[Congenital paramyotonia, adynamia episodica hereditaria, or familial periodic paralysis with paramyotonia and hyperkalemia (author's transl)].

Case-reports of eleven patients diagnosed either as Eulenburg paramyotonia or Gamstorp adynamia episodica hereditaria are reviewed. The connections between both conditions are discussed. The clinical pictures are similar, with predominance of either paramyotonia or adynamia. In both conditions, hyperkaliemia is present and potassium loading may be followed by clinical exacerbation. Electromyographic and histological findings are comparable. Paramyotonia and adynamia probably result from the same physiopathological mechanism : hyperkaliemia modifies the cell membrane permeability to sodium and potassium, leading to depolarization with initial hyperexcitability and subsequent inexcitability. We believe that Eulenburg paramyotonia and Gamstorp adynamia episodica hereditaria are two manifestations of the same condition which could be termed familial periodic paralysis with paramyotonia and hyperkaliemia.