SOUNDS TRIGGER SPIKES IN THE LANDAU-KLEFFNER SYNDROME

Auditory evoked magnetic fields and spontaneous epileptic activity were recorded with a 24-channel planar gradiometer in 7 children with acquired epileptic speech disorders. Six children had a marked loss of speech comprehension (the Landau-Kleffner syndrome-LKS); in one child, only the speech fluency was affected. Auditory evoked fields were abnormal in five patients studied during active disease. Sounds triggered signals identical to the spontaneous spikes in three LKS patients. In two patients, the triggered spikes lagged the tone onset by 100 ms, whereas the interstimulus interval affected the lag in the third. The neural generator sites of spontaneous and triggered spikes did not differ: both were within a 2-6-cm2 patch of cortex aligning the sylvian fissure in one or both hemispheres. The epileptiform activity of LKS patients may be produced by sound-responsive neurons in the nonprimary auditory cortex within the middle and posterior sylvian fissures. The generators of the auditory 100-ms response probably contribute to the spikes in a group of LKS patients, but other pathogenetic mechanisms may coexist.