There remains a need for clinically feasible assessment methods that can be used to verify functional performance and operational competence in a variety of practice settings. Complex and ecologically valid assessment techniques incorporating dual-task and multitask methods may prove useful in validating return-to-activity requirements in civilian and military populations.
Over the last decade, in excess of , military service members have sustained a traumatic brain injury TBI Box 1 , resulting in significant morbidity and a commensurate degradation of military operational readiness. We propose a rationale for shifting the RTD readiness assessment model from an impairment-based approach to a more functionally oriented and standards-based paradigm. Finally, we highlight relevant findings from the dual-task and multitask literature that support this proposed approach to RTD assessment.
The Department of Defense DoD defines traumatic brain injury as head injury via blunt trauma or barotrauma, or both resulting in even momentary alteration of consciousness, loss of consciousness, or posttraumatic amnesia. Mild traumatic brain injury is further characterized as meeting one or more of the following criteria: loss of consciousness for 0 to 30 minutes, alteration of consciousness or mental state for a moment or up to 24 hours, and posttraumatic amnesia for up to 1 day.
This model has been readily adopted for the management of musculoskeletal injury, although its utility for managing RTD determinations among service members with concussion has yet to be validated. In the deployed environment, DoD policy dictates that physical therapists and occupational therapists administer functional RTD assessments of concussed service members. Occupational therapists are typically key providers in concussion care centers in the deployed setting and are highly familiar with combat stress issues. Physical therapists are assigned directly to Brigade Combat Teams and have the clinical training to perform neurologic assessment and rehabilitation.
Physical therapists provide a broad spectrum of services to their units ranging from health promotion and performance optimization to direct-access patient care. Current in-theater policy guidelines require mandatory neurological and functional evaluations for personnel exposed to a specified number of blast-related or blunt trauma—related events.
However, after more than 5 years of military TBI research, legitimate questions remain regarding the sensitivity of symptom- and impairment-based testing paradigms for informing return-to-activity decisions in concussed service members. Following a concussive event, a service member may experience a variable range of sensorimotor, cognitive, and physical sequelae related to primary or secondary injuries affecting body structure or function.
These symptoms may include headaches, dizziness, imbalance, tinnitus, hearing loss, impaired cognitive processing, dysexecutive syndrome, musculoskeletal pain, or comorbid stress symptoms. Department of Defense evidence-based clinical practice guidelines neither support nor discount reliance on patient self-report of symptoms for the management of mTBI.
Until recently, with the widespread adoption of the Zurich guidelines for concussion management, symptom resolution in the absence of more objective findings may have driven premature RTD decisions. Recent in-theater efforts to increase the sensitivity of symptom self-report under more challenging and realistic conditions have included the introduction of a 2-minute RTD exertion test.
Variations of exertional testing also have included the use of push-ups, treadmill running, or step aerobics. However, it is difficult to interpret findings, as there are no normative data for service members in a deployed setting. Balance testing also is commonly incorporated into postconcussive evaluations, either independently or in conjunction with a broader multimodal assessment. Although research indicates that a person's cognitive performance as measured by automated neurocognitive testing typically returns to normal within 1 week of a concussive incident, deficits in balance as measured by the Balance Error Scoring System BESS or force platform systems reveal impairments that outlast discernible cognitive symptoms.
Complex warfighting tasks represent a confluence of multiple domains demanding simultaneous functioning from all. If a provider bases RTD decisions solely upon the absence of isolated impairments in a single domain without a relevant multimodal functional assessment , the risk of premature RTD increases. To date, assessments of cognition and balance have not been found to be predictive of postconcussive symptom development or readiness to return to activity.
Existing clinical tests being used to assess injured service members are hampered by psychometric and practical issues. Clinical measures used by deployed physical therapists and occupational therapists lack sensitivity to high-level functional deficits revealing ceiling effects when used to assess a highly conditioned warrior population. The use of existing clinical measures is further complicated by the lack of normative values in the typical age and activity range of the service member.
Although there are many measures that have been demonstrated valid and reliable to predict falls or other adverse outcomes in aging or clinical populations with more severe neurologic pathology, such evidence is lacking in service members who sustain mTBI. Service members in military operations commonly experience significant physical and mental fatigue, elevated stress levels, inadequate or disrupted sleep, and variability in hydration and nutrition.
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The previous section highlighted a number of symptoms and impairments believed to degrade duty readiness. However, in addition to symptoms of physical discomfort, sensory instability, or disorientation, acutely concussed personnel may experience activity- or participation-level performance deficits in previously highly practiced and well-trained military occupational competencies.
