OBJECTIVE: @entity2657 is a common and potentially devastating sequel of @entity131 . We developed and validated a system capable of tissue impedance analysis, which was found to correlate with @entity2657 . METHODS: Constant sinusoidal current (50 microA), at frequencies from 500 to 5000 Hz, was applied across a bipolar electrode unit superficially placed in a @entity35 brain after @entity131 . @entity35 were randomized to three groups: severe @entity130 ( @entity130 ), mild @entity130 , or sham injury. At 60 h post- @entity130 , cerebral voltage and phase angle were measured at each frequency at the site of injury, at the penumbral region, at the ipsilateral frontal region, and in the contralateral hemisphere. Impedance measurements were also obtained in vivo. The electrical properties of varied injuries and specified locations were compared using a repeated measures analysis of variance (RMANOVA), were correlated with regional tissue water percentage using regression analyses, and were combined to generate polar coordinates. RESULTS: The measured voltage was significantly different at the site of injury (P<0.0001), in the penumbra (P=0.002), and in the contralateral hemisphere (P=0.005) when severe, mild, and sham @entity130 @entity35 were compared. Severely injured @entity35 had statistically different voltage measurements when the various sites were compared (P=0.002). The ex vivo measurements correlated with in vivo measurements. Further, the impedance measurements correlated with measured tissue water percentage at the site of injury (R2=0.69; P<0.0001). The creation of a polar coordinate graph, incorporating voltage and phase angle measurements, enabled the identification of impedance areas unique to normal, mild @entity4 , and severe @entity4 measurements in the @entity35 brain. CONCLUSIONS: Electrical measurements and tissue water percentages quantified regional and severity differences in @entity35 @entity2657 after @entity130 . Impedance was inversely proportional to the tissue water percentage. Thus, impedance measurement can be used to quantify severity of @entity2657 in real time at specific sites.

Regional differences in @entity2657 after XXXX identified by impedance analysis.

@entity131 :: ('MESH:D001930', 'Disease') :: ['traumatic brain injury'] @entity2657 :: ('MESH:D001929', 'Disease') :: ['cerebral edema', 'brain edema', 'Cerebral edema'] @entity4 :: ('MESH:D004487', 'Disease') :: ['edema'] @entity35 :: ('10116', 'Species') :: ['rat', 'Rats', 'rats'] @entity130 :: ('MESH:D014947', 'Disease') :: ['CCI', 'controlled cortical injury']
@entity131 :: (MESH:D001930,Disease) :: ['traumatic brain injury']
