The types of language disorders in 4 young adults with Landau-Kleffner syndrome were analyzed at long-term follow-up at the National Institute of Mental Health, National Center of Neurology and Psychiatry, Chiba, Japan. Age of onset was 4 to 6 years, and the first symptoms of language disorder were an auditory verbal agnosia in 3 cases, and sensory aphasia in 1. All patients showed a sequence of deterioration followed by recovery of language function without intellectual handicap. Sequelae included disability in spoken language, auditory verbal and music perception, and lower Wechsler Verbal scores compared to Performance IQ scores. Epilepsy began at 5 years in 2, and EEG epileptiform abnormalities occurred in all patients. CTs were normal in 3 and one showed an arachnoid cyst in the right anterior temporal lobe. 
COMMENT. Long-term follow-up of children with Landau-Kleffner syndrome into adult life shows a sequence of language disorders beginning at 4 to 6 years of age with sensory aphasia, and auditory verbal agnosia (word deafness), nonverbal agnosia, with or without anosognosia or denial of disability, and later showing improvement in auditory comprehension and speech but awareness of the impairments. The severity of language disorders, epileptic seizures, and EEG epileptiform discharges are not necessarily directly related, and antiepileptic medications which may control the seizures do not usually benefit the language deficits. Landau WM and Kleffner FR, in their original article , state that “EEG improvement tends to parallel improvement in speech reeducation.”
Magnetoencephalography in Landau-Kleffner syndrome has been studied prior to subpial transection in 4 children in Helsinki, Finland. The earliest spike activity on the EEG originated in the intrasylvian cortex, and MEG data focussed on small otherwise overlooked EEG potentials, helping to identify the primary epileptogenic source and influencing the planning of surgery.