Summary about Disease
Familial periodic paralysis (FPP) is a rare genetic condition characterized by episodes of muscle weakness or paralysis that come and go. These episodes are often linked to abnormal levels of potassium in the blood (either high or low). There are different types of FPP, classified based on whether the potassium level is low (hypokalemic), high (hyperkalemic), or normal (normokalemic) during attacks. It is inherited, meaning it is passed down through families.
Symptoms
The primary symptom is episodes of muscle weakness or paralysis, which can range from mild to severe. The weakness typically affects the limbs (arms and legs) but can sometimes involve the muscles of the trunk and, rarely, the respiratory muscles. Other possible symptoms include:
Muscle stiffness (myotonia) in some types
Muscle pain or cramps
Heart palpitations or irregular heartbeat (in severe cases with significant potassium imbalance)
Causes
FPP is caused by mutations in genes that are responsible for ion channels in muscle cells. These channels control the flow of sodium, calcium, and potassium, which are essential for muscle contraction. The specific genes involved depend on the type of FPP:
Hypokalemic FPP: Most commonly caused by mutations in the CACNA1S gene (calcium channel) or the *SCN4A* gene (sodium channel).
Hyperkalemic FPP: Most commonly caused by mutations in the SCN4A gene (sodium channel).
Andersen-Tawil Syndrome: Mutations in the KCNJ2 gene (potassium channel). This syndrome is related to periodic paralysis. These mutations disrupt the proper functioning of the ion channels, leading to abnormal potassium levels and muscle weakness. The condition is inherited in an autosomal dominant pattern, meaning only one copy of the mutated gene is needed to cause the disorder.
Medicine Used
Treatment focuses on preventing and managing episodes of paralysis. Medications used include:
Potassium Chloride (KCl): Used to treat hypokalemic FPP during attacks to raise potassium levels. Also can be taken preventatively.
Acetazolamide (Diamox): A carbonic anhydrase inhibitor that can help prevent attacks in both hypokalemic and hyperkalemic FPP.
Dichlorphenamide (Keveyis): Another carbonic anhydrase inhibitor approved for periodic paralysis.
Thiazide Diuretics: May be used cautiously in hyperkalemic FPP to help the kidneys excrete potassium.
Glucose and Insulin: In severe cases of hyperkalemia, glucose and insulin can be administered intravenously to help move potassium from the blood into cells.
Is Communicable
No, familial periodic paralysis is not communicable. It is a genetic disorder caused by inherited gene mutations and cannot be transmitted from person to person.
Precautions
Precautions focus on preventing attacks and managing symptoms:
Dietary Management: Avoid foods high in carbohydrates and sodium (hypokalemic) or potassium (hyperkalemic), depending on the type of FPP.
Regular Exercise: Regular, moderate exercise can help prevent attacks. Avoid strenuous activity that might trigger an episode.
Avoidance of Triggers: Identify and avoid triggers such as stress, cold temperatures, prolonged rest after exercise, and certain medications.
Potassium Monitoring: Regularly monitor potassium levels, especially during attacks.
Medical Alert Bracelet: Wearing a medical alert bracelet can inform emergency responders about the condition.
How long does an outbreak last?
The duration of an attack can vary significantly, depending on the type of FPP and the individual.
Hypokalemic FPP: Attacks can last from several hours to several days.
Hyperkalemic FPP: Attacks are typically shorter, lasting from 15 minutes to a few hours.
How is it diagnosed?
Diagnosis involves a combination of:
Medical History: Detailed family history of similar symptoms.
Physical Examination: Assessing muscle strength and reflexes.
Potassium Levels: Measuring potassium levels in the blood during an attack.
Electromyography (EMG): A test that measures the electrical activity of muscles.
Genetic Testing: Blood test to identify the specific gene mutation responsible for the condition.
Provocative Testing: Oral Glucose Tolerance Test with monitoring of potassium can be used to provoke an attack for diagnosis.
Timeline of Symptoms
Childhood/Adolescence: Onset of symptoms typically occurs in childhood or adolescence.
Episodes: Attacks are sporadic and unpredictable.
Triggers: Various triggers can initiate the attacks (diet, exercise, stress, temperature).
Progression: Frequency and severity of attacks can vary over time.
Important Considerations
Genetic Counseling: Genetic counseling is recommended for families with FPP to understand the inheritance pattern and the risk of passing the condition to future generations.
Emergency Preparedness: Individuals with FPP and their families should have a plan for managing attacks, including access to medications and knowing when to seek medical attention.
Medication Interactions: Certain medications can trigger or worsen attacks, so it's important to inform all healthcare providers about the diagnosis.
Cardiac Monitoring: In severe cases, especially with Andersen-Tawil Syndrome, cardiac monitoring may be necessary to detect and manage heart rhythm abnormalities.
Renal Function: Long-term use of some medications (like acetazolamide) requires monitoring of renal function.