The Neuropathies of Waldenström's Macroglobulinemia (WM) and IgM-MGUS

Top 10 Clinical Pearls in Paraproteinemic Neuropathies

Paraproteinemic neuropathies represent an important subset of peripheral neuropathies. Once identified, further evaluation into the paraproteinemic subtype, clinical exam pattern, and electrodiagnostic phenotype helps clarify if the paraproteinemia is coincidental or causal of the neuropathy, as not all paraproteinemias cause neuropathy. Of all paraproteinemias, immunoglobulin M (IgM)-associated peripheral neuropathy, or IgM neuropathy, is of particular importance as half of IgM neuropathies also harbor anti-myelin-associated glycoprotein antibodies, which produce a characteristic demyelinating pattern on nerve conduction testing. Immunoglobulin G and immunoglobulin A paraproteinemias are less strongly associated with peripheral neuropathy, except in the setting of multiple myeloma or osteosclerotic myeloma (POEMS syndrome), which have characteristic systemic features. In multiple myeloma, chemotherapy is more likely to result in neuropathy than the myeloma itself. Finally, the presence of systemic features (e.g., cardiomyopathy, nephropathy, recurrent carpal tunnel syndrome, and autonomic insufficiency) should raise concern for hereditary or acquired light (AL) chain amyloidosis. AL amyloidosis can occur in the setting of any light or heavy chain paraproteinemia. Central to the proper evaluation of paraproteinemic neuropathy is electrodiagnostic testing, which helps delineate axonal versus demyelinating paraproteinemic neuropathy, the latter often misdiagnosed as chronic inflammatory demyelinating polyradiculoneuropathy.

Paraneoplastic neuropathies and peripheral nerve hyperexcitability disorders

Peripheral neuropathy is a common referral for patients to the neurologic clinics. Paraneoplastic neuropathies account for a small but high morbidity and mortality subgroup. Symptoms include weakness, sensory loss, sweating irregularity, blood pressure instability, severe constipation, and neuropathic pain. Neuropathy is the first presenting symptom of malignancy among many patients. The molecular and cellular oncogenic immune targets reside within cell bodies, axons, cytoplasms, or surface membranes of neural tissues. A more favorable immune treatment outcome occurs in those where the targets reside on the cell surface. Patients with antibodies binding cell surface antigens commonly have neural hyperexcitability with pain, cramps, fasciculations, and hyperhidrotic attacks (CASPR2, LGI1, and others). The antigenic targets are also commonly expressed in the central nervous system, with presenting symptoms being myelopathy, encephalopathy, and seizures with neuropathy, often masked. Pain and autonomic components typically relate to small nerve fiber involvement (nociceptive, adrenergic, enteric, and sudomotor), sometimes without nerve fiber loss but rather hyperexcitability. The specific antibodies discovered help direct cancer investigations. Among the primary axonal paraneoplastic neuropathies, pathognomonic clinical features do not exist, and testing for multiple antibodies simultaneously provides the best sensitivity in testing (AGNA1-SOX1; amphiphysin; ANNA-1-HU; ANNA-3-DACH1; CASPR2; CRMP5; LGI1; PCA2-MAP1B, and others). Performing confirmatory antibody testing using adjunct methods improves specificity. Antibody-mediated demyelinating paraneoplastic neuropathies are limited to MAG-IgM (IgM-MGUS, Waldenström's, and myeloma), with the others associated with cytokine elevations (VEGF, IL6) caused by osteosclerotic myeloma, plasmacytoma (POEMS), and rarely angiofollicular lymphoma (Castleman's). Paraneoplastic disorders have clinical overlap with other idiopathic antibody disorders, including IgG4 demyelinating nodopathies (NF155 and Contactin-1). This review summarizes the paraneoplastic neuropathies, including those with peripheral nerve hyperexcitability.

Anti-myelin-associated glycoprotein neuropathy: Where do we stand?

Myelin-associated glycoprotein (MAG) is a transmembrane glycoprotein concentrated in periaxonal Schwann cell and oligodendroglial membranes of myelin sheaths that serves as an antigen for immunoglobulin M (IgM) monoclonal antibodies. Individuals who harbor anti-MAG antibodies classically develop a progressive autoimmune peripheral neuropathy characterized clinically by ataxia, distal sensory loss, and gait instability, and electrophysiologically by distally accentuated conduction velocity slowing. Although off-label immunotherapy is common, there are currently no proven effective disease-modifying therapeutics, and most patients experience slow accumulation of disability over years and decades. The typically slowly progressive nature of this neuropathy presents unique challenges when trying to find effective anti-MAG therapeutic agents. Drug development has also been hampered by the lack of validated outcome measures that can detect clinically meaningful changes in a reasonable amount of time as well as by the lack of disease activity biomarkers. In this invited review, we provide an update on the state of clinicometric outcome measures and disease activity biomarkers in anti-MAG neuropathy. We highlight the insensitivity of widely used existing clinicometric outcome measures such as the Inflammatory Neuropathy Cause and Treatment (INCAT) disability score as well as the INCAT sensory subscore in anti-MAG neuropathy, referencing the two previous negative randomized controlled clinical trials evaluating rituximab. We then discuss newly emerging candidate therapeutic agents, including tyrosine kinase inhibitors and enhanced B-cell-depleting agents, among others. We conclude with a practical approach to the evaluation and management of anti-MAG neuropathy patients.

