Calcium and myokymia of brainstem origin.
In five patients with Guillain-Barré syndrome, clinical myokymia increased and myokymic burst amplification occurred when ionized Ca++ was lowered by hyperventilation. Myokymia decreased when ionized Ca++ was increased after IV infusion of CaCl2. These responses were absent or diminished in the four patients with myokymia due to brainstem lesions, suggesting that the blood-brain barrier impedes the effects of altered serum ionized Ca++ on axonal excitability. Altering serum Ca++ can distinguish peripheral and central myokymia.
D000200:Action Potentials / Q000187:drug effects; D000293:Adolescent; D001933:Brain Stem / Q000502:physiology*; D002118:Calcium / Q000502:physiology*; D002122:Calcium Chloride / Q000627:therapeutic use; D002493:Central Nervous System Diseases / Q000150:complications; D005207:Fasciculation / Q000188:drug therapy / Q000209:etiology* / Q000503:physiopathology; D005260:Female; D006801:Humans; D006985:Hyperventilation / Q000150:complications; D008297:Male; D008875:Middle Aged; D009422:Nervous System Diseases / Q000150:complications / Q000209:etiology*; D011129:Polyradiculoneuropathy / Q000150:complications
D002122:Calcium Chloride; D002118:Calcium