The clinical problem of traumatic head injury

Chapter 1
The clinical problem of traumatic head injury


Ramon Diaz-Arrastia1 and Pieter E. Vos2


1 Center for Neuroscience and Regenerative Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD, USA


2 Department of Neurology, Slingeland Hospital, Doetinchem, the Netherlands


Introduction


Traumatic brain injury (TBI) is among the oldest and most common medical afflictions affecting humankind. A South African australopithecine skull estimated to be 3 million years old shows evidence of a lethal skull fracture administered by another early hominid [1], and injuries to the cranium are commonly found in skeletal remains of prehistoric humans. Between 10 and 50% of skulls of prehistoric humans show evidence of cranial trauma [2, 3]. Most of these injuries were a consequence of warfare, but it is also likely that many of these TBIs were accidental and occurred during hunting or otherwise interacting with a harsh environment. The advance of civilization has resulted in a dramatic decrease in interpersonal violence, as recently pointed out in an influential book by Steven Pinker of Harvard University [4], but TBI remains a common and frequently disabling feature of modern life in industrialized as well as industrializing societies.


This book is organized so that the information is maximally useful to practicing clinicians as they encounter patients with TBIs. This often starts at the site of injury, where the decision of regarding transport to an emergency department (ED) for higher-level evaluation and management is made. In cases of severe TBI, some interventions must be started in the field in order to minimize secondary injury. In the ED, the diagnostic and management algorithm is determined by the patient’s level of consciousness, the extent of cranial and extracranial injuries, and findings on neuroimaging studies, usually cranial computerized tomography (CT). A subset of patients require emergent surgical treatment, and care by a neurosurgeon is often lifesaving at this stage. Subsequent to the ED (or operating theater), patients are usually cared for in the intensive care unit, where careful monitoring and interventions are aimed at lowering intracranial pressure and maximizing cerebral perfusion pressure to minimize secondary brain injury. Neurocritical care medicine is a new and rapidly growing subspecialty of neurology and represents a fertile area of research in neurotrauma. Some patients with milder injuries are discharged from the ED with instructions to seek follow-up care in the community, while others with moderate injuries may be admitted to the general hospital ward for close observation. Upon discharge from the hospital, many patients, particularly those with moderate and severe injuries, require inpatient rehabilitation therapy, while others are sent home for outpatient rehabilitation services. The availability of rehabilitation services and specialists varies widely even in wealthy countries, and while it is generally accepted that rehabilitation treatments are valuable, research to identify optimal rehabilitative strategies is still in its infancy. Ultimately, most TBI patients attempt to reintegrate into their communities and resume their normal lives. While many can do so successfully, a substantial fraction experience disabilities that limit their ability to resume their preinjury lifestyle. During the chronic stage after injury, many patients experience long-term and sometimes delayed complications that require continued medical attention.


TBI patients encounter different physicians at each stage of the continuum of care, and while specialists from different disciplines (including emergency medicine, neurosurgery, neurology, neuroradiology, critical care medicine, rehabilitation medicine, psychiatry, and psychology) are involved at each stage, the best care is provided by medical systems that integrate and coordinate care at each stage along the continuum. Unfortunately, such integrated systems of care are rare, even in wealthy countries. This book is a small attempt to bridge that gap by introducing physicians involved at each level with the challenges that face their colleagues at other stages and to point out the needs to those involved in developing integrated systems of care for one of the most common human maladies.


Social burden of TBI


US estimates


TBI is a major cause of death and disability. In the USA alone, approximately 1.7 million sustain a TBI each year, of which 52 000 people die, and another 275 000 are hospitalized and survive [5]. High-risk age groups are those under 4, 15–19, and greater than 65. These figures do not include injury data from military, federal, and Veterans Administration hospitals. As has been the case since prehistory, military personnel are at particular risk of TBI, which reportedly occurs in approximately 15% of those involved in combat operations [6, 7]. TBI is also a common cause of long-term disability. It is estimated that in the USA, 80 000–90 000 people annually experience permanent disability associated with TBI. Currently, more that 3.2 million Americans (or 1% of the population) live with TBI-related disabilities [8]. This results in an enormous burden on patients, their families, and society. Similar data are available from other developed countries. The social burden in mid- and lower-income countries is likely even higher.


