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2 Medical Aspects of Traumatic Brain Injury Robert Labutta Between January 2003 and April 2006, 28 percent of all com- bat casualties from Operation Iraqi Freedom/Operation Enduring F Â reedom requiring treatment at Walter Reed Army Medical Center had a Âtraumatic brain injury (TBI). In a series of TBI cases treated at Walter Reed, 68 percent were caused by blast events (Warden, 2006). Thus understanding TBI, especially some aspects of TBI, such as how blasts cause such injuries, is crucial to military medicine. The topic has been addressed at length in a number of publications (Hoge et al., 2008; Okie, 2005, 2006; RAND, 2008; Singer, 2008), and the summary that follows is intended to provide a general understanding of TBI to set the stage for the subsequent discussion of how OSE technology and tech- niques might improve the delivery of TBI care. Definition and Categorization of Traumatic brain injury The evolving definition of TBI, as currently used by the military, is shown in Box 2-1. Note that TBI involves both an injurious incident This chapter is based on the authorâs presentation and responses to questions raised during the plenary session of the NAE-IOM workshop on Harnessing Systems Engineering to Improve Traumatic Brain Injury Care in the Military Health System on June 11, 2008. The author would like to thank IOM staff member Rick Erdtmann for his assistance in preparing this material for publication. 21
22 Systems Engineering to Improve Traumatic Brain Injury CARE BOX 2-1 Department of Defense Definition of Traumatic Brain Injury Traumatic brain injury (TBI) is a traumatically induced structural injury and/or physiological disruption of brain function as a result of an exter- nal force that is indicated by new onset or worsening of at least one of the following clinical signs, immediately following the event: (1) Any period of loss, or a decreased level, of consciousness. (2) Any loss of memory for events immediately before or after the Âinjury. (3) Any alteration in mental state at the time of the injury (confusion, disorientation, slowed thinking, etc.). (4) Neurological deficits (weakness, loss of balance, change in vision, praxis, paresis/plegia, sensory loss, aphasia, etc.) that may or may not be transient. (5) Intracranial lesion. Source: DOD, 2007. and a change in mental status. The lower limit for closed TBI does not require a loss of consciousness. TBI can be categorized in several ways, such as by the mechanism of the injury: (1) closed-head injuries caused by blunt-force trauma, such as a blow to the head from a fist, a fall, or a car crash; and (2) open- head injuries caused by a penetrating object, such as a bullet, shrapnel, or debris. Blast injuries may involve both categories. TBI can also be categorized by the area(s) of the brain affected, the extent of the effects (diffuse or localized brain involvement), and the duration of effects im- mediately after the injury. The most common way to categorize non-penetrating TBI is by the severity of the injuryâmild, moderate, or severe. The level of severity is classically defined at the time of injury using measures of the state of consciousness (the Glasgow Coma Scale), the duration of the loss of consciousness, and post-traumatic amnesia. The criteria that define these levels are listed in Table 2-1.
Medical Aspects of Traumatic Brain Injury 23 TABLE 2-1 Severity of TBI Based on Clinical Signs Glasgow Loss of Post-Traumatic Severity Coma Scale Consciousness Amnesia Mild 13â15 < 20 minâ1 hr* < 24 hr Moderate 9â12 1â24 hrs > 24 hrs < 7 days Severe 3â8 > 24 hrs > 7 days *This is the range for the upper limit; the lower limit is defined as any alteration in mental status. Source: Adapted from Helmick et al., 2007. In some clinical situations, however, the initial categorization of a TBI does not necessarily correspond to the eventual extent of Âneurological damage or the eventual outcome. For example, the initial injury may not be categorized as severe, but if there is subsequent significant brain swelling or bleeding in the head (intracerebrally, under the dura mater, or between the dura mater and the skull), the pressure created may cause the patient to develop clinically severe dysfunction and marked disability. TBIs are quite common and should not be construed as injuries that occur principally or only during combat. Many TBIs occur in civilian populations and in military populations during peacetime. The CDC estimates that there are 50,000 deaths, 235,000 hospitalizations, and more than 1 million emergency room visits each year due to TBIs (CDC, 2006). Although there are a number of mild, moderate, severe, and penetrating combat-related TBIs, many due to blast injuries, the number of nonÂ combat injuries, such as injuries from motor vehicle crashes, assaults, and falls, remains a significant health care issue for the military. The number of mild TBIs (mTBIs) in military and civilian populations must be estimated because many people with mTBI in both populations do not receive medical evaluation. Langlois and colleagues (2006), for example, calculate that 1.6 to 3.8 million sports-related concussions that are not included in the CDC numbers above occur in the United States annually. Concussion and mTBI are synonyms and can be used interchangeably. Traumatic Brain Injury in the Military Environment The recent increase in combat-related TBIs is largely because of a striking number of mTBI cases. Figure 2-1 shows the number of military
