Primary Periodic Paralysis PPP is a genetic condition that can be progressive and debilitating1,2
A group of rare channelopathies manifesting as recurrent attacks of muscle weakness or temporary paralysis often precipitated by triggers
- This condition includes a spectrum of chronic, autosomal-dominant neuromuscular disorders caused by mutations in the skeletal muscle sodium, calcium, and potassium channel genes3
- Muscle weakness or temporary paralysis is caused by depolarization of the muscle sarcolemma, which in turn causes sodium channel inactivation and reduced fiber excitability3
- Primary Periodic Paralysis PPP is very rare, with only ~4,000 to 5,000 diagnosed individuals in the US4
Educational segment on Primary Periodic Paralysis
Strongbridge Biopharma sponsored an educational segment about Primary Periodic Paralysis on The Balancing Act, “Behind the Mystery: Rare and Genetic Diseases.” The segment features Linda Feld, Vice President of Periodic Paralysis Association (PPA), and Steve Cannon, MD, PhD, neurologist and professor of physiology at UCLA. A broad range of topics related to Primary Periodic Paralysis are addressed within the segment, including symptoms, triggers, misdiagnosis, and genetic testing.
There are several subtypes of Primary Periodic Paralysis PPP with varying prevalence3
Hyperkalemic (~1 in 200,000)3,5
Common symptoms include attacks of weakness in the limbs and elevated serum levels of potassium as the potassium shifts from the muscle to the extracellular space. Sometimes serum potassium levels can remain normal.
Hypokalemic (~1 in 100,000)3,6
Typically manifests as flaccid muscle weakness that can last for at least several hours. Serum levels of potassium usually decrease as the potassium shifts from the extracellular space to skeletal muscle.
Paramyotonia congenita (PMC) (<1 in 100,000)1,7
Patients may present with sustained muscle tensing that prevents muscles from relaxing. PMC can present with elevated or normal serum potassium levels.
Andersen-Tawil syndrome (ATS) (1 in 1 million)3*
Serum potassium levels can be low, high, or normal. Other characteristics include abnormal skeletal features and cardiac abnormalities such as ventricular arrhythmias, prolonged QT interval, and prominent U waves.
*Patients with ATS were not included in clinical trials for KEVEYIS.
PPP triggers can vary from patient to patient, and from one type of PPP to another1,3
- Certain foods or beverages that are high in salt, carbohydrates, or potassium
- Stress or fatigue
- Exposure to cold temperatures or cold air
- Periods of inactivity
- Resting after exercise
Triggers can vary between subtypes of PPP.3
Work with your patients and consider their subtype to help determine their individual triggers.
Signs and symptoms are often nonspecific, and may have varying clinical presentations among patients1,2
Attacks can vary considerably between patients
Attacks can range in severity. In a study* of patients with hyperkalemic periodic paralysis surveyed about their disease1:
- 43.3% said the majority of their attacks were mild (defined as “some limitations on mobility, others would notice I am in an attack”)1
- 15.6% said their attacks were either severe (defined as “can speak, cannot move at all, can call for help”) or very severe (defined as “cannot speak, cannot call for help”)1
Attacks also often range in frequency2†:
- In this survey, the frequency of attacks was 59% weekly, 28% daily, and no attacks in 11%
- As patients age, the frequency of attacks may either increase or decrease; however, in about two-thirds of patients in one study,† there was no change in frequency2
- *Based on a survey of 137 adults (>18 years of age) with a diagnosis of hyperkalemic PPP and a genetic diagnosis. Percentages are based on the total number of respondents who answered a given question.1
- †Based on a survey of 66 self-selected patients over the age of 40 years with a clinical diagnosis of PPP who sought support via the internet.2
PPP can have a significant impact on patients’ everyday lives1
Symptoms can persist after attacks have subsided: Patients have reported experiencing lingering symptoms, including weakness, extreme fatigue, muscle pain, and clumsiness.1‡
The burden of PPP attacks is not only physical: Living with PPP can be stressful, and since stress can trigger attacks, it may compound the problem. Furthermore, the fear of unpredictable future attacks can cause social anxiety in patients.1
Over time, uncontrolled PPP may lead to persistent muscle weakness: In addition to attacks, persistent muscle weakness—constant weakness that can occur independently of attacks and becomes more likely in the fifth and sixth decades of life—may develop as muscle atrophies.2,9
- ‡These symptoms need to be considered within the overall treatment plan. No treatment for Primary Periodic Paralysis PPP is indicated to address all of these symptoms.