Detecting Clinical Signs

The spatial sampling of dEEG may be required not only to localize brain pathology, such as an epileptic spike, but to detect it.

Comparisons of 256-channel dEEG recordings have been made with subsampling that shows what would be seen by conventional (19-channel) EEG. These studies confirm that not only accurate localization, but in some cases the detection of neuropathology, may require the channel densities of 128 or 256 provided by dEEG (Holmes, 2008; Holmes et al., 2004; Lantz et al., 2003). Neuropathology that is limited to a small area of brain near the skull (such as a gyrus of the cortex) may project an EEG field that is invisible to conventional EEG. With 10-20 system placement of conventional EEG, the electrodes are as far as 7 centimeters apart.

Holmes, M. D. (2008). Dense array EEG: Methodology and new hypothesis on epilepsy syndromes. Epilepsia, 49, 3-14.

Holmes, M. D., Brown, M., & Tucker, D. M. (2004). Are "generalized" seizures truly generalized? Evidence of localized mesial frontal and frontopolar discharges in absence. Epilepsia, 45(12), 1568-1579.

Lantz, G., Grave de Peralta, R., Spinelli, L., Seeck, M., & Michel, C. M. (2003). Epileptic source localization with high density EEG: how many electrodes are needed? Clin Neurophysiol, 114(1), 63-69.