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Traumatic Brain Injury in Elders
Traumatic brain injury (TBI) has been called the silent epidemic of developed nations.1 TBI can be categorized by its severity (as defined according the to the Glasgow Coma Scale [GCS]), mechanism (eg, blunt, penetration, or blast trauma), and morphology (eg, type of intracranial bleeding, skull fracture). On the GCS, a score of 13 to 15 is considered mild, 9 to 12 is moderate, and ≤8 is severe. Most episodes of mild TBI involve concussion, and among those, only one of every 10 is associated with positive computed tomography (CT) findings.1 Patients who have a severe TBI or are in a coma often require surgery for intracranial hemorrhage or elevated intracranial pressure.
In the United States, 2% of the population, or approximately 5 to 6 million people, currently live with TBI-related disabilities.2 Although anyone can be affected by TBI, young children, young adults, and elders (≥65 years) are most at risk. Flanagan and colleagues3 state that TBI is far more widespread than realized, accounting for 20 times more hospitalizations than traumatic spinal cord injuries. Each year, TBI afflicts at least 1.4 million individuals and accounts for 50,000 deaths and 235,000 hospitalizations.3 Elders are especially vulnerable and suffer worse outcomes after TBI, as this population has a greater propensity to experience domestic accidents and is more likely than younger persons to have comorbidities, susceptibility to complications, complex health conditions, and a history of polypharmacia.4-6
Although individuals 65 years of age or older represent only 10% of all patients with TBI, they account for 50% of TBI-related deaths.7 Patients who are older than 75 years have the highest TBI-related hospitalization rate (264.4/100,000 population), at least twice the rate for any other age group.8 In addition, the TBI-related fatality rate among patients older than 65 years is more than twice as high as that among patients 20 to 44 years of age, increasing 114% from 18 deaths per 100,000 persons in the younger population to 44 deaths per 100,000 in the older population.8
Although TBI is a major public health problem, especially in elders, research on it is surprisingly lacking. Furlan and Fehlings9 reviewed all abstracts presented at the National Neurotrauma Symposia from 1984 to 2007 and found that of 4194 abstracts, only 41 (1.05%) addressed the effects of age on TBI. Of these 41 studies, 24 were basic research in animals and only seven were clinical studies addressing the effects of aging on TBI. All of the clinical studies reported an adverse effect of age on outcome after TBI (Table).9
According to US Census Bureau, the estimated population of individuals older than 65 years was 35 million in 2006, and this group is anticipated grow to more than 86 million by 2050.3 The increase in TBI-related hospitalizations and fatalities will worsen over the next decade as the world’s population ages, making TBI in the elderly a worldwide problem that will have to be dealt with on a much larger scale in the very near future. Although guidelines for the operative and nonoperative treatment of TBI have been established, and they acknowledge age as a risk factor for poor outcomes and for elevated intracranial hypertension even when the results of a head CT scan are normal, they do not address the special challenges of managing TBI in elders.10,11
Currently, healthcare providers and relatives of patients with TBI often make the choice to provide treatment even when the patient has an extremely small chance of meaningful recovery. With a shift toward a more utilitarian healthcare system, care for elders with TBI may be marginalized. It is therefore pertinent and timely to review the evidence of the effect of age on TBI. We examine this relationship and offer possible explanations as to why trauma-related morbidity and mortality are increased in elders. We also review clinicians’ attitudes and trends regarding treatment for elderly patients with TBI.
Defining Age as a Risk Factor
Biologically, aging starts at 20 years; however, no one would consider a 25-year-old person “old.” So when does age become an independently negative predictive factor for outcome after TBI? Kuhne and colleagues12 calculated the age-dependent cutoff for increasing mortality in patients who have suffered multiple traumatic injuries. They showed that after age 56, mortality increased significantly in patients who sustained multiple traumatic injuries, independent of trauma severity. Severe TBI was the most frequent cause of death, which peaked significantly in patients older than 75 years.
