Spindles-inducing mechanism modulates sleep activation of interictal epileptiform discharges in the Landau-Kleffner syndrome.
OBJECTIVE
Landau-Kleffner syndrome (LKS) is characterized by a marked increase of interictal epileptiform discharges (IEDs) during sleep. During nonrapid eye movement (NREM) sleep, neuronal membrane potential oscillations lead to the appearance of spindles and delta waves in the surface EEG and might develop into paroxysmal synchronization. Spectral analysis allows the quantitative description of the dynamics of delta (slow-wave activity, SWA, 0.5-4.5 Hz) and sigma activity (SA, 12.0-16.0 Hz) and can be used to assess the relation between SA, SWA, and IEDs during sleep.


METHODS
We performed six overnight continuous EEG-polysomnographic studies in three patients with LKS. The temporal series of SWA and SA were obtained from a spike-free derivation lead. The IEDs count was performed on the most active lead. Relations between sigma and SWA and time series of IEDs were tested by means of correlation techniques after data normalization.


RESULTS
Our results revealed a significantly higher correlation between IEDs and SA with respect to SWA in all the subjects, in total sleep time. The same analysis limited to NREM sleep highlights the better correlation between SA and IEDs.


CONCLUSIONS
Our data suggest that neural mechanisms involved in the generation of sleep spindles facilitate IEDs production in LKS.
Nobili
L
L
Child Neuropsychiatry, DSN, Gaslini Institute, Genoa, Italy. nblino@dism.unige.it
Baglietto
M G
MG
Beelke
M
M
De Carli
F
F
De Negri
E
E
Tortorelli
S
S
Ferrillo
F
F
D000367:Age Factors; D000704:Analysis of Variance; D002540:Cerebral Cortex / Q000503:physiopathology; D002675:Child, Preschool; D003700:Delta Rhythm; D004569:Electroencephalography / Q000706:statistics & numerical data*; D006801:Humans; D018887:Landau-Kleffner Syndrome / Q000175:diagnosis* / Q000503:physiopathology; D008564:Membrane Potentials / Q000502:physiology; D017286:Polysomnography / Q000706:statistics & numerical data*; D012890:Sleep / Q000502:physiology*