Quantitative Brain Electrical Activity in the Initial Screening of Mild Traumatic Brain Injuries After Blast

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URL: https://digitalcommons.wayne.edu/oa_theses/442/

Abstract

Objective: Quantitative electroencephalography (QEEG) has been reported to be sensitive in the diagnosis and measurement of mild traumatic brain injury (mTBI) in civilian setting and thus may be a promising tool in individuals who have been exposed to blast forces. Using a swine model, this study investigated EEG changes early after blast exposure. The purpose was to determine if QEEG can detect brain activity abnormalities earlier after blast exposure and to develop a QEEG data analysis protocol.

Methods: Six swines were used in this study. Swine were anesthetized using ketamine and propofol, and exposed to 410-460 kPa blast overpressure. EEG recordings were performed at 15 min before blast, and 15 min, 30 min and 2 hours, and 1, 2, 3 days post-blast using Biopac data acquisition system. Non-invasive surface recording electrodes were placed on the skin over both central (C3, C4) and parietal (P3, P4) areas of the skull. Acknowledge software was used for off-line EEG data analysis. qEEG parameters including frequency, Spectral edge frequency (SEF-90), and power (V²/Hz/Min) of delta, theta, alpha, and beta bands were analyzed and compared between pre-blast and post-blast and different recording locations. Other qEEG parameters including alpha-delta ratio (ADR). Statistical analysis was performed using SPSS software (Repaeted Measures of ANOVA, postHoc LSD).

Results: The EEG activity decreased fast frequency, and increased slower frequency after the blast. The EEG mean frequency have no statistic significant before and after blast at left parietal, left front and right front recording site. At the right parietal recording site, EEG mean frequency decreased from 6.78±2.01 Hz before blast to 3.36±0.28 Hz, 3.10±0.19, 3.47±0.21, 3.43±0.11 at 15 min, 2h, 1d, 2d after blast (P<0.05), returned to 5.25±1.96 Hz, 4.52±1.26 Hz at 30 min, 3d after blast (P>0.05). The SEF-90 have no statistic significant before and after blast at left front recording site. At the left parietal recording site, SEF-90 decreased from 18.22±3.51 Hz before blast to 10.27 ± 1.24 Hz, 10.84 ± 1.22 Hz at 15 min, 2d after blast (P<0.05), respectively, and returned to 14.25±3.01 Hz, 17.27±3.15, 14.94±0.86 Hz, 11.03± 2.03 Hz at 30 min, 2h, 1d, 3d after blast (P>0.05), respectively. At the right parietal recording site, SEF-90 decreased from 20.46±3.63 Hz before blast to 10.43±1.26, 10.74±1.18, 11.98±1.15, 11.44±0.72 at 15 min, 2h, 1d, 2d after blast (P<0.05), respectively, and returned to 13.84 ± 3.97, 13.21 ± 4.49 at 30 min, 3d after blast (P>0.05), respectively. At the right front recording site, SEF-90 decreased from 16.55 ±4.14 Hz before blast to 9.31±1.01 after blast (P<0.05), and returned to 16.10± 3.37, 15.09±2.07, 12.52±1.68, 10.10±0.64, 13.29±1.76 at 30 min, 2h, 1d, 2d, 3d after blast (P>0.05), respectively.

The Lower Alpha band power (8-10 Hz) have no statistic significant before and after blast at right parietal, left front, right front recording site. At the left parietal recording site, Alpha power decreased from 5×10-3±4×10-3 V²/Hz before blast to 4.9× 10-4±4×10-4 V²/Hz, 8.8×10-4±4×10-4 V²/Hz, 1.7×10-4±3×10-5 V²/Hz, 2.5×10-4±8×10-5 V²/Hz at 15 min, 2h, 1d, 2d after blast (P<0.05), respectively, and returned to 1.2×10-3 ±5×10-4 V²/Hz , 7.6×10-4±2×10-4 V²/Hz at 30 min, 3d after blast (P>0.05), respectively. The Beta band power and theta band power, Delta band power, and Alpha-Delta power ratio (ADR) have no statistic significant before and after blast at all recording sites

Conclusions: The EEG activity lost fast frequency, and increased slower frequency after the blast. The EEG power significantly decreased in fast frequency band, and increased in slower frequency band. QEEG is sensitive for cerebral injury and can predict outcome in a swine model of brain injury. This study demonstrated the changes of QEEG after blast indicative of the potential of utilization of multiple parameters of QEEG for diagnosis of blast-induced brain injury. Further studies are necessary to investigate the effectiveness of QEEG in chronic brain injury and recovery

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