European estimates


In Europe, TBI figures are in general comparable to those in the USA. In a recent survey on the costs of brain disorders in Europe, the best available estimates of the prevalence and cost per person for 19 groups of disorders of the brain were identified via a systematic review of the published literature. An economic model was developed to estimate the mean annual costs of persons sustaining a TBI [9]. Most brain disorders have an insidious onset followed by worsening and often chronic symptoms, and for such conditions, the most reliable epidemiologic data constitute prevalence estimates derived from community-based samples. However, TBI differs from other disorders in that their onset is sudden and followed by an intensive period of care followed by rehabilitation and potentially cure. For TBI, incidence rates are mainly available and the cost of patients during a period following disease onset. In the European study, also estimates on the cost of patients suffering from the long-term consequences of TBI were included as an approximation of the costs for patients with a previous onset of disease. The identified cost of TBI studies presented the mean indirect cost of the whole population, including also the zero estimates of patients not working because of other causes than the disorder (e.g., being underage or retired). The economic model was designed to estimate the number and costs of persons in acute trauma care, in rehabilitation, or suffering from the long-term consequences of a previous TBI. We assumed a time horizon of 20 years divided into three phases: acute (first 6 months following the injury), rehabilitation (the following 18 months), and finally a long-term phase. The cost estimate of TBI based on separate estimates for each severity (mild, moderate, and severe TBI) for 2010 was 33.0 billion €PPP [9].


The problem of mild TBI


TBI is usually classified as mild, moderate, and severe, based on the initial Glasgow Coma Score (GCS) recorded in the ED. Severe TBI is defined by a score between 3 and 8, moderate TBI by GCS between 9 and 12, and mild TBI (mTBI) by GCS 13 and 15 [10]. Although it is recognized that this classification scheme has a lot of limitations [11], it has been universally utilized in clinical practice as well as in clinical research. Although severe TBI has been the primary focus of investigation over the past 30 years [12], mTBI is at least 10-fold more prevalent [13, 14]. While the likelihood of favorable recovery is higher in mTBI compared to moderate and severe TBI, many patients with mTBI are left with disabilities that impair their ability to fulfill their work, school, or family responsibilities. It is likely that the social burden resulting from mTBI is at least equivalent to that resulting from severe TBI, given its much higher prevalence [13]. Using incidence and cost data from 1985, Max et al. [15] concluded that 44% of the total lifetime costs associated with TBI were due to mTBI. Since this study did not consider the costs of lost productivity and reduced quality of life, as well as indirect costs borne by family and others, it is likely to be an underestimate of the true societal burden of mTBI.


Mild TBI has been relatively understudied for several reasons. First, most mTBI patients make a seemingly complete recovery, and early identification of mTBI patients who are most likely to suffer persistent symptoms and develop cognitive and neuropsychological deficits is difficult. Second, since mortality and functional dependence on others are relatively rare in mTBI, the outcome assessments that are traditionally used for severe TBI are insufficiently sensitive for the type of cognitive and behavioral disabilities that most commonly result from mTBI [12]. The cognitive and psychiatric consequences of TBI are often nonspecific and overlap with conditions such as developmental, behavioral, mood and thought disorders, and dementia. Further, many of the long-term consequences of TBI manifest years after the trauma and may not be ascribed to the brain injury from which there was an apparently initial complete recovery. For example, TBI early in the preschool years may alter the developmental potential of the young brain and result in problems that only manifest during adolescence and young adulthood, such as substance abuse disorders, mood disorders, and conduct disorders [16]. Similarly, there is an increased risk of late-life dementia in individuals who suffered a TBI in early to midlife, even after an apparent initial complete recovery [17].


TBI as a chronic, lifelong condition

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Aug 6, 2016 | Posted by in NEUROSURGERY | Comments Off on The clinical problem of traumatic head injury

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