Long-term clinical and neurophysiological follow-up of patients with peripheral, neuropathy associated with benign monoclonal gammopathy

Acute/chronic inflammatory polyradiculoneuropathy

Autoimmune neuropathy may present acutely or with a more progressive and/or relapsing and remitting course. Acute inflammatory neuropathy or Guillain-Barré syndrome (GBS) has variable presentations but by far the most common is acute inflammatory demyelinating polyradiculoneuropathy which is characterized by rapidly progressive proximal and distal symmetric weakness, sensory loss, and depressed reflexes. The most common chronic autoimmune neuropathy is chronic inflammatory demyelinating polyradiculoneuropathy, which in its most typical form is clinically similar to acute inflammatory demyelinating polyradiculoneuropathy (proximal and distal symmetric weakness, sensory loss, and depressed reflexes) but differs in that onset is much more gradual, i.e., over at least 8 weeks. While the majority of GBS cases result from a postinfectious activation of the immune system, presumably in a genetically susceptible host, less is understood regarding the etiopathogenesis of chronic inflammatory demyelinating polyradiculoneuropathy. Both acute and chronic forms of these inflammatory neuropathies are driven by some combination of innate and adaptive immune pathways, with differing contributions depending on the neuropathy subtype. Both disorders are largely clinical diagnoses, but diagnostic tools are available to confirm the diagnosis, prognosticate, detect variant forms, and rule out mimics. Given the autoimmune underpinnings of both disorders, immunosuppressive and immunomodulating treatments are typically given in both diseases; however, they differ in their response to treatment.

Severe Paraproteinemic Demyelinating Neuropathy With Impaired Excitability of the Distal Segments of the Peripheral Nerves

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.

Neuropathy associated with IgA monoclonal Gammopathy. A harbinger of AL amyloidosis

Peripheral neuropathy is seen in 15% of patients with IgA monoclonal gammopathy. Treatment and prognosis of dysproteinemic neuropathy is usually guided by the underlying plasma cell disorders, which could be either benign or malignant. The true incidence of hematologic malignancy in patients with neuropathy associated with IgA monoclonal gammopathy is not known. However, patients with IgA M-protein are generally at increased risk for malignant transformation. Since neuropathy may be the first and only organ involvement, neurologists are key contributors in identifying each patient's plasma cell dyscrasia. We report two patients who presented with severe progressive polyneuropathy, had a detectable low-level IgA lambda paraproteinemia dismissed as incidental. Both were diagnosed later with a combination of malignant plasma cell dyscrasia and AL amyloidosis resulting in multiorgan failure and death. Both patients demonstrated red flags for malignant progression including abnormal serum free light chain, rapidly progressive debilitating neuropathy refractory to immunotherapy, prominent autonomic dysfunction, and weight loss. In summary, patients with IgA monoclonal gammopathy presenting with polyneuropathy can be at risk for malignant transformation. Failure to investigate for hematologic malignancy and AL amyloidosis may cause significant delays in treatment and result in fatal outcomes.

Long-term disability and prognostic factors in polyneuropathy associated with anti-myelin-associated glycoprotein (MAG) antibodies

AIM OF THE STUDY

Neuropathy associated with IgM monoclonal gammopathy (MGUS) represents distinctive clinical syndrome, characterized by male predominance, late age of onset, slow progression, predominantly sensory symptoms, deep sensory loss, ataxia, minor motor impairment. More than 50% of patients with neuropathy-associated MGUS possess antibodies against myelin-associated glycoprotein (MAG). Purpose of our study was to assess effects on disease progression of demographic, clinical and neurophysiological variables in our large cohort of patients.

MATERIALS AND METHODS

Forty-three Caucasians patients were followed every eight months for median duration time of 93 months. Extremity strength was assessed with Medical Research Council (MRC) Scale, disability with overall disability status scale (ODSS), modified Rankin Scale and sensory function with Inflammatory Neuropathy Cause and Treatment (INCAT) sensory scale (ISS). Statistical analyses were conducted with parametric or non-parametric measures as appropriate. Survival analysis was used to test predictive value of clinical, demographical and neurophysiological variables. Variance analysis was conducted to explain difference on MRC between patients and groups at different time from onset.

RESULTS

Results showed that demyelinating pattern, older age and absence of treatment were significant risk factors for disability worsening. No other factors emerged as predictors including gender, ataxia and tremor at baseline, level of anti-MAG and IgM protein concentration in serum. Despite worsening of all outcome measures between first and last visit, quality of life (HRQol) judged by patients did not vary significantly.

