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Latov N, Brannagan TH, Sander HW, Gondim FDAA. Anti-MAG neuropathy: historical aspects, clinical-pathological correlations, and considerations for future therapeutical trials. ARQUIVOS DE NEURO-PSIQUIATRIA 2024; 82:1-7. [PMID: 38325389 PMCID: PMC10849826 DOI: 10.1055/s-0043-1777728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Accepted: 11/21/2023] [Indexed: 02/09/2024]
Abstract
BACKGROUND Patients with anti-MAG neuropathy present with distal demyelinating polyneuropathy, IgM monoclonal gammopathy, and elevated titers of anti-MAG antibodies. OBJECTIVE This paper reviews what is known about the clinical presentation, course, pathophysiology, and treatment of anti-MAG neuropathy, with considerations for the design of therapeutic trials. METHODS A literature review of the medical and scientific literature related to anti-MAG neuropathy, and the design of therapeutic clinical trials in peripheral neuropathy. RESULTS Anti-MAG neuropathy can remain indolent for many years but then enter a progressive phase. Highly elevated antibody titers are diagnostic, but intermediate titers can also occur in chronic inflammatory demyelinating polyneuropathy (CIDP). The peripheral nerves can become inexcitable, thereby masking the demyelinating abnormalities. There is good evidence that the anti-MAG antibodies cause neuropathy. Reduction of the autoantibody concentration by agents that target B-cells was reported to result in clinical improvement in case series and uncontrolled trials, but not in controlled clinical trials, probably due to inadequate trial design. CONCLUSION We propose that therapeutic trials for anti-MAG neuropathy include patients with the typical presentation, some degree of weakness, highly elevated anti-MAG antibody titers, and at least one nerve exhibiting demyelinating range abnormalities. Treatment with one or a combination of anti-B-cell agents would aim at reducing the autoantibody concentration by at least 60%. A trial duration of 2 years may be required to show efficacy. The neuropathy impairment score of the lower extremities (NIS-LL) plus the Lower Limb Function (LLF) score would be a suitable primary outcome measure.
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Affiliation(s)
- Norman Latov
- Weil Medical College of Cornell University, Peripheral Neuropathy Center, New York, New York, United States.
| | - Thomas H. Brannagan
- Columbia University, Vagelos College of Physicians and Surgeons, Peripheral Neuropathy Center, Department of Neurology, New York, New York, United States.
| | - Howard W. Sander
- New York University, Department of Neurology, New York, New York, United States.
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Grüter T, Motte J, Bulut Y, Kordes A, Athanasopoulos D, Fels M, Schneider-Gold C, Gold R, Fisse AL, Pitarokoili K. Axonal damage determines clinical disability in chronic inflammatory demyelinating polyradiculoneuropathy (CIDP): A prospective cohort study of different CIDP subtypes and disease stages. Eur J Neurol 2021; 29:583-592. [PMID: 34687104 DOI: 10.1111/ene.15156] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 10/05/2021] [Accepted: 10/14/2021] [Indexed: 12/25/2022]
Abstract
BACKGROUND AND PURPOSE Monitoring of patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is challenging in daily medical practice because the interrelationship between clinical disability, CIDP subtype, and neuronal degeneration is still elusive. The aim of this prospective cohort study was to investigate the role of different electrophysiological variables in CIDP monitoring. METHODS Comprehensive bilateral nerve conduction studies (NCS) and structured clinical examinations were performed in 95 patients with typical CIDP and CIDP variants (age at inclusion 58.6 ± 11.6 years; median [range] inflammatory neuropathy cause and treatment overall disability score (INCAT-ODSS) 3 [0-9]), at time of first diagnosis in 25 of these patients (based on data from the prospective Immune-mediated Neuropathies Biobank registry). After 12 months, 33 patients underwent follow-up examination. Typical CIDP patients and patients with CIDP variants were characterized electrophysiologically and each individual NCS variable and the overall sum score for axonal damage and demyelination were then correlated to clinical disability scores (INCAT-ODSS, modified Medical Research Council (MRS) sum score, and INCAT sensory score). RESULTS As opposed to demyelination markers, the NCS axonal damage variable correlated strongly with disability at both first diagnosis and advanced disease stages in cross-sectional and longitudinal analyses. Distal compound muscle action potential amplitudes of the upper limbs were found to have the strongest correlation with overall clinical function. Typical and atypical CIDP variants had distinct electrophysiological characteristics but, in typical CIDP, axonal degeneration markers were more strongly associated with clinical disability. CONCLUSIONS Total disability is largely determined by the degree of axonal damage, especially in typical CIDP. Although most patients have symptoms predominantly in the legs, NCS of the upper limbs are essential for the monitoring of patients with CIDP and CIDP variants.
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Affiliation(s)
- Thomas Grüter
- Department of Neurology, St. Josef-Hospital, Ruhr-University Bochum, Bochum, Germany.,Immunmediated Neuropathies Biobank (INHIBIT), Ruhr-University Bochum, Bochum, Germany
| | - Jeremias Motte
- Department of Neurology, St. Josef-Hospital, Ruhr-University Bochum, Bochum, Germany.,Immunmediated Neuropathies Biobank (INHIBIT), Ruhr-University Bochum, Bochum, Germany
| | - Yesim Bulut
- Department of Neurology, St. Josef-Hospital, Ruhr-University Bochum, Bochum, Germany.,Immunmediated Neuropathies Biobank (INHIBIT), Ruhr-University Bochum, Bochum, Germany
| | - Anna Kordes
- Department of Neurology, St. Josef-Hospital, Ruhr-University Bochum, Bochum, Germany.,Immunmediated Neuropathies Biobank (INHIBIT), Ruhr-University Bochum, Bochum, Germany
| | - Diamantis Athanasopoulos
- Department of Neurology, St. Josef-Hospital, Ruhr-University Bochum, Bochum, Germany.,Immunmediated Neuropathies Biobank (INHIBIT), Ruhr-University Bochum, Bochum, Germany
| | - Miriam Fels
- Department of Neurology, St. Josef-Hospital, Ruhr-University Bochum, Bochum, Germany.,Immunmediated Neuropathies Biobank (INHIBIT), Ruhr-University Bochum, Bochum, Germany
| | | | - Ralf Gold
- Department of Neurology, St. Josef-Hospital, Ruhr-University Bochum, Bochum, Germany.,Immunmediated Neuropathies Biobank (INHIBIT), Ruhr-University Bochum, Bochum, Germany
| | - Anna Lena Fisse
- Department of Neurology, St. Josef-Hospital, Ruhr-University Bochum, Bochum, Germany.,Immunmediated Neuropathies Biobank (INHIBIT), Ruhr-University Bochum, Bochum, Germany
| | - Kalliopi Pitarokoili
- Department of Neurology, St. Josef-Hospital, Ruhr-University Bochum, Bochum, Germany.,Immunmediated Neuropathies Biobank (INHIBIT), Ruhr-University Bochum, Bochum, Germany
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3
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Koike H, Katsuno M. Paraproteinemia and neuropathy. Neurol Sci 2021; 42:4489-4501. [PMID: 34529193 DOI: 10.1007/s10072-021-05583-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 08/28/2021] [Indexed: 12/16/2022]
Abstract
Paraproteinemia is associated with different peripheral neuropathies. The major causes of neuropathy correlated with paraproteinemia are the deposition of immunoglobulin in the myelin, represented by anti-myelin-associated glycoprotein (MAG) neuropathy; deposition of immunoglobulin or its fragment in the interstitium, represented by immunoglobulin light chain amyloidosis (AL amyloidosis); and paraneoplastic mechanisms that cannot be solely attributed to the deposition of immunoglobulin or its fragment, represented by polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin change (POEMS) syndrome. Patients with anti-MAG neuropathy and POEMS syndrome present with slowing of nerve conduction parameters. This characteristic fulfills the electrodiagnostic criteria for chronic inflammatory demyelinating polyneuropathy (CIDP) defined by the European Academy of Neurology and Peripheral Nerve Society (EAN/PNS). Although direct damage caused by the deposition of amyloid can induce axonal damage in AL amyloidosis, some patients with this condition have features fulfilling the EAN/PNS electrodiagnostic criteria for CIDP. Conventional immunotherapies for CIDP, such as steroids, intravenous immunoglobulin, and plasma exchange, offer no or only minimal-to-modest benefit. Although rituximab can reduce the level of circulating autoantibodies, it may only be effective in some patients with anti-MAG neuropathy. Drugs including melphalan, thalidomide, lenalidomide, and bortezomib for POEMS syndrome and those including melphalan, thalidomide, lenalidomide, pomalidomide, bortezomib, ixazomib, and daratumumab for AL amyloidosis are considered. Since there will be more therapeutic options in the future, thereby enabling appropriate treatments for individual neuropathies, there is an increasing need for early diagnosis.
