About 75% of patients with classic Landau-Kleffner syndrome (LKS) experience seizures, which can predate or postdate the onset of aphasia. The rest, by definition, have an epileptiform EEG. Virtually all seizure types have been reported in association with LKS. Generally, the seizures are easily controlled. In rare cases, they may be intractable and require surgery.37–39 No specific differences have been reported for the LKS variants.
The abnormalities seen on the EEG in LKS, autistic epileptiform regression (AER), and disintegrative epileptiform disorder (DED) are, for the most part, nonspecific. They include a variety of generalized or focal (approximately 10%) epileptiform discharge patterns.
Probably the most common morphologic pattern in LKS is centrotemporal spikes (apart from the possible Rolandic variant) Centrotemporal spikes also are seen commonly in children with autistic spectrum disorders and AER.22 Electroencephalographic abnormalities generally increase during sleep. Overnight EEG recording definitely picks up more abnormalities than does a routine sleep recording. Prolonged recording (over several nights) may be necessary to document epileptiform discharge, including CSWDS.40–42 Amitriptyline activation may increase the likelihood of observing these discharges in some cases.43
In addition to clinically defined variants, a number of electroencephalographic variants exist in the LKS spectrum:
Magnetoencephalography (MEG) may represent yet another level of sensitivity for diagnosis. MEG identified epileptiform activity in 41 (82%) of 50 patients with AER, whereas only 34 (68%) had epileptiform revealed on the EEG.44 Contrasting LKS patients with AER patients, Lewine et al.44 documented primary epileptiform activity during stage III sleep only in the perisylvian region in the LKS patients (bilaterally in 5 of 6) . By contrast, 75% of the AER patients showed independent epileptiform activity in extrasylvian zones in addition to intrasylvian cortex.
MEG has also been used in classic LKS patients to localize the primary epileptogenic region to intrasylvian cortex prior to multiple subpial transection (MST) surgery.45
Reviewed and revised May 2004 by Steven C. Schachter, MD, epilepsy.com Editorial Board.
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