Paramyotonia congenita
The paramyotonia congenita (after the first describer the neurologist Albert Eulenburg ( 1840-1917 ) and paramyotonia congenita Eulenburg or Kältemyotonie ) belongs to the sphere of Natriumkanalmyotonien. It manifests itself in humans by a complicated relaxation of muscles after contraction and in cold weather.
Causes
As genetic cause point mutations have been identified in SCN4A gene on chromosome 17q23. Seen Pathophysiologically the function of the sodium channel in muscle cells impaired ( severely slow inactivation); in cold and repetitive movements so does the sodium influx into the cell. This leads to frequent slight depolarization of the muscle cell and thus to the formation of spontaneous action potentials, which in turn lead to the release of calcium ions and thus cause contraction.
There is evidence that the changes Dungen of the resulting sodium concentration inside and outside the muscle cells could be detected by magnetic resonance imaging.
Symptoms
The disease is life-long. Characteristic are the entering in the cold rigidity of the eyes, face, neck, swallowing and limb muscles (especially the lower arms and legs ) and a occurs after exposure to cold or long physical activity weakness.
Diagnosis
On clinical examination, the delay of the opening of the eyelids after solid Squinting falls on that increases in cold weather. Other characters, such as a fist or Perkussionsmyotonie may be negative.
As further studies are electromyography (with cooling of the limb ) and the analysis of creatine kinase and transaminases in the blood necessary. In addition, a molecular genetic analysis is useful, but not mandatory.
Treatment
For the treatment of the disease are so far hardly any systematic studies. The recommendations are therefore based on not "evidence " based data. For the treatment of paramyotonia congenita mexiletine or alternatively by carbamazepine are recommended.
Sources
Weblink
- Paramyotonia congenita in Online Mendelian Inheritance in Man.
- Muscle disease
- Genetic disorder