Lower Motor Neuron Syndrome Research Articles

Anti-GM2 IgM antibodies: clinical correlates and reactivity with a human neuroblastoma cell line

Anti-GM2 IgM antibodies have been reported in some patients with dysimmune neuropathy or lower motor neuron syndrome, in whom they were often associated with a concomitant reactivity with GM1. To investigate the possible clinical and pathogenetic relevance of these antibodies we measured serum anti-GM2 IgM titers by ELISA in 224 patients with different neuropathies and motor neuron disease and examined their binding to SK-N-SH neuroblastoma cells by indirect immunofluorescence (IIF). High titers of anti-GM2 IgM antibodies were found in eight patients with dysimmune neuropathies including two with multifocal motor neuropathy (MMN), two with purely motor demyelinating neuropathy without conduction block (MN) and four with Guillain–Barré syndrome (GBS). In two MMN patients reactivity with GM2 was associated with anti-GM1 reactivity and in one MN patient with anti-GM1, -GD1a and -GD1b reactivity. All but one patient had a concomitant reactivity with GalNAc-GD1a. Serum IgM from all positive patients intensely stained by IIF the surface of SK-N-SH neuroblastoma cells. This reactivity was blocked by serum pre-incubation with GM2, was not observed with sera from patients without anti-GM2 antibodies including those with high anti-GM1 or other anti-glycolipid antibodies, and correlated with the presence of GM2 in the SK-N-SH neuroblastoma cells. These findings indicate that anti-GM2 antibodies, though infrequent, are strictly associated with dysimmune neuropathies and suggest that SK-N-SH neuroblastoma cells can be a suitable in vitro model to study the functional and biological effects of these antibodies.

Multifocal motor neuropathy: diagnosis and treatment.

Multifocal motor neuropathy (MMN) and some lower motor neuron syndromes are immune-mediated and treatable. These motor syndromes produce weakness that is typically distal and asymmetric, involves the arms early in the course of disease, and progresses slowly. Electrophysiologic abnormalities often include evidence of demyelination, especially focal conduction block, selectively on motor axons. High titers of serum IgM binding to GM1 ganglioside, alone or in a membrane environment, occur in 80-90% of patients with MMN. Treatments for MMN that commonly produce increased strength include IV human immune globulin (HIG) and cyclophosphamide. After an initial treatment with 2 g/kg of HIG, up to 80% of patients with MMN show short-term improvement. Long-term HIG treatment is useful in 60% of MMN patients and has few side effects but is costly. Intravenous cyclophosphamide treatment is effective in 70% of MMN patients but has significant toxicity, and is reserved for patients who have severe disease and do not respond adequately to HIG.

Lymphome à IgM kappa avec anticorps antisulfatides révélé par une neuropathie motrice cervicale simulant une sclérose latérale amyotrophique

It is well known that polyneuropathy is associated with monoclonal IgM kappa. We report the case of a 79-year-old man with lymphoma and motor neuron disease at cervical level simulating amyotrophic lateral sclerosis (ALS). Neurological deficit with inflammatory process evolved within 4 months. Electrophysiological findings showed increased and enlarged muscular potentials with neurogenic patterns. Nerve conduction velocities were normal, with neither multifocal neuropathy nor persistent conduction blocks. Besides mixed cryoglobulinemia type II, antisulfatide antibodies issued from monoclonal IgM were found. They were directed against myelin glycosphingolipids. No antiganglioside GM1 antibodies could be detected. This not only evoked ALS but also proximal motor axonopathy related with monoclonal IgM. This case suggests that antisulfatide antibodies often present in sensitive demyelinating polyneuropathy could also be involved in lower motor neuron syndrome.

Neuromuscular disorders in systemic malignancy.

Paraneoplastic neuronopathies are presumed to be the result of an autoimmune attack directed at neuronal proteins, and both humoral and cell-mediated mechanisms have been postulated. The lower motor neuron syndrome after irradiation to the spinal column is caused by a proximal motor polyradiculopathy. Prevention of brachial plexopathy after radiotherapy for breast cancer may be accomplished by lower doses and surgical management of the axilla. Polymerase chain reaction casts doubt on the distinction between neoplastic and paraneoplastic mechanisms of neuromuscular manifestations of lymphoproliferative diseases. Shared antigenic components may underlie the association between inflammatory neuropathy and malignant melanoma. Advances in chemotherapy strategies against responsive tumors are hindered by the toxic effects of agents on peripheral nerves.

