Cortical excitability decreases in Lennox-Gastaut syndrome.
OBJECTIVE
We used transcranial magnetic stimulation (TMS) to investigate cortical excitability changes in Lennox-Gastaut syndrome (LGS), anticipating we would find a marked increase in excitability compared to other patients with refractory epilepsies.


METHODS
Eighteen patients with LGS were studied. Motor threshold (MT), short intracortical inhibition (paired pulse TMS at 2 and 5 msec interstimulus intervals [ISIs]), intracortical facilitation (10 and 15 msec ISIs), and long intracortical inhibition (100-300 msec ISIs) were measured. Results were compared to those of 20 patients with chronic refractory idiopathic generalized epilepsy (IGE), 20 patients with chronic refractory focal epilepsy, and 20 healthy nonepilepsy controls.


RESULTS
A significant decrease in cortical excitability was observed in LGS compared to the other two groups with refractory epilepsy as evidenced by increased MT and intracortical inhibition at both short (2, 5 msec ISIs), and long (100-300 msec ISIs) as well as decreased intracortical facilitation (10, 15 msec ISIs), (p < 0.01; effect sizes ranging from 0.3 to 1.8). Cortical excitability was also lower in LGS compared to nonepilepsy controls (increased MT and decreased intracortical facilitation; p < 0.05; effect sizes ranging from 0.5 to 0.9).


CONCLUSIONS
Interictal cortical excitability is decreased in LGS; a feature that distinguishes it from other refractory epilepsy syndromes. This decrease may be an important mechanism for the neurobehavioral comorbidities associated with LGS.
Department of Clinical Neurosciences, St Vincent's Hospital, Fitzroy, Victoria, Australia. badawyr@unimelb.edu.au
Radwa A B
RA
Badawy
Richard A L
RA
Macdonell
Simon J
SJ
Vogrin
Alan
A
Lai
Mark J
MJ
Cook
D000293:Adolescent; D000328:Adult; D015331:Cohort Studies; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006801:Humans; D008607:Intellectual Disability / Q000175:diagnosis* / Q000503:physiopathology* / Q000628:therapy; D065768:Lennox Gastaut Syndrome; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D013036:Spasms, Infantile / Q000175:diagnosis* / Q000503:physiopathology* / Q000628:therapy; D050781:Transcranial Magnetic Stimulation / Q000379:methods; D055815:Young Adult