Hypokalemic periodic paralysis

Background

• Autosomal dominant channelopathy
• Symptoms include muscle weakness or paralysis with associated hypokalemia (though potassium levels can be normal), sometimes painful though often painless. Weakness can be from hand to leg to complete paralysis.
• Triggered by strenuous exercise, high carbohydrate meal, high sodium meals, sudden changes in temperature or emotional stress
• Attacks can last several hours to several days
• Most first attacks happen by age 16
• There is no decrease in total body potassium. Blood potassium level is normal between attacks.

Differential Diagnosis

• Guillan Barre - Deep tendon reflexes spared, CN 7 spared
• Thyrotoxic Periodic Paralysis - Distinguished by thyroid studies
• Multiple Sclerosis
• Myasthenia Gravis
• Conversion Disorder
• Spinal Impingement/Epidural Abscess
• ALS
• NMS
• Serotonin Syndrome

Physical Exam

• Reflexes are decreased or absent
• Shoulders and hips, are involved more often than the arms and legs.
• There is flaccid paralysis rather than hypertonia
• There should not be myoclonus or spasticity

Treatment

• Replace potassium appropriately - do not try to correct to normal level as once the muscles release potassium you will likely overcorrect
• Long Term Treatment:
  • Should be initiated by primary physician but often includes eating a low carbohydrate diet and avoiding alcohol
  • Medications to increase potassium: Acetazolamide, Spironolactone, Potassium tablets,

Disposition

• Can be discharged from ED after potassium repletion and resolution of symptoms.