Giant somatosensory evoked potentials : scalp topography and dipole modelling

The abnormally large somatosensory evoked potentials (giant SEPs) observed in a variety of pathological conditions, reflect a primary or secondary hyperexcitability of sensorimonitor cortex. Giant SEPs observed in cortical myoclonus result from an extreme enhancement of certain cotical components ehich constitute normal SEPs. the physiological meachanisms underlying giant SEPs observed in other pathological conditions, though, have been investigated less intensively. In the present study, giant SEPs obtained from stimulation of median nerve in a variety of clinical conditions were examinated by detailed scalp topography ad dipole source analysis, and were compared with normal SEPs. The aim was two-fold: a) clarify wave form morphology and scalp topography, and possibly identifly neural generators, of giant SEPs.