Information Transfer and Multifractal Analysis of EEG in Mild Blast-Induced TBI.

Mild, blast-induced traumatic brain injury (mbTBI) is a common combat brain injury characterized by typically normal neuroimaging findings, with unpredictable future cognitive recovery. Traditional methods of electroencephalography (EEG) analysis (e.g., spectral analysis) have not been successful in detecting the degree of cognitive and functional impairment in mbTBI. We therefore collected resting state EEG (5 minutes, 64 leads) from twelve patients with a history of mbTBI, along with repeat neuropsychological testing (D-KEFS Tower test) to compare two new methods for analyzing EEG (multifractal detrended fluctuation analysis (MF-DFA) and information transfer modeling (ITM)) with spectral analysis. For MF-DFA, we extracted relevant parameters from the resultant multifractal spectrum from all leads and compared with traditional power by frequency band for spectral analysis. For ITM, because the number of parameters from each lead far exceeded the number of subjects, we utilized a reduced set of 10 leads which were compared with spectral analysis. We utilized separate 30 second EEG segments for training and testing statistical models based upon regression tree analysis. ITM and MF-DFA models both generally had improved accuracy at correlating with relevant measures of cognitive performance as compared to spectral analytic models ITM and MF-DFA both merit additional research as analytic tools for EEG and cognition in TBI.

Executive Functioning of Combat Mild Traumatic Brain Injury.

This study investigates neuropsychological deficits in recently deployed veterans with mild traumatic brain injury (mTBI). Veterans discharged from 2007 to 2012 were recruited from Veterans Affairs clinics. Independent groups of participants with mTBI (n = 57) and those without TBI (n = 57) were administered the Beck Depression Inventory-II, Combat Exposure Scale, Word Memory Test, and the Self-Awareness of Deficits Interview. Neuropsychological instruments included the Rey-Osterrieth Complex Figure Test, Letter and Category Fluency, Trail-Making Test-Parts A and B, Christiansen H-abbreviated, Soper Neuropsychology Screen, Wechsler Memory Scale subtests Logical Memory I and II, and the Street Completion Test. The mTBI group performed significantly worse on all of the executive and nonexecutive measurements with the exception of Category Fluency, after controlling for age, depression effort, and combat exposure. Depression and combat exposure were greater for the mTBI group. The mTBI group scored poorer on effort, but only the Multiple Choice subtest was significant. The mTBI group had good awareness of their deficits.