Natural history of 46 patients with multifocal motor neuropathy with conduction block

Taylor, Bruce; Wright, R. Alan; Harper, C. Michel; Dyck, Peter J.

doi:10.1002/(sici)1097-4598(200006)23:6<900::aid-mus9>3.0.co;2-y

Cited by 167 publications

(148 citation statements)

References 33 publications

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“…[2][3][4][5][6] Only 33% of the patients in this series with distal UL-onset weakness responded, and this increased to 50% when only patients with EMG abnormalities restricted to the muscles demonstrating clinical weakness and normal serum CK were considered. It is noted that distal UL weakness may be a prominent and early feature of ALS, 10 and hence it may be difficult to distinguish degenerative anterior horn cell disorders from MMN early in the disease course.…”

Section: Methodology and Treatmentmentioning

confidence: 77%

“…In particular, standard electrophysiologic studies may not identify characteristic conduction block (CB) in patients with MMN, or CB may disappear over time. 1,2 Small case series demonstrating successful treatment of selected patients with asymmetric limb weakness who do not meet the diagnostic criteria of MMN with CB [3][4][5][6] have generated the suggestion that patients with progressive and asymmetric distal lower motor neuron (LMN) limb weakness may warrant a trial of IV immunoglobulin (IVIg). 1 However, uniform treatment with IVIg of all patients with an asymmetric distal PLMNS would produce a significant burden on health care resources, and thus appropriate patient selection is necessary.…”

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confidence: 99%

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Is IVIg therapy warranted in progressive lower motor neuron syndromes without conduction block?

2013

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Objective: To evaluate the likelihood of response to IV immunoglobulin (IVIg) by studying consecutive patients presenting with progressive, asymmetric, pure lower motor neuron (LMN) limb weakness, and to determine the clinical phenotype of those who respond.Methods: Thirty-one consecutive patients with progressive, focal-onset LMN limb weakness, without evidence of clinical upper motor neuron signs; sensory, respiratory, or bulbar involvement; or evidence of motor nerve conduction block on electrodiagnostic studies, were prospectively included in this study. Each patient underwent treatment with IVIg (2 g/kg) for a minimum of 3 months. Electrodiagnostic studies, a neuromuscular symptom score, and expanded Medical Research Council sum score were documented before and after IVIg treatment. The final diagnosis was determined after prolonged clinical follow-up.Results: Only 3 of 31 patients (10%) responded to IVIg. All responders demonstrated distal upper limb-onset weakness, EMG abnormalities confined to the clinically weak muscles, and a normal creatine kinase. This set of features was also identified in 31% of nonresponders presenting with distal upper limb weakness. Sex, age at onset, number of involved limb regions, and the duration of symptoms before treatment were not significantly different between groups. Conclusion:The findings of the present study do not support uniform use of IVIg in patients presenting with progressive asymmetric LMN limb weakness. It is suggested that IVIg treatment be limited to patients who demonstrate clinical and laboratory features suggestive of multifocal motor neuropathy. Classification of evidence:This study provides Class IV evidence that IVIg will not improve muscle function in 90% of patients with progressive, asymmetric, pure LMN weakness. Neurology ® 2013;81:2116-2120 GLOSSARY ALS 5 amyotrophic lateral sclerosis; CB 5 conduction block; CK 5 creatine kinase; CMAP 5 compound muscle action potential; EMRCSS 5 expanded Medical Research Council sum score; GM1 5 ganglioside M1; HRUS 5 high-resolution ultrasonography; IVIg 5 IV immunoglobulin; LMN 5 lower motor neuron; MMN 5 multifocal motor neuropathy; NCS 5 nerve conduction studies; NSS 5 neuromuscular symptom score; PLMNS 5 progressive lower motor neuron syndrome; PMA 5 progressive muscular atrophy; UL 5 upper limb; UMN 5 upper motor neuron.

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Section: Methodology and Treatmentmentioning

confidence: 77%

mentioning

confidence: 99%

Is IVIg therapy warranted in progressive lower motor neuron syndromes without conduction block?