CONCLUSIONS

Our study provides evidence that electrophysiologic pattern, age of onset and absence of treatment are strong predictor of prognosis in anti-MAG polyneuropathy.

Treatment for IgG and IgA paraproteinaemic neuropathy

BACKGROUND

Paraproteinaemic neuropathy refers to those neuropathies associated with a monoclonal gammopathy or paraprotein. The most common of these present with a chronic, predominantly sensory, symmetrical neuropathy, similar to chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) but with relatively more sensory involvement, both clinically and neurophysiologically. The optimal treatment for neuropathies associated with IgG and IgA monoclonal gammopathy of uncertain significance is not known. This is an update of a review first published in 2007.

OBJECTIVES

To assess the effects of any treatment for IgG or IgA paraproteinaemic peripheral neuropathy.

SEARCH METHODS

On 18 January 2014 we searched the Cochrane Neuromuscular Disease Group Trials Specialized Register, CENTRAL, MEDLINE and EMBASE. We also checked bibliographies for controlled trials of treatments for IgG or IgA paraproteinaemic peripheral neuropathy. We checked clinical trials registries for ongoing studies in November 2014.

SELECTION CRITERIA

We considered for inclusion randomised controlled trials (RCTs) and quasi-RCTs using any treatment for IgG or IgA paraproteinaemic peripheral neuropathy. We excluded people with IgM paraproteins. We excluded people where the monoclonal gammopathy was considered secondary to an underlying disorder. We included participants of any age with a diagnosis of monoclonal gammopathy of uncertain significance with a paraprotein of the IgG or IgA class and a neuropathy. Included participants were not required to fulfil specific electrophysiological diagnostic criteria.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methodology to select studies, extract data and analyse results. One trial author provided additional data and clarification.

MAIN RESULTS

We identified one RCT, with 18 participants, that fulfilled the predetermined inclusion criteria. The trial compared plasma exchange to sham plasma exchange in participants with IgG or IgA paraproteinaemic neuropathy over a three-week follow-up period. We identified four other studies but these were not RCTs or quasi-RCTs. The included RCT did not report our predefined primary outcome measure, change in disability six months after randomisation. The trial revealed a modest benefit of plasma exchange in the weakness component of the Neuropathy Disability Score (NDS, now the Neuropathy Impairment Score); the mean improvement with plasma exchange was 17 points (95% confidence interval (CI) 5.2 to 28.8 points) versus 1 point (95% CI -7.7 to 9.7 points) in the sham exchange group at three weeks' follow-up (mean difference (MD) 16.00; 95% CI 1.37 to 30.63, low quality evidence). There was no statistically significant difference in the overall NDS (MD 18.00; 95% CI -2.03 to 38.03, low quality evidence), vibration thresholds or neurophysiological indices. Adverse events were not reported. The trial was at low risk of bias overall, although limitations of trial size and duration reduce the quality of the evidence in support of its conclusions.

AUTHORS' CONCLUSIONS

The evidence from RCTs for the treatment of IgG or IgA paraproteinaemic neuropathy is currently inadequate. More RCTs of treatments are required. These should have adequate follow-up periods and contain larger numbers of participants, perhaps through multicentre collaboration, considering the relative infrequency of this condition. Observational or open trial data provide limited support for the use of treatments such as plasma exchange, cyclophosphamide combined with prednisolone, intravenous immunoglobulin, and corticosteroids. These interventions show potential therapeutic promise but the potential benefits must be weighed against adverse effects. Their optimal use and the long-term benefits need to be considered and validated with well-designed RCTs.

Placebo-controlled trial of rituximab in IgM anti-myelin-associated glycoprotein neuropathy

OBJECTIVE

To determine whether rituximab 375 mg/m(2) was efficacious in patients with immunoglobulin M (IgM) anti-myelin-associated glycoprotein antibody demyelinating neuropathy (IgM anti-MAG demyelinating neuropathy).

METHODS

Fifty-four patients with IgM anti-MAG demyelinating neuropathy were enrolled in this randomized, double-blind, placebo-controlled trial. The inclusion criteria were inflammatory neuropathy cause and treatment (INCAT) sensory score (ISS) ≥4 and visual analog pain scale >4 or ataxia score ≥2. The primary outcome was mean change in ISS at 12 months.

