Paramyotonia Congenita

PARAMYOTONIA CONGENITA (Paramyotonia congenita), a rare disease first described by Eulenburg, characterized by muscle spasms occurring mostly under the influence of cold. The spasms usually affect certain muscle groups (muscles of the face, neck, extremities, and swallowing musculature). The orbicularis oris and palpebrarum muscles are particularly severely and frequently affected. Spasms can last from 15 minutes to several hours, can lead to complete immobility, and under certain conditions threaten life. The disease may appear already at birth, and experienced mothers notice it in newborns by their abnormal movements, too prolonged closing of the eyes when wiping them with cold water, etc. Spasms are associated with paresis, which can last for several days after the cessation of spasms. Damp, cool weather and a room temperature of 10-12° are sufficient to provoke an attack. Under the influence of heat, the spasms usually disappear within a few minutes. The mechanical excitability of muscles is not increased; the faradic excitability of nerves is normal, and of muscles it is decreased, especially during spasms; upon galvanic irritation, a tendency to tetanic contractions is noted even with insignificant currents. In contrast to congenital myotonia of Thomsen (see Myotonia), the immobility caused by spasms does not tend to decrease, but, as indicated, can last for several hours. Nevertheless, Eulenburg and other authors consider paramyotonia to be very close to Thomsen's myotonia, especially since both diseases can be observed in the same family and even combined in the same patient. According to Davidenkov, one can think that paramyotonique symptoms may represent only a phenotypic (attenuated) variation of true Thomsen's disease, but that alongside it there also exists a special gene exhibiting a more attenuated effect. Histopathologically, the picture of the muscles in both diseases is analogous. The pathogenesis of the disease is unknown. Eulenburg assumed a spastic angiospasm of the voluntary musculature, i.e., a temporary narrowing of muscle vessels due to the influence of cold. Therapy consists in applying preventive measures against cold. The disease is usually hereditary and familial, apparently with a dominant type of inheritance. Eulenburg was able to trace it through 6 generations (28 cases).