Long-Term Outcomes and Needs of Military Service Members After Noncombat-Related Traumatic Brain Injury.

OBJECTIVES: Assess the prevalence of self-identified unmet service needs in a military sample an average of 5 years following noncombat traumatic brain injury (TBI). Examine relationships between unmet needs and background, injury-related and outcome variables. METHODS: The study sample consisted of 89 veterans and service members who sustained non-combat TBI between 1999 and 2003, selected from enrollees in the Defense and Veterans Brain Injury Center TBI registry. Semistructured telephone interview was used to collect information about participants' self-reported unmet service needs, symptoms, and functional status. RESULTS: Most participants (65%) reported having at least one unmet service need. The most prevalent needs were "getting information about available post-TBI services" (47%) and "improving memory and attention" (45%). Unmet needs were associated with cognitive difficulties, physical and emotional symptoms, mental health diagnosis/treatment, and poorer functional status. CONCLUSIONS: Needs for services following TBI are associated with poor symptomatic and functional outcomes and may persist for years after injury in military service members and veterans. The study suggests service members' needs post TBI for improved cognition, support for emotional issues, and resources for vocational skills. Information about available services should be made accessible to those recovering from TBI to reduce the incidence of long-term unmet needs.

A multisite study of the relationships between blast exposures and symptom reporting in a post-deployment active duty military population with mild traumatic brain injury.

Explosive devices have been the most frequent cause of traumatic brain injury (TBI) among deployed contemporary U.S. service members. The purpose of this study was to examine the influence of previous cumulative blast exposures (that did or did not result in TBI) on later post-concussion and post-traumatic symptom reporting after sustaining a mild TBI (MTBI). Participants were 573 service members who sustained MTBI divided into four groups by number of blast exposures (1, 2, 3, and 4-10) and a nonblast control group. Post-concussion symptoms were measured using the Neurobehavioral Symptom Inventory (NSI) and post-traumatic stress disorder (PTSD) symptoms using the Post-traumatic Checklist-Civilian version (PCL-C). Results show groups significantly differed on total NSI scores (p<0.001), where symptom endorsement increased as number of reported blast exposures increased. Total NSI scores were significantly higher for the 3- and 4-10 blast groups compared with the 1- and 2-blast groups with effect sizes ranging from small to moderate (d=0.31 to 0.63). After controlling for PTSD symptoms using the PCL-C total score, NSI total score differences remained between the 4-10-blast group and the 1- and 2-blast groups, but were less pronounced (d=0.35 and d=0.24, respectively). Analyses of NSI subscale scores using PCL-C scores as a covariate revealed significant between-blast group differences on cognitive, sensory, and somatic, but not affective symptoms. Regression analyses revealed that cumulative blast exposures accounted for a small but significant amount of the variance in total NSI scores (4.8%; p=0.009) and total PCL-C scores (2.3%; p<0.001). Among service members exposed to blast, post-concussion symptom reporting increased as a function of cumulative blast exposures. Future research will need to determine the relationship between cumulative blast exposures, symptom reporting, and neuropathological changes.

Self-reported mild TBI and postconcussive symptoms in a peacetime active duty military population: effect of multiple TBI history versus single mild TBI.

OBJECTIVE: To investigate the potential cumulative impact of mild traumatic brain injury (MTBI) on postconcussive symptoms. PARTICIPANTS: A total of 224 active duty soldiers reporting MTBI within 1 year of testing. For 101, this MTBI was their only reported traumatic brain injury (TBI); 123 had sustained at least 1 additional MTBI during their lifetime. A No TBI control group (n = 224) was included for comparison. MAIN MEASURE: Self-report symptoms data via questionnaire. Within time since injury subgroups (≤3 months; Post-3 months), symptom endorsement (no symptoms, 1 or 2 symptoms, 3+ symptoms) among soldiers with 1 MTBI was compared with that of soldiers with 2 or more MTBIs. Injured soldiers' symptom endorsement was compared with that of soldiers who had not sustained a TBI. RESULTS: Among the recently injured (≤3 months), those with 2 or more MTBIs endorsed significantly more symptoms than those with 1 MTBI: 67% of soldiers with 2 or more MTBIs reported 3+ symptoms, versus 29% of One MTBI soldiers. Among Post-3 month soldiers, there were no significant differences between MTBI groups. Overall, soldiers with MTBI endorsed significantly more symptoms than those without TBI. CONCLUSION: Past experience of MTBI may be a risk factor for increased symptom difficulty for several months postinjury. Clinicians should ascertain lifetime history of brain injury when evaluating patients for MTBI.

Auditory evoked potentials in the detection of interaural intensity differences in children and adults.

