Receive
e-mail news, tips and updates from MDA or ask us
a quick question.
Periodic Paralysis (PP)
(Hypokalemic and Hyperkalemic)
Definition - one of a group of diseases that
cause problems with the tone and contraction of skeletal muscles; two forms,
hyperkalemic and hypokalemic
Cause - in hyperkalemic, high levels of potassium in the blood interact
in an unknown way with genetically caused abnormalities in sodium channels
(pores that allow the passage of sodium molecules) in muscle cells; in
hypokalemic, low levels of potassium in the blood interact in an unknown way
with genetically caused abnormalities in calcium channels (pores that allow the
passage of calcium molecules) in muscle cells; sometimes also caused by genetic
abnormalities in channels for sodium or potassium
Onset - hyperkalemic, childhood; hypokalemic, early childhood to
adulthood
Symptoms - in both forms, episodic attacks of muscle weakness; muscle
stiffness (myotonia) can occur in hyperkalemic form
Progression - in hyperkalemic, frequency of attacks declines after middle
age; in hypokalemic, number of attacks varies but severe attacks cause nearly
full-blown paralysis
Inheritance - in both forms, autosomal dominant, or produced by a
defective gene contributed by one parent
