Peripheral neuropathy and benign IgG paraproteinaemia

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.

Neuropathies of monoclonal gammopathies of undetermined significance

Although rare, MGUS neuropathies offer a unique glimpse of some the molecular mechanisms of autoimmunity. For this reason alone, they are important disorders and are being studied vigorously in many research centers around the world. In at least some cases, they are potentially treatable. New, safer, and more effective therapies are needed, however. The neurologist and hematologist must work together to develop these treatments.

Clinical features and anti-neural reactivity in neuropathy associated with IgG monoclonal gammopathy of undetermined significance

Neuropathy has been frequently reported in patients with IgG monoclonal gammopathy of undetermined significance (MGUS) but it is still unclear whether this association has clinical or pathogenetic relevance. In order to clarify the possible role of IgG MGUS in the neuropathy we correlated the clinical and electrophysiological features of the neuropathy with the duration and anti-neural activity of the M-protein in 17 patients with neuropathy and IgG MGUS. Ten patients (59%) had a chronic demyelinating neuropathy clinically indistinguishable from chronic inflammatory demyelinating polyneuropathy (CIDP) while 7 (41%) had a predominantly sensory axonal or mixed neuropathy. In 80% of patients in the CIDP-like and 28% in the sensory group the IgG M-protein became manifest several months to years after onset of the neuropathy. Antibodies to one or more neural antigens (including tubulin, a 35KD P0-like nerve myelin glycoprotein, GD1a, GM1 and chondrotin sulfate C) were found in 40% of patients with CIDP-like and 43% with sensory neuropathy but also in 37% patients with IgG MGUS without neuropathy. Neuropathy associated with IgG MGUS is probably less heterogeneous than previously considered suggesting that this association may not be merely casual. The evidence for primary pathogenetic role of IgG M-proteins in the neuropathy remains however elusive.

Pathogenesis and therapy of neuropathies associated with monoclonal gammopathies

Approximately 10% of patients with peripheral neuropathy of otherwise unknown etiology have an associated monoclonal gammopathy. Both the neuropathies and the monoclonal gammopathies in these patients are heterogeneous, but several distinct clinical syndromes that may respond to specific therapies can be recognized. It is important to recognize these syndromes because monoclonal gammopathies also occur in 1% of the normal adult population, and in some cases, monoclonal gammopathies are coincidental and unrelated to the neuropathy. In patients with IgM monoclonal gammopathies, IgM M proteins frequently have autoantibody activity and are implicated in the pathogenesis of the neuropathy. IgM M proteins that bind to myelin-associated glycoprotein (MAG) have been shown to cause demyelinating peripheral neuropathy; anti-GM1 antibody activity is associated with predominantly motor neuropathy, and anti-sulfatide or chondroitin sulfate antibodies are associated with sensory neuropathy. The IgM monoclonal gammopathies may be malignant or nonmalignant, and polyclonal antibodies with the same specificities are associated with similar clinical presentations in the absence of monoclonal gammopathy. IgG or IgA monoclonal gammopathies are associated with neuropathy in patients with osteosclerotic myeloma or the POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy myeloma, and skin changes). Amyloidosis or cryoglobulinemic neuropathies can occur with either IgM or IgG and IgA monoclonal gammopathies. Therapeutic intervention depends on the specific clinical syndrome but is generally directed at removing the autoantibodies, reducing the number of monoclonal B cells, and interfering with the effector mechanisms.

IgG monoclonal paraproteinaemia and peripheral neuropathy

Five patients with peripheral neuropathy and benign IgG monoclonal paraproteinemia are reported, all of whom had a sensorimotor neuropathy with a remitting and relapsing course. The serum paraprotein level did not correlate with the patient's clinical status. Electrophsyiological studies showed marked slowing of conduction velocity and conduction block in four of the patients and mild slowing in the other. Sural nerve biopsies demonstrated a demyelinating neuropathy with inflammatory cell infiltrates in each of the five patients. Three of the patients had evidence of myelin/Schwann cell reactivity on immunofluorescence studies and in all nerves dense expression of major histocompatability complex class I and II molecules was evident within the endoneurium, on invading mononuclear cells, endothelial cells and Schwann cells. All the patients responded to treatment, plasmapheresis being particularly effective. Four patients have achieved prolonged remissions after all treatment had ceased. These five cases of peripheral neuropathy and IgG paraproteinaemia were identical in their clinical, electrophysiological and pathological features to patients with chronic inflammatory demyelinating polyneuropathy.

