Paramyotonia congenita

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Classification according to ICD-10
G71.1 Myotonic Syndrome
- Paramyotonia congenita (Eulenburg disease)
ICD-10 online (WHO version 2019)

The paramyotonia congenita (as Kältemyotonie or after Erstbeschreiber, the neurologist Albert Eulenburg (1840-1917) with paramyotonia congenita Eulenburg called) belongs to the sphere of the sodium channel myotonia . In humans, it manifests itself in the difficulty of relaxing the muscles after contraction and when it is cold.

causes

Point mutations in the SCN4A gene on chromosome 17q23 have been identified as the genetic cause . From a pathophysiological point of view, the function of the sodium channel in the muscle cells is impaired (greatly reduced inactivation) ; In the case of cold and repetitive movements, the influx of sodium into the cell increases. This leads to a permanent slight depolarization of the muscle cell and thus to the development of spontaneous action potentials, which in turn lead to the release of calcium ions and thus cause a contraction.

There is evidence that the changes in the resulting sodium concentration inside and outside the muscle cells could be detectable using magnetic resonance imaging .

Symptoms

The disease lasts for life. Characteristic are the stiffness of the eyes, face, neck, swallowing and extremity muscles (especially the forearms and legs) that occur in the cold, as well as weakness and pain in the skeletal muscles after exposure to the cold or after a short period of physical activity.

diagnosis

The clinical examination reveals the delay in opening the eyelids after squeezing them tightly, which increases when it is cold. Other signs, such as fist closure or percussion myotonia, can be negative.

Electromyography (with cooling of the extremities) and the analysis of creatine kinase and transaminases in the blood are necessary as further examinations . In addition, a molecular genetic examination is useful, but not mandatory.

treatment

To date, there are hardly any systematic studies on the treatment of the disease. The recommendations are therefore based on non “evidence” based data. Mexiletine or, alternatively, carbamazepine are recommended for the treatment of Paramyotonia congenita .

References

  1. ^ Albert Eulenburg: About a familial form of congenital paramyotonia that can be traced back through six generations. In: Neurologisches Centralblatt 1886; 12, pp. 265-272.
  2. ↑ a b S1 guideline for myotonic dystrophies and nondystrophic myotonia . In: AWMF online
  3. ↑ HB Huttner et al: 23Na magnetic resonance imaging (MRT) in patients with paramyotonia congenita (Eulenburg). In: Akt Neurol. 2004; 31. doi: 10.1055 / s-2004-833427

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