OBJECTIVE: The goal of the current study was to identify neurophysiological indices of binaural processing in children with no history of hearing loss or listening problems. The results will guide our efforts to diagnose children for whom impaired binaural processing may contribute to difficulty understanding speech in adverse listening environments. Our main aim was to document the cortical auditory evoked potentials (AEPs) in response to interaural intensity differences (IIDs) in children. It is well known, however, that the morphology of AEPs is substantially different in children and adults. Comparison of AEPs in response to IIDs between children and adults allowed us to evaluate age-related differences in the AEP waveform of binaural processing. DESIGN: Nine children (ages 7 yr 0 mo to 9 yr 4 mo) and 11 adults (23 to 34 yr) with normal hearing and no known or suspected neurological or academic problems listened to click stimuli under earphones. Click trains consisted of broadband noise of 1-msec duration with a click rate of 100 Hz. In the experimental condition (IID-present) 50-msec intervals containing an interaural intensity difference of 20 dB were introduced periodically in the continuous stream of otherwise diotic click trains. The diotic trains alternated in intensity between 50 and 70 dB peSPL. In the baseline condition (IID-absent), the same continuous diotic click stream utilized in the IID-present condition was presented with no IID. Finally, for comparison with existing literature on AEPs in children and adults, we presented monaural click trains of 50-msec duration, like those used in the IID stimulus (but with no continuous stream) to the left ear at 70 dB peSPL, with an interstimulus interval of 750 msec. Stimuli were presented in separate blocks for each stimulus type and AEPs were recorded in a passive listening condition. RESULTS: A prominent AEP activation was present in both age groups for the IID-present condition; the IID-absent condition did not evoke substantial AEPs. Adult waveform characteristics of the AEPs to monaural clicks and IID-present around 100 and 200 msec were comparable to previous reports. The children demonstrated the expected AEP activation patterns in response to monaural clicks (i.e., positivity around 100 msec, followed by prominent negativity around 250 msec); however their AEP waveforms to IIDs were mainly comprised of a prolonged positivity around 200 to 250 msec after stimulus onset. A two-step temporal-spatial Principal Component Analysis (PCA) was used to evaluate the temporal (time) and spatial (electrode location) composition of the AEP waveforms in children and adults in response to IID-present and IID-absent conditions. Separate repeated-measures ANOVAs with factor scores as the dependent variable were conducted for each temporal factor (TF) representing the waveform deflections around 100, 200 and 250 msec (i.e., TF110, TF200, and TF255) at the frontocentral spatial factor (SF1). Significantly greater negative activation was observed in adults than in children in response to IID-present for TF110. The IID-present condition evoked a significantly greater waveform inflection for TF200 in both age groups than IID-absent. A positive going activation for TF255 was observed in the IID-present condition in children but not in adults. CONCLUSIONS: This study compared obligatory AEPs in response to binaural processing of IIDs in children and adults with normal hearing. The morphology of the AEP waveform in children was different for monaural clicks and IID-present stimuli. The difference between AEPs for monaural clicks and IID-present did not occur in adults. It is likely that polarity reversal of the AEPs in response to the IID accounts for the observed AEP morphology in children.

Predictive value of an early Glasgow Outcome Scale score: 15-month score changes.

OBJECT: Does an early Glasgow Outcome Scale (GOS) assessment provide a reliable indicator of later outcome in a patient with traumatic brain injury (TBI)? The authors examined the utility of the GOS during early treatment as a predictor of outcome score 15 months postinjury by analyzing outcome score change in a group of patients with closed head injuries. METHODS: Glasgow Outcome Scale scores assessed within 3 months of injury (baseline) were compared with scores obtained at 15 months postinjury in 121 patients, primarily young military personnel. Score changes between baseline and 8 months postinjury were also studied in a subgroup of 72 patients. The impact of initial injury severity (determined by the duration of unconsciousness) on score change was also explored. The GOS scores at three time points within the 15-month period-baseline (within 3 months of injury), 8, and 15 months postinjury-were examined to ascertain when the maximal GOS score had been reached. CONCLUSIONS: Baseline GOS score was a reliable predictor of outcome in patients with an initial score of 5 (no disability) or 4 (mild disability), but not in patients with an initial score of 3 (severe disability). Patients who remained unconscious for more than 24 hours did not have significantly lower outcome scores than those who experienced loss of consciousness for less than 24 hours at 15 months postinjury. Interestingly, the duration of unconsciousness did not affect the likelihood of an improved score during the study period in patients with a GOS score of 3 or 4 at baseline. An updated evaluation conducted after the early phases of treatment is needed to provide a realistic prognosis of severe TBI.

Perception of auditory movement in children with poor listening skills: an ERP study.

Long-latency ERP components were examined for scalp activation differences in children with poor and good listening skills in response to auditory movement created by IIDs. Eighteen children were grouped based on a parent questionnaire (CHAPS; Smoski et al, 1998) and clinical evaluation by a licensed audiologist. Obligatory cortical responses were recorded to an auditory movement and an auditory control task. Results showed greatest activation at fronto-central electrode sites. P1, N1, and P2 showed no significant effects. Significant differences in N2 amplitude and latency were present between groups at the lateral electrode sites (FC3, FC4) in the auditory movement but not in the auditory control task. More specifically, good listeners exhibited predominance of activation over the right hemisphere for left-moving sounds, whereas the poor listeners exhibited symmetric activation. These results suggest that abnormal hemispheric activation may be one of the reasons behind poor listening skills observed in some school-aged children.

Non-voluntary and voluntary processing of emotional prosody: an event-related potentials study.

The present study investigated whether event-related potentials (ERPs) reflect non-voluntary vs voluntary processing of emotional prosody. ERPs were obtained while participants processed emotional information non-voluntarily (i.e. while evaluating semantic characteristics of a stimulus) and voluntarily (i.e. while evaluating emotional characteristics of a stimulus). Results suggest that emotional prosody is processed around 160 ms after stimulus onset under non-voluntary processing conditions (when the attention is diverted from the emotional meaning of the tone of voice); and around 360 ms under voluntary processing conditions. The findings support the notion that emotional prosody is processed non-voluntarily in the comprehension of a spoken message.