Amyloid-like IgM deposition neuropathy with multiple mononeuropathies and generalized neuropathy

Amyloid-like IgM deposition neuropathy is a distinct entity in the setting of IgM monoclonal gammopathy in which endoneurial perivascular entire IgM-particle accumulation leads to a painful sensory followed by motor peripheral neuropathy. We report a 77-year-old man presenting with progressive multiple mononeuropathies starting with painless right foot drop. Electrodiagnostic studies showed severe axonal sensory-motor neuropathy superimposed by multiple mononeuropathies. Laboratory investigations were remarkable for biclonal gammopathy of IgM kappa, IgA lambda and severe sudomotor and mild cardiovagal autonomic dysfunction. A right sural nerve biopsy showed multifocal axonal neuropathy, prominent microvasculitis, and prominent large endoneurial deposits of Congo-red negative amorphous material. Laser dissected mass spectrometry-based proteomics identified IgM kappa deposit without serum amyloid-P protein. This case has several distinctive features, including motor preceding sensory involvement, prominent IgM-kappa proteinaceous deposits replacing most of the endoneurium, a prominent inflammatory component, and improvement of motor strength after immunotherapy.

Bing–Neel Syndrome: Update on Diagnosis and Treatment

Bing–Neel syndrome (BNS) is a rare neurological complication of Waldenström macroglobulinaemia. We highlight key issues in clinical presentation, diagnosis, and treatment while focusing on new and emerging therapies available for patients diagnosed with BNS. It is anticipated that further development of Bruton Tyrosine Kinase (BTK) inhibitors and less toxic chemoimmunotherapies will improve treatment delivery and response.

Differential Diagnosis of Waldenström's Macroglobulinemia and Early Management: Perspectives from Clinical Practice

Waldenström's Macroglobulinemia (WM) is a clonal B-lymphocyte neoplasm characterized by the presence of IgM monoclonal protein and ≥10% bone marrow involvement with lymphoplasmacytic cells. Several mature B-cell and plasma cell disorders can potentially produce monoclonal IgM immunoglobulin and hence, careful consideration of the differential diagnosis is vital. Clinico-pathological features, immunophenotype, and MYD88 mutation status help distinguish WM from other plasma cell and lymphoproliferative disorders. Treatment is only indicated in patients symptomatic from adenopathy or organomegaly, neuropathy, hyper viscosity, cryoglobulinemia, cold agglutinin disease, cytopenia's or amyloidosis. Alkylators (cyclophosphamide, bendamustine) in combination with anti-CD20 antibodies and novel targeted agents including Bruton tyrosine kinase (BTK) inhibitors like ibrutinib are the mainstay of frontline treatment in symptomatic WM.

Paraproteinemias and Peripheral Nerve Disease

This article provides an overview of the clinical features, diagnosis, and treatment of the major paraprotein-related peripheral neuropathies, including monoclonal gammopathy of undetermined significance, Waldenström macroglobulinemia, POEMS syndrome, multiple myeloma, transthyretin amyloidosis, and light chain amyloidosis. For each paraprotein neuropathy, the epidemiology, demographics, systemic findings, and electrophysiologic features are presented. Pharmacologic treatment of transthyretin amyloid polyneuropathy also is reviewed.

Identification of a Candidate Gene Set Signature for the Risk of Progression in IgM MGUS to Smoldering/Symptomatic Waldenström Macroglobulinemia (WM) by a Comparative Transcriptome Analysis of B Cells and Plasma Cells

Waldenström Macroglobulinemia (WM) is a B-cell lymphoma characterized by the precursor condition IgM monoclonal gammopathies of undetermined significance (IgM MGUS). We performed a gene expression profiling study to compare the transcriptome signatures of bone marrow (BM) B-cells and plasma cells of 36 WM patients, 13 IgM MGUS cases, and 7 healthy subjects used as controls (CTRLs) by Affymetrix microarray. We determined 2038 differentially expressed genes (DEGs) in CD19+ cells and 29 DEGs genes in CD138+ cells, respectively. The DEGs identified in B-cells were associated with KEGG pathways, mainly involved in hematopoietic cell lineage antigens, cell adhesion/focal adhesion/transmembrane proteins, adherens junctions, Wnt-signaling pathway, BCR-signaling pathway, calcium signaling pathway, complement/coagulation cascade, platelet activation, cytokine-cytokine receptor interactions, and signaling pathways responsible for cell cycle, apoptosis, proliferation and survival. In conclusion, we showed the deregulation of groups of genes belonging to KEGG pathways in the comparison among WM vs. IgM MGUS vs. CTRLs in B-cells. Interestingly, a small set of genes in B-cells displayed a common transcriptome expression profile between WM and IgM MGUS compared to CTRLs, suggesting its possible role in the risk of transformation of IgM MGUS to WM.