RESULTS

Twenty-six patients were randomized to a group receiving 4 weekly infusions of 375 mg/m(2) rituximab, and 28 patients to placebo. Intention-to-treat analysis, with imputation of missing ISS values by the last observation carried forward method, showed a lack of mean change in ISS at 12 months, 1.0 ± 2.7 in the rituximab group, and 1.0 ± 2.8 in the placebo group. However, changes were observed, in per protocol analysis at 12 months, for the number of patients with an improvement of at least 2 points in the INCAT disability scale (p = 0.027), the self-evaluation scale (p = 0.016), and 2 subscores of the Short Form-36 questionnaire.

CONCLUSIONS

Although primary outcome measures provide no evidence to support the use of rituximab in IgM anti-MAG demyelinating neuropathy, there were improvements in several secondary outcomes in per protocol analysis.

LEVEL OF EVIDENCE

This study provides Class I evidence that rituximab is ineffective in improving ISS in patients with IgM anti-MAG demyelinating neuropathy.

Paraproteinemic neuropathies

The term paraproteinemic neuropathy refers to a heterogeneous group of neuropathies, which share the common feature of a homogeneous immunoglobulin in the serum. The presence of a monoclonal gammopathy indicates an underlying clonal B-cell expansion, which may appear in the context of a lymphoproliferative disorder. If a neoplastic origin of the gammopathy is identified, the treatment should be targeted to the neoplasm. In most patients, however, the monoclonal gammopathy is not associated with malignant haematological disorders, and is defined as monoclonal gammopathy of undetermined significance.

Clinical spectrum and evolution of monoclonal gammopathy-associated neuropathy: an observational study

BACKGROUND

Paraproteinemic neuropathy (PPN) is often under-diagnosed because of its clinical and electrophysiological variability. Progression of neuropathy is considered an alarm bell for possible malignant conversion of underlying monoclonal gammopathy (MG).

OBJECTIVE

To report clinical presentation, course, and evolution in a group of patients with PPN in order to identify findings useful for achieving the diagnosis, suspecting progression, and recognizing the underlying hematological conditions.

PATIENTS AND METHODS

Thirty-nine patients with PPN underwent clinical examination, electrodiagnostic studies, cerebrospinal fluid analysis, and laboratory tests. These parameters were compared between the different peak groups.

RESULTS

IgM MG was found in 51.4%, IgG MG in 33.3%, and IgA MG in 10.3% of our cohort. PPN appeared as mainly sensory, demyelinating, mildly progressive neuropathy, regardless of the type of peak or light chain. However, axonal findings were present in many IgG patients and in part of the IgM patients and a small number of the IgG patients may have presented with motor symptoms at the onset. The IgM patients had a significant tendency toward clinical worsening and IgG subjects had a more elevated rate of malignancy. IgA-related neuropathies were rare, heterogenous, and with a high tendency to evolution and malignancy.

CONCLUSIONS

Most of PPN often present a relatively monomorphic clinical picture but they can be clinically heterogenous and must be suspected even if sensory impairment and demyelination are not the dominant features. Tendency to malignancy seems globally elevated and needs intensive follow-up. Diagnostic approach to patients presenting with peripheral neuropathy should always include the typing of monoclonal immunoglobulins in serum and urine. In contrast, patients presenting with MG should be submitted to nerve conduction study/electroneurography and neurological evaluation.

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.

Canomad presenting without ophthalmoplegia and responding to intravenous immunoglobulin

The acronym CANOMAD encompasses chronic ataxic neuropathy combined with ophthalmoplegia, M protein, cold agglutinins, and anti-disialosyl antibodies.Herein we describe 2 patients presenting with progressive ataxic neuropathy who only developed ophthalmoplegia after a significant delay post-presentation, which in 1 case had features indicative of brainstem dysfunction. Both patients were found to have an IgM paraprotein and anti-disialosyl antibodies. They responded to treatment with intravenous immunoglobulin, thus illustrating the importance of diagnosing this condition.

IgM monoclonal gammopathy-associated neuropathies with different IgM specificity

BACKGROUND AND PURPOSE

  Antibodies directed against myelin-associated glycoprotein (MAG) are believed to be the most frequent biologic marker of the neuropathies associated with IgM monoclonal gammopathy of undetermined significance (MGUS). The objective of this study was to examine the prevalence of antiganglioside and/or sulfatide-positive patients and their clinical findings, including therapeutic response, compared to anti-MAG-positive or seronegative patients.

METHODS

  We prospectively followed 46 patients with MGUS who were diagnosed in our tertiary referral centers for polyneuropathy since 1997. All patients underwent nerve conduction studies and were tested for anti-MAG, gangliosides, and sulfatide antibodies. All the anagraphic and clinical data (including symptoms, disability scale, therapy, secondary malignancy development) were recorded in a database and compared between three patients' groups (anti-MAG-positive; antiganglioside/sulfatide-positive; no reactivity).

