Landau-Kleffner syndrome and its variants

Controversy surrounds the classification of Landau-Kleffner syndrome (LKS) and the disorders considered its variants.1 Although the classic form of LKS has been well described, clinical and electroencephalographic similarities between LKS and other developmental and acquired cognitive and behavioral disorders associated with an epileptiform electroencephalogram (EEG) raise questions as to the boundaries of LKS. Is it a distinct entity or a subtype of a broader syndrome with a single etiology but multiple clinical phenotypes? The fact that a given child may exhibit features common to several different disorders (e.g., LKS, autism, disintegrative disorder), either simultaneously or at various times over the course of development, adds to the confusion.

Given this uncertainty, attempts have been made to delineate homogeneous subgroups within the developmental language disorders, autistic spectrum disorders, and disintegrative disorders on the basis of the presence or absence of:

• language abnormalities
• behavioral abnormalities
• cognitive abnormalities
• EEG abnormalities

Without a clear understanding of etiology or pathophysiology, however, the rationale for these demarcations remains controversial. The central, unresolved issue is whether the epileptiform discharges cause or contribute to language, behavioral, or cognitive regression in these disorders.2–4

The aim of these pages is to outline the boundaries of LKS and its variants, shedding light on where they diverge and overlap. The initial pages characterize the clinical findings that may distinguish LKS from its putative variants and describe the electroencephalographic features that may distinguish them:

Clinical features of the Landau-Kleffner syndrome
Clinical features of LKS variants
Diagnosis
Differential diagnosis
EEG variants: Continuous spikes and waves during slow sleep
EEG variants: Centrotemporal (Rolandic) spikes
EEG variants: Occipital spikes or spikes and waves

Other pages highlight areas of debate and summarize the results of treatment and the outcome:

How are epilepsy and epileptiform EEG abnormalities related to language and cognitive disorders in LKS?
What is the etiology of LKS?
Treatment
Outcome

Adapted from: Nass R and Gross A. Landau-Kleffner syndrome and its variants. In: Devinsky O and Westbrook LE, eds. Epilepsy and Developmental Disabilities. Boston: Butterworth-Heinemann; 2001;79–92.
With permission from Elsevier (www.elsevier.com).
Reviewed and revised May 2004 by Steven C. Schachter, MD, epilepsy.com Editorial Board.