Peripheral Nerve Hyperexcitability Syndromes

Peripheral nerve hyperexcitability (PNH) syndromes are an uncommon group of conditions characterized by spontaneous discharges from motor nerve fibres. These are largely immunological (sometimes secondary to neoplasm such as thymoma), and some forms are known to be genetic. Sometimes, they can be secondary to neuropathic or anterior horn cell disease. Electrophysiology shows myokymia or neuromyotonia, and antibodies against voltage-gated potassium channels are often detected. Immunotherapy leads to favorable outcomes and hence, these uncommon conditions are important.