RESULTS

  Anti-MAG reactivity was present in 17 (37%) patients; other 17 patients (37%) had antiganglioside/sulfatide reactivity and 12 (26%) had no reactivity. Patients with antiganglioside/sulfatide positivity, although heterogeneous by a clinical and neurophysiological point of view, had the most severe neuropathic manifestations and a higher disability score at nadir (P < 0.001). These patients had a better response to both intravenous immunoglobulin therapy and rituximab.

CONCLUSIONS

  Our results suggest that antiganglioside/sulfatide-positive patients form a relevant portion of patients with MGUS-associated polyneuropathy seen in tertiary care centers and should be considered in future studies on treatment response.

Non-anti-MAG DADS neuropathy as a variant of CIDP: clinical, electrophysiological, laboratory features and response to treatment in 10 cases

BACKGROUND AND PURPOSE

Some patients within the spectrum of chronic inflammatory demyelinating polyradiculoneuropathies (CIDP) have distal acquired demyelinating symmetric (DADS) neuropathy, usually associated with anti-myelin-associated-glycoprotein (MAG) IgM monoclonal gammopathy. The aim of this retrospective study was to investigate patients with DADS neuropathy without anti-MAG antibodies, and study their response to immunotherapy.

METHODS

Patients were selected on the basis of (i) 'Definite CIDP' according to the EFNS/PNS Guideline criteria, (ii) The presence of disproportionately prolonged motor latencies resulting in a terminal latency index (TLI) ≤ 0.25 in at least two motor nerves and (iii) The absence of anti-MAG antibodies on ELISA. Response to immunotherapy was defined as persistent improvement by at least one point on the INCAT disability score.

RESULTS

Data from 146 CIDP patients were analysed, and 10 patients were included. Six had clinically pure sensory neuropathy, and four had sensorimotor neuropathy. Ataxia was present in nine patients, generalized areflexia in seven and postural tremor in two. Five of the 10 patients had abnormal sensory potentials only in the upper limbs. An associated condition was found in nine patients: two chronic lymphocytic leukaemias, four IgG monoclonal gammopathies (one associated with non-Hodgkin's lymphoma) and two IgM monoclonal gammopathies of unknown significance. Patients were mostly improved with intravenous immunoglobulin (IVIg), corticosteroids, plasma exchanges, or a combination thereof.

CONCLUSION

DADS neuropathy without anti-MAG antibodies is more likely to be considered a variant of CIDP. In addition, such patients should be systematically investigated for an associated haematological or immunological condition.

Polyneuropathy associated with IgM vs IgG monoclonal gammopathy: comparison between clinical and electrophysiological findings

OBJECTIVE

The neuropathy associated with IgM monoclonal gammopathy (IgM-MG) is regarded as a sensorimotor, mainly demyelinating neuropathy. It is not fully known whether the neuropathy in IgG-MG is caused by the same mechanisms and shows the same electrophysiological characteristics. We aimed at making a comparison between clinical and neurophysiological findings in these two conditions.

PATIENTS AND METHODS

Twenty-seven patients with IgM-associated neuropathy [18 with anti-myelin-associated glycoprotein (anti-MAG) antibodies] were compared with 15 age-matched patients with IgG-associated neuropathy.

RESULTS

Patients with IgM-associated neuropathy (especially those with anti-MAG antibodies) had significantly clinically more severe disabilities with involvement of both motor and sensory functions compared with patients with IgG-associated neuropathy in whom clinical sensory disturbances were more prominent than motor dysfunction. Motor and sensory conduction velocities were significantly lower and distal latencies significantly longer in the IgM group than in the IgG group concerning the median, ulnar and peroneal nerves. Fifty-four per cent of the patients in the IgM group did not present a sensory response of the median nerve vs 13% in the IgG group. There was also a significant difference concerning absent responses from the peroneal and sural nerves in the IgM vs IgG group (peroneal: 48% vs 13%, sural: 88% vs 27%).

CONCLUSION

Polyneuropathy associated with IgM-MG, especially when associated with anti-MAG antibodies, appears to have more of a demyelinating involvement that meets the criteria for demyelination. This was not as clear in those associated with IgG. The IgG neuropathy showed less and milder deficit in the electrophysiological studies.

Placebo-controlled trial of rituximab in IgM anti-myelin-associated glycoprotein antibody demyelinating neuropathy

OBJECTIVE

Report a double-blind, placebo-controlled study of rituximab in patients with anti-MAG demyelinating polyneuropathy (A-MAG-DP).