Such deficits likely reflect diffuse involvement across multiple domains eg, sensorimotor, cognitive, musculoskeletal and, although subtle in some cases, can clearly have duty-limiting or even career-limiting implications if improperly managed. Deficits associated with concussion also may result in participation restrictions Box 2. Duty-limiting barriers to participation may range from distraction or prolonged reaction times during patrolling by an infantryman, or degraded telecommunication performance by a radio operator, to unsafe or poorly executed vehicle handling during convoy operations by a truck driver.
Impaired service member job performance has significant implications for safety and operational effectiveness for the individual, unit, and mission.
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Body functions are physiological functions of body systems including psychological functions. Body structures are anatomical parts of the body such as organs, limbs, and their components. Impairments are problems in body function or structure such as a significant deviation or loss.
Activity: qualified as an individual capacity ie, the ability to execute a task or an action or performance the ability of the individual to perform an activity in his or her current environment. Participation restrictions are problems an individual may experience in involvement in life situations. The International Classification of Functioning, Disability and Health ICF model provides a framework to illustrate the complex interplay of factors, including the health condition of concussion, affected body structure or body function systems, task performance deficits, and personal or environmental factors that collectively contribute to limitations in duty readiness or operational competence Figure.
This model highlights service member capabilities and limitations at every level of consideration. Body structure and function deficits include known vulnerabilities affecting functioning at the systems level and behavior. Activity and participation blocks summarize relevant warfighting task skills of varying complexity among duty-ready service members who are healthy.
Finally, environmental and personal factors influencing service member resilience propose theorized limits on service member performance. The process of defining a service member's duty readiness is complex. Competence as a warfighter demands not only technical prowess in military skills, it also necessitates resilience, self-efficacy, the capacity for complex thought, and other personal factors highlighted in the Figure , which are both abstract and difficult to measure using conventional clinical or impairment-based means.
Within the field of development economics, Sen 47 has described individual capabilities as vectors in the mathematical sense , which may be summed together to obtain an abstract representation of one's total level of functioning. From a theoretical perspective, we might draw on this approach and conceive of readiness as the vector-sum of relevant military competencies and other nonparametric characteristics such as the capacity for complex thinking, resilience, or even self-efficacy deemed critical for mission success. This approach acknowledges and normalizes the heterogeneous nature of inputs into the readiness equation and accounts for individual differences in outcomes based on an individual's premorbid capability set and coping strategies.
Conceptually, this approach mirrors the complex contributions to functioning in the framework posed by the ICF model. It is likely that any advance in readiness assessment methods not recognized as ecologically valid by the warfighter community will fall short in key domains of realism, generalizability, and complexity necessary to determine safe and appropriate return of injured service members to duty.
Foundational competencies or standards of soldiering are described in terms of warrior tasks and battle drills. Duty readiness in the operational environment also requires proficiency with integrated, multiperson, unit-level activities known as battle drills. In order to objectively measure service member performance in a way that is ecologically valid, an assessment must simulate the vocational demands of military tasks, demonstrate complexity adequate to account for fluid conditions in an operational environment, and challenge known mTBI-related vulnerabilities.
Although the idea of assessing service member performance on unmodified warrior tasks to guide RTD decisions might be attractive from the standpoint of simplicity, such an approach can be problematic from a clinical perspective. Without a consistent methodological approach, clinicians may find interpretation of performance challenging. For example, if the tested service member is experienced, he or she may be able to rely on rote motor memory even in the presence of residual deficits if the tested task is not assessed with elements of complexity or unpredictability associated with a real-world scenario.
Although not yet widely available throughout the DoD, preliminary efforts in select military treatment facilities and laboratories to assess mTBI-related deficits have focused on developing realistic duty scenarios to challenge service members across the range of functioning ie, body function to activity level demands. These approaches include highly sophisticated, immersive virtual reality VR —based assessments; observational, scenario-based programs; and more clinically oriented testing that draws on components of each.
Immersive VR systems such as the Computer Assisted Rehabilitation Environment CAREN provide highly sensitive, instrumented means of assessing physical, sensorimotor, and cognitive performance during ambulation and other functional movements in a laboratory-based environment. As a clinical tool, the CAREN has been used extensively within larger DoD medical centers to assess and treat duty-limiting postconcussive deficits in service members using highly realistic operational scenarios and complex task conditions.
In contradistinction to the laboratory-based VR approach, recent efforts by rehabilitation providers at military installations such as Fort Campbell, Kentucky, and Fort Bragg, North Carolina, have made significant progress in developing RTD testing modules that integrate traditional military training techniques with observational methods from a multidisciplinary team.
