Re: Isaac's Syndrome

Posted By CCF neuro MD MM on November 03, 1998 at 16:39:46:

In Reply to: Isaac's Syndrome posted by Karen on November 03, 1998 at 13:22:39:






Dear Forum
I've read that Isaac's Syndrome is an antibody-mediated potassium channelopathy and that it's symptoms include muscle twitches and cramps.  Does muscle weakness ever occur with this syndrome?  If it is an immune mediated condition (whereby the immune system is attacking the potassium channels) like immune-mediated motor neuropathy why couldn't it cause muscle weakness also?  
In most autoimmune diseases (such as rheumatoid arthritis or multiple sclerosis etc.) the immune system's repetitive attacks cause irreparable damage to the body's organs.  Why wouldn't continual attacks on the potassium channels cause permanent damage to the potassium channels with Isaac's Syndrome?  Any information would be appreciated.

Thanks,
Karen  



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Muscle weakness is not described as part of the clinical picture of Isaacs syndrome.
This is probably because potassium channels mediate excitability of the muscle cell membranes, the actual force of subsequent contraction is related to calcium flow so the problem is one of increased excitability not weakness.
Antibodies to channels or receptors are not necesarily destructive, they may block or modulate the activities of  these structures, as opposed to simply causing their destruction, a phenomenon which is described particularly in myasthenia gravis.
Another protective factor is that the cell can resynthesize channels
without being destroyed itself.