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Affiliation(s)
- Haruki Koike
- Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan.
| | - Masahisa Katsuno
- Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan
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4
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Khodulev VI, Kabaeva KN, Stepanova JI, Shcharbina NY. Severe Paraproteinemic Demyelinating Neuropathy With Impaired Excitability of the Distal Segments of the Peripheral Nerves. J Clin Neuromuscul Dis 2021; 23:43-48. [PMID: 34431801 DOI: 10.1097/cnd.0000000000000357] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
ABSTRACT We report clinical and detailed nerve conduction findings in case of polyneuropathy associated with kappa light chains monoclonal gammopathy of undetermined significance with progression to lymphoproliferative disorder. A 55-year-old man had a predominantly distal, chronic (5 years duration), slowly progressive, symmetric, predominantly sensory impairment with sensory ataxia, and mild weakness. M protein was identified by serum protein electrophoresis. The kappa/lambda ratio of free light chains was significantly elevated to 11.96. The cerebrospinal fluid protein level was elevated at 3.5 g/L. This case study has revealed 2 unusual electrophysiological phenomena-a very unusual prolongation of distal motor latencies of compound muscle action potentials (CMAP) up to 86.5 ms and impaired excitability of the distal segments of the peripheral nerves. The distal CMAP areas were considerably lower compared with the proximal CMAP areas. Radiography of the skull revealed osteolytic lesions.
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Affiliation(s)
- Vasily I Khodulev
- Functional Diagnostics Department, Republican Research and Clinical Center of Neurology and Neurosurgery, Minsk, Belarus
| | - Katsiaryna N Kabaeva
- Department of Clinical Hematology and Transfusiology, Belarusian Medical Academy of Postgraduate Education, Minsk, Belarus
| | - Julia I Stepanova
- Scientific Research Laboratory, Belarusian Medical Academy of Postgraduate Education, Minsk, Belarus ; and
| | - Natallia Y Shcharbina
- Clinical Unit "Eleous" at Religious Community, "All Saints Parish in Minsk Eparchy of Belarusian Orthodox Church", Minsk, Belarus
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5
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Antibody testing in neuropathy associated with anti-Myelin-Associated Glycoprotein antibodies: where we are after 40 years. Curr Opin Neurol 2021; 34:625-630. [PMID: 34267053 DOI: 10.1097/wco.0000000000000975] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE OF REVIEW The diagnosis of Myelin-Associated Glycoprotein (MAG) neuropathy is based on the presence of elevated titers of IgM anti-MAG antibodies, which are typically associated with IgM monoclonal gammopathy, and a slowly progressive, distal demyelinating phenotype. The condition, however, can be under or over diagnosed in patients with mildly elevated antibody titers, absent monoclonal gammopathy, or an atypical presentation. The purpose of this paper is to examine recent advances in our understanding of the currently available anti-MAG antibody assays, their reliability, and their use in deciding treatment or monitoring the response to therapy. RECENT FINDINGS Higher titers of anti-MAG antibodies are more likely to be associated with the typical MAG phenotype or response to therapy. Mildly elevated antibody levels can occur in patients with chronic inflammatory demyelinating polyneuropathy. Testing for cross-reactivity with HNK1 can add to the specificity of the antibody assays. Patients with MAG neuropathy can present with an atypical phenotype and in the absence of a detectable monoclonal gammopathy. SUMMARY Assays for anti-MAG antibodies by Enzyme-Linked Immunosorbent Assay can be improved by testing for antibody binding at multiple serum dilutions, the inclusion of antigen-negative microwells as internal controls for each sample, testing for cross-reactivity with HNK1, and formal validation. The diagnosis needs to be considered in patients with demyelinating neuropathy, even in the absence of a monoclonal gammopathy or typical phenotype. The change in antibody levels needs to be considered in evaluating the response to therapy with B-cell depleting agents.
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Memon AB, Madani S, Ahmad BK, Grover K, Arcila-londono X, Schultz L, Sripathi N. Value of terminal latency index and sensory electrophysiology in idiopathic and diabetic chronic inflammatory demyelinating polyradiculoneuropathy. Clin Neurophysiol Pract 2019; 4:190-193. [PMID: 31886444 PMCID: PMC6920505 DOI: 10.1016/j.cnp.2019.08.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 08/13/2019] [Accepted: 08/23/2019] [Indexed: 10/26/2022] Open
Abstract
OBJECTIVES To evaluate sensory electrophysiology, terminal latency index (TLI), and treatment response in idiopathic and diabetic chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). METHODS We performed a retrospective review of 147 patients with CIDP who underwent electrodiagnostic evaluation (January 2000-December 2015). Eighty-nine patients fulfilled electrophysiological criteria described by the Ad hoc Subcommittee of the American Academy of Neurology and Albers et al. Fifty-eight patients were divided into idiopathic (N = 40) and diabetic (N = 18) groups. These groups were compared for age, sex, cerebrospinal fluid protein, response to treatment, sensory response abnormalities, and TLI measurements using chi-square tests for binary and categorical variables and using t-tests and mixed-effects models for continuous variables. RESULTS The difference in abnormal rates of sensory responses was significant for the sural nerve, with the idiopathic group having a lower rate than the diabetic group (80% vs. 100%, p < 0.001). No group differences in the TLI measurements were significant. CONCLUSIONS Sural sensory responses may have some value in differentiating idiopathic CIDP from diabetic CIDP. Larger prospective studies are needed to confirm our findings. SIGNIFICANCE Our study suggests that abnormal sural sensory potentials may have some significance in differentiating idiopathic CIDP from diabetic CIDP.
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Affiliation(s)
- Anza B. Memon
- Department of Neurology, Henry Ford Health System, Detroit, MI, USA,Wayne State University, School of Medicine, Detroit, MI, USA,Corresponding author at: 2799 W Grand Blvd, Detroit, Michigan 48202, USA.
| | - Sarah Madani
- Department of Neurology, Henry Ford Health System, Detroit, MI, USA
| | | | - Kavita Grover
- Department of Neurology, Henry Ford Health System, Detroit, MI, USA,Wayne State University, School of Medicine, Detroit, MI, USA
| | - Ximena Arcila-londono
- Department of Neurology, Henry Ford Health System, Detroit, MI, USA,Wayne State University, School of Medicine, Detroit, MI, USA
| | - Lonni Schultz
- Department of Neurology, Henry Ford Health System, Detroit, MI, USA
| | - Naganand Sripathi
- Department of Neurology, Henry Ford Health System, Detroit, MI, USA,Wayne State University, School of Medicine, Detroit, MI, USA
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7
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Abstract
Since the discovery of an acute monophasic paralysis, later coined Guillain-Barré syndrome, almost 100 years ago, and the discovery of chronic, steroid-responsive polyneuropathy 50 years ago, the spectrum of immune-mediated polyneuropathies has broadened, with various subtypes continuing to be identified, including chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and multifocal motor neuropathy (MMN). In general, these disorders are speculated to be caused by autoimmunity to proteins located at the node of Ranvier or components of myelin of peripheral nerves, although disease-associated autoantibodies have not been identified for all disorders. Owing to the numerous subtypes of the immune-mediated neuropathies, making the right diagnosis in daily clinical practice is complicated. Moreover, treating these disorders, particularly their chronic variants, such as CIDP and MMN, poses a challenge. In general, management of these disorders includes immunotherapies, such as corticosteroids, intravenous immunoglobulin or plasma exchange. Improvements in clinical criteria and the emergence of more disease-specific immunotherapies should broaden the therapeutic options for these disabling diseases.
