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

Abstract

Introduction Peripheral 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. Methods We 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. Results A 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. Discussion Primary 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.

Acquired hyperexcitable peripheral nerve disorders: Clinical and laboratory features, therapeutic responses, and long‐term follow‐up

“…Our patients presented across a wide age range with heterogenous peripheral and central clinical features, which largely followed the trend documented in the literature. 1,8,9 The pattern of exclusive CASPR2 antibody positivity (14 patients) being more common than the LGI-1 positivity (5 patients), seen in this study, was as observed in other studies. In the single patient with mercury toxicity and CASPR2 positivity, the autoimmunity was probably triggered by the mercury toxicity, as has been described.…”

A Chinese female patient with LGI1 and mGluR5 antibodies: A case report

“…Recent researches have proved that autoimmune mechanisms play a vital role in the pathophysiology of PNHS, serum CASPR2 and LGI1 antibodies may be pathogenic for primary PNHS, mainly through interfering with the function of the VGKC-complex. [ 3 ] After-discharges are considered electrophysiological manifestations that are effective in diagnosing PNHS. [ 6 ] However, our patient’s electromyography showed peripheral nerve damage.…”

“…[ 2 ] Peripheral nerve hyperexcitability syndrome (PNHS) may observed in anti-LGI1 AE patients. [ 3 ]…”

“…[2] Peripheral nerve hyperexcitability syndrome (PNHS) may observed in anti-LGI1 AE patients. [3] Anti-metabotropic glutamate receptor 5 (mGluR5) encephalitis is another type of AE which is extremely rare worldwide. Only 12 cases have been reported so far.…”