Normokalemic

Normokalemic

Nondystrophic Myotonias and Periodic Paralyses

This chapter from McGraw Hill's Myology, third edition; editors Andrew Engel and Clara Franzini-Armstrong,  give a comprehensive look at the nondystrophic myotonias and periodic paralyses, written by one of the world's top teams in the field.

Chapter from Myology, third edition: Nondystrophic Myotonias and Periodic Paralyses by Frank Lehmann-Horn, Reinhardt Rudel and Karin Jurkat-Rott.

Our thanks to Professor Dr. Lehmann-Horn, Dr. Jurkat-Rott and Dr. Rudel for your kind permission to include this valuable information on our website!

How is periodic paralysis diagnosed?

Do you suspect that you might have periodic paralysis? The periodic paralyses are a rare group of disorders and there are many conditions which cause an imbalance in serum potassium. So how does the doctor tell the difference between paralysis or weakness caused by an ion channelopathy and any of the other numerous disorders, conditions and reactions which might produce the same symptoms?

Emergency Treatment of the HyperKPP and/or PMC Attack

Hyperkalemic Periodic Paralysis and Paramyotonia Congenita can occur singly or in combination. 

While most attacks of Hyperkalemic Periodic Paralysis are brief and do not require emergency intervention, occasionally the serum potassium level will be high enough to cause cardiac distress, or muscle stiffness may interfere with respiration.  Attacks of weakness in Paramytonia Congenita are usually mild to moderate in severity, but myotonia of chest, diaphragm and throat muscles can be life-threatening under some circumstances. 

Talk to your physician 

Pursuing a Diagnosis of Periodic Paralysis:


A free workbook to download for those who are in the diagnostic process, contains information on each type of PP, diagnostic testing, available therapies, how to determine episode triggers and  work out a management plan. download here

Tracking Triggers - Food and Beverage Chart

Use this chart to help determine patterns to your food triggers. Blanks have been left for you to individualize the chart to your needs. Check food labels for sodium content, etc. This chart is intended to be utilized as an adjunct to a food journal.

Chart Comparing Periodic Paralyses

This chart allows comparison of the forms of primary periodic paralysis, symptoms, clinical and cardiac signs, effect of potassium, triggers and therapies. 

 

Comparison of Five Forms of Periodic Paralysis

Introduction:

The major features found in all the periodic paralyses are:

1. Attacks almost always begin before the age of 25, though occasionally later in life. ATS patients can develop first symptoms at any age.

2. Serum potassium fluctuates shortly before an attack, but serum potassium level will normalize before the attacks resolves and will be within the normal range between attacks. This is not a disorder of the blood but one in which there is an inappropriate shift of fluid, K+ and NA+ during attacks. 

The Potassium Draw: Special Measures

When evaluating patients for periodic paralysis it is vital to obtain accurate results from blood draws. Because potassium levels which vary only a fraction of a point may be enough to trigger weakness in some patients, the lab may need to be made aware of specialized procedures which should ideally be used to obtain samples for K+ evaluation.

From "A Manual of Laboratory Diagnostic Tests" by Frances Fischbach, Page 247-253.

Potassium (K+) Normal Values: 3.5-5.0 mmol/liter 4.0-4.7 mmol/liter (average)

Physician's Sheet: Acetazolamide Drug Interactions

Acetazolamide (aka Diamox) is frequently prescribed as therapy for the periodic paralyses. While most patients take this drug without incident it can interact with other drugs. Physicians should be aware of potential problems which might arise.

Malignant Hyperthermia

Periodic Paralysis Patients at Increased Risk of MH

Patients with Hyperkalemic periodic paralysis and Paramyotonia Congenita are at increased risk for Malignant Hyperthermia (MH) during surgery. 

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