Clinical Use of the Automated Neuropsychological Assessment Metrics TBI-Mil Expanded Battery in Evaluating Concussion Recovery: A Retrospective Study.

INTRODUCTION: This retrospective study evaluated the use of the Automated Neuropsychological Assessment Metrics (ANAM4) Expanded battery in a clinical setting to determine if the resolution of physiological symptoms, in the absence of neurocognitive assessment, was sufficient data in the return-to-duty (RTD) determination. MATERIALS AND METHODS: In this study, 508 U.S. Naval Academy midshipmen were diagnosed with concussion and prescribed a standard treatment protocol. As directed by the protocol, they were evaluated and tracked by medical providers until determined to have normal balance and to be asymptomatic at rest and with exertion. Upon the resolution of these physiological symptoms, the midshipmen were referred for neurocognitive (ANAM4) testing. When results indicated a return to neurocognitive baseline, a RTD determination was made. RESULTS: The analysis of data in this study indicated that RTD determinations based solely on the resolution of physiological symptoms would have resulted in 25.1% of the sample being returned to duty before neurocognitive recovery. Additional analysis of the ANAM4 reliable change index (RCI) data for each of the concussed patients revealed a pattern of scores that correlated with an expected length of recovery. Individuals with at least one RCI greater than or equal to -1.64 returned to neurocognitive baseline in 8.92 days, whereas individuals with 2 or more RCIs greater than or equal to -1.25 (but less than -1.64) returned to baseline in 5.78 days, and those with a difference in measured reaction times that were greater or equal to -1.25 returned to baseline in 3.20 days. Furthermore, findings indicated that female service members required additional time for the resolution of physical symptoms as compared to their male counterparts. The mean number of days from injury to being deemed symptoms free in males was approximately 14, as compared to females who were deemed symptom free in 21 days. This difference is statistically significant. CONCLUSIONS: Findings of this investigation revealed three specific outcomes. First, a computerized neurocognitive assessment instrument should be used as an adjunct measure in evaluating the resolution of physiological symptoms following a concussive injury. Second, results revealed that based on the RCIs of postinjury ANAM4 assessments, it is possible to estimate the remaining recovery time needed for a return to neurocognitive baseline. Third, results of this analysis revealed that gender appears to be a factor in time between concussive injury and resolution of symptoms.

Comparison of baseline-referenced versus norm-referenced analytical approaches for in-theatre assessment of mild traumatic brain injury neurocognitive impairment.

PRIMARY OBJECTIVE: To examine differences between the baseline-referenced and norm-referenced approaches for determining decrements in Automated Neuropsychological Assessment Metrics Version 4 TBI-MIL (ANAM) performance following mild traumatic brain injury (mTBI). RESEARCH DESIGN: ANAM data were reviewed for 616 US Service members, with 528 of this sample having experienced an mTBI and 88 were controls. METHODS AND PROCEDURES: Post-injury change scores were calculated for each sub-test: (1) normative change score = in-theater score - normative mean and (2) baseline change score = in-theater score - pre-deployment baseline. Reliable change cut-scores were applied to the change and the resulting frequency distributions were compared using McNemar tests. Receiver operator curves (ROC) using both samples (i.e. mTBI and control) were calculated for the change scores for each approach to determine the discriminate ability of the ANAM. MAIN OUTCOMES AND RESULTS: There were no statistical differences, p < 0.05 (Bonferonni-Holm corrected), between the approaches. When the area under the curve for the ROCs were averaged across sub-tests, there were no significant differences between either the norm-referenced (0.65) or baseline-referenced (0.66) approaches, p > 0.05. CONCLUSIONS: Overall, the findings suggest there is no clear advantage of using the baseline-referenced approach over norm-referenced approach.

The Walter Reed palm-held psychomotor vigilance test.

This field-portable reaction time test and analysis software run on devices using the Palm operating system. It is designed to emulate a test and commercial device widely used in sleep deprivation, shift work, fatigue, and stimulant drug research but provides additional capabilities. Experimental comparisons with the standard commercial device in a 40-hour total sleep deprivation study show it to be comparably sensitive to selected experimental variables. A Pocket PC-compatible version is under developement.

Visual perception, psychomotor performance, and complex motor performance during an overnight air refueling simulated flight.

INTRODUCTION: Visual perception task, complex motor flight task, and psychomotor vigilance task performances were evaluated in U.S. Air Force pilots navigating a high-fidelity fixed wing jet simulator over 26.5 h of continuous wakefulness. METHODS: Eight military pilots on flight status performed the primary task of flying a simulated 12.5-h overnight mission in an Air Refueling Part Task Trainer (ARPTT): Response omission to presentation of single- and double-light stimuli displayed in random sequence across the cockpit instrument panel was the metric used to assess choice visual perception task (CVPT) performance. Deviation from an established azimuth heading in the ARPTT during the CVPT was the flight metric used to assess complex motor performance. Speed, lapse, false start, and anticipation were the metrics used to assess psychomotor vigilance task (PVT) performance during crew rest periods. RESULTS: Significant visual perceptual, complex motor, and psychomotor vigilance (speed and lapse) impairments occurred at 19 h awake in the eight-subject group. CVPT response omissions significantly correlated with ARPTT azimuth deviations at r = 0.97, and with PVT speed at r = -0.92 and lapses at r = 0.90. ARPTT azimuth deviations significantly correlated with PVT speed at r = -0.92 and lapses at r = 0.91. CONCLUSIONS: Acute sleep deprivation degrades visual perceptual, complex motor, and simple motor performance. Complex motor impairments strongly correlate with visual perceptual impairments. This research provides support for the use of visual perceptual measures as surrogates of complex motor performance in operational situations where the primary cognitive inputs are through the visual system.

High-frequency EEG as measure of cognitive function capacity: a preliminary report.

BACKGROUND: High-frequency EEG (HFE) as a potential predictor of alertness/drowsiness was first proposed by Kaplan and Loparo. Sampling EEG at 950 Hz, they established an HFE bandwidth of interest ranging from 100-475 Hz. We extend their work by applying discrete Fourier transform (DFT) of HFE signals sampled at 1000 Hz and partitioned into spectral bands along specific frequency ranges for the assessment of sleep-wake state transition, sleep, and active cognitive engagement. METHODS: There were 13 volunteers (6 men, 7 women, 30 +/- 3 yr) who participated in a 40-h sleep-deprivation study, during which time they performed multiple cognitive tasks. EEG, in synchrony with other physiological signals, was collected at a sampling rate of 1000 Hz. EEG and task performance results from two volunteers are discussed in this preliminary analysis of the C3-C4 region data. Spectral components obtained from DFT are delineated into five main frequency bands: low, (LFB, 1-15 Hz); intermediate (IFB, 16-50 Hz); and 3 high frequency bands: HFB1 (51-100 Hz); HFB2 (101-200 Hz); and HFB3 (201-500 Hz) for analysis purposes. RESULTS: LFB in the 1-15 Hz range at 0.40 spectrum proportion indicated declining alertness; LFB above 0.50 signals transition to sleep; and LFB at 0.70 indicates Stage 2/3 sleep. HFB3 in the 201-500 Hz range at 0.25 and above was a marker of cognitive function and/or capacity. CONCLUSIONS: HFE may provide a quantitative measure of cognitive function capacity. LFB may provide a measure for awake, asleep, or awake-sleep transition, and HFB3 an estimate of cognitive task engagement. HFE may be applied for electroencephalographic monitoring of cognitive performance.