METHODS

Twenty-six patients were randomized to four weekly infusions of 375 mg/m(2) rituximab or placebo. Sample size was calculated to detect changes of > or = 1 Inflammatory Neuropathy Course and Treatment (INCAT) leg disability scores at month 8. IgM levels, anti-MAG titers, B cells, antigen-presenting cells, and immunoregulatory T cells were monitored every 2 months.

RESULTS

Thirteen A-MAG-DP patients were randomized to rituximab and 13 to placebo. Randomization was balanced for age, electrophysiology, disease duration, disability scores, and baseline B cells. After 8 months, by intention to treat, 4 of 13 rituximab-treated patients improved by > or = 1 INCAT score compared with 0 of 13 patients taking placebo (p = 0.096). Excluding one rituximab-randomized patient who had normal INCAT score at entry, and thus could not improve, the results were significant (p = 0.036). The time to 10m walk was significantly reduced in the rituximab group (p = 0.042) (intention to treat). Clinically, walking improved in 7 of 13 rituximab-treated patients. At month 8, IgM was reduced by 34% and anti-MAG titers by 50%. CD25+CD4+Foxp3+ regulatory cells significantly increased by month 8. The most improved patients were those with high anti-MAG titers and most severe sensory deficits at baseline.

INTERPRETATION

Rituximab is the first drug that improves some patients with A-MAG-DP in a controlled study. The benefit may be exerted by reducing the putative pathogenic antibodies or by inducing immunoregulatory T cells. The results warrant confirmation with a larger trial.

Diagnosis and treatment in inflammatory neuropathies

The inflammatory neuropathies are a large diverse group of immune-mediated neuropathies that are amenable to treatment and may be reversible. Their accurate diagnosis is essential for informing the patient of the likely course and prognosis of the disease, informing the treating physician of the appropriate therapy and informing the scientific community of the results of well-targeted, designed and performed clinical trials. With the advent of biological therapies able to manipulate the immune response more specifically, an understanding of the pathogenesis of these conditions is increasingly important. This review presents a broad overview of the pathogenesis, diagnosis and therapy of inflammatory neuropathies, concentrating on the most commonly encountered conditions.

Contribution of electron microscopy to the study of neuropathies associated with an IgG monoclonal paraproteinemia

A typical monoclonal IgG dysglobulinemia whether benign (monoclonal gammopathy of undetermined significance, MGUS) or malignant can give rise to peripheral neuropathy by damaging nerves. At first, neurotoxicity of the chemotherapy if the patient is treated must be ruled out in such cases. Indeed, a variety of other mechanisms have been described: endoneurial deposits of immunoglobulin, infiltration of the immunoglobulin within myelin sheaths, POEMS syndrome, deposits of amyloid, chronic inflammatory demyelinating polyradiculoneuropathy and infiltration of malignant cells. Ultrastructural examination of a nerve biopsy can be decisive in combination with routine histological and immunopathological examinations. Characterization of the mechanism of the neuropathy in a dysglobulinemic context is important as it governs therapeutic options, which in certain cases are particularly beneficial.

Paraproteinemic neuropathy

Paraproteinemia frequently is associated with peripheral neuropathy. The clinical manifestations can be protean owing to the potential for multiple organ involvement. A methodical diagnostic approach to patients who have a plasma cell dyscrasia and neuropathy is necessary to ensure the appropriate detection of more widespread systemic involvement.

Treatment for IgG and IgA paraproteinaemic neuropathy

BACKGROUND

Paraproteinaemic neuropathy refers to those neuropathies associated with a monoclonal gammopathy or paraprotein. Typically it presents with a chronic predominantly sensory, symmetrical neuropathy, similar to chronic inflammatory demyelinating polyradiculoneuropathy but with relatively more sensory involvement, both clinically and neurophysiologically. The optimal treatment for IgG and IgA monoclonal gammopathy of uncertain significance neuropathies is not known.

OBJECTIVES

The objective of this review is to examine the efficacy of any treatment for IgG or IgA paraproteinaemic peripheral neuropathy.

SEARCH STRATEGY

We performed searches of the Cochrane Neuromuscular Disease Group Trials register (May 2005), MEDLINE (from January 1966 to May 2005), EMBASE (from January 1980 to May 2005). We also checked bibliographies for controlled trials of treatments for IgG or IgA paraproteinaemic peripheral neuropathy.

