LENNOX-GASTAUT SYNDROME - A NEW VISTA

Lennox-Gastaut syndrome (LGS) is regarded as a model of the epileptic syndrome because of its specific clinicoelectrical manifestation. Howe ver, a close investigation reveals that its outline is somewhat vague, having the borderland around it. Precise diagnosis in an individual c ase is not always easy. In this paper, the diagnostic criteria of LGS are described. According to these criteria, cases with LGS were subcla ssified into the typical and the atypical cases, and also cases in the borderland of LGS were reviewed. On the other hand, our prospective l ong-term follow-up study revealed that cortical mechanisms played an i mportant role in the pathophysiology, clinical features and refractori ness of LGS. Secondary bilateral synchrony (SBS) is supposed to be a m ode of expression of cortical mechanisms of LGS. A newly developed met hod with coherence and phase analysis demonstrated that the pathophysi ology was based on SBS in 33% of the typical LGS cases. This finding i s not only crucial for the choice of rational treatment including epil epsy surgery, such as callosotomy, but also contributes to a more refi ned subclassification of LGS.