IgM paraprotein and anti-MAG sensory polyneuropathy associated with Waldenstrom's macroglobulinaemia and medullary carcinoma of the thyroid

A previously fit and well 76-year-old man, presented with distal lower limb sensory symptoms suggestive of peripheral sensory neuropathy, associated with positive anti-MAG antibodies (myelin associated glycoprotein) and IgM paraprotein. Bone marrow biopsy showed lymphoplasmocytoid lymphoma (Waldenstrom's macroglobulinaemia, WM), consequently positive for MYD88 mutation. He subsequently developed medullary carcinoma of the thyroid, most likely secondary to WM. He underwent a successful total thyroidectomy and four treatment doses of rituximab, which proved beneficial. He is currently stable and under multidisciplinary monitoring. His sensory symptoms have improved following rituximab treatment and his WM is under control.

Current and Emerging Treatments for Waldenström Macroglobulinemia

Waldenström macroglobulinemia (WM) is a rare lymphoplasmacytic lymphoma. The primary goal of therapy is to reduce symptoms related to direct infiltration of the bone marrow and decrease monoclonal IgM-associated complications. Active agents in the management of WM can be broadly classified as rituximab-alkylator combination therapy, proteasome inhibitor-based therapy, and Bruton's tyrosine kinase inhibitor-based therapy. MYD88L265P and CXCR4 genetic status are pivotal for tailoring treatment options. Ibrutinib is a suitable treatment option for both treatment-naïve and relapsing WM patients. Recent advances in the intracellular B cell and cytokine signaling pathways have contributed to the development of novel therapeutic strategies. Current clinical trials are promising and may further advance WM-directed therapy.

Association of small-fiber polyneuropathy with three previously unassociated rare missense SCN9A variants

BACKGROUND

Small fiber polyneuropathy (SFN) involves ectopic firing and degeneration of small-diameter, somatic/autonomic peripheral axons. Causes include diabetes, inflammation and rare pathogenic mutations, including in SCN9-11 genes that encode small fiber sodium channels.

AIMS

The aim of this study is to associate a new phenotype-immunotherapy-responsive SFN-with rare amino acid-substituting SCN9A variants and present potential explanations.

METHODS

A retrospective chart review of two Caucasians with skin biopsy confirmed SFN and rare SCN9A single nucleotide polymorphisms not previously reported in neuropathy.

RESULTS

A 47-year-old with 4 years of disabling widespread neuropathic pain and exertional intolerance had nerve- and skin biopsy-confirmed SFN, with blood tests revealing only high-titer antinuclear antibodies and low complement C4 consistent with B cell dysimmunity. Six years of intravenous immunoglobulin (IVIg) therapy markedly improved sensory and autonomic symptoms and normalized his neurite density. After whole exome sequencing revealed a potentially pathogenic SCN9A-A3734G variant, sodium channel blockers were tried. Herpes zoster left a 32-year-old with disabling exertional intolerance ("chronic fatigue syndrome"), postural syncope and tachycardia, arm and leg paresthesias, reduced sweating, and distal hairloss. Screening revealed antinuclear and potassium channel autoantibodies, so prednisone and then IVIg were prescribed with great benefit. During 4 years of immunotherapy, his symptoms and function improved, and all abnormal biomarkers (autonomic testing and skin biopsies) normalized. Whole exome sequencing then revealed two nearby compound heterozygous SCN9A variants that were computer-predicted to be deleterious.

CONCLUSIONS

These cases newly associate three novel amino acid-substituting SCN9A variants with immunotherapy-responsive neuropathy. Only larger studies can determine whether these are contributory or coincidental, but they associate new variants with moderate or high likelihood of pathogenicity with a new highly related phenotype.

Waldenstrom-associated anti-MAG paraprotein polyneuropathy with neurogenic tremor

A 71-year-old female patient presented with a 14-year history of slowly progressive distal limb numbness, paraesthesia and reduced vibration perception, ataxic gait and intentional tremor. Examination revealed with a length-dependent sensory neuropathy. Nerve conduction studies showed a chronic sensorimotor inflammatory demyelinating polyneuropathy. Intravenous immunoglobulin treatment (on two occasions) proved ineffective. Serum electrophoresis showed increased monoclonal IgM with kappa light chains. Anti-myelin-associated glycoprotein (MAG) levels were extremely elevated, >70 000 BTU. Bone marrow biopsy revealed 15%-20% small B cells and positive MYD88 mutation, indicative of Waldenstrom macroglobulinaemia. A diagnosis of Waldenstrom-associated anti-MAG paraprotein neuropathy with intentional (neurogenic) tremor was made. Repeat nerve conduction study showed a severe sensory demyelinating neuropathy with no axonal lesion. Treatment with rituximab was given for 1 month with minimal improvement. Repeat anti-MAG levels dropped to 53 670 BTU, with minimal clinical improvement.