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8
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Distal Acquired Demyelinating Symmetric Neuropathy. Neuromuscul Disord 2018. [DOI: 10.1007/978-981-10-5361-0_45] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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9
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Morphology of Donor and Recipient Nerves Utilised in Nerve Transfers to Restore Upper Limb Function in Cervical Spinal Cord Injury. Brain Sci 2016; 6:brainsci6040042. [PMID: 27690115 PMCID: PMC5187556 DOI: 10.3390/brainsci6040042] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2016] [Revised: 09/19/2016] [Accepted: 09/21/2016] [Indexed: 11/21/2022] Open
Abstract
Loss of hand function after cervical spinal cord injury (SCI) impacts heavily on independence. Multiple nerve transfer surgery has been applied successfully after cervical SCI to restore critical arm and hand functions, and the outcome depends on nerve integrity. Nerve integrity is assessed indirectly using muscle strength testing and intramuscular electromyography, but these measures cannot show the manifestation that SCI has on the peripheral nerves. We directly assessed the morphology of nerves biopsied at the time of surgery, from three patients within 18 months post injury. Our objective was to document their morphologic features. Donor nerves included teres minor, posterior axillary, brachialis, extensor carpi radialis brevis and supinator. Recipient nerves included triceps, posterior interosseus (PIN) and anterior interosseus nerves (AIN). They were fixed in glutaraldehyde, processed and embedded in Araldite Epon for light microscopy. Eighty percent of nerves showed abnormalities. Most common were myelin thickening and folding, demyelination, inflammation and a reduction of large myelinated axon density. Others were a thickened perineurium, oedematous endoneurium and Renaut bodies. Significantly, very thinly myelinated axons and groups of unmyelinated axons were observed indicating regenerative efforts. Abnormalities exist in both donor and recipient nerves and they differ in appearance and aetiology. The abnormalities observed may be preventable or reversible.
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10
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Distinct lymphocytes subsets in IgM-related neuropathy: clinical-immunological correlations. Neurol Sci 2014; 36:303-8. [DOI: 10.1007/s10072-014-1935-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Accepted: 08/30/2014] [Indexed: 10/24/2022]
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Abstract
Chronic neuropathies are operationally classified as primarily demyelinating or axonal, on the basis of electrodiagnostic or pathological criteria. Demyelinating neuropathies are further classified as hereditary or acquired-this distinction is important, because the acquired neuropathies are immune-mediated and, thus, amenable to treatment. The acquired chronic demyelinating neuropathies include chronic inflammatory demyelinating polyneuropathy (CIDP), neuropathy associated with monoclonal IgM antibodies to myelin-associated glycoprotein (MAG; anti-MAG neuropathy), multifocal motor neuropathy (MMN), and POEMS syndrome. They have characteristic--though overlapping--clinical presentations, are mediated by distinct immune mechanisms, and respond to different therapies. CIDP is the default diagnosis if the neuropathy is demyelinating and no other cause is found. Anti-MAG neuropathy is diagnosed on the basis of the presence of anti-MAG antibodies, MMN is characterized by multifocal weakness and motor conduction blocks, and POEMS syndrome is associated with IgG or IgA λ-type monoclonal gammopathy and osteosclerotic myeloma. The correct diagnosis, however, can be difficult to make in patients with atypical or overlapping presentations, or nondefinitive laboratory studies. First-line treatments include intravenous immunoglobulin (IVIg), corticosteroids or plasmapheresis for CIDP; IVIg for MMN; rituximab for anti-MAG neuropathy; and irradiation or chemotherapy for POEMS syndrome. A correct diagnosis is required for choosing the appropriate treatment, with the aim of preventing progressive neuropathy.
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Affiliation(s)
- Norman Latov
- Department of Neurology and Neuroscience, Weill Medical College of Cornell University, 1305 York Avenue, Suite 217, New York, NY 10021, USA
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12
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Zivković SA. Rituximab in the treatment of peripheral neuropathy associated with monoclonal gammopathy. Expert Rev Neurother 2014; 6:1267-74. [PMID: 17009914 DOI: 10.1586/14737175.6.9.1267] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Peripheral neuropathy associated with immunoglobulin (Ig)M gammopathy and anti-myelin-associated glycoprotein antibodies is frequently treatment-resistant and different treatment regimens carry substantial toxicity and side effects. More recently, the chimeric anti-CD20 monoclonal antibody rituximab has shown benefits in the treatment of peripheral neuropathy associated with IgM gammopathy with a favorable side-effect profile. There are no published reports of its use in the treatment of neuropathy associated with IgG and IgA gammopathies. Rituximab is usually given at 375 mg/m(2) intravenously with four weekly doses that may be repeated after 6-12 months. Large controlled studies are still pending but rituximab is an exciting and promising treatment offering another option in the treatment of peripheral neuropathy associated with IgM monoclonal gammopathy.
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Affiliation(s)
- Sasa A Zivković
- Department of Neurology, University of Pittsburgh Medical Center, PUH F875, 200 Lothrop Street, Pittsburgh, PA 15213, USA.
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Luigetti M, Padua L, Mazza S, Rossini PM, Sabatelli M, Lo Monaco M. Clinical–neurophysiological correlations in a series of patients with IgM-related neuropathy. Clin Neurophysiol 2013; 124:1899-903. [DOI: 10.1016/j.clinph.2013.02.116] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2012] [Revised: 02/03/2013] [Accepted: 02/18/2013] [Indexed: 01/06/2023]
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Multifocal motor neuropathy, multifocal acquired demyelinating sensory and motor neuropathy, and other chronic acquired demyelinating polyneuropathy variants. Neurol Clin 2013; 31:533-55. [PMID: 23642723 DOI: 10.1016/j.ncl.2013.01.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Chronic acquired demyelinating neuropathies (CADP) constitute an important group of immune neuromuscular disorders affecting myelin. This article discusses CADP with emphasis on multifocal motor neuropathy, multifocal acquired demyelinating sensory and motor neuropathy, distal acquired demyelinating symmetric neuropathy, and less common variants. Although each of these entities has distinctive laboratory and electrodiagnostic features that aid in their diagnosis, clinical characteristics are of paramount importance in diagnosing specific conditions and determining the most appropriate therapies. Knowledge regarding pathogenesis, diagnosis, and management of these disorders continues to expand, resulting in improved opportunities for identification and treatment.
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Abstract
The identification of autoantibodies associated with dysimmune neuropathies was a major contribution to the characterization of peripheral nerve disorders, the understanding of their pathophysiology, and the clinical diagnosis of neuropathies. Antibodies directed to GM1, GQ1b, and disyalilated gangliosides, and anti-MAG antibodies are very useful in the diagnosis of acute or chronic motor or sensory-motor neuropathies with or without monoclonal IgM. Anti-onconeural anti-Hu and anti-CV2/CRMP antibodies allow when they are detected the diagnosis of paraneoplastic neuropathies. This chapter focuses on the description of these antibodies as diagnostic markers and on their immunopathogenesis. We give a background overview on the origin of these antibodies, their detection, and review those studies, which clearly show that these antibodies are capable of binding to the target tissues in peripheral nerve and thereby can exert a variety of pathophysiological effects. The corresponding electrophysiological and histological changes observed both in human and animal models are exemplified in order to get a better understanding of the immune mechanisms of these antibody-mediated neuropathies.
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Affiliation(s)
- Andreas Steck
- Department of Neurology, University Hospital Basel, Basel, Switzerland.
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16
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Crone C, Krarup C. Neurophysiological approach to disorders of peripheral nerve. HANDBOOK OF CLINICAL NEUROLOGY 2013; 115:81-114. [PMID: 23931776 DOI: 10.1016/b978-0-444-52902-2.00006-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Disorders of the peripheral nerve system (PNS) are heterogeneous and may involve motor fibers, sensory fibers, small myelinated and unmyelinated fibers and autonomic nerve fibers, with variable anatomical distribution (single nerves, several different nerves, symmetrical affection of all nerves, plexus, or root lesions). Furthermore pathological processes may result in either demyelination, axonal degeneration or both. In order to reach an exact diagnosis of any neuropathy electrophysiological studies are crucial to obtain information about these variables. Conventional electrophysiological methods including nerve conduction studies and electromyography used in the study of patients suspected of having a neuropathy and the significance of the findings are discussed in detail and more novel and experimental methods are mentioned. Diagnostic considerations are based on a flow chart classifying neuropathies into eight categories based on mode of onset, distribution, and electrophysiological findings, and the electrophysiological characteristics in each type of neuropathy are discussed.
