Teaching Pearls:

• Periodic Paralysis occurs as a result of genetic channelopathies that can cause bilateral UE and LE weakness
  • More pronounced in proximal vs distal muscle groups
  • No loss of bulbar muscle functions or respiratory muscles
  • Hypo or a-reflexic on exam
  • Evidence of hypokalemia on labs.
  • Seen in younger patients <20 years of age.
  • Symptoms occur during rest after strenuous exercise, high carbohydrate diet, fasting state
• Primary acquired cause of periodic paralysis is due to thyrotoxicosis
  • Theorized to increased Na/K channels causing hyperpolarization, making it harder to reach threshold to set off action potential.
  • Classically seen in Asian young males
  • Seen in younger patients >20 years of age.
• Differential Diagnosis
  • Myasthenia Gravis
    • Bulbar muscle involvement that gets worse with activity
  • GBS
    • Ascending motor and sensory involvement, symmetric
  • Tick Paralysis
    • Motor abnormalities, no sensory defect, asymmetric
  • Botulism
    • Bulbar involvement, spread in craniocaudal direction
  • Acute myelopathy
    • Motor involvement, hyperreflexic
• Treatment
  • Treat underlying etiology of periodic paralysis
  • Behavioral modification
    • Avoid strenuous exercise and high carbohydrate meal intake
  • Oral medications
    • Consider acetazolamide
    • Consider spironolactone