Artikel
Reduced electrocorticographic beta-activity precedes spreading depolarization
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Veröffentlicht: | 4. Juni 2012 |
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Objective: Spreading Depolarisations (SDs) occur during the first days after severe injury of the brain. They have been reported after traumatic brain injury (TBI), subarachnoid hemorrhage (SAH), malignant hemispheric stroke (MHS) and intracerebral bleeding. SDs are associated with reduction in amplitude as "Spreading Depression" or as "isoelectric SDs" without alteration in potential difference. SDs are thought to cause additional brain damage and may be an important factor for secondary brain injury. However, recently their close association with bad outcome after TBI was reported. Therefore prediction of SDs could be an important measure regarding patient outcome or even allow treatment and reduce brain damage. Since SD is measured as large current shifts, alterations of electrocorticographic activity could precede such events. We therefore analyzed electrocorticographic activity quantitatively by conventional frequency bands after TBI, SAH and MHS and their association with SDs.
Methods: A total of 47 patients, 23 patients after MHS, 21 after SAH and 3 after TBI were included in a preliminary and explorative analysis. All procedures of the study were approved by the universities ethics board. Written consent was obtained from patients or their legal guardian. A subdural electrode strip was placed over the region of interest during surgery and continuous electrocorticographic (ECoG) recordings were made over the next days. In 62% of the patients SDs were recorded. A retrospective analysis of the quantitative ECoG was made using LabChart 7 (Adinstruments).
Results: Mean hourly data of the two hours before and after the SD event were further investigated. Quantitative frequencies at 14–40 Hz were lower within close proximity to SDs when compared to hourly data not adjacent to SDs (p <0.05). This was used in a preliminary multivariate model to predict SDs. There were no significant differences in quantitative ECoG bands between MHS, TBI and SAH patient subgroups (p >0.05).
Conclusions: A frequency band shift precedes SDs and therefore might allow prediction of SDs. This ultimately could support treatment, although the potential benefit for the patient is yet unkown.