Introduction
Dysimmune neuropathies represent an expanding field of a very heterogeneous group of disorders of highly diverse clinical presentations and variable underlying pathophysiology. The diagnostic process is frequently complex and many uncertainties regarding classifications remain, with some of those having very recently appeared as a result of new knowledge. The most exciting aspect of dysimmune neuropathies, within the very wide spectrum of neuromuscular disorders where many are of a genetic basis and unfortunately still mostly untreatable, is certainly their potential for treatment. Recent progress and knowledge indicate that the previous tendencies to clump these disorders in large groups may neither be appropriate nor practical, as treatment modalities vary widely, including in entities with closely related clinical or electrodiagnostic pictures. More splitting appears likely to occur as new data emerge, separating previously grouped disorders. This is not, however, without problems and difficulties with the rarity of the diseases in question and the obvious overlaps that will persist.
In view of the increasing diversity and new developments concerning this group of peripheral nervous system diseases, the need for a dedicated book on the dysimmune neuropathies became apparent. With a primary clinical focus, we have attempted to effectively and comprehensively cover the knowledge base for all main areas, with integration in each chapter of the various epidemiological, diagnostic, and therapeutic elements so as to provide the reader with a readily accessible but as exhaustive as possible clinically directly relevant text.
Starting with Guillain-Barré syndrome, substantial developments have progressively happened in the field over the past century since the initial description of the disorder, including, within the last several years, considerable new knowledge in all areas including diagnostics, pathophysiology, treatment modalities, and potential for novel therapeutic avenues. The chapter offers an up-to-date summary of these important elements of interest. In the chapter on chronic inflammatory demyelinating polyneuropathy (CIDP), the various developments in diagnostic techniques, enhanced by nerve imaging, treatment and use of objective evaluation tools are considered. In the context of the increasing heterogeneity of this entity, with the recent significant discoveries of new antinodal and antiparanodal antibodies in a subset of affected patients, considerable widening the CIDP spectrum has occurred in the last few years. The relative higher prevalence of CIDP compared to other dysimmune neuropathies also led to the need to elaborate on differential diagnosis and mimics as well as the many described associations of CIDP with other diseases. Multifocal motor neuropathy (MMN), which is one of the “newer” dysimmune neuropathies, is also described in its historical, epidemiological, diagnostic, and therapeutic aspects in a chapter that discusses the many important questions that make MMN more than just a single-treatment-responsive disease. A separate chapter focuses on the paraprotein-associated inflammatory neuropathies, particularly the IgM paraproteinaemias. This chapter offers the essential description of a common case scenario in patients with suspected dysimmune neuropathy and highlights the fundamental knowledge required to manage this also heterogeneous, frequently complex and often challenging set of disorders. Polyneuropathy Organomegaly Endocrinopathy M-Protein Skin (POEMS) syndrome is detailed in a dedicated chapter, which was felt essential to elaborate on this rare and previously fatal condition, also associating a neuropathy and a paraprotein, but for which diagnostic modalities and criteria have changed over the years, and importantly, currently available treatments now offer a significantly improved prognosis. An individual chapter covers vasculitic neuropathy. The heterogeneity of this form of dysimmune neuropathy is also wide, ranging from the purely neuropathic nonsystemic forms to those where the neuropathy is part of more diffuse disease. Diagnosis relies on a high index of clinical suspicion and detailed histopathology which is well-illustrated in this chapter which also details the important therapeutic aspects. A dedicated chapter covers the paraneoplastic neuropathies, which although necessarily part of a subsequently unconfirmed differential in many encountered cases of dysimmune neuropathy, represents an area of expanding knowledge both for diagnosis and management. A further separate chapter details cervicobrachial and lumbosacral radiculopexus neuropathies. This is one of the only two anatomically-defined chapters in this volume, the reason being the specific nature of such presentations, which necessitates correct identification of a dysimmune aetiology versus many others, as well as the particular histopathological processes involved, identified in the last few years with important implications for management. The final chapter of this volume elaborates on a new, but substantial clinical problem. Again, this section is necessarily wide, as informs the reader of the dysimmune small fiber neuropathies, to be identified among the many neuropathies of this very specific and separate histopathological subcategory. Identifying those with an immunological basis in this expanding and exciting area is greatly important, as may lead to the need to consider treatments which would otherwise be discounted.
I am extremely grateful to all the recognized major international experts who have kindly contributed to the chapters of this book. All are authorities in the field who have done extensive research, but also and most importantly, they have long and exhaustive direct day-to-day clinical experience in the diagnosis and management of the disorders they describe and detail. We hope this text will cater for the needs of all clinicians in the field and provide readers with a comprehensive, up-to-date and in-depth coverage of the current knowledge-base and thereby ultimately contribute to enhancing the standards of clinical care for the many patients affected by this group of diseases, worldwide.
The timing of the completion of this volume in March/April 2020 is for us all, a moment of profound anxiety and uncertainty due to the COVID-19 pandemic. Undoubtedly, this already has had, for several weeks and will have, for many more to come, substantial consequences on our patients’ lives and on the clinical management of their diseases. One hopes that despite the essential focus on the current pandemic, we are capable as healthcare professionals of remaining equally attentive to the needs of our patients with chronic diseases such as dysimmune neuropathies, some of whom will be, themselves or their families, at greater risk, others with less access to care and more still, with many compounded difficulties in their daily lives. Our first challenge at this point will be to ensure they are remembered and continue being looked after in these difficult times.