Peripheral neuropathy in monoclonal gammopathy of undetermined significance: prevalence and immunopathogenetic studies

In an unselected series of patients with monoclonal gammopathy of undetermined significance (MGUS) we found neuropathy in 2 of 34 patients with IgG (6%), 2 of 14 with IgA (14%), and 8 of 26 with IgM MGUS (31%). The neuropathy was subclinical in 6 patients (1 IgG, 1 IgA, and 4 IgM). Patients with IgG or IgA MGUS had a prominent motor impairment with electrophysiologic and morphologic findings suggestive of predominant axonal degeneration. No deposit of the M-protein in sural nerve and no reactivity of the M-protein with nerve was detected in these patients. Patients with IgM MGUS had a prominent sensory impairment with evidence of predominant demyelination. In 6 of these patients the M-protein reacted with the myelin-associated glycoprotein (MAG). The higher prevalence of neuropathy in patients with IgM MGUS may be related to the frequent reactivity of IgM M-proteins with MAG.

Cyclosporin A therapy in paraprotein-associated neuropathy

A case of IgG paraprotein-associated demyelinating neuropathy complicated by respiratory failure, which was unresponsive to standard immunosuppressive drug therapy, is reported. Cyclosporin A therapy resulted in a marked clinical recovery with objective improvement in nerve conduction and vital capacity. The beneficial response suggests that cell-mediated immunity is an important pathogenetic mechanism, and that cyclosporin A may be useful in the treatment of other refractory cases of paraprotein-associated neuropathy.

The clinical spectrum of peripheral neuropathies associated with benign monoclonal IgM, IgG and IgA paraproteinaemia. Comparative clinical, immunological and nerve biopsy findings

Observations have been made on a consecutive series of 62 patients with peripheral neuropathy associated with benign monoclonal paraproteinaemia. The paraprotein class was IgM in 46 cases, IgG in 11 and IgA in 5. Although showing variations between patients, the clinical picture was similar for those with either IgM or IgG paraproteins, usually consisting of a late-onset, slowly progressive, distal sensorimotor demyelinating polyneuropathy, often with tremor and ataxia as prominent features. Tremor was slightly more common in patients with IgM paraproteins, in whom there was a male preponderance. The patients with both paraprotein classes were indistinguishable clinically and electrophysiologically from chronic idiopathic demyelinating polyneuropathy. In the 5 patients with an IgA paraprotein, there was a distal sensorimotor neuropathy in 4 which was demyelinating in 1. In 1 there was proximal demyelinating motor neuropathy. Immunoglobulin deposition on myelin was observed only in the patients with IgM paraproteinaemia, more commonly with a kappa light chain. No deposition of immunoglobulin in the endoneurium was seen. IgM deposits on the perineurium are a feature of normal nerve and were present in all cases. Widely spaced myelin was confined to cases with IgM paraproteins in which immunoglobulin deposition was detected on myelin. The response to treatment could not be assessed systematically but, in general, the patients with IgG and IgA paraproteins responded more satisfactorily (to corticosteroids, cytotoxic drugs, or plasma exchange) than did those with an IgM paraprotein.

