A rare genetic neurological disorder characterized by adult onset of peripheral nerve hyperexcitability causing painful muscle cramps and fasciculations in the limbs, hyperreflexia, stiffness, and muscle pain. Other hypersensitivity-hyperexcitability symptoms are asthma, gastroesophageal reflux, migraine, tremor, cold hyperalgesia, and cardiac conduction defects. Autonomic signs and symptoms, neuropathic pain, cognitive deficits, and anxiety are also observed. [from
ORPHANET]