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With the aid of chronic subdural electrodes we have been able to record from the posterior banks of the sylvian fissure, auditory evoked potentials (AEPs) that had morphologies and peak latencies compatible with the primary AEPs described by Celesia and Puletti (1969). These AEPs had amplitudes that were not only affected by the side of stimulus(More)
BACKGROUND Despite lateralizing signs, clinical lateralization of partial seizures may be difficult. We evaluated the usefulness of ictal unilateral blinking as a new lateralizing sign. METHODS We retrospectively searched our seizure database over a 30-month period and collected videotapes of patients with ictal unilateral blinking. After initial review,(More)
Electrical stimulation studies have demonstrated that a "supplementary motor area" (SMA) exists in humans. However, its precise functional organization has not been well defined. We reviewed the extraoperative electrical stimulation studies of 15 patients with intractable epilepsy who were evaluated with chronically implanted interhemispheric subdural(More)
Functional localization prior to cortical resections for intractable seizures has usually been performed in the operating room in awake patients. Chronically placed subdural electrodes offer the possibility of performing such testing outside of the operating room and without the unavoidable stresses and time limitations of the surgical setting. The use of(More)
OBJECTIVE To investigate the lateralization and localization of ictal EEG in focal epilepsy. METHODS A total of 486 ictal EEG of 72 patients with focal epilepsy arising from the mesial temporal, neocortical temporal, mesial frontal, dorsolateral frontal, parietal, and occipital regions were analyzed. RESULTS Surface ictal EEG was adequately localized in(More)
We have evaluated the afterdischarge thresholds and functional response thresholds in 21 patients with chronically implanted arrays of subdural electrodes. Afterdischarge thresholds varied from 2 to greater than 15 mA over the tested cortex, by as much as 12 mA in individual patients, and by as much as 12 mA between adjacent electrodes. Thresholds for(More)
Movement-related potentials (MRPs) associated with tongue protrusions and vocalizations were recorded from chronically implanted subdural electrodes over the lower perirolandic area in 7 patients being evaluated for epilepsy surgery. In 3 patients, tongue protrusions elicited a clearly defined, well localized slow negative Bereitschaftspotential (BP) at the(More)
The recovery function of evoked potentials to posterior tibial nerve stimulation was studied. Intrasurgical recordings were made from interspinous ligaments at lumbar levels and from high thoracic-low cervical level. In addition, surface recordings were obtained from neck-scalp derivations. The recovery function of the potentials recorded from lumbar and(More)