Neurological impairment in a patient with concurrent cervical disc herniation and POEMS syndrome

PURPOSE

POEMS syndrome is a rare clonal plasma cell disease characterized by polyneuropathy, organomegaly, endocrinopathy, M protein, and skin changes. We report a rare case of neurological impairment in patients with concurrent cervical disc herniation and POEMS syndrome.

METHODS

A patient presented to a local hospital with C3/4 and C4/5 disc herniation, apparent spinal cord compression concomitant with neurological signs, and concurrent POEMS syndrome. Anterior cervical discectomy and fusion was performed.

RESULTS

The limb numbness was only slightly alleviated, and 10 days postoperatively the patient complained of muscle weakness of the extremities and was referred to our hospital. The patients exhibited non-typical neurological signs and an enlarged liver and spleen that could not be explained. Electroneuromyography and immunofixation electrophoresis produced abnormal results. We diagnosed concurrent POEMS syndrome, for which drug therapy was prescribed. The patient's symptoms receded.

CONCLUSION

Patients presenting with cervical spondylopathy and non-typical neurological signs and symptoms or other systemic problems should be evaluated for the presence of concurrent disease and ruled out differential diagnoses.

POEMS syndrome: clinical update

POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, M-protein, skin changes) is a rare paraneoplastic syndrome, caused by a plasma cell proliferative disorder, which is most commonly lambda restricted. The neurological hallmark, which forms one of the mandatory criteria for diagnosis, is a subacute onset demyelinating neuropathy, which can be rapidly disabling and painful. A number of multi-system features are also characteristic of this disorder, and certainly not restricted to those included in its acronym, which though limited, remains a useful and memorable name, helping distinguish POEMS syndrome from other paraproteinaemic neuropathies. The discovery of vascular endothelial growth factor (VEGF) in association with POEMS syndrome has been extremely useful in aiding clinical diagnosis, and monitoring response to treatment, as well as helping understand the underlying mechanism of disease. Interestingly, however, treatment targeting VEGF has been disappointing, suggesting other disease mechanisms or inflammatory processes are also important. Current understanding of the pathogenesis of POEMS syndrome is outlined in detail in the accompanying article by Cerri et al. Here, we review the clinical features of POEMS syndrome, differential diagnosis and available treatment options, based on current literature.

Neurologic Complications of Lymphoma, Leukemia, and Paraproteinemias

PURPOSE OF REVIEW

This article reviews the spectrum of neurologic complications associated with lymphoma, leukemia, and paraproteinemic disorders. While leptomeningeal metastasis is the most common complication of lymphoma and leukemia and peripheral neuropathy is the most common complication of paraproteinemic disorders, clinicians need to be familiar with the diverse neurologic complications of these disorders.

RECENT FINDINGS

Lymphomatous nervous system involvement can be difficult to diagnose, especially when it is the presenting symptom. CSF cytology and flow cytometry, as well as the imaging pattern, assist in diagnosis. Neurologic complications are less common in Hodgkin lymphoma; however, some unique paraneoplastic syndromes are associated with Hodgkin lymphoma, including primary central nervous system angiitis, limbic encephalitis, and cerebellar degeneration. Recent reports suggest that anti-metabotropic glutamate receptor 5 (mGluR5) antibodies are associated with limbic encephalitis and that anti-Tr antibodies are associated with cerebellar degeneration in Hodgkin lymphoma. Polyneuropathy, organomegaly, endocrinopathy, monoclonal plasma cell disorder, and skin changes (POEMS) syndrome is often misdiagnosed as chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). A lambda protein, thrombocytosis, and elevated vascular endothelial growth factor (VEGF) can all be helpful clues in diagnosis. Early recognition is important, as the neuropathy responds to radiation therapy or chemotherapy.

SUMMARY

Neurologic involvement can occur throughout the disease course in lymphoma and leukemia, including at presentation, with systemic progression, and at relapse. In paraproteinemias, the peripheral neuropathy phenotype, monoclonal protein type, and associated autonomic and systemic features aid in identification of an underlying plasma cell disorder.

[Clinical and electromyography characteristics of chemotherapy-induced polyneuropathy]

AIM

The study aimed at determining clinical and electromyography characteristics and developing the methods of CIPN treatment.

MATERIAL AND METHODS

A clinical and electromyographic examinations and treatment of 30 with CIPN symptoms developed after polychemotherapy were performed. The authors developed treatment schemes included allopathic, homeopathic drugs, hydrotherapy and pharmacopuncture.