2013

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“…A longitudinal study of 46 patients with multifocal motor neuropathy [35], followed for a median of 2.3 years, demonstrated that spontaneous improvement or resolution may not occur. Although this study did not focus on therapy, IVIg and cyclophosphamide appeared to be associated with neurological improvement, which was seldom complete or sustained.…”

Section: Ivig In the Long-term Treatment Of Multifocal Motor Neuropathymentioning

confidence: 99%

Multifocal motor neuropathy: and then, 20 years later IVIg therapy

2007

Swiss Arch Neurol Psychiatr

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SummaryLéger J-M, Lievens I. Multifocal motor neuropathy: and then, 20 years later … IVIg therapy. Schweiz Arch Neurol Psychiatr. 2007;158:81-5. Multifocal motor neuropathy is a distinct entity, whose treatment differs from that of other chronic immune-mediated neuropathies, mainly chronic inflammatory demyelinating polyradiculoneuropathy and its variant, multifocal acquired demyelinating sensory and motor neuropathy, although they share some electrophysiological characteristics. From the first descriptions intravenous immunoglobulins have been considered to be the gold standard of treatment for multifocal motor neuropathy. New therapeutic strategies are required, however, that focus on the effects and the costs of this therapy over long-term follow-up.

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“…The mean age at onset is 40 years, with a range of 20-70 years. 9,22,32 In almost 80% of patients, the first symptoms occur between age 20 years and 50 years. The most common initial symptoms are wrist drop, grip weakness, and foot drop.…”

mentioning

confidence: 99%

“…[18][19][20][21][22][23] Whether conduction block must be present for the diagnosis of MMN is debatable. Various open and placebo-controlled studies have shown that treatment with high-dose intravenous immunoglobulin leads to improvement of muscle strength.…”

mentioning

confidence: 99%

Multifocal motor neuropathy

Wokke¹,

Doorn²,

Hoogendijk³

et al. 2013

Neuromuscular Disease a Case-Based Approach

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In 1985, Parry and Clarke 1 studied nerve conduction in two patients with a lower-motor-neuron syndrome characterised by progressive, asymmetric, predominantly distal weakness without sensory loss and found conduction block. Soon afterwards, others reported patients with similar characteristics. 2,3 Weakness in patients with a lower-motor-neuron syndrome with conduction block was shown to be reversible with immunomodulating therapy and associated with high titres of IgM antibodies to GM1 ganglioside. 4 Hence, a separate disorder emerged: multifocal motor neuropathy (MMN). [4][5][6][7][8][9][10][11] The disorder was thought to be immune mediated, possibly through IgM antibodies that bind gangliosides on human peripheral nerves. 12 The differential diagnosis of MMN includes motor-neuron disease 13,14 and demyelinating neuropathies.15-17 Diagnosis of MMN is supported by the finding of motor but not of sensory abnormalities on nerve-conduction studies. [18][19][20][21][22][23] Whether conduction block must be present for the diagnosis of MMN is debatable. Various open and placebo-controlled studies have shown that treatment with high-dose intravenous immunoglobulin leads to improvement of muscle strength. Intravenous immunoglobulin is now the treatment of first choice in MMN. [24][25][26][27] Many clinical and electrophysiological studies have improved our understanding of MMN in the past 15 years, but the disease mechanisms underlying weakness in MMN are poorly understood. Clinical featuresMMN is characterised by slowly progressive weakness and muscle atrophy that develops gradually over several years. 8,11,22,23,[28][29][30][31] More men than women are affected, at a ratio of 2·6. The mean age at onset is 40 years, with a range of 20-70 years. 9,22,32 In almost 80% of patients, the first symptoms occur between age 20 years and 50 years. The most common initial symptoms are wrist drop, grip weakness, and foot drop. Weakness develops asymmetrically and is more prominent in the arms than in the legs. 22,23 In most patients with onset in the legs, the abnormalities also eventually affect the arms and become the most prominent.33 Symptoms and signs in the distal muscles prevail for a long time, but eventually weakness in proximal muscle groups of the arms, but not of the legs, may develop. 32,33 Weakness is typically more pronounced than the degree of atrophy suggests.11,22 Nevertheless, atrophy of affected muscles can be substantial in patients with a long disease duration. Other motor symptoms include muscle cramps and fasciculations in about two-thirds of patients. 3,19,21 Myokymia has been reported occasionally. 3,19,21 Tendon reflexes are commonly reduced in affected regions, although these are rarely brisk in the arms. 4,21,22,28,30 Single cases of cranial-nerve involvement have been reported. 21,[34][35][36] Respiratory failure due to unilateral or bilateral phrenic-nerve palsy can occur, even at the beginning of the disorder. 35,37,38 Some patients report feelings of paraesthesia or numbness but sensory l...

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Natural history of 46 patients with multifocal motor neuropathy with conduction block

Cited by 167 publications

References 33 publications

Is IVIg therapy warranted in progressive lower motor neuron syndromes without conduction block?

Is IVIg therapy warranted in progressive lower motor neuron syndromes without conduction block?

Multifocal motor neuropathy: and then, 20 years later IVIg therapy

Multifocal motor neuropathy

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