Welcome to the Rare Classroom, a new series from Patient Worthy. Rare Classroom is designed for the curious reader who wants to get informed on some of the rarest, most mysterious diseases and conditions. There are thousands of rare diseases out there, but only a very small number of them have viable treatments and regularly make the news. This series is an opportunity to learn the basics about some of the diseases that almost no one hears much about or that we otherwise haven’t been able to report on very often.

Eyes front and ears open. Class is now in session.

The rare disease that we will be learning about today is:

Periodic Paralysis

It’s also known as myoplegia paroxysmalis familiaris, but we’ll stick with periodic paralysis for now.

What is Periodic Paralysis?

• Periodic paralysis is characterized by temporary episodes of muscle weakness or paralysis​
• A physically disabling condition with unpredictable attacks that vary in severity and duration and can take a toll on a patient’s ability to confidently engage in everyday activities.​
• Very rare​, affecting ~5,000 to 6,000 individuals in the US​
• Diagnosis is complicated and misdiagnosis is common.​
• Treatment should be tailored to the particular type of periodic paralysis an individual has​

How Do You Get It?

• Major risk factor is genetic inheritance​
• Gene mutations cause periodic paralysis​ and are inherited from parents
  • Family history isn’t always obvious
• Only one parent need carry the mutated gene, and that parent may not show symptoms​
• Each child of an affected parent has a 50% chance of inheriting the gene mutation​
• No prenatal test is available at present​

What Are The Symptoms?

Hypokalemic Periodic Paralysis

• Muscle weakness​
  • Strength usually normal between attacks
• Paralysis
• Attacks last for a few hours or persist for several days​
• May develop chronic muscle weakness later in life​
• One of the earliest symptoms in children is a myotonic lid lag (lagging of upper eyelid on downward gaze)​
• Muscle pains
• Burning or tingling in hands or feet
• Triggers:
  • Getting too hungry
  • Unexpected exercise
  • Certain medications
  • Very high or low temperatures
  • Sleeping

Hyperkalemic Periodic Paralysis

• Muscle weakness
• Muscle hyperexcitability
• Mild attacks are frequent and involve only a particular group of muscles, and may be unilateral, partial, or monomelic​
  • Duration varies from a few hours to almost 8 days but seldom exceeds 72 hours
• Attacks may increase in frequency until attacks occur almost daily. ​
• Permanent muscle weakness may be seen later in the course of the disease and may become severe. The frequency starts diminishing by age 30
• Triggers:
  • Too much potassium
  • Weather changes
  • Periods of inactivity
  • Resting after exercise
  • Eating chilled foods/drinks
  • Getting too hungry

How Is It Treated?

• Goal: Relief of symptoms, treatment of attacks that are underway and preventing further attacks
• Medical attention may be needed to manage severe attacks​
• KEVEYIS was shown to reduce the number, duration, and severity of attacks of primary periodic paralysis. KEVEYIS is taken twice a day.
• Lifestyle changes are part of the treatment plan​
• Health care team includes:
  • Neurologist
  • Primary Care Physician
• Oral potassium supplement can treat attacks in hypokalemic periodic paralysis
  • Other hypokalemic options include acetazolamide (off-label) and potassium-sparing diuretics
  • Triamterene
  • Spironolactone​
  • Avoid sodium, high carbs, and natural sweeteners
  • Increase potassium intake
• Beta-adrenergic stimulants can improve weakness in hyperkalemic disease
  • Thiazide diuretics
  • Carbonic anhydrase inhibitors ​
  • Reduce potassium intake
  • Increase carb intake
  • Increase sugar intake when attack begins

Where Can I Learn More???

• Check out our cornerstone on this disease here.