RESULTS AND CONCLUSION

Most of the patients were diagnosed with axonal polyneuropathy with affection of long nerves of the limbs, some patients had a combination of axonopathy with myelopathy. After treatment, regression of neuropathy symptoms and improvement of quality of life was noted in all patients.

Diagnosis and management of neuropathies associated with plasma cell dyscrasias

Neuropathies associated with plasma cell dyscrasias are a major cause of morbidity for patients managed by medical oncologists. Because of similarities in clinical presentation and on nerve conduction studies, identifying the underlying disease leading to a paraproteinemic neuropathy can often be difficult. In addition, the degree of neurologic deficit does not strictly correlate with the extent of abnormalities on common clinical laboratory testing. Fortunately, with increasing understanding into the biologic mechanisms of underlying hematologic diseases, additional biomarkers have recently been developed, thus improving our diagnostic capacity. Neuropathies associated with plasma cells dyscrasias are seen with Monoclonal gammopathy of undetermined significance (MGUS) particularly IgM subtype, followed by IgG and IgA MGUS, multiple myeloma, Waldenström's macroglobulinemia, amyloid, Castleman's disease, and POEMS syndrome. The mechanisms of neuronal injury associated with plasma cell dyscrasia vary based on underlying diagnosis and include malignant infiltration, immune-mediated antibody deposition, or local compression of nerve roots. The polyneuropathies are frequently demyelinating, although axonal and mixed neuropathies can also be seen. As demonstrated by the cases included in this review, patients frequently present with symmetric sensory disturbance, followed by progressive motor weakness. Unfortunately, because of the complexity of diagnostic testing, patients are frequently examined late, often after receiving several ineffective therapies. The aim of this case-based review is to provide clinicians with insight on how to properly recognize these atypical neuropathies and send the appropriate diagnostic work, increasing the likelihood of accurately classify the patient's underlying hematologic disorder.

Clinical spectrum of Castleman disease-associated neuropathy

OBJECTIVE

To define the peripheral neuropathy phenotypes associated with Castleman disease.

METHODS

We conducted a retrospective chart review for patients with biopsy-proven Castleman disease evaluated between January 2003 and December 2014. Patients with associated peripheral neuropathy were identified and divided into 2 groups: those with Castleman disease without POEMS syndrome (CD-PN) and those with Castleman disease with POEMS syndrome (CD-POEMS). We used a cohort of patients with POEMS as controls. Clinical, electrodiagnostic, and laboratory characteristics were collected and compared among patient subgroups.

RESULTS

There were 7 patients with CD-PN, 20 with CD-POEMS, and 122 with POEMS. Patients with CD-PN had the mildest neuropathy characterized by predominant sensory symptoms with no pain and mild distal sensory deficits (median Neuropathy Impairment Score of 7 points). Although both patients with CD-POEMS and patients with POEMS had a severe sensory and motor neuropathy, patients with CD-POEMS were less affected (median Neuropathy Impairment Score of 33 and 66 points, respectively). The degree of severity was also reflected on electrodiagnostic testing in which patients with CD-PN demonstrated a mild degree of axonal loss, followed by patients with CD-POEMS and then those with POEMS. Demyelinating features, defined by European Federation of Neurologic Societies/Peripheral Nerve Society criteria, were present in 43% of the CD-PN, 78% of the CD-POEMS, and 86% of the POEMS group.

CONCLUSION

There is a spectrum of demyelinating peripheral neuropathies associated with Castleman disease. CD-PN is sensory predominant and is the mildest phenotype, whereas CD-POEMS is a more severe sensory and motor neuropathy. Compared to the POEMS cohort, those with CD-POEMS neuropathy have a similar but less severe phenotype. Whether these patients respond differently to treatment deserves further study.

Autoimmune-mediated peripheral neuropathies and autoimmune pain

Peripheral neuropathies have diverse acquired and inherited causes. The autoimmune neuropathies represent an important category where treatment is often available. There are overlapping signs and symptoms between autoimmune neuropathies and other forms. Making a diagnosis can be challenging and first assisted by electrophysiologic and sometimes pathologic sampling, with autoimmune biomarkers providing increased assistance. Here we provide a review of the autoimmune and inflammatory neuropathies, their available biomarkers, and approaches to treatment. Also discussed is new evidence to support a mechanism of autoimmune pain.

