Successful Use of Intravenous Immunoglobulin as Initial Monotherapy in Landau‐Kleffner Syndrome

Summary:Purpose : There is a need for new and more effective therapies for Landau‐Kleffner syndrome. In this article we present the first case in which a patient with Landau‐Kleffner syndrome was given intravenous immunoglobulin (IVIG) as his first and only therapy and responded to it. Methods : This previously healthy, left‐handed boy presented at 31 months of age with a 3‐month history of auditory agnosia, behavioral abnormalities, and progressive, eventually complete loss of speech. Electroencephalography (EEG) showed frequent and, in sleep, continuous right central and temporal spike slow wave discharges. Metabolic workup, magnetic resonance imaging, and auditory evoked potentials were normal. Cere‐brospinal fluid IgG index was high (18%). The patient was treated with IVIG, as his initial and only therapy, receiving 500 mg/kg/day over four consecutive days. Results : On the third day of IVIG, the patient started using single words, and on the fourth, two‐word sentences. Two weeks later his speech and behavior returned to normal. At the end of 4 days of IVIG therapy, EEG was within normal limits. Two months later, however, he had a severe relapse clinically and by EEG. He promptly responded to another course of IVIG. A subsequent cerebrospinal fluid IgG index showed normalization (6%). Three months later he had essentially normal speech and behavior. Conclusions : Repeated, immediate, and remarkable clinical and EEG responses of this patient suggest that IVIG was helpful as first‐line therapy in the treatment of Landau‐Kleffner syndrome. It also supports the hypothesis that immunological mechanisms contributed to his symptoms.