Primary periodic paralyses.
OBJECTIVE
To review the current knowledge about primary periodic paralyses (PPs).


RESULTS
Periodic paralyses are a heterogeneous group of disorders, clinically characterized by episodes of flaccid muscle weakness, occurring at irregular intervals. PPs are divided into primary (hereditary) and secondary (acquired) forms of which the secondary PPs are much more common than the primary PPs. Primary PPs are due to mutations in genes encoding for subunits of channel proteins of the skeletal muscle membrane, such as the muscular sodium, potassium or calcium channels, or the SCL4A1 protein. Primary PPs include entities such as hyperkalemic PP, hypokalemic PP, paramyotonia congenita von Eulenburg, Andersen's syndrome, thyrotoxic PP, distal renal tubular acidosis, X-linked episodic muscle weakness syndrome and congenital myasthenic syndromes. Attacks of weakness or myotonia may be triggered or enhanced by vigorous exercise, cold, potassium-rich food, emotional stress, drugs such as glucocorticosteroids, insulin or diuretics, or pregnancy. Depending on the pathomechanism, episodes of weakness may respond to mild exercise, ingestion of potassium, carbohydrates, salbutamol, calcium gluconate, thiazide diuretics, carboanhydrase inhibitors, such as acetazolamide or dichlorphenamine, and episodes may be prevented by avoidance of potassium-rich food, or drugs, which increase serum potassium.


CONCLUSIONS
This review presents and discusses current knowledge and recent advances in the etiology, molecular genetics, genotype-phenotype correlations, pathogenesis, diagnosis and treatment of primary PPs.
Finsterer
J
J
Neurological Department, Krankenanstalt Rudolfstiftung, Vienna, Austria. fifigs1@yahoo.de
D015220:Calcium Channels / Q000235:genetics; D020746:Calcium Channels, L-Type; D002886:Chromosomes, Human, Pair 17 / Q000235:genetics; D041321:Chromosomes, Human, X; D005817:Genetic Counseling; D006011:Glycogen Storage Disease Type IV / Q000175:diagnosis / Q000235:genetics / Q000503:physiopathology; D006801:Humans; D020514:Hypokalemic Periodic Paralysis / Q000175:diagnosis / Q000235:genetics / Q000503:physiopathology; D020967:Myotonic Disorders / Q000175:diagnosis / Q000235:genetics / Q000503:physiopathology; D010245:Paralyses, Familial Periodic / Q000175:diagnosis / Q000235:genetics* / Q000503:physiopathology*; D017354:Point Mutation / Q000235:genetics
C412223:CACNA1S protein, human; D015220:Calcium Channels; D020746:Calcium Channels, L-Type