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Affiliation(s)
- Clarissa Crone
- Department of Clinical Neurophysiology, Rigshospitalet and University of Copenhagen, Copenhagen, Denmark
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17
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Pihan M, Decaux O, Marcorelles P, Bahon-Riedinger I, Lemercier S, Gainche-Salmon A, Doncker AV. Neuropathies associées à une IgM monoclonale anti-MAG. Rev Med Interne 2012; 33:686-92. [DOI: 10.1016/j.revmed.2012.05.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2012] [Accepted: 05/14/2012] [Indexed: 12/23/2022]
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18
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Bayat E, Kelly JJ. Neurological complications in plasma cell dyscrasias. HANDBOOK OF CLINICAL NEUROLOGY 2012; 105:731-46. [PMID: 22230530 DOI: 10.1016/b978-0-444-53502-3.00020-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Affiliation(s)
- Elham Bayat
- Department of Neurology, The George Washington University, Washington, DC, USA
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Zara G, Zambello R, Ermani M. Neurophysiological and clinical responses to rituximab in patients with anti-MAG polyneuropathy. Clin Neurophysiol 2011; 122:2518-22. [DOI: 10.1016/j.clinph.2011.05.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2011] [Revised: 05/19/2011] [Accepted: 05/21/2011] [Indexed: 12/29/2022]
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20
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Short and long-term effect of IVIg in demyelinating neuropathy associated with MGUS, experience of a monocentric study. Rev Neurol (Paris) 2011; 167:897-904. [PMID: 22023823 DOI: 10.1016/j.neurol.2011.04.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2010] [Revised: 04/12/2011] [Accepted: 04/26/2011] [Indexed: 11/23/2022]
Abstract
BACKGROUND The optimal treatment for demyelinating neuropathy associated with MGUS and anti-MAG neuropathy is not known. METHODS We retrospectively studied the efficacy of IVIg in 14 patients with DN-MGUS (seven IgM and seven IgG/A) and seven with anti-MAG neuropathies, treated in our reference center between 2002 and 2007. Patients were clinically evaluated before the first infusion, after the first infusion, and after the last IVIg treatment. RESULTS Anti-MAG neuropathy: after a single infusion, one patient improved and six were stable. At last follow-up (mean: 15.6months [range: 3.5-31], mean number of IVIg courses: 8 [2-33]), one patient maintained her improvement from baseline. DN-MGUS: after a single infusion, nine patients improved (64%), four were stable and one deteriorated further. The factor predictive of short-term response to IVIg was relapsing neuropathy responding better in the walking score analysis (Fisher exact test: P=0.005). At last follow-up (mean: 22.6months [range 2-72], mean number of IVIg courses: seven [1-24]), neurological status improved in four patients, five patients remained stable, including three who are still under regular IVIg, and four had deteriorated. Improvement from baseline persisted for a prolonged period in two patients after IVIg were stopped. Patients who were responders on Norris after the first IVIg course were significantly better responders at long-term follow-up than the others (P=0.001). We report no serious adverse effect. CONCLUSION IVIg are not very efficient in the management of anti-MAG neuropathies. Nevertheless, they have a frequent short-term beneficial effect in DN-MGUS, which was maintained at long-term follow-up in one-third of our patients. When a DN-MGUS patient is regularly treated by IVIg courses, frequent periodic clinical evaluations must be performed to determine when to stop treatment and switch to another one.
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Wang L, Chopp M, Szalad A, Liu Z, Bolz M, Alvarez FM, Lu M, Zhang L, Cui Y, Zhang RL, Zhang ZG. Phosphodiesterase-5 is a therapeutic target for peripheral neuropathy in diabetic mice. Neuroscience 2011; 193:399-410. [PMID: 21820491 DOI: 10.1016/j.neuroscience.2011.07.039] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2011] [Revised: 06/17/2011] [Accepted: 07/19/2011] [Indexed: 12/16/2022]
Abstract
Peripheral neuropathy is a common and major complication of diabetes, the underlying mechanisms of which are not fully understood. Using a mouse model of type II diabetes, the present study investigated the role of phosphodiesterase-5 (PDE5) in peripheral neuropathy. BKS.Cg-m+/+Leprdb/J (db/db) mice were treated with sildenafil, a specific inhibitor of PDE5, at doses of 2 and 10 mg/kg or saline. Levels of PDE5 and morphometric parameters in sciatic nerve tissue as well as the motor and sensory function were measured in these mice. In diabetic mice, PDE5 expression in sciatic nerve tissue was significantly upregulated, whereas the myelin sheath thickness, myelin basic protein (MBP), and subcutaneous nerve fibers were significantly reduced. Treatment with sildenafil significantly improved neurological function, assayed by motor and sensory conducting velocities and thermal and mechanical noxious stimuli, concomitantly with increases in myelin sheath thickness, MBP levels, and subcutaneous nerve fibers. In vitro, hyperglycemia upregulated PDE5 in Schwann cells and reduced Schwann cell proliferation, migration, and expression of brain-derived neurotrophic factor (BDNF). Blockage of PDE5 with sildenafil increased cyclic guanosine monophosphate (cGMP) and completely abolished the effect of hyperglycemia on Schwann cells. Sildenafil upregulated cGMP-dependent protein kinase G I (PKGI), whereas inhibition of PKGI with a PKG inhibitor, KT5823, suppressed the inhibitory effect of sildenafil on Schwann cells. These data indicate that hyperglycemia substantially upregulates PDE5 expression and that the cGMP/PKG signaling pathway activated by sildenafil mediates the beneficial effects of sildenafil on diabetic peripheral neuropathy.
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Affiliation(s)
- L Wang
- Department of Neurology, Henry Ford Health Sciences Center, 2799 W. Grand Boulevard, Detroit, MI 48202, USA
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Matà S, Ambrosini S, Mello T, Lolli F, Minciacchi D. Anti-myelin associated glycoprotein antibodies recognize HNK-1 epitope on CNS. J Neuroimmunol 2011; 236:99-105. [PMID: 21621858 DOI: 10.1016/j.jneuroim.2011.05.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2011] [Revised: 05/04/2011] [Accepted: 05/06/2011] [Indexed: 11/18/2022]
Abstract
Antibodies to myelin-associated glycoprotein (MAG) are associated with demyelinating polyneuropathy and are specific for the HNK-1 epitope. To test if anti-MAG IgM recognize HNK-1 on CNS, sera from 20 patients and 238 controls were tested on rat slices by indirect immunofluorescence (IIF). IgM from anti-MAG positive patients, but not from control sera, stained rat brain with perineuronal or neuropil pattern, depending on the CNS region. IIF titers significantly correlated with ELISA anti-MAG titers. The staining of patients' sera were inhibited by mouse anti-HNK-1 monoclonal antibody. Our results demonstrate that anti-MAG IgM recognizes HNK-1 outside the peripheral nerve myelin carriers.
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Affiliation(s)
- Sabrina Matà
- Department of Neurological and Psychiatric Sciences, University of Firenze, Italy.
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Pupil-involving third nerve palsy as a manifestation of anti-myelin-associated glycoprotein neuropathy. J Neuroophthalmol 2010; 31:29-33. [PMID: 21164358 DOI: 10.1097/wno.0b013e3181f2e27a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
A 56-year-old man developed a pupil-involving left third nerve palsy. Imaging studies of the brain and intracranial vessels were normal. Neurological examination demonstrated a sensory polyneuropathy and mild distal weakness. Nerve conduction studies showed prolonged distal motor latencies. An enzyme-linked immunosorbent assay test detected high titers of anti-myelin-associated glycoprotein (MAG) antibodies. The patient improved with prednisone and rituximab treatment. Anti-MAG neuropathy should be considered when evaluating a patient with an undiagnosed cranial neuropathy, especially in the setting of a sensory neuropathy.
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Luigetti M, Madia F, Conte A, Tonali P, Sabatelli M. Neuropathy with predominant small fiber involvement associated with abnormal anti-MAG titer. Intern Med 2010; 49:2627-9. [PMID: 21139305 DOI: 10.2169/internalmedicine.49.4200] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We describe a patient with painful neuropathy associated with an abnormal anti-MAG titer in which predominant involvement of intra-epidermal nerve fiber was documented. Electrophysiological studies revealed low-borderline amplitude of sensory and compound motor action potentials registering from lower limbs and normal conduction velocity. Sural nerve biopsy disclosed only a slight loss of myelinated fiber. Skin biopsy performed at the proximal thigh and at the distal leg was consistent with a non-length-dependent small fiber neuropathy. It is likely that in this case anti-MAG antibodies played a role in the pathogenesis of small fiber neuropathy.
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Affiliation(s)
- Marco Luigetti
- Institute of Neurology, Catholic University of Sacred Heart, Rome, Italy.