SELECTION CRITERIA

We included randomised and quasi-randomised controlled trials using any treatment for IgG or IgA paraproteinaemic peripheral neuropathy. People with IgM paraproteins were excluded. We excluded participants where the monoclonal gammopathy was considered secondary to an underlying disorder. We included participants of any age with a diagnosis of monoclonal gammopathy of uncertain significance with a paraprotein of the IgG or IgA class and a neuropathy. Included participants were not required to fulfil specific electrophysiological diagnostic criteria.

DATA COLLECTION AND ANALYSIS

The full texts of potentially relevant studies were obtained and assessed and independent data extraction was performed by three authors. Additional data and clarification were received from one author.

MAIN RESULTS

We identified only one randomised controlled trial with 18 participants which fulfilled the predetermined inclusion criteria. Four other trials were identified but these were not randomised controlled trials. The included trial revealed a modest short-term benefit of plasma exchange in IgG or IgA paraproteinaemic neuropathy, over a short follow-up period, when compared to sham plasma exchange.

AUTHORS' CONCLUSIONS

The evidence from randomised controlled trials for the treatment of IgG or IgA paraproteinaemic neuropathy is currently inadequate. More randomised controlled trials of treatments are required. These should have adequate follow-up periods and contain larger numbers of participants, perhaps through multicentre collaboration, considering the relative infrequency of this condition. Observational or open trial data provide limited support for the use of treatments such as plasma exchange, cyclophosphamide combined with prednisolone, intravenous immunoglobulin and corticosteroids. These show potential therapeutic promise but the potential benefits must be weighed against adverse effects. Their optimal use and the long-term benefits need to be considered and validated with well-designed randomised controlled trials.

Additional causes for distal sensory polyneuropathy in diabetic patients

OBJECTIVE

To assess the frequency of additional causes of distal sensory polyneuropathy (DSP) in patients with diabetes mellitus (DM).

METHODS

Retrospective review of patients with DM and DSP during a 5 year period. A quantitative sensory score (QSS) was determined at the initial evaluation and extensive laboratory and EMG studies were performed. Patients with one or more potential causes for DSP were compared to those with DM alone.

RESULTS

Fifty five patients (53%) had potential additional causes for DSP. These included: neurotoxic medications (seven), alcohol abuse (six), and B12 deficiency and renal disease (four each). The most common laboratory abnormalities were: abnormally low levels of vitamin B6 (11) or B1 (10), monoclonal gammopathy (eight), and hypertriglyceridaemia (eight). Twenty six (25%) subjects had more than one additional cause. Nine (9%) had three or more demyelinating features on EMG. There was a trend toward a lower QSS score (p = 0.05) and reduced mean amplitude of the sensory potentials in those with additional causes. Those with additional causes more often had upper limb sensory symptoms (p = 0.001) and sensory findings (p = 0.003).

CONCLUSION

There was a high frequency of additional sources of DSP in patients with DM. These patients more often had sensory symptoms and findings in the hands. Tests that may be useful in the evaluation of DSP in diabetic patients include measures of vitamins B1, B6, B12, serum triglycerides, and immunofixation.

Length dependence in polyneuropathy associated with IgM gammopathy

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.

A data base for 3000 monoclonal immunoglobulin cases and a new classification

Data from monoclonal immunoglobulin cases screened in our laboratory for 40 years were used to assemble a cohort of 3094 cases selected according to immunoelectrophoresis and immunofixation interpretation and clinical data availability. Molecular distribution and original classification were used to establish five categories of cases: multiple myeloma (MM) and Waldenstrom macroglobulinemia (WM), other lymphoproliferative diseases, cases associated with heavy immunological diseases or other tumors, and benign cases. Free light chain (FLC) cases comprise 7% of the cohort, pluriclonal Ig, 6%. More than 50% of 1335 cases with identified diagnoses are not malignant hemopathies. Male/female ratio is less than 1 for MM cases and close to 1 for benign and other lymphoproliferative cases. Males are a majority in MW and associated cases. Follow-up periods range from 5 to 30 years for 263 cases. The main characteristics of this data base have been defined and the benefit of the original classification is highlighted. Future studies will investigate improvements resulting from immunofixation and current urinary analysis practices, as well as long-term follow-up, pluriclonal Ig cases, cryoglobulins, the meaning of the presence of FLC and malignant transformation.

Characterization of neuropathies associated with elevated IgM serum levels

BACKGROUND

In contrast to the IgM monoclonal gammopathies the neuropathy associated with polyclonal IgM gammopathy has not been well characterized.

OBJECTIVE

To characterize the neuropathy in patients with elevated serum IgM.