24 Systems Engineering to Improve Traumatic Brain Injury CARE 3,500 2005 2927 3,000 2006 2007 Number of Patients 2,500 2,000 1,500 971 1,000 395 500 175 62 47 25 37 46 36 46 52 1 0 Mild Moderate Severe Penetrating Missing TBI Severity FIGURE 2-1 Severity of TBI cases treated at DVBIC Sites, 2005â2007. Source: Labutta, 2008. Figure 2-1.eps personnel with TBI war wounds (by severity level) who were evacuated out of the combat theater to one of the DVBIC network sites between 2005 and 2007. In other words, moderate, severe, and penetrating TBI are easily recognized, recorded, and accounted for. In addition, the effects on the individual are usually obvious and generally result in long-term disability. The number of these injuries is directly related to the intensity of conflict and type of weaponry. However, for mTBI, also known as concussion, the number recorded is primarily a function of patient reporting and provider identification, since the effects of mTBI are less evident by comparison, are most often transient, and may be overshadowed by other diagnoses and mission requirements. Conse- quently, the disproportionate part of the increase in mTBI during 2007 may the result of improved processes and an increase in the locations where cases are ascertained and reported. Among deployed U.S. military personnel, TBIsâespecially moder- ate to severe casesâare often associated with other injuries to the face, neck, spine, and extremities, particularly following a blast. Improved body armor and advanced lifesaving measuresâincluding new equip- ment and drugs, better treatment protocols, and faster transport to higher level medical assistanceâhave resulted in more troops surviving serious wounds. Awareness of TBI among health professionals has also increased, which has resulted in more intensive screening and detection and fewer misdiagnoses.
Medical Aspects of Traumatic Brain Injury 25 Diagnosis and Treatment In patients with multiple injuries, TBI may not be clinically ap- parent unless there is a penetrating wound to the head. Even if TBI is suspected, it may not be the most urgent clinical need (e.g., a patient with mTBI may also have massive hemorrhaging due to an extremity injury). In these situations, the urgency and the priority of care may be directed toward other wounds and their overall effects. In general, for moderate, severe, and penetrating TBI, clinical care is directed toward the prevention of brain swelling, bleeding in the head, and poor cere- bral blood flow. These are the secondary effects of TBI that can lead to further neuronal damage. As such, hemorrhage, hypotension, hypoxia, electrolyte imbalance, fever, seizures, and infection must receive initial attention and control. The early identification and management of subdural hematoma is critical. The mortality rate associated with a four-hour delay follow- ing injury is 85 percent, compared with 30 percent if there is surgical control within four hours of the injury (Seelig et al., 1981). Unchecked brain swelling following an injury is extremely serious. In many cases, a large portion of the skull may be removed to relieve intracranial pres- sure and allow the brain to swell without causing additional damage. Brain injury resulting from primary and secondary effects may result in long-lasting symptoms and clinical manifestations affecting motor, sensory, mood, memory, and higher reasoning functions depending on the locus of the injury. mTBIs are more difficult to diagnose than moderate and severe cases. A standard magnetic resonance imaging (MRI) scan for an mTBI patient most often appears normal. Thus the diagnosis requires a history of injury and an acute alteration of mental status at the time of injury. Advanced functional neuroimaging techniques, such as diffusion tensor imaging, are now being used to visualize affected areas in patients with mTBI, but these techniques are in early development and are currently used primarily as research tools. Somatic, cognitive, and emotional/behavioral changes commonly accompany concussion (Figure 2-2), and one or more of these symptoms may be present in a given patient. Post-traumatic stress disorder (PTSD) is a co-morbid condition commonly associated with TBI, and the symp- tom crossover with TBI can make differentiating the two conditions problematic. Some symptoms, however, are more clearly identified with