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25
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Les polyneuropathies avec IgM monoclonale anti-MAG : étude descriptive clinique, biologique, électrophysiologique et anatomopathologique d’une cohorte de 13 patients. Rev Neurol (Paris) 2009; 165:1071-9. [DOI: 10.1016/j.neurol.2009.04.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2008] [Revised: 03/17/2009] [Accepted: 04/24/2009] [Indexed: 11/17/2022]
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Faber CG, Notermans NC, Wokke JHJ, Franssen H. Entrapment in anti myelin-associated glycoprotein neuropathy. J Neurol 2009; 256:620-4. [PMID: 19306083 DOI: 10.1007/s00415-009-0132-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2008] [Revised: 09/23/2008] [Accepted: 10/23/2008] [Indexed: 11/25/2022]
Abstract
Anti-myelin associated glycoprotein (MAG) neuropathy is a chronic disorder in which IgM antibodies react with Schwann cell glycoproteins, including MAG and peripheral myelin protein 22 (PMP22). Nerve conduction studies show features of axon loss and predominantly distal slowing consistent with demyelination. Because a genetic loss of PMP22 function yields hereditary neuropathy with liability to pressure palsies (HNPP), loss of PMP22 function due to anti- MAG antibodies may result in increased sensitivity to entrapment. We investigated this by performing standardized electrophysiological studies in 16 patients with anti-MAG neuropathy and 16 disease controls with genetically confirmed HNPP. Disproportionate slowing relative to adjacent segments occurred in similar proportions of patients with anti-MAG neuropathy and HNPP, and was of the same magnitude in each group. Affected were the elbow, carpal tunnel and the wrist-hand segments of the median and ulnar nerves. However, in anti-MAG neuropathy as compared to HNPP, absolute values of distal motor latencies and conduction velocities outside entrapment sites were slower and amplitudes were lower. In conclusion, increased sensitivity for entrapment may occur in anti-MAG neuropathy and contribute to part of the nerve damage.
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Affiliation(s)
- Catharina G Faber
- Dept. of Neurology, University Hospital Maastricht, 5800, 6202 AZ, Maastricht, The Netherlands.
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Yiannikas C, Vucic S. Utility of somatosensory evoked potentials in chronic acquired demyelinating neuropathy. Muscle Nerve 2008; 38:1447-1454. [DOI: 10.1002/mus.21078] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Abstract
PURPOSE OF REVIEW To provide clinically useful guidelines in the management of neuropathy associated with monoclonal gammopathy from a review of the most recent literature and our own experience. RECENT FINDINGS Recent data on neuropathy associated with monoclonal gammopathy come from better descriptions of subgroups, and from new treatment compounds that have shown encouraging results in different entities. SUMMARY Neuropathies associated with monoclonal gammopathy are relatively rare and most often the neuropathy reveals the monoclonal gammopathy. These conditions require combined neurological and haematological assessments. Their clinical presentations are highly heterogeneous but most have an electrophysiological demyelinating pattern. The main described subgroup is IgM anti-(myelin-associated glycoprotein) neuropathy, which presents as a relatively benign, slowly progressive sensory neuropathy. Nerve biopsy should be considered in patients with progressive and disabling axonal neuropathy. Neuropathies associated with monoclonal gammopathy have various neurological and general outcomes, including life-threatening entities such as light-chain amyloid neuropathy and POEMS syndrome. Treatment choice is wide and depends both on the underlying haematological disorder and severity of the neuropathy. Intravenous immunoglobulin should be assessed in demyelinating monoclonal gammopathy of undetermined significance neuropathy. Malignant haematological disorders should be treated per se. The possibility of a malignant evolution of monoclonal gammopathy of undetermined significance warrants regular haematological monitoring.
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Affiliation(s)
- Pierre Lozeron
- Department of Neurology, Bicêtre Hospital, Assistance Publique-Hôpitaux de Paris, Université Paris-Sud, Paris, France.
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Gondim FAA, De Sousa EA, Latov N, Sander HW, Chin RL, Brannagan TH. Anti-MAG/SGPG associated neuropathy does not commonly cause distal nerve temporal dispersion. J Neurol Neurosurg Psychiatry 2007; 78:902-4. [PMID: 17353253 PMCID: PMC2117731 DOI: 10.1136/jnnp.2006.111930] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Patients with anti-myelin associated glycoprotein (anti-MAG) neuropathy have uniform slowing without temporal dispersion, but do usually have disproportionately distal slowing. We evaluated distal compound muscle action potential (CMAP) dispersion in 29 patients with anti-MAG/sulphated glucuronyl paragloboside (SGPG) neuropathy (titres > or = 12,800). Among 138 motor responses, 15% (tibial), 7.3% (peroneal), 10.7% (median) and 13.8% (ulnar) had distal CMAP duration > 9 ms. Disproportionate distal slowing with normal distal CMAP duration in the arms may be useful to differentiate chronic inflammatory demyelinating polyneuropathy from anti-MAG/SGPG associated neuropathy.
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Affiliation(s)
- F A A Gondim
- Department of Neurology, Weill Medical College of Cornell University, New York, NY, USA
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Jaskowski TD, Prince HE, Greer RW, Litwin CM, Hill HR. Further comparisons of assays for detecting MAG IgM autoantibodies. J Neuroimmunol 2007; 187:175-8. [PMID: 17537521 DOI: 10.1016/j.jneuroim.2007.04.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2007] [Revised: 04/19/2007] [Accepted: 04/24/2007] [Indexed: 10/23/2022]
Abstract
Anti-MAG antibodies are commonly found in the sera of patients with demyelinating sensorimotor neuropathy and IgM paraproteinemia. Our objective here was to compare MAG results obtained by two different laboratories using similar methods (Western blot, EIA, IFA). Western blot (WB) employing MAG from monkey was less sensitive (72.5%) than myelin IFA (92.5%; monkey nerve) and EIA (97.5%; human MAG) when compared to WB using human MAG and is most likely due to methodology (not antigen source). EIA detected low titers of MAG IgM antibodies in suspected patient sera (negative by other methods) that were also SGPG IgM-positive. Patients having low titers by EIA, but negative by WB may have other autoimmune neuropathies without demyelination.
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Affiliation(s)
- Troy D Jaskowski
- Associated Regional and University Pathologists (ARUP), Institute for Clinical and Experimental Pathology, 500 Chipeta Way, Salt Lake City, UT 84108, USA.
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Caliandro P, Stålberg E, La Torre G, Padua L. Sensitivity of conventional motor nerve conduction examination in detecting patchy demyelination: A simulated model. Clin Neurophysiol 2007; 118:1577-85. [PMID: 17524765 DOI: 10.1016/j.clinph.2007.04.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2005] [Revised: 02/08/2007] [Accepted: 04/17/2007] [Indexed: 11/17/2022]
Abstract
OBJECTIVE To evaluate, in 5 simulated motor nerves with patchy demyelination: (1) the sensitivity of the conventional motor conduction examination; (2) the conduction velocity of single axons (SA-CV). METHODS Four damaged segments were simulated in each nerve. Myelin impairment was generated by varying two parameters: (1) percent reduction in conduction velocity, i.e. degree of damage (DEGREE); (2) percentage of affected axons, i.e. extent of damage (EXTENT). Myelin impairment was simulated in axons with different diameters. We evaluated: (1) conduction velocity; (2) temporal dispersion of the negative phase of compound motor action potential (CMAP); (3) amplitude decay of CMAP; (4) SA-CV of 20 randomly-chosen axons. RESULTS When the damage involved both large and small axons, the conduction velocity was pathological only when severe myelin damage involved a large number of axons. Temporal dispersion and amplitude decay were more sensitive than conduction velocity in detecting the damage. In damage involving only large axons or only small axons, all parameters remained in the normal range. SA-CV evaluation was much more sensitive than the conventional studies, regardless of the diameter of the damaged axons. CONCLUSIONS Conventional studies are not sensitive in detecting minimal myelin damage. Decomposing the CMAPs and randomly studying 20 SA-CVs would increase the sensitivity of damage detection. SIGNIFICANCE These results contribute to a better understanding of the relationship between axonal properties and neurophysiological findings in motor nerve demyelination.
