Acquired epileptic aphasia¹ is an epileptic syndrome described in the International Classification of Epilepsies by the eponym Landau–Kleffner syndrome (LKS). Typical LKS^2,3 is part of the epileptic encephalopathy of late childhood defined by¹: age of onset ranging from 3 to 10 years in children with previously normal language development;² insidious or abrupt acquired aphasia with verbal auditory agnosia; behavior disturbances (attention deficit and hyperactivity);³ seizures that may be nocturnal, focal motor, secondarily generalized, or atypical absences with an awake electroencephalographic (EEG) showing focal or multifocal spikes-and-waves predominantly over the temporal regions (Fig. 30–1);⁴ and sleep EEG reveals activation of interictal EEG abnormalities and, during the course of the syndrome in the acute phase, nonrapid eye movement (NREM) subcontinuous or continuous spike-waves during sleep (CSWS) (Fig. 30–1).

Typical LKS is not related to nonconvulsive status epilepticus, which presents as a subacute progressive aphasia in adults,⁴ or acquired lesions with seizures such as cysticercosis⁵ or astrocytoma.⁶ LKS represents a subtype of idiopathic focal epilepsies with acquired cognitive deficits.^7,8 Other subtypes of idiopathic focal epilepsies related to LKS are described by several terms in the literature: acquired opercular syndrome with epilepsy, frontal epilepsy with or without autistic regression, atypical partial benign epilepsy or pseudo-Lennox–Gastaut syndrome, and idiopathic or symptomatic CSWS⁸ (Table 30–1)