ACQUIRED MOTOR NEURON DISORDERS

The acquired motor neuron disorders are a heterogeneous group of conditions in which motor neuron degeneration or dysfunction produces the predominant manifestation of weakness, while the sensory system is clinically spared. The disorders most commonly seen in clinical practice are amyotrophic lateral sclerosis, late manifestations of poliomyelitis, and lower motor neuron syndromes, including motor neuropathy. Less often, acquired motor neuron disorders may complicate metabolic, toxic, or systemic disorders. The pathogenesis of most acquired motor neuron disorders is poorly understood, and treatment is mainly supportive; however clues to understanding the pathogenesis of amyotrophic lateral sclerosis are emerging, and new pharmacologic therapies are available. There is a growing sense of hope that combinations of drugs that are currently being tested may impact the survival of amyotrophic lateral sclerosis.

A study of P300 in patients who have had a kidney transplant after a period of dialysis

High titers of serum antibodies against GM1 ganglioside occur frequently in patients with lower motor neuron (LMN) syndromes. We compared the specificities of the antiganglioside antibody reactivities in LMN patients with those arising after immunization of Lewis rats with several ganglioside containing preparations including purified GM1, human central nervous system (CNS) grey matter and white matter. Serums with high titers of anti-GM1 antibodies from patients with LMN syndromes usually showed limited cross-reactivity to other glycolipids but often bound to a Gal(β1-)GalNAc-containing neoglycoprotein. In contrast, serums with anti-GM1 antibody arising after immunization showed broad cross-reactivity with other glycolipids but did not bind to the neoglycoprotein. We conclude that the serum patterns of antiganglioside antibody reactivity secondary to immunization with gangliosides and CNS components are different from the natural autoantibodies found in LMN patients. The antiganglioside antibodies seen in LMN patients are unlikely to be a result of autoreactivity to gangliosides after nervous tissue damage.

Motor neuron disease and monoclonal gammopathy.

In a study to determine the prevalence of monoclonal gammopathy (MG) among patients with motor neuron disease (MND), 6 out of 56 (10.7%) were found to have a monoclonal paraprotein. Of these 6 patients, 4 had an IgG and 2 had an IgA paraprotein. The clinical syndromes consisted of amyotrophic lateral sclerosis in 2 patients, lower motor neuron syndrome with preserved reflexes in at least one limb in 3 patients, and motor neuropathy with multifocal conduction block in 1 patient. The presence of gammopathy appears to correlate with the absence of marked upper motor neuron involvement and with elevated CSF protein concentration. An underlying malignant disorder was ruled out in all 6 patients, and they were considered to have MG of undetermined significance (MGUS). In a control group of 121 age-matched patients with other neuroimmunological disorders, 5 patients (4.13%) had MG. Four of these had gammopathy associated with malignant myeloma, and 1 had MGUS. These results support previous reports of increased prevalence of MGUS in patients with MND and suggest that an autoimmune mechanism may play a role in the disease.

The clinical correlates of high‐titer IgG anti‐GM1 antibodies

Serum IgG anti-GM1 antibodies have been reported to occur in a variety of disorders, including Guillain-Barré syndrome and chronic polyneuropathies. Of over 5,000 serums tested in our laboratory, high titers of selective IgG anti-GM1 antibodies (> 1:1,000) and without binding to sulfatide were found in 35 patients. Clinical correlation revealed that almost all patients had axonal, motor neuropathies. One subgroup was comprised of individuals with an acute motor neuropathy, described either as an acute axonal Guillain-Barré-like syndrome that was occasionally associated with a prodrome of Campylobacter jejuni enteritis or as Chinese paralysis syndrome. A second group of patients had chronic asymmetric lower motor neuron (LMN) syndromes with no conduction block or other evidence of demyelination. The presence of selective high-titer IgG anti-GM1 antibody reactivity in serum is uncommon but when present is strongly associated with acute axonal motor neuropathies or chronic asymmetric LMN syndromes.

