Cryoglobulinemic peripheral neuropathy: neurophysiologic evaluation in twenty-two patients

Neurosurgical Intervention for Nerve and Muscle Biopsies

(1) Background: Neurologic and musculoskeletal diseases represent a considerable portion of the underlying etiologies responsible for the widely prevalent symptoms of pain, weakness, numbness, and paresthesia. Because of the subjective and often nonspecific nature of these symptoms, different diagnostic modalities have been explored and utilized. (2) Methods: Literature review. (3) Results: Nerve and muscle biopsy remains the gold standard for diagnosing many of the responsible neurological and musculoskeletal conditions. However, the need for invasive tissue sampling is diminishing as more investigations explore alternative diagnostic modalities. Because of this, it is important to explore the current role of neurosurgical intervention for nerve and muscle biopsies and its current relevance in the diagnostic landscape of neurological and musculoskeletal disorders. With consideration of the role of nerve and muscle biopsy, it is also important to explore innovations and emerging techniques for conducting these procedures. This review explores the indications and emerging techniques for neurological intervention for nerve and muscle biopsies. (4) Conclusions: The role of neurosurgical intervention for nerve and muscle biopsy remains relevant in diagnosing many neurological and musculoskeletal disorders. Biopsy is especially relevant as a supportive point of evidence for diagnosis in atypical cases. Additionally, emerging techniques have been explored to guide diagnostics and biopsy, conduct less invasive biopsies, and reduce risks of worsening neurologic function and other symptoms secondary to biopsy.

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.

Understanding the Cryoglobulinemias

PURPOSE OF THE REVIEW

Cryoglobulins are immunoglobulins with the ability to precipitate at temperatures <37 °C. They are related to hematological disorders, infections [especially hepatitis C virus (HCV)], and autoimmune diseases. In this article, the state of the art on Cryoglobulinemic Vasculitis (CV), in a helpful and schematic way, with a special focus on HCV related Mixed Cryoglobulinemia treatment are reviewed.

RECENT FINDINGS

Direct - acting antivirals (DAA) against HCV have emerged as an important key in HCV treatment to related Cryoglobulinemic Vasculitis, and should be kept in mind as the initial treatment in non-severe manifestations. On the other hand, a recent consensus panel has published their recommendations for treatment in severe and life threatening manifestations of Mixed Cryoglobulinemias. HCV-Cryoglobulinemic vasculitis is the most frequent form of CV. There are new treatment options in HCV-CV with DAA, with an important number of patients achieving complete response and sustained virologic response (SVR). In cases of severe forms of CV, treatment with Rituximab and PLEX are options. The lack of data on maintenance therapy could impulse future studies in this setting.

The vasculitic neuropathies: an update

PURPOSE OF REVIEW

Vasculitic neuropathy is a heterogeneous disorder that usually occurs in systemic diseases, but less commonly appears as nonsystemic vasculitic neuropathy (NSVN). This review is intended to highlight recent developments in the field of vasculitic neuropathies.

RECENT FINDINGS

A Peripheral Nerve Society guideline provides data-driven consensus recommendation on classification of vasculitic neuropathies and diagnosis/treatment of NSVN. NSVN is sometimes accompanied by subclinical inflammation of adjacent skin. Amyotrophic lateral sclerosis with sensory involvement can mimic NSVN. Systemic vasculitides with neuropathy include polyarteritis nodosa, microscopic polyangiitis (MPA), rheumatoid vasculitis, Churg-Strauss syndrome (CSS), and hepatitis C-related mixed cryoglobulinemic vasculitis (MCV). At autopsy, MPA affects limb nerves diffusely, with maximal damage in proximal/middle segments. CSS can be accompanied by antineutrophil cytoplasmic antibodies (ANCAs), but most patients with neuropathy lack ANCAs. Cryoglobulinemic neuropathies are usually caused by vasculitis, irrespective of phenotype. Two randomized trials revealed rituximab to be noninferior to cyclophosphamide for inducing remission in ANCA-associated vasculitis. Many reports also document efficacy of rituximab in MCV.

SUMMARY

Consensus guidelines on NSVN should be evaluated prospectively. MPA-associated vasculitic neuropathy results from vasculitic lesions distributed diffusely throughout peripheral extremity nerves. Rituximab is effective for ANCA-associated and cryoglobulinemic vasculitis with neuropathy.

[Vasculitis associated with viral infections]

VIRUSES, THE CAUSE OF VASCULITIS: Although the majority of systemic vasculitis are of unknown causes, the responsibility of a viral infection has been formally demonstrated in some of them and specific treatment can permanently cure them. Each virus incriminated accounts for a particular type of vasculitis. HEPATITIS B VIRAL INFECTION (HBV): Is the cause of polyarteritis nodosa in 36 to 50% of cases. The onset of the symptomatology is acute, usually within a few months following the infection; it is comparable to that observed in the absence of HBV infection. CRYOGLOBULINEMIA RELATED TO THE HEPATITIS C VIRUS (HCV): The clinical manifestations are those of systemic vasculitis with particular tropism for the skin (involvement generally inaugural and almost constant), peripheral nerves and the glomerula. They occur fairly late during the infection. VASCULITIS ASSOCIATED WITH HIV INFECTION: There is strong tropism for the peripheral (multi-neuritis) and central nervous system. During acute parvovirus B19 infection Vasculitis lesions have occasionally been reported following the viremic phase, generally limited to one or several flares of vascular purpura predominating on the lower limbs. FOLLOWING VARICELLA-HERPES ZOSTER INFECTION: Vasculitis occasionally develops in the form of a central neurological deficiency (locomotor deficiency with or without aphasia around one month after an ophthalmologic herpes zoster) or involving the retina or, more rarely, the skin or the kidneys. VASCULITIS ASSOCIATED WITH CYTOMEGALOVIRAL INFECTION: Predominantly observed in immunodepressed patients, vasculitis after CMV infection is diffuse and basically involving the digestive tube, notably the colon, the central nervous system and the skin. A RARE COMPLICATION OF AN HTLV1 INFECTION: Vasculitis of the retina often in the form of necrotic retinitis is often associated with spasmodic paraparessia.

THERAPEUTIC STRATEGY

For many vasculitis of viral origin, corticosteroid and immunosuppressive treatments are only indicated in second intention following failure with antiviral agents and the combination of antivirals and plasma exchanges.

Paraproteinemia and neuropathy

Paraprotein-associated neuropathies are a diverse group of disorders. The pathogenesis of many of them is poorly understood. Treatments have usually consisted of plasma exchange, corticosteroids, intravenous immunoglobulin, and other immunosuppressive therapies. Response to treatment has varied from good to very poor. Most recent work in this field has had two goals: achieving a better understanding of pathogenesis and developing better treatments. Such diverse entities as hepatitis C virus, vascular endothelial growth factor, and cytokines now appear to play a role in pathogenesis. More aggressive therapies such a bone marrow transplantation, interferon-alpha, and Rituximab have shown some promise.