This information is provided by the National Institutes of Health (NIH) Genetic and Rare Diseases Information Center (GARD).
Isaacs’ syndrome is a rare neuromuscular disorder that is characterized by progressive muscle stiffness; continuously contracting or twitching muscles
(myokymia); and diminished reflexes. Signs and symptoms generally develop between ages 15 and 60, with most people experiencing symptoms before age 40. Although the exact underlying cause is unknown, there appear to be hereditary and acquired (non-inherited) forms of the condition. Treatment is based on the signs and symptoms present in each person.
For more information, visit GARD.