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Bae JS, Kim BJ. Subclinical diabetic neuropathy with normal conventional electrophysiological study. J Neurol 2007; 254:53-9. [PMID: 17508139 DOI: 10.1007/s00415-006-0261-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2005] [Accepted: 04/10/2006] [Indexed: 10/23/2022]
Abstract
BACKGROUND For early detection and prevention of diabetic neuropathy, it is important to identify subclinical diabetic neuropathy. Routine nerve conduction study often fails to detect early stage of neuropathy. OBJECTIVES The purpose of this study is to evaluate the clinical usefulness of electrophysiological indexes in detecting early diabetic neuropathy with no objective clinical or electrophysiological abnormalities. MATERIALS AND METHODS Nerve conduction study of upper/lower limbs was investigated in 31 subclinical diabetic neuropathy patients with normal nerve conduction studies(group I), 38 clinical diabetic neuropathy patients with normal nerve conduction studies(group II) and 31 normal controls. Residual latency (RL), terminal latency index (TLI) and modified F ratio (MFR) were calculated and compared among groups. RESULTS Compared with controls, MFR of lower limbs and TLI of both upper/lower limbs were significantly decreased in both group I and II (p<0.05). RL was increased in both groups, but the difference was not statistically significant. Comparing the indexes between group I and II, there was no significant difference. CONCLUSIONS RL, TLI and MFR, which reflect distal conduction slowing, may be useful indexes to identify subclinical diabetic neuropathy. The results also suggest that electrophysiological changes that are obscured in routine nerve conduction study are present before the clinical manifestation.
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Affiliation(s)
- Jong Seok Bae
- Dept. of Neurology, Inje University College of Medicine Busan, Seoul, Korea(O)
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Lupu VD, Mora CA, Dambrosia J, Meer J, Dalakas M, Floeter MK. Terminal latency index in neuropathy with antibodies against myelin-associated glycoproteins. Muscle Nerve 2007; 35:196-202. [PMID: 17068765 DOI: 10.1002/mus.20678] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Neuropathy with antibodies against myelin-associated glycoproteins (MAG/SGPG-N) and hereditary sensorimotor neuropathy type 1 (HMSN1) are characterized by chronic demyelination with little conduction block. Electrodiagnostic studies suggest that in HMSN1 conduction slowing occurs uniformly along the nerve, whereas in MAG/SGPG-N it is predominantly distal. Some but not all previous reports have shown that the terminal latency index (TLI) was useful to distinguish MAG/SGPG-N from chronic idiopathic demyelinating polyneuropathy. We compared median TLI from 21 patients with MAG/SGPG-N with those obtained from 26 patients with HMSN1, 20 with HMSN2, and 12 healthy volunteers. All patients with TLI <0.26 had MAG/SGPG-N, and all patients with TLI > or =0.32 had HMSN1. In the remaining patients with intermediate TLI values, ulnar distal motor latency (DML) aided in differentiation between MAG/SGPG-N and HMSN1 with an overall sensitivity of 100% and specificity of 98%. In conclusion, median TLI in combination with ulnar DML can further guide the demyelinating neuropathy evaluation toward hereditary or autoimmune causes.
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Affiliation(s)
- Vitalie D Lupu
- EMG Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA
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Franssen H, Notermans NC. Length dependence in polyneuropathy associated with IgM gammopathy. Ann Neurol 2006; 59:365-71. [PMID: 16437567 DOI: 10.1002/ana.20785] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE In polyneuropathy associated with monoclonal IgM gammopathy, nerve conduction studies may show disproportionate distal slowing consistent with segmental demyelination. This was suggested to represent a length-dependent demyelinating process, starting in distal and proceeding to proximal segments. Because the evidence for this is incomplete, we assessed whether length dependence occurs in IgM neuropathy. METHODS In 22 patients with IgM neuropathy, 20 disease controls with chronic inflammatory demyelinating polyneuropathy (CIDP) and 36 normal controls, we investigated motor conduction, sensory conduction, and needle electromyography for nerves with short, intermediate-length, and long axons as well as conduction in short segments of the ulnar nerve from proximal to distal. To compare variables in nerves of different length, we normalized individual values with respect to the median in normal controls. RESULTS In IgM neuropathy, distal slowing and features of axon loss increased with nerve length, and ulnar nerve conduction became gradually slower from proximal to distal when the elbow segment was excluded. In CIDP, no clear length dependence was found except for distal amplitude. INTERPRETATION The disproportionate distal slowing in IgM neuropathy may be part of a length-dependent process, assuming that this process is randomly distributed due to a generalized exposure to IgM.
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Affiliation(s)
- Hessel Franssen
- Department of Clinical Neurophysiology, Neuromuscular Research Group, Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, Utrecht, The Netherlands.
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Lombardi R, Erne B, Lauria G, Pareyson D, Borgna M, Morbin M, Arnold A, Czaplinski A, Fuhr P, Schaeren-Wiemers N, Steck AJ. IgM deposits on skin nerves in anti-myelin-associated glycoprotein neuropathy. Ann Neurol 2005; 57:180-7. [PMID: 15668968 DOI: 10.1002/ana.20364] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Anti-myelin-associated glycoprotein (anti-MAG) neuropathy is a chronic demyelinating neuropathy with predominant involvement of large sensory fibers and deposits of IgM and complement on sural nerve myelinated fibers. We assessed the presence of IgM deposits on skin myelinated nerve fibers and the involvement of unmyelinated axons in anti-MAG neuropathy. Skin biopsies were performed in 14 patients with anti-MAG neuropathy, in 8 patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), and in 2 patients with IgM paraproteinemic neuropathy. Biopsies were taken at the proximal thigh in 20 patients, at the distal leg in 21 patients, at the proximal arm in 13 patients, and at the hand or fingertip in 10 patients. We found IgM deposits on dermal myelinated fibers in all anti-MAG neuropathy patients, with a greater prevalence at the distal site of the extremities. Deposits were located throughout the length of the fibers and at the paranodal loops. CIDP and IgM paraproteinemic neuropathies did not show any deposit of IgM. Anti-MAG neuropathy and CIPD patients showed a decrease in epidermal nerve fiber density reflecting an associated axonal loss. In anti-MAG neuropathy, both large- and small-diameter nerve fibers are affected, and specific deposits of IgM are found on skin myelinated nerve fibers.
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Affiliation(s)
- Raffaella Lombardi
- Neurobiology Unit, Department of Research and Neurology, University Hospital of Basel, Basel, Switzerland
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Abstract
Recent advances in neuroimmunology have led to improvements in the pathogenesis, diagnosis, prognosis, and treatment of many neuromuscular disorders. The value of autoantibody testing is increasing steadily in neurologic practice. Not all antibodies have a high yield in diagnosis. In some disorders, such as generalized adult onset of myasthenia gravis, Lambert-Eaton myasthenic syndrome,Miller Fisher syndrome, and multifocal motor neuropathy,autoantibody tests provide accurate diagnosis and can be considered biologic markers of these disorders.
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Affiliation(s)
- Rahman Pourmand
- State University of New York, Stony Brook, NY 11794-8121, USA.
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Isoardo G, Migliaretti G, Ciaramitaro P, Rota E, Poglio F, Tavella A, Paolasso I, Cavallo F, Bergamasco B, Cocito D. Differential diagnosis of chronic dysimmune demyelinating polyneuropathies with and without anti-MAG antibodies. Muscle Nerve 2004; 31:52-8. [DOI: 10.1002/mus.20230] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Capasso M, Torrieri F, Di Muzio A, De Angelis MV, Lugaresi A, Uncini A. Can electrophysiology differentiate polyneuropathy with anti-MAG/SGPG antibodies from chronic inflammatory demyelinating polyneuropathy? Clin Neurophysiol 2002; 113:346-53. [PMID: 11897535 DOI: 10.1016/s1388-2457(02)00011-1] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVES Patients with polyneuropathy and antibodies to myelin-associated glycoprotein (MAG) and sulphated glucuronyl paragloboside (SGPG) differ from chronic inflammatory demyelinating polyneuropathy (CIDP) because of a slower, progressive course, symmetrical and predominantly sensory involvement of legs, predominantly distal slowing of motor conductions, and poorer response to therapy. We studied whether a wide set of electrophysiologic parameters may differentiate these two neuropathies. METHODS We reviewed the electrophysiological studies of 10 patients with anti-MAG/SGPG antibodies and 22 with CIDP examining: (1) motor conduction velocity and distal compound muscle action potential amplitude; (2) conduction block (CB) and temporal dispersion; (3) distal motor latency and terminal latency index (TLI); (4) F wave and proximal conduction time; and (5) sensory conduction and occurrence of abnormal median with normal sural sensory potential. RESULTS Anti-MAG/SGPG neuropathies showed: (1) more severe involvement of peroneal nerves; (2) more frequent disproportionate distal slowing of motor conductions (TLI< or =0.25) and absent sural potential, and (3) no CB. However 3/22 CIDP patients also had at least two nerves with TLI< or =0.25 and no CB. CONCLUSIONS Electrophysiologic findings suggest in anti-MAG/SGPG neuropathy a length-dependent process with a likely centripetal evolution. A disproportionate slowing of conduction in distal segments of motor nerves suggests the diagnosis of anti-MAG/SGPG neuropathy, although it is not pathognomonic.
