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Clinical‐pathologic correlations in voltage‐gated Kv1 potassium channel complex‐subtyped autoimmune painful polyneuropathy
Author(s) -
Lahoria Rajat,
Pittock Sean J.,
Gadoth Avi,
Engelstad Janean K.,
Len Vanda A.,
Klein Christopher J.
Publication year - 2017
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.25371
Subject(s) - medicine , autoantibody , pathology , polyneuropathy , guillain barre syndrome , nerve biopsy , biopsy , histopathology , peripheral neuropathy , immunology , antibody , diabetes mellitus , endocrinology
: Voltage‐gated Kv1 potassium channel complex (VGKC) autoantibodies subtyped for leucine‐rich glioma‐inactivated 1 (LGI1), contactin‐associated‐proteinlike 2 (CASPR2), and Kv IgGs have a spectrum of neurological presentations. Painful polyneuropathy is seen in some patients, but nerve pathology descriptions are lacking. Methods : Clinicopathologic features were studied in subtyped VGKC‐autoantibody‐seropositive patients who had undergone nerve biopsies. Results : Five patients were identified, 1 LGI1 IgG positive and 1 CASPR2 IgG positive, but all negative for Kv1.1‐, 1.2‐, 1.6‐subtyped IgG autoantibodies. Median symptom duration was 17 months. Pain was the predominant symptom; 3 had mild sensory loss and/or weakness. Histopathological abnormalities were limited to axonal loss in 3. None had mononuclear cellular infiltrates. Electron micrographs revealed no interstitial abnormalities. Three patients reported marked improvement in pain with immunotherapy. Conclusions : The nerve biopsy histopathology of patients subtyped for LGI1 and CASPR2 IgGs within the VGKC‐complex spectrum disorders shows either normal density or axonal fiber loss without inflammatory infiltrates. A reversible neural hyperexcitable mechanism is considered to be the cause of this painful polyneuropathy. Muscle Nerve 55 : 520–525, 2017