Specially designed assessment modules challenge service member performance under highly realistic and progressively more difficult operational scenarios designed to approximate the real-world stresses of combat. As with VR, this approach has both strengths and limitations. Although anecdotal evidence suggests good face validity and favorable RTD generalizability, scenario-based training lacks the precise measurement and repeatability of instrumented laboratory-based assessment techniques.
Also, like VR, implementation of this approach requires significant resources, including costly technology, substantial logistical support, a large dedicated clinical staff, and numerous staff member hours to coordinate and execute. Thus far, assessment modules have not yet been standardized across sites, and test psychometrics have not yet been established.
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Another RTD assessment approach seeking to bridge the sensitivity of laboratory measures with the ecological validity of scenario-based techniques uses militarized functional clinical test tasks. Although many DoD providers have sought to objectively quantify performance on specific warrior tasks such as time to don a protective mask or time to complete a road march below a specified symptom severity level , such efforts have been neither standardized nor validated and likely lack the complexity to discriminate duty readiness. To address such limitations, recent efforts by a team of military and civilian rehabilitation scientists have led to the development of a novel battery of militarized dual tasks and multitasks designed to challenge known mTBI-related vulnerabilities.
This battery, known as the Assessment of Military Multitasking Performance AMMP , represents a preliminary attempt to incorporate complex clinical testing methods into RTD assessment and illustrates a potential application of the standards-based assessment paradigm in a clinical environment. Given the importance of defeating ceiling effects associated with impairment-based clinical measures, the adoption of a more complex RTD assessment approach such as one using dual-task and multitask methods is appealing for evaluating service members with mTBI.
Multitask assessment methods are used with success by clinicians with patients recovering from moderate TBI and mild stroke to tax multiple cognitive demands. Multitask scenarios provide semistructured challenges of problem-solving and organization skills required in daily routines and work activities but have not been examined in mTBI. Dual-task and multitask approaches provide ways to probe activity- and participation-level performance in service members with mTBI, although military-specific tasks have not been described in the literature. In the following sections, characteristics and evidence supporting each approach are highlighted to provide an overview of their potential prognostic utility and clinical feasibility in assessing service members with mTBI.
Dual-task assessment methods require an individual to perform a primary task while simultaneously performing a secondary task, with combined performance compared with one's baseline performance in each single-task condition. Reduction in performance of a task when executed in conjunction with a secondary task is termed the dual-task cost eg, cost in time or in number of errors of performing 2 tasks simultaneously.
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The interpretation of dual-task paradigms follows the view that human processing resources are limited and capacity must be shared to accomplish both tasks, often resulting in dual-task performance costs. Many studies have revealed accentuated deficits in dual-task abilities following concussion and mTBI during postural control tasks acutely, with impairments sometimes persisting several months postinjury. The ability to do 2 tasks at once is theorized to require executive control. Attention must be allocated appropriately to perform both tasks successfully.
Laboratory studies using cognitive dual tasks reveal slower reaction and response times and increased cognitive task error following sports concussions. The ability to orient, allocate attention to, and switch focus between visual stimuli is impaired, which is correlated with problems with obstacle avoidance while walking. These dual-task gait deficits have been observed to persist over longer time frames than cognitive deficits after concussion and could influence mobility on uneven terrain.
Dual tasks that have been used clinically include memory tasks executed during walking and running conditions. One example of a dual task formulated to challenge a military service member population could involve administering the Illinois Agility Test which requires rapid direction changes and obstacle avoidance, consistent with service member physical training activities while performing a secondary cognitive task to challenge dynamic stability, agility, and cognitive function simultaneously. Dual-task scenarios tailored to service members could be designed in a similar way by using compact technologies eg, inertial sensory measures to improve measure sensitivity in forward-deployed or remote environments where safe and timely RTD decisions are most critical.
Competence in everyday life requires the ability to multitask, using multiple cognitive and motor abilities to plan, organize, and carry out complex tasks Box 3. Standardized testing of multitask performance is used in occupational therapy and neuropsychology to approximate the demands of a real-world environment ie, role engagement and is valued for its ecological validity. The evaluator observes performance for errors in action while a patient is given free rein to perform prescribed multistep everyday tasks that involve an array of multiple objects, task demands, and rules. Interleaving: Tasks are dovetailed ie, alternated or coordinated in accordance with a plan.
Only one task performed at a time: Tasks are performed one at a time due to either cognitive or physical constraints, further reinforcing interleaving. Interruptions and unexpected outcomes: Tasks are dynamic and may have unanticipated interruptions or situations where things do not go as originally planned. Performance-based multitask assessments have been developed that focus on frontal lobe dysfunction that occurs with stroke and TBI.
