Coupling of minor motor events and epileptiform discharges with arousal fluctuations in NFLE.
OBJECTIVE
We recently demonstrated that in nocturnal frontal lobe epilepsy (NFLE) highly stereotyped minor motor events (MMEs, in the form of short-lasting stereotyped movements involving the limbs, the axial musculature, and/or the head), could occur in either the presence or absence of an epileptiform discharge (ED). In lack of a systematic analysis, both MMEs and EDs were frequently observed to occur in association with arousal fluctuations. Hereby, in the same group of refractory NFLE subjects, we report a methodical neurophysiolgical investigation set out to investigate whether, and how, the arousal mechanism, monitored through visual scoring of the cyclic alternating pattern, modulates the expression of MMEs and EDs.


METHODS
The relationship of MMEs, EDs and arousal fluctuation was assessed in subjects explored using implanted electrodes.


RESULTS
The occurrence of both EDs and MMEs was associated with higher level of arousal (p < 0.0001). Multivariate logistic regression analysis shows a significant effect of interaction of EDs and MMEs during CAP sleep (p < 0.001).


CONCLUSIONS
Both MMEs and EDs are associated with arousal. We suggest that recurrence of EDs in itself can induce an increase in arousal level, which in turn, through a gate effect, facilitate the occurrence of MMEs. Thus, MMEs wouldn't be a direct effect of EDs, but rather originate from an indirect effect related to loss of cortical inhibition, which is secondary to arousal. In this perspective MMEs may be regarded as the result of aspecific dishinibition, triggered by internal epileptiform stimuli, of innate motor patterns generated by central pattern generators (CPGs). The CPG system might represent, through arousal facilitation, the substrate of the heterogeneous expression of MMEs in NFLE.
Terzaghi
Michele
M
Sleep Medicine and Epilepsy Unit, IRCCS C.Mondino Institute of Neurology Foundation, Pavia, Italy. michele.terzaghi@mondino.it
Sartori
Ivana
I
Mai
Roberto
R
Tassi
Laura
L
Francione
Stefano
S
Cardinale
Francesco
F
Castana
Laura
L
Cossu
Massimo
M
LoRusso
Giorgio
G
Manni
Raffaele
R
Nobili
Lino
L
D000328:Adult; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000503:physiopathology*; D002940:Circadian Rhythm / Q000502:physiology; D015897:Comorbidity; D004567:Electrodes, Implanted; D004569:Electroencephalography / Q000706:statistics & numerical data*; D017034:Epilepsy, Frontal Lobe / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology*; D005260:Female; D005625:Frontal Lobe / Q000503:physiopathology; D006801:Humans; D008297:Male; D020183:Nocturnal Paroxysmal Dystonia; D012008:Recurrence; D020921:Sleep Arousal Disorders / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology*; D012894:Sleep Stages / Q000502:physiology; D019956:Stereotypic Movement Disorder / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology*; D013577:Syndrome; D014743:Videotape Recording