1. Nervenarzt. 2011 Apr;82(4):511-20; quiz 521.

[Muscle channelopathies. Myotonias and periodic paralyses].

[Article in German]

Jurkat-Rott K, Lerche H, Lehmann-Horn F.

Abteilung für Neurophysiologie, Universität Ulm, Albert-Einstein-Allee 11, 89081,
Ulm. karin.jurkat-rott@uni-ulm.de

The myotonias and familial periodic paralyses are muscle channelopathies. They
have in common an impaired muscle excitation that is caused by mutations in
voltage-gated Na(+), K(+), Ca(2+), and Cl(-) channels. Membrane hyperexcitability
usually results in myotonic stiffness; with increasing membrane depolarization
hyperexcitability can be transiently turned into hypoexcitability causing
transient weakness as in severe myotonia. Hypoexcitability due to long-lasting
depolarization that inhibits action potential generation is the common mechanism
for the periodic paralyses. Interictally, the ion channel malfunction may be
compensated, so that specific exogenous or endogenous provocative factors are
required to produce symptoms in the patients. An especially obvious triggering
agent is the level of serum potassium, the ion decisive for resting membrane
potential and degree of excitability. Periodic paralysis mutations for which the
ion channel malfunction is not fully compensated interictally cause progressive
myopathy.

PMID: 21484581 [PubMed - indexed for MEDLINE]