Neuropathy associated with monoclonal gammopathies of undetermined significance

Monoclonal proteins (IgM, IgG, and IgA) in the serum or urine of patients with neuropathy may provide a marker for amyloidosis, myeloma, lymphoma, leukemia, Waldenström's macroglobulinemia, or monoclonal gammopathy of undetermined significance (MGUS). The clinical characteristics, course, and electromyographic features among neuropathies associated with monoclonal IgM (IgM-MGUS, 31 patients), monoclonal IgG (IgG-MGUS, 24 patients), and monoclonal IgA (IgA-MGUS, 10 patients) evaluated between 1980 and 1986 were compared. Four statistically significant differences set IgM-MGUS neuropathies apart from IgG-MGUS and IgA-MGUS neuropathies: (1) higher frequency of sensory loss and ataxia, (2) higher frequency of nerve conduction abnormality--10 attributes were significantly worse (none were significantly better), (3) higher frequency of dispersion of the compound muscle action potential, and (4) higher frequency of IgM-MGUS in the MGUS neuropathy cohort than is characteristic of MGUS without neuropathy seen at our institution or than is encountered in epidemiological surveys. These differences were not thought to be due to selection or severity biases. Neither the amount of IgM nor the estimated size of the monoclonal peak was associated with severity of neuropathy. The type and severity of IgM-MGUS neuropathies with anti-myelin-associated glycoprotein antibodies were not significantly different from those without anti-myelin-associated glycoprotein antibodies. A simple relationship between the presence and amount of IgM-MGUS or anti-myelin-associated glycoprotein antibodies and neuropathy cannot be assumed.

AAEE case report #17: Peripheral neuropathy in monoclonal gammopathy of undetermined significance

Monoclonal gammopathy of undetermined significance (MGUS) is the most common paraproteinemia associated with polyneuropathy. Although the clinical and electrodiagnostic manifestations most resemble those of chronic inflammatory demyelinating polyneuropathy, some patients manifest a pure sensory neuropathy or neuronopathy. The M protein is usually IgM, and its concentration in serum is low. Nerve pathology from patients with demyelinating disease shows a reduction of large myelinated fibers and segmental demyelination with remyelination. In some cases, the M protein possesses antibody activity against components of the myelin sheath or axon. These neuropathies may respond to treatment with steroids, immunosuppressant agents, and plasma exchange.

Peripheral neuropathy associated with plasma cell dyscrasia: a clinical and electrophysiological follow-up study

Thirteen patients with polyneuropathy associated with plasma cell dyscrasia had serial electrophysiological studies. Five patients with monoclonal IgG had motor and/or sensory symptoms of which 4 correlated with slow motor and sensory nerve conduction. The 4 patients with monoclonal IgM reactive with myelin-associated glycoprotein (MAG), had predominantly motor symptoms, demyelination in the nerve biopsy and slow motor and sensory nerve conduction. Four patients with monoclonal IgM without anti-MAG activity had mainly sensory symptoms, axonal neuropathy on nerve pathology and slow or absent sensory nerve conduction. After treatment with plasmapheresis and chemotherapy 9 patients improved clinically and 4 were unchanged. Criteria for electrophysiologic improvement were presence of sensory or motor responses that were absent before treatment, conduction velocity increased by more than 10 m/s and increase of amplitude by more than 100%. Electrophysiological studies showed improvement in 7, were unchanged in 4, and worse in 2. Sensory velocities in ulnar and sural nerves were significantly improved following treatment (P less than 0.002) and the same trend was noted for the sensory velocity in the median nerve (P less than 0.19). We conclude that nerve conduction studies in combination with clinical examinations are useful in documenting the effects of treatment in these neuropathies.

Benign monoclonal IgAK gammopathy associated with polyneuropathy and dysautonomia

The first case of benign IgAK monoclonal gammopathy associated with peripheral neuropathy is described. Dysautonomia is an unusual, yet prominent, manifestation of neuropathy in this patient. Electrodiagnostic testing and nerve biopsy were compatible with demyelination and axonal loss. Myelin sheath, perineural, and endoneural interstitial tissue fixation of anti-IgA and anti-kappa light chains was demonstrated by direct immunofluorescence microscopy. Absorption studies utilizing human peripheral nerve myelin resulted in complete removal of the paraprotein band. Analytic procedures with myelin-associated glycoprotein and gangliosides, however, were negative. Based on these findings, an alternative etiology for this neuropathy is hypothesized.

Polyneuropathy in paraproteinaemia

Paraproteinaemias are frequently associated with peripheral neuropathies. "Benign" paraproteinaemia, myeloma and Waldenströms macroglobulinaemia may present clinically as polyneuropathy. Therefore immunoelectrophoresis is strongly recommended in the routine diagnosis of polyneuropathies of unknown origin. Peripheral neuropathies associated with paraproteinaemia are clinically, electrophysiologically, pathologically and probably also pathogenetically heterogeneous. There are subgroups such as demyelinating neuropathy associated with IgM paraproteinaemia, which show quite distinctive features. This survey describes the different types of paraproteinaemia and their associated peripheral neuropathies. The incidence, pathogenesis and therapy of peripheral neuropathy associated with monoclonal gammopathies are discussed.

