Paramyotonia Congenita (PMC) is one of the periodic paralyses caused by mutations in the sodium channel. PMC causes muscle stiffness (myotonia) which is made worse by chilling or activity. Myotonia usually eases when the patients moves about, or "warms up" through physical activity. In PMC myotonia develops during activity, which is paradoxical or self-contradictory. This is where Paramyotonia Congenita gets its name, from the paradoxical nature of the myotonia.
Originally published in Lifeline; Newsletter of The California Chapter of the American College of Emergency Physicians Christopher Fee, MD and Susan B. Promes, MD FACEP Alameda County California Medical Center, Highland General Hospital
Pain is an often overlooked component of the periodic paralyses. Patients who report muscle pain in association with their episodes are too often told that the periodic paralyses are not painful despite many authoritative reports to the contrary. In fact the pain which accompanies the periodic paralyses is described in some of the literature as prominent or constant.
What happens during an attack of Periodic Paralysis?
People with Periodic Paralysis (PP) have episodes in which their muscles become weak or paralyzed in response to variations in the amount of potassium in their blood. These variations occur during sleep, they may result from food the person has eaten, from a sudden change in a person's activity level, from rest after activity, emotional stress, from becoming chilled, or a number of other factors. Potassium levels vary all the time.
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