The most common familial periodic paralysis syndrome is usually associated with low potassium, but there are less common forms characterized by high or normal potassium It is characterized by recurrent attacks of weakness or paralysis of the somatic musculature, with loss of the deep tendon reflexes. Preventive therapy includes potassium supplementation and possibly a low-carbohydrate, low-salt, and high-potassium diet. Imipramine and acetazolamide are said to be useful in acute attacks.