<p class="first" id="P2">Abnormal high frequency oscillations (HFOs) in EEG recordings
are thought to be reflections
of mechanisms responsible for focal seizure generation in the temporal lobe and neocortex.
HFOs have also been recorded in patients and animal models of infantile spasms. If
HFOs are important contributors to infantile spasms then anticonvulsant drugs that
suppress these seizures should decrease the occurrence of HFOs. In experiments reported
here, we used long-term video/EEG recordings with digital sampling rates capable of
capturing HFOs. We tested the effectiveness of vigabatrin (VGB) in the TTX animal
model of infantile spasms. VGB was found to be quite effective in suppressing spasms.
In 3 of 5 animals, spasms ceased after a daily two week treatment. In the other 2
rats, spasm frequency dramatically decreased but gradually increased following treatment
cessation. In all animals, hypsarrhythmia was abolished by the last treatment day.
As VGB suppressed the frequency of spasms, there was a decrease in the intensity of
the behavioral spasms and the duration of the ictal EEG event. Analysis showed that
there was a burst of high frequency activity at ictal onset, followed by a later burst
of HFOs. VGB was found to selectively suppress the late HFOs of ictal complexes. VGB
also suppressed abnormal HFOs recorded during the interictal periods. Thus VGB was
found to be effective in suppressing both the generation of spasms and hypsarrhythmia
in the TTX model. Vigabatrin also appears to preferentially suppress the generation
of abnormal HFOs, thus implicating neocortical HFOs in the infantile spasms disease