Furthermore, phenotypic heterogeneity has been reported in voltage gated potassium channel (VGKC) associated disorder.
A classification has been proposed that distinguishes immune mediated PNH (irrespective of whether VGKC antibodies are detected by standard assays) from non immune forms of PNH that includes toxins, anterior horn cell degeneration in motor neuron disease and genetic disorders10.
Sleep disturbance during the acute phase of limbic encephalitis is known, acute insomnia or hypersomnia has been described almost in one fourth of patients with positive VGKC
antibodies (1) but there was no PSG finding in this series.
Anti-LGI1 antibodies are against the VGKC
complex and are mostly expressed in the hippocampus (7).
CSF obtained from a lumbar puncture was sent to an outside laboratory for serology on an autoimmune panel and confirmed the presence of antibodies towards the LGI1 portion of the VGKC
complex and no other autoimmune antibody including antiCASPR2, another anti-VGKC antibody.
Abbreviations APCs: Antigen-presenting cells BMI: Body mass index CRP: C-reactive protein EEG: Electroencephalography ET-1: Endothelin-1 HIV: Human immunodeficiency virus HPA: Hypothalamus-pituitary-adrenal axis hsCRP: High-sensitivity CRP IFN: Interferon ICAM: Intracellular adhesion molecule ICV: Intracerebroventricular IL: Interleukin MIP: Macrophage inhibitory protein NK: Natural killer Non-REM: Nonrapid eye movement OSA: Obstructive sleep apnea REM: Rapid eye movement sleep SWS: Slow-wave sleep Th: T helper TNF: Tumor necrosis factor VGKC
: Voltage-gated potassium channels WBC: White blood cells.
These antibodies are directed against two categories of antigens: (1) intracellular antigens (Hu, Ma2, CRMP5, amphiphysin, etc.) and (2) cell surface antigens (the VGKC complex, NMDAR, AMPARs, GABABRs, mGluR5 receptor, GlyRs, etc.).
Thus far, it is still unclear whether antibody-mediated PNS, for example, VGKC complex antibody-associated limbic encephalitis, is driven by serum or intrathecal antibodies.
Patients with limbic encephalitis and antibodies against cell surface antigens such as VGKC or NMDAR often respond to immunotherapies, such as corticosteroids, intravenous immunoglobulin (IVIG), or plasma exchange.
Keywords: Cramp-fasciculation syndrome (CFS), peripheral nerve hyperexcitability, voltage-gated potassium channel (VGKC)-complex proteins, neuropathic pain
Voltage-gated potassium channel (VGKC)-complex antibodies are often found in CFS patients.