Isaacs’ syndrome, also called neuromyotonia, is a rare neuromuscular disorder. The condition makes your nerves fire too much, which overstimulates your reflexes and muscles. It causes muscle stiffness, muscle cramps, slow reflexes and excessive sweating. Symptoms get progressively worse over time and can affect daily activities.
Isaacs’ syndrome is a rare neuromuscular disorder. The condition causes nerves within your peripheral nervous system to be overly excited, leading to involuntary muscle firing. People with the condition experience stiffness, cramps and twitching in their muscles. It can also affect your autonomic nervous system, leading to changes in sweating and heart rate.
It’s also called:
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Isaacs’ syndrome is extremely rare. Scientists aren’t sure how many people have it, but only a couple hundred cases have been reported.
Symptoms of muscle cramps and muscle twitching (fasciculations) are extremely common in adults and aren’t usually serious. For the vast majority of people, these symptoms don’t indicate a more serious neurologic condition like Isaacs’ syndrome.
The signs of Isaacs’ syndrome usually begin between the ages of 15 and 60. But it has been reported in younger people and even infants.
The disorder may be associated with other conditions, including:
Neuromyotonia can be:
The signs and symptoms of Isaacs’ syndrome generally happen throughout the day, even during sleep. Muscle symptoms are most common in your arms and legs, but they can affect other muscles in your body.
Symptoms include:
Your healthcare provider may order tests to confirm Isaacs’ syndrome or rule out other disorders. Tests may include:
Sometimes, Isaacs’ syndrome is misdiagnosed as another disorder, such as stiff-person syndrome, rippling muscle syndrome or cramp-fasciculation syndrome.
There’s no cure for Isaacs’ syndrome. Treatment aims to address your symptoms and maximize daily function. If Isaacs’ syndrome is associated with another autoimmune disease or a malignancy, then treatment of these other conditions is important well. For Isaacs’ syndrome, your healthcare provider might recommend:
Because scientists don’t understand what causes Isaacs’ syndrome, there currently aren’t any strategies to prevent it.
The outlook for someone with Isaacs’ syndrome varies. It depends on the severity of the disorder, the underlying cause, treatment effectiveness and any associated medical conditions.
Neuromyotonia symptoms progressively worsen over time. They can significantly limit movement and interfere with daily activities.
Although there’s currently no cure, the condition isn’t generally fatal.
Some people with Isaacs’ syndrome have found success managing the physical and psychological effects of Isaacs’ syndrome by:
If you’re diagnosed with neuromyotonia, consider asking your doctor the following questions:
A note from Cleveland Clinic
Isaacs’ syndrome is a rare neuromuscular disorder that causes overactive nerves and muscles. If you’ve been diagnosed with the condition, talk to your healthcare provider. They can test you for related conditions and help you manage symptoms such as muscle twitching and stiffness.
Last reviewed by a Cleveland Clinic medical professional on 04/01/2022.
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