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Affiliation(s)
- Margherita Capasso
- Center for Neuromuscular Diseases, University G. d'Annunzio, Chieti, Italy
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Cocito D, Isoardo G, Ciaramitaro P, Migliaretti G, Pipieri A, Barbero P, Cucci A, Durelli L. Terminal latency index in polyneuropathy with IgM paraproteinemia and anti-MAG antibody. Muscle Nerve 2001; 24:1278-82. [PMID: 11562906 DOI: 10.1002/mus.1145] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Criteria for the diagnosis of chronic inflammatory demyelinating polyneuropathy (CIDP) are met by the polyneuropathy associated with immunoglobulin M (IgM) paraproteinemia and anti-myelin-associated glycoprotein (MAG) antibody (MAG-CIDP). However, MAG-CIDP differs from other types of CIDP, mainly in its poorer response to treatment. The utility of terminal latency index (TLI) as an electrophysiological marker for MAG-CIDP has been debated. In this study we confirmed its diagnostic usefulness and evaluated TLI threshold values for motor nerves investigated in routine nerve conduction studies. Median, ulnar, peroneal, and tibial TLIs of 11 subjects with MAG-CIDP, 18 with CIDP, and 76 healthy controls were compared, and threshold values for MAG-CIDP evaluated as the lowest value with a likelihood ratio higher than 10. Mean TLI values and TLIs of all but the peroneal nerve were significantly lower in MAG-CIDP. Median nerve TLI of 0.26 and ulnar nerve TLI of 0.33 were identified as the threshold TLI values for MAG-CIDP.
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Affiliation(s)
- D Cocito
- Unità Operativa di Neurofisiologia Clinica, Dipartimento di Neuroscienze, Università di Torino, Via Cherasco 15, 10126 Torino, Italy.
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Attarian S, Azulay JP, Boucraut J, Escande N, Pouget J. Terminal latency index and modified F ratio in distinction of chronic demyelinating neuropathies. Clin Neurophysiol 2001; 112:457-63. [PMID: 11222967 DOI: 10.1016/s1388-2457(01)00469-2] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE To evaluate indexes calculated from standard electrophysiological data in differentiating chronic demyelinating polyneuropathy (CDP). METHODS Nerve conduction study of upper limbs was investigated in 19 chronic inflammatory demyelinating polyneuropathy (CIDP) patients, 25 anti-myelin-associated glycoprotein/sulfated glucuronyl paragloboside antibodies (MAG/SGPG) CDP patients, 13 Charcot-Marie-Tooth disease type 1A (CMT1A) patients and 22 controls. Terminal latency index (TLI) was used to compare the wrist-to-thenar muscle segment with the elbow-to-wrist conduction velocity. Modified F ratio (MFR) was used to compare the spinal cord-to-elbow segment latency with that of the wrist-to-thenar muscle segment. RESULTS Compared with controls, TLI was decreased in 21 anti-MAG/SGPG CDP patients while MFR was either decreased or was normal. In 16 CIDP patients, MFR was increased while TLI was either normal or increased. In CMT1A both TLI and MFR were in normal ranges. The sensitivity of MFR as a supportive finding in CIDP was found to be 84% and its specificity 89%. The sensitivity of TLI as a mean of diagnosis of anti-MAG/SGPG CDP was found to be 93% and its specificity 90%. CONCLUSIONS The results of TLI and MFR facilitates distinction between different types of CDP. In CIDP, MFR was significantly higher and TLI showed no change; in the anti-MAG/SGPG CDP, TLI and MFR were significantly lower; in CMT1A, TLI and MFR showed no change in comparison with the controls.
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Affiliation(s)
- S Attarian
- Department of Neurology and Neuromuscular Diseases, University Hospital La Timone, 264 rue Saint-Pierre, 13385, Marseille, France.
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Abstract
A number of presentations of chronic demyelinating polyneuropathy have been identified, each distinguished by its phenotypic pattern. In addition to classic chronic inflammatory demyelinating polyneuropathy (CIDP), which is characterized clinically by symmetric proximal and distal weakness and sensory loss, several regional variants can be recognized: multifocal motor neuropathy (MMN: asymmetric and pure motor), multifocal acquired demyelinating sensory and motor (MADSAM) neuropathy (asymmetric, sensory, and motor), and distal acquired demyelinating symmetric (DADS) neuropathy (symmetric, distal, sensory, and motor). There are also temporal, pathological, and disease-associated variants. This review describes a clinical scheme for approaching the chronic acquired demyelinating polyneuropathies that leads to a rational use of supportive laboratory studies and treatment options. In addition, we propose new diagnostic criteria for CIDP that more accurately reflect current clinical practice.
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Affiliation(s)
- D S Saperstein
- Department of Neurology, Wilford Hall Medical Center, 2200 Bergquist Drive, Suite 1 (MMCN), San Antonio, Texas 78236-5300, USA.
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Chapter 13 Peripheral Neuropathy Treatment Trials. ACTA ACUST UNITED AC 2001. [DOI: 10.1016/s1877-3419(09)70020-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Abstract
Electrodiagnostic studies comprising electromyography (EMG) and nerve conduction studies (NCS) are well-established objective methods for the diagnosis, quantification and classification of polyneuropathies (PNP). This paper reviews examination techniques, their pathophysiological interpretation, examination strategies and diagnostic criteria for the diagnosis and classification of a PNP. The routine electrodiagnostic evaluation includes sensory NCSs performed with surface or needle electrodes, motor NCSs, F-wave studies and EMG by qualitative or quantitative techniques. Sensory NCSs and F-wave studies have a high sensitivity in PNPs and the different techniques complement each other. The distinction between a PNP with predominantly axonal loss and a PNP with predominantly demyelination is one of the major aims of the electrophysiological examination. There are, however, large variation in suggested criteria for predominantly demyelination. The degree of slowing in conduction taken to indicate demyelination varies between a decrease of 50 to 30% from mean of controls, distal latency prolongation criteria vary from 35% to 70% of mean of controls, F-wave latency prolongation criteria vary from 120% to 150% of upper limit of controls, and criteria for partial motor conduction block vary from 11 to 50% reduction of CMAP amplitude and/or area between proximal and distal stimulation. Needle EMG studies may be valuable in order to detect and quantify denervation activity, to assess chronicity by an evaluation of the extent of reinnervation, and to evaluate the topographical distribution of changes. It is concluded that electrodiagnostic studies are valuable in patients with suspected PNP and the results may have consequences for prognosis and therapy of individual patients. Large variation in examination techniques, strategies, interpretations and diagnostic criteria have been found among electromyographers and it is suggested that the value of electrodiagnostic studies may be further improved by international standardisation.
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Affiliation(s)
- B Johnsen
- Department of Clinical Neurophysiology, University Hospital, Nørrebrogade HH, DK 8000, Aarhus, Denmark
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Ponsford S, Willison H, Veitch J, Morris R, Thomas PK. Long-term clinical and neurophysiological follow-up of patients with peripheral, neuropathy associated with benign monoclonal gammopathy. Muscle Nerve 2000; 23:164-74. [PMID: 10639606 DOI: 10.1002/(sici)1097-4598(200002)23:2<164::aid-mus4>3.0.co;2-y] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The incidence of hematological malignancy in patients with monoclonal gammopathy of undetermined significance (MGUS) has been assessed as 17% to 25%. To ascertain whether this is true of neuropathy associated with MGUS, a long-term (5-42 years) retrospective clinical and neurophysiological follow-up was conducted in 50 cases (immunoglobulin M [IgM], n = 38; IgG, n = 11; IgA, n = 1). Only three patients developed hematological malignancy. Of 25 survivors with IgM paraproteinemia, 7 had myelin-associated glycoprotein antibodies with typical clinical features. Evoked distal muscle amplitudes were significantly smaller than for the other paraprotein classes. Preferential distal demyelination manifested by relative prolongation of distal motor latency was not apparent in the cases of long duration. Two patients with IgM antidisialosyl antibodies and cold agglutinating activity had a large fiber neuropathy with intermittent oculofacial involvement. Both responded to intravenous immunoglobulin. Findings in the remaining patients were varied. Recognition of IgM subgroups is important both for prognosis and possible response to treatment.