Neuropathies associated with lymphoma†

Neuropathy occurs with various manifestations as a consequence of lymphoma, and an understanding of the etiology is necessary for proper treatment. Advances in medical imaging have improved the detection of peripheral nerve involvement in lymphoma, yet tissue diagnosis is often equally important. The neoplastic involvement of the peripheral nervous system (PNS) in lymphoma can occur within the cerebrospinal fluid (CSF), inside the dura, or outside of the CSF space, affecting nerve root plexuses and peripheral nerves. The infiltration of either cranial or peripheral nerves in lymphoma is termed neurolymphomatosis (NL). These infiltrations can occur as mononeuropathy, multifocal neuropathy, symmetric neuropathies, or plexopathies. In rare cases, intravascular lymphoma (IL) can affect the PNS and an even rarer condition is the combination of NL and IL. Immune-mediated and paraneoplastic neuropathies are important considerations when treating patients with lymphoma. Demyelinating neuropathies, such as Guillain-Barré syndrome and chronic inflammatory demyelinating polyradiculoneuropathy, occur more frequently in non-Hodgkin's lymphoma than in Hodgkin's disease. Paraproteinemic neuropathies can be associated with lymphoma and paraneoplastic neuropathies are rare. While the treatment of lymphomas has improved, a knowledge of neurotoxic, radiotherapy, neoplastic, immune-mediated and paraneoplastic effects are important for patient care.

Paraproteinemic neuropathies

PURPOSE OF REVIEW

Monoclonal gammopathies are common in the general population and occur in 10% of patients with peripheral neuropathy. It is important for the clinician to be able to determine whether an association exists between the paraprotein and the neuropathy. The clinical phenotype of the neuropathy, as well as the type of monoclonal protein, provides clues for the diagnosis. Optimal management of paraproteinemic neuropathies requires appropriate evaluation of the monoclonal protein for an underlying hematologic disorder.

RECENT FINDINGS

Clinical studies in paraproteinemic neuropathies have provided a better understanding of these disorders, but much is still unknown regarding the pathophysiologic mechanisms. Recent clinical trials in immunoglobulin M (IgM) neuropathy have shown that better outcome measures and treatment approaches are needed. Peripheral blood stem cell transplantation has shown promising improvements in the treatment of polyneuropathy, organomegaly, endocrinopathy, monoclonal plasma cell disorder, and skin changes (POEMS) syndrome and immunoglobulin light chain (AL) amyloidosis.

SUMMARY

Recognizing the frequent association of neuropathy with monoclonal proteins and evaluating for a hematologic malignancy should enable physicians to find better treatments and ultimately improve neuropathy outcome.

Neuromuscular issues in systemic disease

The neuromuscular system can be involved in several systemic conditions. Clinical manifestations can appear at onset or throughout the course of the disease process. New investigational methods, including imaging of peripheral nerves, new laboratory tests, and antibodies, are available. In addition to symptomatic therapies, specific treatment options, such as for familial amyloid neuropathy and Fabry's disease, are becoming increasingly available. Pathomechanisms vary depending on the underlying disease process. In addition to metabolic, hormonal, immune, and antibody-mediated mechanisms, in some generalized diseases, genetic causes need to be considered. This review focuses on different aspects of the peripheral nervous system including the nerve roots, plexuses, mononeuropathies and generalized neuropathies, neuromuscular junction disorders, muscle, and autonomic nervous system.

Chemotherapy-induced peripheral neurotoxicity: a critical analysis

With a 3-fold increase in the number of cancer survivors noted since the 1970s, there are now over 28 million cancer survivors worldwide. Accordingly, there is a heightened awareness of long-term toxicities and the impact on quality of life following treatment in cancer survivors. This review will address the increasing importance and challenge of chemotherapy-induced neurotoxicity, with a focus on neuropathy associated with the treatment of breast cancer, colorectal cancer, testicular cancer, and hematological cancers. An overview of the diagnosis, symptomatology, and pathophysiology of chemotherapy-induced peripheral neuropathy will be provided, with a critical analysis of assessment strategies, neuroprotective approaches, and potential treatments. The review will concentrate on neuropathy associated with taxanes, platinum compounds, vinca alkaloids, thalidomide, and bortezomib, providing clinical information specific to these chemotherapies.

Waldenström macroglobulinemia: 2013 update on diagnosis, risk stratification, and management

DISEASE OVERVIEW

Waldenström macroglobulinemia (WM) is a lymphoplasmacytic lymphoma with immunoglobulin M (IgM) monoclonal protein. Clinical features include anemia, thrombocytopenia, hepatosplenomegaly, and lymphadenopathy.

DIAGNOSIS

The presence of IgM monoclonal protein associated with ≥10% clonal lymphoplasmacytic cells in bone marrow confirms the diagnosis.

RISK STRATIFICATION

Age, hemoglobin level, platelet count, β2 microglobulin, and monoclonal IgM concentrations are characteristics required for prognosis.

RISK-ADAPTED THERAPY

Not all patients who fulfill WM criteria require therapy; these patients can be observed until symptoms develop. Rituximab-based therapy is used in virtually all US patients with WM and can be combined with alkylating agent or purine nucleoside analog (or both). The preferred Mayo Clinic nonstudy therapeutic induction is rituximab, cyclophosphamide, and dexamethasone. Future stem cell transplantation should be considered in induction therapy selection.