Direct immunofluorescence findings in peripheral nerve from patients with diabetic neuropathy

Direct immunofluorescence examination was performed on peripheral nerve from 16 patients with diabetes mellitus and 53 additional patients with peripheral neuropathy of diverse cause. Six nerves from patients with diabetes mellitus yielded positive findings: 4 had granular and lamellar deposition of IgM within the perineurium (of which 2 also had fibrinogen, IgA, C3, and albumin and 1 also had IgG); 1 had IgM, C3, and C4, and perineurial fibrinogen; the sixth contained linear perineurial C3 and fibrinogen. These 6 nerves contained axonal degeneration (3), axonal degeneration with chronic demyelination (1), microvasculitis with wallerian degeneration (1), and no pathological change (1). Sixteen of 53 nerves from nondiabetics yielded positive findings with immunofluorescence, possibly as a result of vascular leakage or as a manifestation of impaired removal of plasma proteins. The deposition of immunoreactants, as well as other plasma proteins, in peripheral nerve from patients with diabetes mellitus probably represents a "trapping" phenomenon reflecting altered basement membrane permeability. Alternatively, the changes could reflect a defect in the blood-nerve barrier in diabetic microangiopathy.

Plasma exchange treatment of peripheral neuropathy associated with plasma cell dyscrasia

Plasma exchange was used to treat 10 patients with polyneuropathy and a monoclonal antibody (plasma cell dyscrasia). Six patients had improvement of the neuropathy, while three patients had stabilisation of the neuropathy during plasma exchange. The patients who improved maintained a 64% or greater decrease in the monoclonal antibody between exchanges. Patients with axonal polyneuropathy as well as patients with demyelinating polyneuropathy recovered some neurologic function. With cessation of plasma exchanges, the monoclonal antibody titre approached pre-treatment levels and the neuropathy progressed. Plasma exchange was effective in rapidly lowering the level of monoclonal antibody and allowing for some recovery of neurologic function.

Polyneuropathy and benign monoclonal gammopathy

Recently the rather frequent occurrence of benign monoclonal gammopathy (BMG) has been reported in peripheral neuropathy. Sometimes this syndrome is part of a multisystemic disorder in which organomegaly, endocrine disturbances, skin changes and focal bone lesions may also occur. The clinical picture and the cerebro-spinal fluid findings resemble the chronic relapsing Guillain-Barré syndrome. The polyneuropathy seems to be of the primarily demyelinating type. The pathogenetic relationship with the gammopathy is as yet not clear, but treatment of the plasma cell dyscrasia has a favourable effect on the polyneuropathy. We report our experiences with 5 patients with polyneuropathy and BMG and compare our clinical, laboratory and histological data with the literature.

Monoclonal gammopathy with neurological signs and symptoms. A clinical, neurophysiological and muscle biopsy study

Clinical, neurophysiological and muscle biopsy findings in ten patients with monoclonal gammopathy are reported. Three patients had polyneuropathy, one had hemiparkinsonism, one migraine and radicular symptoms and one paresthesiae and radicular symptoms. Amyloidosis was not found in muscle biopsy specimens. All but one patient with neurological findings also had positive immunofluorescence staining for tissue-bound immunoglobulins in muscle biopsy specimens. The tissue-bound immunoglobulins usually belonged to the same class as the M-component. None of the biopsies of patients without neurological findings were positive.

Peripheral neuropathy and solitary myeloma: analysis of serum and CSF IgG in two cases

Clinical and laboratory findings of two patients affected by solitary myeloma, IgG3 lambda type, with peripheral neuropathy are reported. In both cases the same IgG isoelectrofocusing pattern was found in cerebrospinal fluid and serum samples. Data are consistent with damage of the blood-brain barrier.

