title: Short latency somatosensory evoked potentials in brain-dead patients using restricted low cut filter setting.
abstract: This paper describes the SSEP patterns in BD when using restricted filter bandpass setting, with special emphasis on the dissociation of some SSEP components when cephalic and non-cephalic references are used. A characteristic SSEP pattern was found: absence of N20 and later responses in the Cc'-Fpz lead and preservation of all or some of the so-called subcortical components in the rest of the derivations. We noted an interesting dissociation in which some SSEP components were not recorded in the scalp-non cephalic derivations, but they were still present in the neck-cephalic and spine channels, with inverse polarity. We selected a restricted bandpass for the scalp-non cephalic, the neck-cephalic and the spine derivations, and we found this dissociation not only for P13-N13 and P14-N14, but for Nm-Pm' and Pm-Nm' components. It is likely that components Nm-Pm' and Pm-Nm' are "far-field potentials" that appear when the slow wave N18 is filtered out by the use of a restricted low filter setting. Our data further suggest that all components after N14-P14, recorded with restricted filter bandpass also recognize two distinct generator sources. Rostral generators are located probably in the brainstem and/or thalamus, but at least a significant part of these SSEP components are generated at the very lower part of the medulla oblongata (dorsal column nuclei) and/or at the upper cervical spine.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Institute of Neurology and Neurosurgery, Department of Clinical Neurophysiology, Havana, Cuba.
authors.forename: C
authors.initials: C
authors.lastname: Machado
authors.forename: P
authors.initials: P
authors.lastname: Valdès
authors.forename: O
authors.initials: O
authors.lastname: García
authors.forename: P
authors.initials: P
authors.lastname: Coutin
authors.forename: J
authors.initials: J
authors.lastname: Miranda
authors.forename: J
authors.initials: J
authors.lastname: Román
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001926:Brain Death; D001933:Brain Stem / Q000502:physiology / Q000503:physiopathology; D002648:Child; D003422:Critical Care; D004569:Electroencephalography / Q000379:methods*; D004596:Electroretinography; D005073:Evoked Potentials, Somatosensory; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012016:Reference Values