eMedicine Specialties > Neurology > Neuromuscular Diseases

Multifocal Motor Neuropathy With Conduction Blocks: Follow-up

Author: Sasa Zivkovic, MD, MSc, Assistant Professor, Department of Neurology, Division of Neuromuscular Diseases, University of Pittsburgh and VA Pittsburgh Healthcare System
Contributor Information and Disclosures

Updated: Jan 25, 2008

Follow-up

Further Inpatient Care

Most patients are treated as outpatients, although they may have to be admitted with severe exacerbations.

Further Outpatient Care

Outpatient care consists of clinic visits to neurologists, physiatrists, and occupational and physical therapists.

Inpatient & Outpatient Medications

IVIG infusions are usually administered on an outpatient basis in the physician's office or at home.

Complications

  • Most complications are related to treatment. IVIG can lead to aseptic meningitis, thromboembolic events, and kidney failure; cyclophosphamide can lead to myelosuppression, hemorrhagic cystitis, and bladder carcinoma.
  • Rarely, patients develop phrenic nerve involvement leading to respiratory insufficiency.

Prognosis

Prognosis is usually good, and 70-80% of patients respond to treatment. Even in patients who do not respond to therapy, weakness is only slowly progressive and up to 94% of patients remain employed.

Patient Education

For excellent patient education resources, visit eMedicine's Brain and Nervous System Center.

Miscellaneous

Medicolegal Pitfalls

  • Multifocal motor neuropathy (MMN) with conduction block is uncommon, and most patients require referral to a neurologist who specializes in neuromuscular disorders.
  • Considering whether patients with MMN may actually have ALS with predominantly lower motor neuron involvement is important because prognosis and treatment are significantly different.
    • On examination, confirm the absence of upper motor neuron signs in MMN. Signs of more severe muscle atrophy may point towards the diagnosis of ALS.
    • Electrodiagnostic studies are helpful to distinguish MMN from ALS with predominant lower motor neuron involvement. The presence of ongoing denervation on EMG findings is more suggestive of a motor neuron disorder.
  • Conversely, MMN should be considered in the differential diagnosis of patients with lower motor neuron disorders.
  • Proximal conduction blocks may be difficult to demonstrate using conventional electrodiagnostic studies.
  • MMN should be distinguished from Lewis-Sumner syndrome (MADSAM), as the latter may respond to steroids and plasma exchange, while these treatments may worsen or are ineffective in MMN.
  • Use of cyclophosphamide should be reserved for more severely affected patients and close monitoring for potential adverse events is warranted.
 


More on Multifocal Motor Neuropathy With Conduction Blocks

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Differential Diagnoses & Workup: Multifocal Motor Neuropathy With Conduction Blocks
Treatment & Medication: Multifocal Motor Neuropathy With Conduction Blocks
Follow-up: Multifocal Motor Neuropathy With Conduction Blocks
Multimedia: Multifocal Motor Neuropathy With Conduction Blocks
References
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References

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Further Reading

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Keywords

MMN, multifocal motor neuropathy with conduction block, acquired immune-mediated demyelinating neuropathy, amyotrophic lateral sclerosis, ALS, demyelinating injury, axonal injury, anti-GM1 antibodies, intravenous immunoglobulin, IVIG, cyclophosphamide, muscle atrophy, autoimmune peripheral neuropathy, autoimmune peripheral neuropathy, nerve conduction study, NCS, multifocal motor involvement, axonal degeneration

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Contributor Information and Disclosures

Author

Sasa Zivkovic, MD, MSc, Assistant Professor, Department of Neurology, Division of Neuromuscular Diseases, University of Pittsburgh and VA Pittsburgh Healthcare System
Sasa Zivkovic, MD, MSc is a member of the following medical societies: American Academy of Neurology and American Association of Neuromuscular and Electrodiagnostic Medicine
Disclosure: Nothing to disclose.

Medical Editor

Paul E Barkhaus, MD, Professor, Department of Neurology, Medical College of Wisconsin; Director of Neuromuscular Diseases, Milwaukee Veterans Administration Medical Center
Paul E Barkhaus, MD is a member of the following medical societies: American Academy of Neurology, American Association of Neuromuscular and Electrodiagnostic Medicine, and American Neurological Association
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

Managing Editor

Glenn Lopate, MD, Associate Professor, Department of Neurology, Division of Neuromuscular Diseases, Washington University School of Medicine; Chief of Neurology, St Louis ConnectCare, Consulting Staff, Barnes Jewish Hospital
Glenn Lopate, MD is a member of the following medical societies: American Academy of Neurology, American Association of Neuromuscular and Electrodiagnostic Medicine, and Phi Beta Kappa
Disclosure: Nothing to disclose.

CME Editor

Selim R Benbadis, MD, Professor, Director of Comprehensive Epilepsy Program, Departments of Neurology and Neurosurgery, University of South Florida School of Medicine, Tampa General Hospital
Selim R Benbadis, MD is a member of the following medical societies: American Academy of Neurology, American Academy of Sleep Medicine, American Clinical Neurophysiology Society, American Epilepsy Society, and American Medical Association
Disclosure: Nothing to disclose.

Chief Editor

Nicholas Y Lorenzo, MD, Chief Editor, eMedicine Neurology; Consulting Staff, Neurology Specialists and Consultants
Nicholas Y Lorenzo, MD is a member of the following medical societies: Alpha Omega Alpha and American Academy of Neurology
Disclosure: Nothing to disclose.

 
 
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