Seneviratne U, Cook M, DʼSouza W. Epileptiform K-Complexes
and Sleep Spindles: An Underreported
Phenomenon in Genetic Generalized Epilepsy. J Clin Neurophysiol. 2016
Apr;33(2):156-61.
Abstract
PURPOSE:
To study the frequency of epileptiform K-complexes and sleep
spindles as well as clinical variables influencing those abnormalities.
METHODS:
We prospectively performed 24-hour ambulatory EEGs in a
cohort of patients with genetic generalized epilepsy diagnosed and classified
according to the International League against Epilepsy criteria. Overlapping of
epileptiform discharges with K-complexes and sleep spindles was defined as
epileptiform K-complexes and epileptiform sleep spindles. The presence of
epileptiform K-complexes and sleep spindles was tabulated for each patient, and
frequencies were calculated. We performed multiple regression analysis to study
the influence of clinical predictors on the occurrence of epileptiform
K-complexes and sleep spindles. The predictor variables tested in the model were
seizure-free duration, epilepsy duration, genetic generalized epilepsy
syndrome, number of antiepileptic drugs, use of sodium valproate, and use of
lamotrigine.
RESULTS:
A total of 107 patients (37 males and 70 females) were
studied. The mean age was 28.5 ± 10.7 years (range, 13-58). Juvenile absence
epilepsy was the most common epilepsy syndrome in the cohort (31.8%), followed
by generalized epilepsy with tonic-clonic seizures only (26.2%), juvenile
myoclonic epilepsy (26.2%), and childhood absence epilepsy (14%). Epileptiform
K-complexes and sleep spindles were seen in 65.4% and 10.3% of patients,
respectively. None of the clinical variables had any significant impact on the
occurrence of epileptiform K-complexes and sleep spindles in our multivariable
analysis.
CONCLUSIONS:
Epileptiform K-complexes are common in the sleep EEGs of
patients diagnosed with genetic generalized epilepsy. This underreported
phenomenon highlights the important association of arousals and epileptiform
discharges in genetic generalized epilepsy.
Cortical and sub-cortical excitability during spindles and
K-complexes, putative attractors of epileptic activity Ioannides AA 1 , Liu L 1
1AAI Scientific Cultural Services Ltd, Lab for Human Brain Dynamics, Nicosia,
Cyprus
Purpose: The ARMOR project (www.armor-project.eu) is
developing a platform for home monitoring of epilepsy patients. During sleep
stage II (SS2) the frequency of specific types of epileptic activity is high.
It is believed that large graphoelements of SS2, spindles and K-complexes act
as attractors of epileptic activity.
Method: We studied high quality whole night sleep MEG
recordings of four normal subjects [1]. The brain activity during K-complexes
and spindles was compared with activity shortly during targeted baseline
periods that included periods before (1-2 seconds) the graphoelements, quiet
core periods of sleep stages [1], including SS2 and the awake state, with
separate comparisons performed in the time and frequency domains.
Results: We showed widely distributed cortical foci of
activity with hot spots during spindles around the central sulcus, parietal and
prefrontal cortex, and during K-complexes the strongest hot spots in the
anterior and motor cingulate. The statistical comparisons between periods of
large K-complex and spindle activity with targeted baseline periods confirmed
these findings with very high statistical significance (p< 0.0001) for each
subject. However, the same comparisons showed distinct sub-cortical areas for
each baseline period, suggesting significant changes in sub-cortical excitation
in different sleep stages, even in the quiet periods, consistent with our
earlier study [1].
Conclusion: Our results highlight the need to monitor
epileptic activity during sleep with simultaneous characterization of sleep
stages. This need will be satisfied by the output of the ARMOR project that has
home monitoring capability, allowing such a characterization to be followed
over extended periods and thus probe the evolution of epilepsy with unprecedented
detail.
Acknowledgment: The work was partially funded by the European
Commission under the Seventh Framework Program with grant ARMOR, agreement
number 287720.
References: [1] Ioannides AA et al. (2009) MEG identifies
dorsal medial brain activations during sleep, NeuroImage 44: 455-68.
http://armor.tesyd.teimes.gr/documents/10184/16090/Montreal_abstract.pdf/5dfcb580-e0f1-4ad5-b0cb-e67e839f3f85
Note polyspikes overlapping on the ascending limb of the surface negative wave of the K-complex.
Note polyspike-wave
discharges admixed with the terminal part of a sleep spindle.
Note polyspike-wave discharges in the middle of a sleep spindle. This is best realized in the central electrodes
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