DESIGN

Retrospective review.

SETTING

Academically based neuropathy center.

PATIENTS

45 patients with elevated quantitative immunoglobulin M were identified.

MAIN OUTCOME MEASURES

Patients are described with regard to clinical phenotype, electrodiagnostic features of demyelination or focality, presence of IgM monoclonal gammopathy, and presence of autoantibody activity.

RESULTS

Elevated IgM levels occurred in 45 (11.5%) of 391 patients. Of these, 24 (53%) had polyclonal gammopathy and 21 (47%) had an IgM monoclonal gammopathy. Anti-nerve antibodies occurred in 14/21 (67%) of patients with monoclonal gammopathy, as compared to 1/24 (4%) with polyclonal gammopathy. Clinically, most patients in all groups had a predominantly large fiber sensory neuropathy. Thirty patients underwent electrodiagnostic testing. Of these, 22/30 (73%) fulfilled at least one published criteria for CIDP, including 92% of the monoclonal gammopathy patients and 59% of the polyclonal gammopathy patients. Fifteen of the 30 patients had evidence of focality or multifocality, with 14 of these 15 showing evidence of demyelination.

CONCLUSIONS

Monoclonal and polyclonal IgM patients have similar distributions of neuropathy phenotypes. Neuropathy in association with elevated serum IgM, with or without monoclonal gammopathy or autoantibody activity, is more likely to be demyelinating or multifocal. Serum quantitative IgM level and immunofixation in neuropathy patients may aid in identification of an immune mediated or a demyelinating component.

Neuropathology of paraneoplastic neuropathy with anti-disialosyl antibody

We report a paraneoplastic neuropathy with severe motor involvement following sensory-ataxic disturbance. Anti-disialosyl immunoglobulin M (IgM) antibody was detected in the course of malignant lymphoma of diffuse large B-cell type, which usually spares the motor system. Onset was subacute, with relapsing and remitting sensory ataxia, muscle weakness, bulbar palsy, respiratory paralysis, and ophthalmoplegia; only neck rotation was retained in the terminal stage. Autopsy showed no lymphoma cells infiltrating the nervous system. Motor neurons survived in the spinal cord, but mean diameter of the ventral spinal nerve roots was reduced considerably. The gracile fasciculus and the sural nerve were more markedly degenerated than proximal portions. Morphometric study showed that most of the proximal motor and sensory axons did not extend distally. This autopsy report provides further definition of a neuropathy associated with malignant lymphoma and IgM antibodies against disialosyl residues.

IgA monoclonal gammopathy of undetermined significance with peripheral neuropathy

Monoclonal gammopathy of undetermined significance (MGUS) and peripheral neuropathy may be causally linked. In most cases, the M-protein is of IgG or IgM type. Peripheral neuropathy associated with IgA MGUS is uncommon, and there are limited reports. Here, we report a case of a 55-year-old male who was diagnosed to have symmetrical sensorimotor peripheral neuropathy associated with IgA MGUS with deposits of IgA-monoclonal protein in the myelin sheath.

Clinical presentations of peripheral neuropathies

This article addresses the clinical presentations of different peripheral neuropathies. The topic is discussed briefly with emphasis on the most important clinical features. MR imaging of the peripheral nerves is a rapidly advancing field, and it is hoped that the basic understanding of the clinical presentations of peripheral neuropathies will encourage radiologists to get more involved in MR imaging of the peripheral nerves.

Paraneoplastic neurologic syndromes

Cancer can affect the nervous system through many metastatic and nonmetastatic mechanisms, including side effects of cancer treatment, infections, coagulopathy, and metabolic or nutritional deficits. Paraneoplastic neurologic disorders (PND) are an extensive group of syndromes that cannot be explained by any of these complications and may affect any part of the nervous system. PND often develop before the presence of a cancer is known and their recognition may lead to the tumor diagnosis.

