CASPR2 antibody-associated peripheral nerve hyperexcitability: clinical features, treatment response, and renal manifestations in a case series

We report the clinical features, treatment response, and renal manifestations of 20 patients with voltage-gated potassium channel (VGKC) antibody-positive peripheral nerve hyperexcitability syndrome.This case series included 20 patients evaluated for clinical features, laboratory parameters, VGKC antibodies, electrophysiological findings, and treatment response. High-resolution CT of the chest was performed in all patients.20 patients (17 males, 3 females), all predominantly presented with unremitting lower-limb pain, myokymia, hyperhidrosis, and autonomic dysfunction. All received intravenous methylprednisolone (1 g daily for five days). Four required intravenous immunoglobulin, two underwent plasma exchange, and one received both. One patient required rituximab. Three patients had nephrotic-range proteinuria.Early diagnosis requires clinical suspicion, antibody testing, and electrophysiological confirmation. Most patients responded to corticosteroids, with a generally monophasic course and low relapse rate. Nephrotic-range proteinuria is an important association warranting renal biopsy.