ABSTRACT
Peripheral nerve hyperexcitability syndromes (PNHS) encompass a spectrum of a heterogeneous condition with clinical as well as electrophysiological manifestations of peripheral nerve hyperexcitability. The PNHS consist of Isaacs syndrome, Morvan syndrome and Cramp-fasciculation syndrome, which cause widespread symptoms and signs while without evident peripheral nerve disease. Probably the most well-known condition of PNHS is Isaacs syndrome, often called acquired neuromyotonia. Clinical symptoms of PNHS are characterized by muscle twitching, cramps, stiffness, and neuropathic pain. The electrophysiological findings that are very useful in the diagnosis of PNHS are spontaneous myokymic, neuromyotonic, and cramp discharges. An overview of the history, clinical manifestations, pathophysiology, electrophysiological findings and management of PNHS is presented.