The clinical and diagnostic role of anti‐GM1 antibody testing

There is increasing evidence that multifocal motor neuropathy (MMN) and some lower motor neuron (LMN) syndromes are immune-mediated and treatable. The frequent occurrence of high titers of anti-GM1 antibodies in these motor neuropathies raised hopes that serum testing would provide useful diagnostic information. Unfortunately, in routine practice, simple quantification of IgM binding to GM1 ganglioside has proved to be a test with poor sensitivity and specificity. We have found that much greater sensitivity and specificity for MMN and LMN syndromes can be obtained by determining serum antibody binding to panels of antigens, such as GM1, histone H3, and NP-9. These results suggest that combined measurement of serum antibody binding to GM1 and other antigens can provide tests that are useful in the diagnosis and management of motor neuropathy syndromes.

Immunofixation superior to plasma agarose electrophoresis in detecting small M-components in patients with polyneuropathy

Monoclonal immunoglobulins (M-components) in blood are found in some patients with polyneuropathy and are thought to be of pathogenetic importance, especially if the M-component is of IgM isotype. As the finding of an M-component may indicate a treatable polyneuropathy, the potential of the method to uncover an M-component is of importance. Cellulose acetate or agarose electrophoresis used in routine practice may miss small M-components covered by other proteins. We therefore applied the uncovering and specific method of immunofixation in comparison with agarose electrophoresis on patients investigated for polyneuropathy. Of 83 consecutive patients, 5 had M-components. Two of these 5 patients, one with an axonal polyneuropathy and the other with a lower motor neuron syndrome, had extra bands on agarose electrophoresis, verified as IgG M-components by immunofixation. In the 3 additional patients an M-component was uncovered only by immunofixation, not seen in the agarose electrophoresis of plasma; 2 of them were of IgM isotype and one was of IgG isotype. These 3 patients were diagnosed as having a demyelinating (i.e., possibly immune-mediated) polyneuropathy by means of neurophysiology and in one by means of nerve biopsy. A 6th patient had 2 small bands in the gamma region on the agarose electrophoresis, verified as oligoclonal bands of IgG isotype by immunofixation but was not judged as an M-component. Three out of the 83 patients, were judged as having motor neuron diseases. All remaining 80 were found to have polyneuropathy. In 38 (47.5%) of these 80 patients the polyneuropathy was associated with other diseases or deficiency states whereas in 42 (52.5%) no obvious cause was found. The prevalence of M-components in patients without obvious associated diseases or laboratory evidence of deficiency states (i.e., idiopathic polyneuropathy) was 7% (3 out of 42 patients). In conclusion, immunofixation was superior to agarose electrophoresis of plasma in detecting “hidden” small M-components in patients with “idiopathic” demyelinating polyneuropathy.

Central motor delay in the motor neuron diseases

Objective: To quantitatively estimate upper motor neuron (UMN) loss in ALS.Methods: We used the recently developed triple stimulation technique (TST) to study corticospinal conduction to 86 abductor digiti minimi muscles of 48 ALS patients. This method employs a collision technique to estimate the proportion of motor units activated by a transcranial magnetic stimulus. At the same time, it yields an estimate of lower motor neuron (LMN) integrity.Results: The TST disclosed and quantified central conduction failures attributable to UMN loss in 38 sides of 24 patients (subclinical in 15 sides), whereas conventional motor evoked potentials detected abnormalities in only 18 sides of 12 patients (subclinical in two sides). The increased sensitivity of the TST to detect UMN dysfunction was particularly observed in early cases. Increased central motor conduction times (CMCT) occurred exclusively in sides with conduction failure. In sides with clinical UMN syndromes, the TST response size (but not the CMCT) correlated with the muscle weakness. In sides with clinical LMN syndromes, the size of the peripherally evoked compound muscle action potentials correlated with the muscle weakness.Conclusion: The TST is a sensitive method to detect UMN dysfunction in ALS. It allows a quantitative estimate of the UMN loss, which is related to the functional deficit. Therefore, the TST has a considerable impact on diagnostic certainty in many patients. It will be suited to follow the disease progression and therapeutic trials.

Immunosuppressive treatment in lower motor neuron syndrome with autoantibodies against GM1 ganglioside.

We report the results of immunosuppressive treatment with intravenous cyclophosphamide in 12 patients with lower motor neuron syndrome and elevated titers of serum autoantibodies to GM1 ganglioside. All patients had lower motor neuron dysfunction including proximal or distal weakness, fasciculation and muscle atrophy, but no upper motor neuron dysfunction such as hyperreflexia, spasticity or Babinski's sign. Electrophysiological studies revealed no evidence of conduction block, but EMG findings of acute or chronic denervation in the limbs were present. Serum biochemistry and immunological studies were negative for M protein. After a 6-month follow-up, despite a fall in antibody titer, there was no significant clinical improvement in any of the patients.