Although these assessments evaluate high-level executive functioning deficits and require prioritization of tasks, switching sets, and prospective memory, such metrics are not reflective of military vocational demands. Effective multitasking is essential during combat operations. A report by Fischer and Mautone 81 on multitasking requirements in military environments suggests that environments vary along 3 main dimensions: type of multitask required decision making, information monitoring, and task-flow management , intensity of multitask, and consequences of failure.
Multiple sensory, motor, and cognitive systems contribute to successful multitasking skills, systems that may be compromised following mTBI. Service members may perform well on impairment-based assessments that evaluate single-component processes in nondistracting and nonstressful environments. Performance deficits become evident when tasks are presented with less structure and increasing difficulty, requiring real-time decision making and the effective allocation of cognitive, physical, and sensorimotor resources across multiple simultaneous demands.
Theorized military multitask scenarios should focus on the multisystem vulnerabilities associated with concussion and mTBI. Examples of multitask formulations that may prove useful in discriminating RTD readiness have recently been described. Although highly realistic computer graphics and meticulously scripted scenario content allow an examiner to target known mTBI-related vulnerabilities, this assessment differs from more sophisticated VR approaches in its simplicity and clinical feasibility.
The task can be projected to any treatment environment that will support a computer monitor and an exercise step with or without inertial sensor data collection. Another task approximates the physical agility required for military individual movement techniques while intermittently challenging visual sensory stability and attention to detail verbal identification of targets during target sighting through a simulated weapon scope. Demands of this test task are consistent with rapidly changing physical, sensory, and cognitive demands in a combat environment.
Determination about service members' readiness to RTD following mTBI is still informed primarily by a patient's self-report of symptoms and by clinical tests that assess performance within distinct body structure or function domains. Widespread adoption of a theoretical framework that measures service member fitness for duty at the activity or participation level would be highly desirable to improve prognostication of real-world warfighting performance.
General acceptance of a paradigm that conceives of an individual's readiness , not as the absence of impairments but as a vector-sum of military competencies, represents an important ideological shift from what a member cannot do, to what he or she can do. Although this type of standards-based construct may be difficult to quantify using conventional impairment-based testing, complex assessment methods should help to bridge this assessment gap. Measures of postconcussive functional performance emerging to address RTD assessment challenges within the DoD include immersive virtual environments; field or scenario-based programs; and clinical tests incorporating dual-task and multitask methods.
Although each of these approaches has relative strengths and limitations, all are challenged by a general lack of clarity on how to externally validate duty readiness following mTBI. Measurement may be further confounded by the expense required to install, administer, and sustain technologically sophisticated or intensive assessment programs, dramatically limiting use of certain methods outside of hub military treatment facilities. Such barriers constrain the widespread feasibility of these approaches and make DoD-wide standardization of RTD metrics difficult.
Development of militarized dual-task and multitask methods represent a potential solution to these practice and dissemination barriers given the relative feasibility of clinical assessment techniques, demonstrated utility of dual-task and multitask assessment in civilian patients with TBI, and their strong face validity for commanders, service members, and clinicians. Dual-task and multitask testing methods may be more time consuming to administer than impairment-based assessments and not necessarily feasible for all environments of care.
Future research efforts should continue to explore and develop standards-based criteria to guide RTD and RTP decision making, not only in the wake of mTBI but also to address the broad spectrum of potential duty- or play-limiting deficits. Standards-based metrics do not replace traditional clinical decision making by clinicians who manage patients and their injuries. Such methods provide military clinicians with additional data points for evaluating abilities more clearly related to functional occupational demands. Oxford University Press is a department of the University of Oxford.
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Google Scholar. Margaret M. Mary V. Leslie F. Karen L. The authors thank Lynne M. Cite Citation. Permissions Icon Permissions. Box 1. Traumatic Brain Injury Definition. Box 2. Time, Tempo, and Command; J. Lewis, et al. Human Problems in Organizational Devolution; J. Redefining Command and Control; R. Command and Control: A Biased Combination?
Persoon, et al. Mission Command in Ambiguous Situations; A. Vogelaar, E. Mirabella, et al. Paris, et al. Shattuck, D. Murphy, K. Coping with Interrogations; J. Laberg, et al. Jeffery, et al. Omodei, et al. Research Challenges for the Human in Command; C. McCann, R. The Contributors. Neem contact met mij op over Events Sprekers Incompany. Welkom terug. Uw account. Agenda Seminars Masterclasses e-learning Sprekers Incompany.
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