Neuromuscular hyperexcitability associated with acetylcholine receptor antibodies in a child. 
This report describes the clinical and electrophysiological features of an 8-year-old boy with autoimmune neuromuscular hyperexcitability.  He presented with features of lower extremity pain, stiffness, and rippling muscles.  The diagnosis was made by electromyography and supported by the presence of an antibody directed against nicotinic acetylcholine receptors.  His symptoms responded to immunomodulatory treatment with intravenous immunoglobulin.  Response to immunomodulatory therapy has not previously been described in the pediatric population with autoimmune neuromuscular hyperexcitability.  This case highlights that this is a treatable condition.