26 Systems Engineering to Improve Traumatic Brain Injury CARE Somatic Symptoms Headache Dizziness Fatigue Vision Memory Anxiety Concentration Irritability Attention Depression Insight Sleep Cognitive Behavioral Symptoms Symptoms FIGURE 2-2 Categories of post-concussive symptoms. Sources: Arciniegas et al., 2005; Labutta, 2008. Figure 2-2.eps one condition than the other (Figure 2-3). The type and frequency of symptoms reported after an mTBI depends on several factors, especially the severity of TBI and the period of time since the injury. Most indi- viduals with mTBI recover within a few weeks. Studies show that 80 to 90 percent fully recover within one year (Levin et al., 1987), but a small percentage continue to have persistent symptoms (Alexander, 1995). Post-deployment screening surveys indicate that 10 to 20 percent of military personnel report experiencing an mTBI during their deploy- ment. Most (up to two-thirds) are asymptomatic at the time of the post- deployment survey. The remainder (approximately 5 to 10 percent of the total) acknowledge nonspecific symptoms on their post-deployment survey (TBI Task Force, 2007). It is important to understand that the presence of TBI-related symptoms alone, persistent or not, does not in itself establish a diagnosis of mTBI. The delay in the resolution of these symptoms may be complicated by other factors, such as anxiety, depres- sion, PTSD (Hoge et al., 2008), pain, or the effects of medication. Proper treatment of mTBI requires early identification, the moni- toring and management of symptoms (e.g., headache, dizziness, sleep disturbance), as well as adequate rest prior to return to duty. The latter requirement is important for two reasons. First, reinjury before adequate
Medical Aspects of Traumatic Brain Injury 27 PTSD TBI Attention Headache Flashbacks problems Nausea Re-experiencing Depression Vomiting phenomenon Anxiety Dizziness Figure 2-3.eps FIGURE 2-3 Distinct and common symptoms of PTSD and TBI. Source: Labutta, 2008. healing of the initial injury may make the subsequent injury more severe and the recovery of cognitive function slower (Guskiewicz et al., 2003). Second, a soldier or marine whose symptoms affect his or her cognition, such as judgment, concentration, or memory, may jeopardize his or her own safety, as well as the safety and effectiveness of his or her unit. Moderate and severe cases of TBI are initially treated by controlling secondary factors, such as swelling and bleeding, that can potentially cause further brain damage. For concomitant injuries to the face, neck, or elsewhere, standard surgical or medical treatment is provided to at- tend to the most critical needs. Following acute critical care, these TBI patients require both acute and chronic rehabilitative care. Rehabilitation often takes many months and involves a variety of specialty teams, such as physical therapists, occupational therapists, hearing and vision specialists, mental health workers, social workers, and other specialists. The coordination of care by skillful case managers is critical to preventing unnecessary delays and redundant services. In all cases, educating injured service members about their symptoms, instructing them about necessary follow-up, and reinforcing their expectations for full recovery are essential to proper management.
28 Systems Engineering to Improve Traumatic Brain Injury CARE Longer term care often involves moving the patient to another medical facility in the DOD or Department of Veterans Affairs health care system, where the variety of treatments necessary for managing TBI patients can present challenges for both patients and providers. Good coordination and common clinical practice guidelines can improve the quality of care. Effective family education and support are essential for the smooth, satisfactory management of TBI patients. Family and patient support groups have been shown to be an important ancillary service in pro- moting recovery. Community-based programs are considered the best approach for long-term management. The same general principles of medical care apply to TBI patients, whether they are military or civilian. However, care in combat situations must be based on preparing seriously injured patients to be quickly evacuated from the combat zone and preparing less seriously injured patients to return to duty so the military mission can be accomplished. These requirements and the need to employ all able military personnel make the environment of care different for military personnel than for civilians. In the following chapter, the management of TBIs in deployed personnel is described in more detail. References Alexander, M.P. 1995. Mild traumatic brain injury: pathophysiology, natural history, and clinical management. Neurology 45(7): 1253â1260. Arciniegas, D.B., C.A. Anderson, J. Topkoff, and T.W. McAllister. 2005. Mild traumatic brain injury: a neuropsychiatric approach to diagnosis, evaluation, and treatment. Neuropsychiatric Disease and Treatment 1(4): 311â327. CDC (Centers for Disease Control and Prevention). 2006. Traumatic Brain Injury in the United States: Emergency Department Visits, Hospitalizations, and Deaths. Prepared by Division of Injury Response, National Center for Injury Prevention and Control, Centers for Disease Control and Prevention, U.S. Department of Health and Human Services. January 2006. Available online at http://www.cdc.gov/ncipc/pub-res/TBI_in_ US_04/TBI%20in%20the%20US_Jan_2006.pdf (accessed August 18, 2008). DOD (U.S. Department of Defense). 2007. Traumatic Brain Injury: Definition and Reporting. Memorandum. HA Policy 07-030. Dated October 1, 2007. Available online at http://mhs. osd.mil/Content/docs/pdfs/policies/2007/07-030.pdf (accessed August 13, 2008). Guskiewicz, K, M. McCrea, S. Marshall, R. Cantu, C. Randolph, W. Barr, J. Onate, and J.Â Kelly. 2003. Cumulative effects associated with recurrent concussion in collegiate football players: the NCAA Concussion Study. Journal of the American Medical AssoÂ ciaÂtion 290(19): 2549â2555.
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