Paramyotonia Congenita
Paramyotonia congenita is an autosomal-dominant myotonic condition with at least two distinct genetic etiologies involving the sodium channel: α subunit (SCN4A) located at chromosome 17q35 and a muscle chloride channel (CLCN1) located at chromosome 7q35.
The worsening of the myotonia with exercise is referred to as paradoxical myotonia. Weakness or stiffness may occur together or separately, there is cold and exercise aggravation, hypertrophy of musculature, and more severe involvement of hands and muscles of the face and neck. Myotonic episodes usually subside within a matter of hours, but may last days. Some patients become worse with a potassium load. On electrodiagnostic studies, there is a drop in CMAP amplitude with cooling. Dense fibrillations disappear below 28 degrees Celsius, myotonic bursts disappear below 20 degrees Celsius, and electrical silence may occur below 20 degress Celsius. Treatment has involved mexiletine or tocainide.
More medical literature on Medic.Studio
More on the topic Paramyotonia Congenita:
-
Infectious diseases -
Internal diseases -
Obstetrics and Gynaecology -
Pediatrics -
Veterinary medicine -
-
Conflictology -
Ecology -
Economy -
Finance -
History -
Law -
Medicine -
Philosophy -
Religious studies -