Multifocal motor neuropathy

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Classification according to ICD-10
G61.8 Multifocal motor neuropathy
ICD-10 online (WHO version 2019)

The multifocal motor neuropathy (MMN) is an acquired, slowly progressive disease of motor nerves without involving sensitive or vegetative nerve fibers . It belongs to the polyneuropathies and is immune-mediated. Ganglioside -GM1 antibodies can often be detected. The disease is attributed to the Guillain-Barré syndrome . The MMN was first described by Perry & Clark in 1988.

Clinical picture

In 94% of cases, MMN manifests itself in an asymmetrical muscle weakness distal to the extremities, whereby the upper extremities are initially more frequently affected than the lower extremities. The MMN primarily affects the ulnar nerve and the median nerve . Despite the muscle weakness, muscle atrophy rarely occurs , but muscle cramps and fasciculations can also occur. The cranial nerves are rarely involved (2%), and very rarely (1%), respiratory paralysis occurs due to the involvement of the diaphragmatic nerves .

The disease is very rare and has a prevalence of at least 0.6 per 100,000 people. It usually occurs between the ages of 30 and 50. Men are two to three times more likely to be affected than women. The first symptoms appear earlier in men, an average of 38 years old, as opposed to an average age of 45 years for women.

Diagnosis

Structure of a nerve cell

MMN is often confused with diseases of the lower motor neuron with a traumatic , pressure-related ( nerve compression syndrome ), degenerative ( spinal muscular atrophy ; amyotrophic lateral sclerosis ) or hereditary origin. The differentiation is mainly made clinically and electrophysiologically. Blood or CSF analyzes and imaging are only helpful or necessary in exceptional cases. The decisive factor is the detection of nerve conduction blocks (NLB) in the motor electroneurographs , the sensitive neurographs are normal.

Differential diagnostics

Amyotrophic lateral sclerosis and myositis must be excluded from the differential diagnosis . A porphyria , an intoxication with lead and a monoclonal gammopathy may show similar symptoms. When MADSAM (Multifocal acquired demyelinating sensory and motor neuropathy or Lewis Sumner syndrome) is a neuropathy with similar hospital as MMN, but additional (multifocal) sensory deficits occur with pathological sensitive Neurografien. The latter responds to corticosteroids .

therapy

Treatment is usually with immunoglobulins . In forty to sixty percent of affected patients, immunoglobulins can prevent the disease from progressing. During maintenance therapy, which lasted an average of six years, the mean dose was increased from twelve to seventeen grams per week. An unfavorable prognosis with severe weakness and disability was associated with the length of time the disease was untreated, but not with the length of immunoglobulin therapy.

Web links

Individual evidence

  1. ^ GJ Parry, S. Clarke: Multifocal acquired demyelinating neuropathy masquerading as motor neuron disease. In: Muscle & nerve. Volume 11, Number 2, February 1988, pp. 103-107, ISSN  0148-639X . doi : 10.1002 / mus.880110203 . PMID 3343985 .
  2. Jean-Marc Léger, Raquel Guimarães-Costa, Ruxandra Iancu Ferfoglia: The pathogenesis of multifocal motor neuropathy and an update on current management options . In: Therapeutic Advances in Neurological Disorders . tape 8 , no. 3 , March 16, 2015, ISSN  1756-2856 , p. 109-122 , doi : 10.1177 / 1756285615575269 , PMID 25941538 , PMC 4409549 (free full text).
  3. German Society for Neurology, MMN, effectiveness of immunoglobulins confirmed by pannational Dutch study (PDF; 376 kB), 2010
  4. ^ Andreas Baumann, Matthias Sturzenegger, MMN , Schweiz Med Forum 2006; 6: 981–987 p. 981
  5. a b E. A. Cats, WL van der Pol u. a .: Correlates of outcome and response to IVIg in 88 patients with multifocal motor neuropathy. In: Neurology. Volume 75, Number 9, August 2010, pp. 818-825, ISSN  1526-632X . doi : 10.1212 / WNL.0b013e3181f0738e . PMID 20805527 .