MANAGEMENT OF REFRACTORY DISEASE

Bortezomib, thalidomide, everolimus, lenalidomide, and bendamustine have all been shown to have activity in WM. Given WM's natural history, reduction of complications will be a priority for future treatment trials.

Neuropathy and monoclonal gammopathy

The association of neuropathy with monoclonal gammopathy has been known for several years, even if the clinical and pathogenetic relevance of this association is not completely defined. This is not a marginal problem since monoclonal gammopathy is present in 1-3% of the population above 50 years in whom it is often asymptomatic, and in at least 8% of patients is associated with a symptomatic neuropathy, representing one of the leading causes of neuropathy in aged people. Monoclonal gammopathy may result from malignant lymphoproliferative diseases including multiple myeloma or solitary plasmocytoma, Waldenström's macroglobulinemia (WM), other IgM-secreting lymphoma or chronic lymphocytic leukemia, and primary systemic amyloidosis (AL). In most instances it is not associated with any of these disorders and is defined monoclonal gammopathy of undetermined significance (MGUS) for its possible, though infrequent, evolution into malignant forms. Several data support the pathogenetic role of the monoclonal gammopathy in the neuropathy particularly when of IgM isotype where IgM reactivity to several neural antigens has been reported. Increased levels of VEGF have been implicated in POEMS syndrome. However, there are as yet no defined therapies for these neuropathies, as their efficacy has not been confirmed in randomized trials.

Amyloid-like IgM deposition neuropathy: a distinct clinico-pathologic and proteomic profiled disorder

Some patients with immunoglobulin paraproteinemic neuropathy have intra-nerve deposits that morphologically mimick amyloid, but do no stain with Congo red. Patients with amyloid-like deposits were identified. The nerve amyloid-like aggregates were studied by laser microdissection and dual mass spectrometry. Three male patients, all with IgM gammopathy, and neuropathy were identified. Follow-up, disease duration was 5, 19, and 7 years, respectively. All had progressive asymmetric sensory-onset distal axonal polyneuropathy with late motor involvement. Autonomic symptoms occurred in only one after 13 years of symptoms. None had clinical cardio-renal involvement. One had skin papules with dermal amyloid-like deposits. Endoneurial amyloid-like deposits had granulo-fibrillar ultrastructure. Mass spectrometry of laser-dissected deposits identified IgM pentameric macroglobulin (heavy, light, and joining chains) without amyloid-associated proteins including absent apolipoprotein E and serum amyloid P-component. Amyloid-like neuropathy has distinct clinical, pathologic, and proteomic features which expand the spectrum of IgM neuropathies. Patients have favorable survival, relative absence of autonomic features, and distinct proteomic profiles of the infiltrative protein in nerve.

Heterogeneous spectrum of neuropathies in Waldenström's macroglobulinemia: a diagnostic strategy to optimize their management

Neuropathy in Waldenström's macroglobulinemia (WM) is very heterogeneous. We retrospectively studied 40 patients with WM and neuropathy to analyze the different presentations and mechanisms encountered and to propose a diagnostic strategy. Twenty-five patients (62.5%) had axonal neuropathy, related to the following mechanisms: amyloid neuropathy (n = 5), cryoglobulinemic neuropathy (n = 5), neuropathy associated with tumoral infiltration (n = 2), vasculitic neuropathy (n = 2), a clinical motor neuropathy possibly of dysimmune origin (n = 6), or an unclassified mechanism (n = 5). A demyelinating pattern was observed in 15 patients, 10 having anti-myelin-associated glycoprotein (anti-MAG) antibodies and 5 having neuropathy related to chronic inflammatory demyelinating polyradiculoneuropathy. On the basis of these results, we propose a diagnostic strategy combining: (1) an EMG to distinguish between a demyelinating and an axonal pattern; (2) measurement of anti-MAG and anti-ganglioside antibodies; (3) screening for "red flag" features to orientate further investigations. This strategy may help clinicians to identify the mechanism of neuropathy in order to adapt the therapeutic strategy.

Waldenström macroglobulinemia: 2012 update on diagnosis, risk stratification, and management

DISEASE OVERVIEW

Waldenström macroglobulinemia (WM) is a lymphoplasmacytic lymphoma with immunoglobulin M (IgM) monoclonal protein. Clinical features include anemia, thrombocytopenia, hepatosplenomegaly, and lymphadenopathy.

DIAGNOSIS

Presence of IgM monoclonal protein associated with ≥10% clonal lymphoplasmacytic cells in bone marrow confirms the diagnosis.

RISK STRATIFICATION

Age, hemoglobin level, platelet count, β(2) microglobulin, and monoclonal IgM concentrations are characteristics required for prognosis.