Peripheral neuropathies associated with monoclonal proteins

Peripheral neuropathies associated with monoclonal proteins have received considerable attention as a clinically important group of chronic late-onset neuropathies. When a monoclonal protein is found in patients with peripheral neuropathy of unknown cause, as occurs in 10% of such cases, usually no associated disease is discovered; hence MGUS. Less often, disorders such as multiple myeloma, AL amyloidosis, Waldenström's macroglobulinemia, osteosclerotic myeloma, and lymphoma are found. Demyelinating neuropathies associated with MGUS of all classes, but particularly IgM, Waldenström's macroglobulinemia, and osteosclerotic myeloma typically follow an indolently progressive course, and frequently respond to treatments aimed at interfering with putative underlying immune mechanisms. By contrast, axonal neuropathies associated with MGUS, multiple myeloma, and AL amyloidosis have generally shown no response to therapy. Recently, IgM monoclonal and polyclonal antibodies directed against human peripheral nerve antigens including MAG and various glycolipids such as GM1 ganglioside have been found in patients with specific neuropathy syndromes. Anti-MAG antibodies occur in predominantly sensory demyelinating neuropathies, whereas elevated titers of anti-GM1 ganglioside antibodies are associated with lower motor neuron syndromes with multifocal motor conduction block. Although the evidence for autoimmune mechanisms in some monoclonal protein-associated neuropathies is mounting, a causal connection between monoclonal proteins and these neurologic syndromes has yet to be established.

Motor inhibition and excitation are independent effects of magnetic cortical stimulation.

We administered magnetic cortical stimulation (MCS) during voluntary contraction of intrinsic hand muscles to 8 patients with motor neuron disease (MND), 5 patients with pure lower motor neuron syndromes (LMN), a patient with severe subacute sensory neuropathy (SSN), and 10 healthy volunteers. Patients with MND had clinical evidence of upper MND and elevated thresholds for (3 patients) or absence of (5 patients) motor evoked potentials (MEPs). MCS during sustained contraction inhibited electromyographic activity in 6 of 8 patients with MND, without preceding MEPs. MCS had no effect on the electromyogram (EMG) of the other 2 patients with MND. In normal subjects and patients with LMN, inhibition of EMG was never seen without a preceding MEP, regardless of stimulus intensity. In the patient with SSN, MCS elicited normal MEPs and inhibited the EMG in a pattern similar to normal subjects, whereas supramaximal electrical stimulation of median and ulnar nerves failed to inhibit the EMG despite normal M and F responses. Our findings indicate that the inhibitory effects of MCS on EMG are not dependent solely on changes in afferent feedback caused by the muscle twitch produced by the MEP, or on Renshaw cell inhibition. We suggest that some of the inhibitory and excitatory effects of MCS on the motor system are mediated by distinct cortical elements, which may have different susceptibilities to pathophysiological processes in MND.

Different patterns of glycolipid antibody reactivity: lower motor neuron syndromes vs. immunization

High titers of serum antibodies against G M1 ganglioside occur frequently in patients with lower motor neuron (LMN) syndromes. We compared the specificities of the antiganglioside antibody reactivities in LMN patients with those arising after immunization of Lewis rats with several ganglioside containing preparations including purified G M1, human central nervous system (CNS) grey matter and white matter. Serums with high titers of anti-G M1 antibodies from patients with LMN syndromes usually showed limited cross-reactivity to other glycolipids but often bound to a Gal(β1-)GalNAc-containing neoglycoprotein. In contrast, serums with anti-G M1 antibody arising after immunization showed broad cross-reactivity with other glycolipids but did not bind to the neoglycoprotein. We conclude that the serum patterns of antiganglioside antibody reactivity secondary to immunization with gangliosides and CNS components are different from the natural autoantibodies found in LMN patients. The antiganglioside antibodies seen in LMN patients are unlikely to be a result of autoreactivity to gangliosides after nervous tissue damage.

