Patient

Myoclonus is the sudden, involuntary jerking of a muscle or group of muscles. Myoclonic jerks may occur alone or in sequence, in a pattern or without pattern. They may occur infrequently or many times each minute. Myoclonus sometimes occurs in response to an external event or when a person attempts to move. The twitching cannot be controlled by the person experiencing it.

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.

A case study

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 Often Overlooked

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.

First Actions:

• Respiratory and cardiac arrest are possible.
• Check vitals - cardiac diliatation may cause hypotension and low pulse pressure
• Call for Cardiac Monitoring/EKG
• Draw electrolytes to determine serum K+
• Provide 02 - thimble may not reflect 02 saturation due to cardiac dilitation
• Lie patient in coma position to avoid aspiration.

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.

What is Thyrotoxic Hypokalemic Periodic Paralysis?

Thyrotoxic Hyperkalemic Periodic Paralysis (TPP) is an uncommon disorder with three characteristics which occur at the same time:  

1. too much thyroid hormone

2. low levels of potassium in the blood (hypokalemia)

3. muscle weakness or paralysis 

What is Andersen-Tawil Syndrome?

What is Paramyotonia Congenita?

Paramyotonia congenita (PMC) is a muscle disorder which causes muscle stiffness (myotonia) that appears during exercise and becomes much more severe upon exposure to cold. The myotonia which occurs during attacks of PMC may be so severe that the patient cannot inhale and exhale properly, and movement becomes difficult. The medical term myotonia means that the muscle fibers are slow to relax after contraction.

What is Hyperkalemic Periodic Paralysis?

Hyperkalemic Periodic Paralysis (HyperKPP) is a rare inherited muscle disorder which causes episodes of paralysis or weakness. It's estimated to occur in only one of 250,000 individuals, though since it is inherited there may be several patients in a single family. It was only recognized as a separate disorder in 1955.