Plasma cell dyscrasia and peripheral neuropathy: identification of the myelin antigens that react with human paraproteins

In some cases of polyneuropathy and plasma cell dyscrasia, the monclonal antibodies react with human peripheral nerve myelin. To identify the myelin antigens involved, we separated the proteins of human central and peripheral nerve myelin by polyacrylamide gel electrophoresis, transferred the proteins onto nitrocellulose sheets, and used an immunoenzymatic technique to detect the reactive antigens. Serum IgM but not IgG from three patients with neuropathy and complement-fixing anti-human myelin IgM paraproteins immunostained a protein of approximately 100,000 daltons in human peripheral nerve myelin and a protein or closely migrating proteins of similar size in human central nervous system myelin. In a fourth patient, both IgM and IgG immunostained the antigen. Immunostaining was specific for the paraprotein light chain type, and absorption of the patients' sera with human peripheral nerve myelin eliminated the reaction with the central nervous system proteins. No reaction was seen with rabbit peripheral nerve myelin or with membranes prepared from human myotubes, human T cells, or human fibroblasts. Control sera from six patients with neuropathy and IgM paraproteins that did not react with myelin, from four patients with IgM paraproteins but no neuropathy, and from three normal subjects did not immunostain myelin.

Autoantibody to nerve tissue in a patient with a peripheral neuropathy and an IgG paraprotein

The antibody activity of a benign IgG lambda paraprotein to nerve tissue in a case of peripheral neuropathy has been investigated using immunohistochemical methods on tyrpsin-treated, formalin-fixed, paraffin-embedded tissue. IgG lambda was found in th sural nerve biopsy of the patient. Specific binding of the purified IgG lambda paraprotein and its isolated F(ab')2 fragment to homologous nerve and brain tissue was demonstrated. Similar activity was not demonstrable on fresh frozen cryostat sections. The results suggest that tests for autoantibodies to nerve tissue in neuropathological disorders should not be confined to fresh frozen tissue substrates.

Myeloma neuropathy: passive transfer from man to mouse

Mice were injected daily, for up to 10 weeks, with purified monoclonal immunoglobulin G from patients with myelomatous polyneuropathy or benign gammopathy. The animals developed a demyelinating polyneuropathy with slowed nerve conduction velocities. The putative antinerve factor may be an antibody since injection of Fab fragments from the monoclonal immunoglobulin G produced a similar demyelination. This provides evidence of a circulating factor in the serum of myeloma patients with polyneuropathy that reproduces typical features of the human disease on passive transfer. This disorder is thus distinguished from other neuropathies that occur as remote effects of malignant disease but have no identified pathogenic factors associated with them.

Peripheral neuropathy and plasma cell neoplasias: a report of 10 cases

Ten patients with peripheral polyneuropathy associated with plasma cell neoplasias are reported. Progressive sensorimotor polyneuropathy was the presenting complaint in all patients. CSF protein concentration was elevated in most patients. The electrophysiological and pathological changes were consistent with a primary segmentary demyelinating disease. All patients were male and younger than the average patient with myeloma. None presented with high tumour mass or overt multiple myeloma. Six were affected with single or multiple plasmacytomas with osteolytic lesions. Unusual haematological features such as polycythaemia, thrombocytosis and lymphadenopathy were often combined with the polyneuropathy. Skin hyperpigmentation, gynaecomastia and diabetes mellitus were noted in some patients. Complete recovery of the polyneuropathy was observed in some patients after either cyclophosphamide and corticosteroid therapy or radiotherapy of localized plasmacytoma, suggesting a direct relationship between the plasmacytic proliferation and the neuropathy. The nature of the postulated factor produced by the plasma cells and responsible for nerve injury is discussed and the importance of a careful search for plasma cell proliferation in men with obscure polyneuropathies is outlined.

