Reduplicative paramnesia in Morvan's syndrome

BackgroundMorvan's syndrome is characterized by peripheral nervous system hyperexcitibility (myokymia and neuromyotonia), hyperhydrosis, sleep disorder, limb paresthesias, and encephalopathy. Voltage gated potassium channel antibodies (VGKC abs) are frequently present. Reduplicative paramnesia (RP) has not been reported with this disorder.ObjectiveTo describe a patient with Morvan's syndrome presenting with RP.DesignSingle case study.PatientA 64-year-old man with several years of myokymia and myoclonus with escalating parasomnia and confusion developed the delusion that a replica of his house and its contents existed 40 mi away.ResultsSerum VGKC ab titer was elevated. Neuropsychological testing disclosed executive function and memory deficits. Electromyography demonstrated diffuse myokymia. Treatment with intravenous immunoglobulin and prednisone produced improvement of RP and myoclonus, but not myokymia.ConclusionRP may occur in patients with VGKC ab-associated Morvan's syndrome. Both RP and nervous system hyperexcitability may respond to immunotherapy including intravenous immunoglobulin and corticosteroids.