Cramp fasciculation syndrome is a rare peripheral nerve hyperexcitability disorder. It is more severe than the related and common disorder known as benign fasciculation syndrome

Benign fasciculation syndrome

Benign fasciculation syndrome is a neurological disorder characterized by fasciculation of various voluntary muscles in the body. The twitching can occur in any voluntary muscle group but is most common in the eyelids, arms, legs, and feet. Even the tongue may be affected. The twitching may be...

, causing fasciculations, cramps, pain, fatigue, and muscle stiffness similar to those seen in neuromyotonia

Neuromyotonia

Neuromyotonia , also known as Isaacs' syndrome, is a form of peripheral nerve hyperexcitability that causes spontaneous muscular activity resulting from repetitive motor unit action potentials of peripheral origin.-Causes:...

, another related condition. Patients with CFS, like those with neuromyotonia, may also experience paresthesias.

Most cases of cramp fasciculation syndrome are idiopathic.

Cramp fasciculation syndrome is diagnosed by clinical examination and electromyographic study (EMG). Fasciculation is the only abnormality, if any, seen with EMG.

Cramp fasciculation syndrome is a chronic condition. Treatment options include anti-seizure medications such as carbamazepine, as well as immunosuppressant medications and plasmapheresis.