Polyneuropathy with monoclonal gammopathy: studies of 11 patients

Among patients with chronic idiopathic nonfamilial polyneuropathy studied 3 to 21 years after onset, we identified 11 cases associated with monoclonal gammopathy (MCG) (5 with IgGk, 4 with IgMk, 2 with IgG lambda). The patients, aged 29 to 80 years, presented with sensorimotor polyneuropathy of insidious onset and slow, nonfluctuating progression, delayed motor and sensory nerve conduction, and increased cerebrospinal fluid (CSF) protein. None of the patients in the initial or follow-up study (mean, 9.2 years) had or developed signs of multiple myeloma, malignant plasma cell dyscrasia, macroglobulinemia syndrome, amyloidosis, neoplasia, or other associated illness. The CSF revealed abnormalities of protein electrophoresis or immunoelectrophoresis in 9 of the 11 patients. Three of 5 sural nerve biopsies studied by immunofluorescence demonstrated deposition in nerve fibers of the light chain characteristic of the abnormal circulating immunoglobulin. The findings suggest that these patients form a distinct subset of the dysimmune neuropathies. Although the immunoglobulin deposition and abnormal protein patterns in serum and CSF could be secondary to nerve damage, we propose that an immunopathological mechanism underlies the neuropathy. Immunosuppressants had minimal to marked beneficial effect in 4 of 5 patients, indicating that this polyneuropathy is potentially treatable.

Paraproteinaemia in neurological disease: incidence, associations, and classification of monoclonal immunoglobulins

Fifty-six patients presenting with neurological complaints were found to have paraproteinaemia unassociated with immunocytic malignancy; 16 patients presented with peripheral neuropathy. There was an association between IgM paraproteinaemia and an idiopathic neuropathy with markedly slowed nerve conduction velocities.

Plasma cell dyscrasia with polyneuritis and dermato-endocrine alterations. Report of a new case outside Japan

A new syndrome has been described comprising polyneuropathy, oedema, hyperpigmentation and thickening of the skin, gynaecomastia in males and amenorrhoea in females, monoclonal gammopathy, papilloedema and diabetes. There is frequent osteosclerosis with or without plasmacytoma, hepatosplenomegaly and polycythaemia. There is a good response to corticosteroids, immunosuppressive drugs and occasionally to excision or irradiation of the plasmacytoma. This syndrome was first described in Japan, and is still seen predominantly there, and only occasionally in other areas. An example in a 51-year-old Spanish female is described: she had a spectacular response to prednisone and melphalan. The aetiopathogenic possibilities are discussed.

Isoelectric focusing and quantitative estimation of cerebrospinal fluid and serum IgG in idiopathic polyneuropathy

Isoelectric focusing and quantitative estimation of serum and CSF IgG were performed in 85 patients with idiopathic polyneuropathy (IP), subdivided according to the clinical course (acute, subacute, recurrent, chronic). Acute IP very frequently had an increase of oligoclonal and/or polyclonal serum IgG during the progressive phase and blood-CSF barrier damage accompanied by polyclonal IgG intrathecal synthesis during the stationary phase. Polyclonal IgG intrathecal synthesis was also present in several not acute IP and seemed to forecast unfavorable course. Oligoclonal IgG synthesis occurs very rarely within CSF but is a frequent finding in serum of patients with IP. Abnormalities of the IgG serum pattern are neither specific for any clinical course of IP nor of prognostic value. The possible significance of such findings is discussed.

Neuropathy, amyloidosis, and monoclonal gammopathy

Three cases of neuropathy with monoclonal gammopathy and amyloid deposits in peripheral nerves are described. They appeared to present a benign gammopathy because of the duration of the neuropathy in the absence of any clinical or biological sign of myeloma or macroglobulinaemia. The pathological abnormality found in the sural nerves of the three patients was characterised by a marked loss of myelinated and unmyelinated nerve fibres because of active axonal degeneration with Wallerian degeneration. The most striking feature in all three cases was the finding of deposits identified as an accumulation of microfibrils.

Significance of immunoglobulin deposition in peripheral nerve in neuropathies associated with paraproteinaemia

Direct and indirect immunofluorescent studies of sural nerves were carried out in two patients with paraproteinaemia and neuropathy, in four other patients with axonal or demyelinating neuropathies, and in one normal sural nerve. IgM was demonstrated directly in the two cases of paraproteinaemia and neuropathy, and indirectly, using the serum of one of these cases, in a case of axonal neuropathy and in one case of chronic Guillain-Barré syndrome. In the latter case, IgM deposition also occurred after exposure to normal serum. These results suggest that the paraprotein itself did not directly cause neuropathy, but that immunoglobulin deposition is probably a secondary process, caused by diffusion into damaged nerves.