial consisting of three times weekly intravenous dosing of ARA 290 (2 mg; n = 12) or placebo (n = 10) for 4 wks. Inclusion criteria were a diagnosis of neuropathy and a spontaneous pain score of ≥5 (Brief Pain Inventory [BPI]). Endpoints assessed were changes in pain intensity and the small fiber neuropathy screening list (SFNSL) score, quality of life (SF-36), depressive symptoms (Inventory of Depressive Symptomatology [IDS]) and fatigue (Fatigue Assessment Scale [FAS]). No safety concerns were raised by clinical or laboratory assessments. The ARA 290 group showed significant (p < 0.05) improvement at wk 4 in SFNSL score compared with placebo (Δ -11.5 ± 3.04 versus Δ -2.9 ± 3.34 [standard error of the mean]). Additionally, the ARA 290 group showed a significant change from baseline in the pain and physical functioning dimensions of the SF-36 (Δ -23.4 ± 5.5 and Δ -14.6 ± 3.9, respectively). The mean BPI and FAS scores improved significantly but equivalently in both patient groups. No change was observed in the IDS. ARA 290 appears to be safe in patients with sarcoidosis and can reduce neuropathic symptoms.

Efficacy of intravenous immunoglobulin for small fiber neuropathy associated with sarcoidosis

BACKGROUND

Small fiber neuropathy (SFN) is commonly associated with sarcoidosis and can cause significant morbidity to afflicted patients. The appropriate treatment of this condition, when associated with sarcoidosis, is not well established.

METHODS

Descriptive case series of three patients with sarcoidosis and SFN. The presenting clinical features, skin biopsy results, autonomic reflex screen and quantitative sudomotor axon reflex testing (QSART) findings, and response to therapy are delineated.

RESULTS

We describe three patients with biopsy-proven sarcoidosis who developed intractable neuropathic pain and/or symptoms related to associated autonomic dysfunction despite treatment with various immunosuppressive medications and narcotic analgesics. QSART showed evidence of a postganglionic sudomotor abnormality in one patient and was normal in the other two. Skin biopsy findings were abnormal, demonstrating a non-length-dependent sensory SFN in all three patients. Painful neuropathic symptoms, as well as symptoms related to dysautonomia from SFN responded significantly to treatment with intravenous immunoglobulin (IVIG).

CONCLUSION

IVIG appears to be effective in relieving symptoms from SFN associated with sarcoidosis, suggesting an underlying immune mechanism. Larger prospective, controlled studies would be needed to confirm this response to IVIG and to further elucidate the underlying pathobiology behind this association with sarcoidosis.

Peripheral nervous system manifestations of Sjögren syndrome: clinical patterns, diagnostic paradigms, etiopathogenesis, and therapeutic strategies

Sjögren syndrome is among the most common autoimmune diseases affecting adults in the United States, and is frequently regarded as an immune-mediated exocrinopathy exclusively causing dry eyes and dry mouth. However, as a systemic rheumatic disease, there can be various "extraglandular" complications. The eclectic permutation of peripheral nervous system (PNS) syndromes which occur in Sjögren patients are among the most common and severe extraglandular complications. This review article highlights the evaluation, differential diagnosis, immunopathogenic mechanisms, and potential treatment options of these PNS complications encountered by neurologists. The sensory neuropathies constitute the most frequent PNS complication. Sjögren patients can suffer from severe neuropathic pain, with small-fiber neuropathy causing lancinating or burning pain which can disproportionately affect the proximal torso or extremities, and the face (ie, in a "non-length-dependent distribution"). The technique of skin biopsy, assessing for the intraepidermal nerve fiber density of unmyelinated nerves, provides a useful technique for neurologists to diagnose small-fiber neuropathies, especially when there is such a non-length-dependent distribution. Other diagnostic techniques (ie, electromyography/nerve-conduction studies, evoked potentials, nerve and muscle biopsy) may be useful in specific subtypes of neuropathies. A rational approach to treatment requires a careful appraisal of the clinical subtype of the neuropathy, as well as a familiarity with such discriminating immunopathogenic mechanisms. The application of the traditional armamentarium used for neuropathic pain can be especially challenging. Sjögren patients can suffer from debilitating fatigue, sicca symptoms, and autonomic findings; as such manifestations can be complications of various neuropathic agents, neurologists should understand how to minimize such iatrogenic complications. Therefore, this article will empower neurologists to more effectively collaborate with rheumatologists, in the diagnosis and treatment of Sjögren patients with PNS complications.