RISK-ADAPTED THERAPY

Not all patients who fulfill WM criteria require therapy; these patients can be observed until symptoms develop. Rituximab-based therapy is used in virtually all US patients with WM and can be combined with alkylating agent or purine nucleoside analog (or both). The preferred Mayo Clinic nonstudy therapeutic induction is rituximab, cyclophosphamide, and dexamethasone. Future stem-cell transplantation should be considered in induction therapy selection.

MANAGEMENT OF REFRACTORY DISEASE

Bortezomib, thalidomide, lenalidomide, and bendamustine have all been shown to have activity in WM. Given WM's natural history, reduction of complications will be a priority for future treatment trials.

An update on monoclonal gammopathy and neuropathy

Peripheral neuropathy associated with monoclonal gammopathy is a rare but important cause of neuropathy that can herald serious underlying disease. IgM monoclonal gammopathy of undetermined significance (MGUS) is the most commonly found monoclonal gammopathy associated with neuropathy, with characteristic clinical, electrophysiologic, and pathologic features. The IgG and IgA monoclonal gammopathies are rarely associated with specific neuropathies. Standard immunomodulatory agents including steroids, intravenous immunoglobulin, and plasmapheresis have shown limited efficacy in IgM MGUS. Neuropathies associated with specific lymphoproliferative disorders may not respond to treatments aimed at that disorder. Case series had shown promising results with rituximab, a monoclonal antibody that targets the B cell surface antigen CD20 and results in a rapid and sustained depletion of B cells; however, two recent randomized controlled trials with rituximab failed to provide evidence of efficacy in primary outcome measures, despite reduction in antibody levels. Long-term studies looking at the association between specific immunologic markers and disease recurrence are needed to ultimately develop targeted therapies.

To what extent can multimorbidity be viewed as a determinant of postural control in stroke patients?

OBJECTIVE

To investigate the determinants of postural imbalance after stroke in geriatric patients admitted for low-intensity rehabilitation in skilled nursing facilities (SNFs), particularly the role of multimorbidity.

DESIGN

Cross-sectional study design.

SETTING

Fifteen SNFs.

PARTICIPANTS

All patients who were admitted for rehabilitation after stroke in one of the participating SNFs (N=378) were eligible.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

The Berg Balance Scale (BBS) was selected as a measure of standing balance and the Functional Ambulation Categories (FAC) as a measure of walking balance.

RESULTS

Multimorbidity was present in 34% of the patients. The patients with multimorbidity differed from the patients without multimorbidity with respect to age, proprioception, and vibration sense, but not for any of the cognitive tests, muscle strength, or sitting balance. Patients with multimorbidity had, on average, lower scores on both outcome measures. In linear regression analyses, both the BBS and FAC were best explained by multimorbidity, muscle strength, and the interaction between muscle strength and static sitting balance (overall explained variance 66% and 67%, respectively), while proprioception added only to the variance of the FAC.

CONCLUSIONS

Multimorbidity was independently related to postural imbalance after stroke in patients admitted for rehabilitation in SNFs. Muscle strength and the interaction of muscle strength with static sitting balance were important determinants of both standing and walking balance, indicating these factors as essential targets for rehabilitation.

IgM-monoclonal gammopathy neuropathy and tremor: a first epidemiologic case control study

INTRODUCTION

Small case series suggest tremor occurs frequently in IgM-monoclonal gammopathy of undetermined significance (IgM-MGUS) neuropathy. Epidemiologic study to confirm this association is lacking. Whether the neuropathy or another remote IgM-effect is causal remains unsettled.

MATERIALS AND METHODS

An IgM-MGUS neuropathy case cohort (n = 207) was compared to age, gender, and neuropathy impairment score (NIS) matched, other-cause neuropathy controls (n = 414). Tremor details were extracted from structured neurologic evaluation. All patients underwent nerve conductions.

RESULTS

Tremor occurrence was significantly higher in IgM-MGUS case cohort (29%) than in control cohort (9.2%) (p = 0.001). In IgM-MGUS cases, tremor was associated with worse NIS (p = 0.025) and demyelinating nerve conductions (p = 0.020), but 11 of 60 (18%) IgM-MGUS cases with tremor had axonal neuropathy. In other-cause neuropathy controls, tremor was associated with axonal nerve conductions (p = 0.03) but not with NIS severity (p = 0.57). Tremor occurrence associated with older age in controls, (p = 0.004) but not in IgM-MGUS cases (p = 0.272). Most IgM-MGUS tremor cases (49/60) had a postural-kinetic tremor, 8 had rest tremor, 3 had mixed rest-action. Alternative causes of tremor was identified in 42% of IgM-MGUS cases, the most common type is inherited essential tremor 6/60 (p = 0.04).

CONCLUSIONS

This first epidemiologic case-control study validates association between IgM-MGUS neuropathy and tremor. Among IgM-MGUS neuropathy cases, severity as well as type of neuropathy (demyelinating over axonal) correlated with tremor occurrence. IgM-MGUS paraproteinemia may increase tremor expression in persons recognized with common other risk factors for tremor.