Severe sensory ataxia and demyelinating polyneuropathy with IgM anti-GM2 and GalNAc-GD1A antibodies

Several polyneuropathy syndromes have been described with polyclonal serum immunoglobulin G (IgG) or immunoglobulin M (IgM) binding to gangliosides GM2 and GalNAc-GD1a that contain the terminal trisaccharide moiety GalNAc(beta1-4)Gal(alpha2-3)NeuAc. We describe the clinical and electrodiagnostic features in two patients with serum IgM monoclonal anti-GM2 and anti-GalNAc-GD1a antibodies. These patients had slowly progressive, panmodal sensory loss with severe sensory ataxia. Electrodiagnostic testing showed demyelinating features. Prominent improvement in gait ataxia occurred after treatment with human immune globulin but not after other immunomodulating therapies. Enzyme-linked immunoabsorbent assay and thin-layer chromatography demonstrate that the patient's serum monoclonal IgM bound to gangliosides GM2 and GalNac-GD1a but not to gangliosides without the GalNAc(beta1-4)Gal(alpha2-3)NeuAc moiety. This neuropathy differs from previously reported neuropathy syndromes associated with polyclonal GM2 and GalNAc-GD1a antibodies and from other chronic demyelinating polyneuropathies. We conclude that a distinct syndrome of chronic demyelinating neuropathy with sensory ataxia, unresponsive to corticosteroids, is associated with monoclonal IgM binding to gangliosides with a terminal GalNAc(beta1-4)Gal(alpha2-3)NeuAc trisaccharide moiety. Diagnosis of this syndrome is important to direct appropriate treatment.

Risk factors for hematological malignancy in polyneuropathy associated with monoclonal gammopathy

Polyneuropathy associated with monoclonal gammopathy of undetermined significance (MGUS) is a well-known disease entity. Of the patients with monoclonal gammopathy without neuropathy, 25% develop a hematological malignancy during long-term follow-up. Whether the frequency of hematological malignancy is similar in patients with polyneuropathy associated with monoclonal gammopathy and whether hematological screening is necessary in these patients is unknown. To determine the frequency of and risk factors for a hematological malignancy, we investigated 104 patients with polyneuropathy and monoclonal gammopathy. Potential diagnostic variables were obtained from medical history, physical and neurological examination, and laboratory analysis. The associations between potential diagnostic variables and outcome, hematological malignancy, were evaluated by univariable and multivariable logistic-regression analysis. Among our patients, 23 had a hematological malignancy (8 multiple myeloma, 10 low-grade lymphoma, 3 plasmacytoma, 1 Castleman's disease and 1 POEMS syndrome [polyneuropathy, organomegaly, endocrinopathy, M-protein, and skin changes]). Weight loss, progression of the neuropathy, and an M-protein level > 1 g/L were independent risk factors for malignancy. Extensive screening is indicated in patients with these features.

Clinical spectrum of chronic acquired demyelinating polyneuropathies

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.

Features of sensory ataxic neuropathy associated with anti-GD1b IgM antibody

Some reports have called sensory ataxic neuropathy (SAN) associated with IgM antibody against b-series gangliosides a chronic form of Miller Fisher syndrome (MFS), but this has yet to be established. We examined five patients with SAN and eight patients with IgG anti-GQ1b-positive MFS. Only one patient with SAN complained of diplopia, whose ocular movement was not limited. The other four patients had neither diplopia nor limitation of ocular movement. All the SAN patients had severe deep sense impairment, whereas one patient with MFS showed only mild vibratory sense impairment. All sera from the SAN patients had remarkably high IgM antibody titers to the b-series gangliosides GD3, GD2, GD1b, GT1b, GQ1b, GQ1b alpha, fucosyl-GD1b, and alpha galactosyl [alpha fucosyl] GD1b. An absorption study confirmed that the anti-GQ1b antibodies cross-reacted with GD3, GD2, GD1b, and GT1b. In contrast, only two samples from the MFS patients had IgG antibody to GD3, and no sample reacted with GD2, GD1b, or GT1b. SAN has different clinical or serological features from MFS, and therefore is not a chronic form of it.

Paraneoplastic syndromes of the spinal cord, nerve, and muscle

Cancer can affect the peripheral nervous system by non-metastatic, sometimes immune-mediated mechanisms. Recognition of these paraneoplastic syndromes is important because it can lead to the detection of the tumor, and also helps to avoid unnecessary studies to determine the cause of the neurologic symptoms in patients with cancer. Many paraneoplastic syndromes of the peripheral nervous system are not associated with serum antibodies that serve as markers of paraneoplasia. For this group of disorders the diagnosis depends on the clinician's index of suspicion and conventional electrophysiologic and laboratory tests. Treatment of the tumor, immunotherapy, or both may improve some of these syndromes. This review focuses on paraneoplastic syndromes of the spinal cord, peripheral nerve, and muscle.

The role of antiglycolipid antibodies in peripheral neuropathies

The role of antiglycolipid antibodies in peripheral neuropathy continues to be defined in terms of clinical-serological associations and innovative experimental work establishing the role of these antibodies in pathogenesis. The present review focuses on the major developments in this field over the past 12 months.