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Affiliation(s)
- S Ponsford
- Department of Clinical Neurophysiology, Walsgrave Hospital, Clifford Bridge Road, Coventry, CV2 2DX, UK.
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Gorson KC. Clinical features, evaluation, and treatment of patients with polyneuropathy associated with monoclonal gammopathy of undetermined significance (MGUS). J Clin Apher 1999; 14:149-53. [PMID: 10540371 DOI: 10.1002/(sici)1098-1101(1999)14:3<149::aid-jca8>3.0.co;2-9] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A number of common disorders of the peripheral nervous system are closely linked to a monoclonal gammopathy. In a minority of patients, the neuropathy represents the sentinel feature of a malignant plasma cell dyscrasia, such as multiple myeloma or its osteosclerotic variant, Waldenstrom's disease, amyloidosis, cryoglobulinemia or lymphoma; the vast majority have so-called "monoclonal gammopathy of undetermined significance" (MGUS). Sensory symptoms predominate with paresthesias, numbness, imbalance, and gait ataxia. Electrodiagnostic studies show mixed demyelinating and axonal features and often may be indistinguishable from findings in chronic inflammatory demyelinating polyneuropathy. Some have a pure axonal polyneuropathy, and in these patients the relationship to the paraprotein is less certain. With limited success, correlations have been made between the immunoglobulin type (IgM, IgG, or IgA) and the clinical and electromyographic characteristics of the neuropathy. The treatment of MGUS neuropathies poses a considerable challenge. Patients with IgG/IgA-MGUS have improved with corticosteroids or intravenous immune globulin. Only the benefit of plasma exchange has been substantiated in a controlled trial. The IgM neuropathies tend to be more refractory but often improve with similar regimens, particularly if cytotoxic agents are added in doses sufficient to reduce the amount of the M-protein. In addition to plasma exchange, chlorambucil, and cyclophosphamide, interferon-alpha is a novel therapy that holds promise for patients with IgM neuropathies associated with anti-myelin associated antibodies.
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Affiliation(s)
- K C Gorson
- Neurology Service, St. Elizabeth's Medical Center, Tufts University School of Medicine, Boston, Massachusetts 02135, USA.
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Abstract
High titers of serum antibodies to neural antigens occur in several forms of neuropathy. These include neuropathies associated with monoclonal gammopathy, inflammatory polyneuropathies, and paraneoplastic neuropathies. The antibodies frequently react with glycosylated cell surface molecules, including glycolipids, glycoproteins, and glycosaminoglycans, but antibodies to intracellular proteins have also been described. There are several correlations between antibody specificity and clinical symptoms, such as anti-MAG antibodies with demyelinating sensory or sensorimotor neuropathy, anti-GM1 ganglioside antibodies with motor nerve disorders, antibodies to gangliosides containing disialosyl moieties with sensory ataxic neuropathy and Miller-Fisher syndrome, and antibodies to the neuronal nuclear Hu antigens with paraneoplastic sensory neuronopathy. These correlations suggest that the neuropathies may be caused by the antibodies, but evidence for a causal relationship is stronger in some examples than others. In this review, we discuss the origins of the antibodies, evidence for and against their involvement in pathogenic mechanisms, and the implications of these findings for therapy.
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Affiliation(s)
- R H Quarles
- Laboratory of Molecular and Cellular Neurobiology, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 49 Convent Drive, Building 49, Room 2A28, Bethesda, Maryland 20892, USA
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Weiss MD, Dalakas MC, Lauter CJ, Willison HJ, Quarles RH. Variability in the binding of anti-MAG and anti-SGPG antibodies to target antigens in demyelinating neuropathy and IgM paraproteinemia. J Neuroimmunol 1999; 95:174-84. [PMID: 10229128 DOI: 10.1016/s0165-5728(98)00247-1] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Densitometry of immunostained Western blots or thin layer chromatograms and enzyme-linked immunosorbent assays (ELISAs) were used to compare the relative strengths of IgM binding to myelin-associated glycoprotein (MAG), P0 glycoprotein, peripheral myelin protein-22 (PMP-22), sulfate-3-glucuronyl paragloboside (SGPG), and other potential target antigens in a series of eleven patients with sensory or sensorimotor demyelinating neuropathy and IgM paraproteinemia. The IgM from all patients exhibited reactivity with both MAG and SGPG, and there was a statistically significant correlation between the overlay assays and ELISAs for measuring the strength of IgM binding to MAG and to SGPG. However, the data revealed variations in the relative strengths with which the antibodies bound to the potential target antigens and heterogeneity in their fine specificities. First, there was a poor correlation between the strength of binding to MAG and to SGPG, respectively. Second, reactivity with MAG or SGPG in a few of the patients was only detected by one of the two assay systems. Third, about one-third of the patients' IgM absolutely required the sulfate on SGPG for reactivity, whereas the others retained some reactivity after removal of the sulfate. Fourth, IgM from two of the patients exhibited unusually strong reactivity with the proteins of compact myelin, P0 and PMP22. These relative differences in strengths of antibody binding to the potential antigens were compared with the patients' clinical presentations and with their responses to intravenous immunoglobulin (IVIg) therapy in a clinical trial in which they participated. For the most part, these variations did not correlate with clinical presentation, which was relatively homogeneous in this series of patients. However, an inverse relationship was noted between degree of reactivity to MAG by ELISA and response to IVIg. Two of the patients who responded had only mild elevations of IgM antibodies to nerve glycoconjugates and exhibited some unusual immunochemical and clinical characteristics in comparison to the other patients. The results demonstrate differences in the relative strengths with which anti-MAG and anti-SGPG IgM antibodies from different patients bind to potential neural target antigens which may affect pathogenic mechanisms and response to therapy.
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Affiliation(s)
- M D Weiss
- Myelin and Brain Development Section, Laboratory of Molecular and Cellular Neurobiology, National Institutes of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
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Abstract
OBJECTIVE To compare the clinical and electrodiagnostic features and response to treatment in patients with IgM-MGUS and IgG-MGUS associated polyneuropathy. MATERIAL AND METHODS Retrospective review of 34 consecutive patients with MGUS associated neuropathy evaluated over 5 years. RESULTS There were 19 patients with IgM-MGUS and 15 with IgG-MGUS. There were no differences in age, duration of symptoms, or distribution of motor and sensory symptoms or signs. IgM-MGUS patients had prolonged distal latencies of the median and ulnar motor potentials, greater slowing of the peroneal nerve conduction velocity and more often absent ulnar sensory potentials. Half of the patients in both groups improved following immunotherapy. CONCLUSION IgM-MGUS patients had more severe demyelination on the nerve conduction studies, but there were no clinical features that differentiated the 2 groups. IgM and IgG-MGUS patients improved with plasma exchange and other immune therapies. Anti-MAG antibodies failed to distinguish a subgroup of patients with IgM-MGUS neuropathy.
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Affiliation(s)
- D Simovic
- Neurology Service, St Elizabeth's Medical Center, Tufts University School of Medicine, Boston, MA 02135, USA
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Pedersen SF, Pullman SL, Latov N, Brannagan TH. Physiological tremor analysis of patients with anti-myelin-associated glycoprotein associated neuropathy and tremor. Muscle Nerve 1997; 20:38-44. [PMID: 8995581 DOI: 10.1002/(sici)1097-4598(199701)20:1<38::aid-mus5>3.0.co;2-i] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Tremor is often associated with anti-myelin-associated glycoprotein (anti-MAG) peripheral neuropathy (PN), but its physiology has never been accurately described. This study quantified the physiological characteristics of tremors in patients with anti-MAG demyelinating PN. Eighteen patients with tremor and PN with demyelinating features (ages 30-86, mean = 66.5 years) were evaluated for anti-MAG antibodies (positive considered > or = 1:3200) and for tremor amplitude, frequency, side-to-side relationships, and electromyographic (EMG) activation patterns. Thirteen patients had anti-MAG titers >1:3200 and 8 had both positive anti-MAG titers and tremors. Anti-MAG PN patients revealed tremors higher in amplitude, lower in frequency, with greater side-to-side amplitude ratios, greater amplitude variability, and more consistent cocontracting antagonist EMG patterns that do not attenuate with inertial loading. We conclude that anti-MAG PN tremor is not due only to exaggerated physiologic mechanisms but may reflect a distinctive form of neurogenic tremor.
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Affiliation(s)
- S F Pedersen
- Department of Neurology, College of Physicians and Surgeons of Columbia University, New York, New York, USA
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