Makindo Medical Notes

Related Subjects: Hyperkalaemia | ECG - Hyperkalaemia | Hypokalemia | Hyperkalaemic and Hypokalaemic Periodic Paralysis | Resuscitation - Advanced Life Support | Action Potential

Both hypokalaemic and hyperkalaemic paralysis are not caused by defects in potassium channels but rather in calcium and sodium channels, respectively. There are three distinct forms of periodic muscle paralysis related to potassium dysregulation.

Forms of Potassium-Related Periodic Muscle Paralysis

Hypokalaemic Periodic Muscle Paralysis

• Caused by an autosomal dominant defect in calcium channels.
• Most common form associated with thyrotoxicosis.
• Episodes often triggered by high-carbohydrate meals or heavy physical exertion, and symptoms may last for days.
• Avoid excessive exertion and treat with a low-carbohydrate, low-sodium diet.

Hyperkalaemic Periodic Muscle Paralysis

• Caused by an autosomal dominant defect in sodium channels (SCN4A gene).
• Episodes are triggered by rest following exercise, fasting, or oral potassium intake and typically last 1-2 hours.
• Patients may experience relief from weakness with mild exercise.
• Episodes can be terminated by IV calcium gluconate or IV furosemide.

Normokalaemic Periodic Muscle Paralysis

• Similar to the hyperkalaemic form but with normal potassium levels during attacks.
• Treatment involves acetazolamide to prevent attacks.