Peripheral nerve hyperexcitability syndrome: A clinical, electrophysiological, and immunological study

AbstractIntroductionPeripheral nerve hyperexcitability syndrome (PNHS) is characterized by muscle fasciculations and spasms. Nerve hyperexcitability and after‐discharges can be observed in electrophysiological studies. Autoimmune mechanisms play a major role in the pathophysiology of primary PNHS.MethodsWe retrospectively conducted a case–control study recruiting patients with clinical and electrophysiological features of PNHS. Control patients were diagnosed with other neuronal or muscular diseases. Contactin‐associated protein2 (CASPR2) and leucine‐rich glioma‐inactivated1 (LGI1) antibodies were examined.ResultsA total of 19 primary PNHS patients and 39 control patients were analyzed. The most common symptoms for the case group were fasciculations (11/19) and muscle spasms (13/19). Case group patients were likely to demonstrate electrodiagnostic findings of nerve hyperexcitability (17/19) and after‐discharges in the tibial nerve (19/19). We found high prevalence of CASPR2 (9/19) and LGI1 (6/19) antibodies in the case group.DiscussionPrimary PNHS patients were likely to show after‐discharges in the tibial nerve. The pathogenesis of PNHS is autoimmune CASPR2 and LGI1 antibodies are possible pathogenic antibodies for primary PNHS.