Autoantibodies to GM1 ganglioside: different reactivity to GM1-liposomes in amyotrophic lateral sclerosis and lower motor neuron disorders

We studied the ability of anti-GM1 ganglioside antibodies to bind to GM1 in a lipid, “membrane-like” environment. Liposomes containing GM1 were synthesized to simulate this environment. We then compared the binding of anti-GM1 a autoantibodies to GM1-liposomes and to purified GM1. Antibody binding was quantified using enzyme-linked immunosorbent assay methodology. Our results showed a 250-fold variation in the ability of anti-GM1 antibodies to bind to GM1-liposomes. There was no correlation between GM1-liposome binding and the carbohydrate specificities of the anti-GM1 antibodies. However, anti-GM1 antibodies from patients with amyotophic lateral sclerosis (ALS) showed a 4 fold greater binding to GM1-liposomes than antibodies from patients with lower motor neuron (LMN) syndromes. We conclude that a lipid, presumably “membrane-like”, environment may greatly influence the degree of anti-GM1 antibody binding to GM1. The low levels of anti-GM1 antibody binding to GM1-liposomes in patients with LMN syndromes may provide a diagnostic means for distinguishing these patients from those with ALS. Anti-GM1 antibodies from patients with ALS may bind especially well to neuronal membranes containing GM1 in vivo.

Lower motor neuron syndromes defined by patterns of weakness, nerve conduction abnormalities, and high titers of antiglycolipid antibodies

We studied 74 patients with progressive, asymmetrical lower motor neuron syndromes. Clinical features of these patients, including age, sex, disease duration, patterns of weakness, and reflex changes, were evaluated by review of records. In each patient the clinical features were compared to the type of nerve conduction abnormalities and to the specificities of high-titer serum antiglycolipid antibodies. Antibody specificities were determined by an enzyme-linked immunosorbent assay using purified glycolipids and carbohydrates as substrates. Our results show that high titers of antibodies to glycolipids are common in sera of patients with lower motor neuron syndromes. Selective patterns of reactivity indicate that specific carbohydrate epitopes on the glycolipids are the targets of the high-titer antibodies in individual patients with lower motor neuron syndromes. Several distinct lower motor neuron syndromes can be identified based on clinical, physiological, and antiglycolipid antibody characteristics. These syndromes include multifocal motor neuropathy with evidence of multifocal conduction block on motor, but not sensory, axons and frequent (84%) high titers of anti-GM1 ganglioside antibodies; a lower motor neuron syndrome with predominantly distal weakness early in the disease course, no conduction block, and a high incidence (64%) of anti-GM1 antibodies; and a lower motor neuron syndrome with predominant early weakness in proximal muscles and serum antibodies to asialo-GM1 that do not cross-react with GM1 ganglioside.

Hand weakness in elderly patients

Weakness of the hand is a common problem in the elderly. When joint and vascular diseases have been ruled out, a systematic anatomic approach to the possible neurologic causes can be used to sort through nonspecific symptoms and the complexity of hand anatomy. Syndromes of the peripheral nerves supplying the hand (ie, median, ulnar, radial) are common and are generally caused by compression of these nerves in their pathway through the elbow, forearm, or wrist. Other common causes of hand weakness include lower motor neuron syndromes involving the brachial plexus; cervical radiculopathy amyotrophic lateral sclerosis; and myasthenia gravis. Along with a careful history and physical examination, several tests are helpful in discerning the nature and location of lesions. Electromyography, magnetic resonance imaging, computed tomography, and myelography may all be used to exclude or support a diagnosis.

Pathological findings in idiopathic orthostatic hypotension. Its relationship with Parkinson's disease.

IN 1925, Bradbury and Eggleston 1 isolated from among the diverse forms of orthostatic a clinical entity of slow progressive course characterized by neurological signs, in addition to orthostatic and slow fixed pulse rate. This condition is now generally recognized as idiopathic orthostatic hypotension (IOH). 2 The associated neurological symptoms vary from case to case and may include pyramidal, extrapyramidal, cerebellar, and lower motor neuron syndromes. They are slight and indefinite in the cases of Bradbury and Eggleston. 1 Their onset may be delayed many years after the postural changes, or they may even be absent, as in seven of the 30 cases of Thomas and Schirger. 3 Tremor, rigidity, and frozen facial expression are particularly frequent, and sometimes the clinical picture mimics Parkinson's disease, as in 13 of the 15 cases of Schatz and his colleagues 4 and in 11 of the 23 neurological cases of