How are episodes of weakness triggered in familial periodic paralysis?

In familial periodic paralysis, episodes of muscle weakness are primarily triggered by fluctuations in blood potassium levels, which lead to the depolarization of muscle fibers and a subsequent loss of electrical excitability.12

Specific factors that can precipitate these attacks include:

• Rest after exertion: Attacks frequently occur during periods of relaxation following strenuous exercise.132
• Dietary factors: Consumption of carbohydrates or alcohol can trigger episodes.2
• Potassium level changes: Depending on the specific type of the disorder, attacks are associated with either abnormally low (hypokalemic) or high (hyperkalemic) levels of potassium in the blood. In hyperkalemic periodic paralysis, for instance, oral potassium therapy can induce an attack.12
• Sleep: In hypokalemic periodic paralysis, the onset of weakness often occurs at night during sleep.3

These conditions are generally inherited as autosomal dominant disorders involving mutations in ion channels or pumps within the skeletal muscle membrane, which disrupt normal ion movement.134