Mass13 reported in 2002 that elderly patients with TBI are at a disadvantage. Analyzing a database of 2664 TBI patients, he calculated the threshold age for increasing mortality to be 39 years, according to univariate analysis, and 66 years, according to multivariate analysis. Stitzel and colleagues4 provided information on the ideal “threshold” beyond which age becomes an important factor for outcome following the three most common types of head injuries. For traumatic subarachnoid hemorrhage, the threshold age is 58 years; for subdural hematoma, 54 years; and for cerebral contusions, 47 years.4 Gan and colleagues14 reported that only one in five elders is expected to have a favorable outcome after TBI.
Bouras and colleagues15 identified an age group on the “edge,” who have a better potential for a good outcome after TBI than older patients with a poor prognosis. This age group, comprised of individuals between 65 and 74 years old, appear to have a better outcome and a significantly lower mortality rate than individuals 75 years or older, who, despite maximal medical and surgical care, respond poorly.
Ageism
Ageism refers to stereotyping, generalizing, and discriminating based solely on a person’s chronological age and is most commonly directed at the elderly population.16 An important question is whether ageism can negatively affect the potential recovery during rehabilitation after the elder experiences a TBI or any other injury.
Furlan and Fehlings9 distributed a questionnaire to neuroscientists, clinicians, and healthcare providers to examine their attitudes toward elderly patients with TBI. The response rate to the questionnaire was 27%. The authors found that neuroscientists were more affected by ageism than their clinical colleagues, with female respondents showing a slightly more positive attitude toward elderly patients than their male counterparts.
Available data clearly show that older patients do more poorly after a trauma than younger individuals. It is unclear whether the worsened outcome in elders is due to an exaggerated pathophysiologic response or to attitudes of ageism among healthcare providers and the public, but it is likely that both are contributors in many cases. Although preclinical and clinical research on elders should be emphasized, we should also not dismiss the idea that treatment and rehabilitation tailored especially for this population could improve outcomes.17
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Factors Contributing to Worsened Outcomes in Elders
Mortality is greater among elders across all injury severities, including mild TBI, than among younger persons. Older individuals who survive TBI also have lower long-term survival rates than their age-matched noninjured peers, indicating that TBI predisposes elders to premature death.3 Which factors may account for the worsened outcomes in elders? Some insights on biologic mechanisms can be gained from animal studies, whereas several factors have been attributed in humans, such as falls, comorbidities, and polypharmacy.
Findings From Animal Models
Although there is a paucity of data on TBI in aged animals, as most animal research on TBI is performed on young adult and adolescent rats or mice, some insights on worsened outcomes in elders following TBI may be gleaned from the few studies that have included older animal models. One study that specifically examined the effect of age on TBI found that microglia cells and astrocytes have a more intensive and prolonged response to TBI in aged animals than in younger animals.18 The return to microglia baseline expression of mRNA was delayed in aged mice, supporting the hypothesis that enhanced gliosis may be responsible for the poor outcome in elderly patients. The detrimental effects of aging on outcome from TBI were also described in a behavioral, magnetic resonance imaging, and histological study in aged mice.19 In this study, aged mice showed increased vulnerability to neurodegeneration, demonstrating greater loss of function, prolonged acute edema, and increased opening of the blood–brain barrier. Finally, a study that examined the effects of age on recovery after stroke in a rat model reported that apoptosis started on day 3 and took 7 days to fully develop in young rats, whereas apoptosis was fully developed by day 3 in aged rats.20 Based on their findings, the authors concluded that while the aged brain has the capability to mount a cytoproliferative response to an injury, the timing of the cellular and genetic response to the injury is dysregulated in aged animals, compromising their functional recovery. Although stroke is a different mechanism from TBI, apoptosis is common after TBI, and these observations may indicate an increased vulnerability and response to injury and a decreased capacity for repair with age.
Human Factors
The Centers for Disease Control and Prevention (CDC) reported a 27% increase from 2002 to 2006 in TBI-related death among individuals 75 years of age or older.7 As individuals age, they become more likely to fall and sustain a TBI. Persons older than 75 years also had the highest TBI-related hospitalization rate associated with unintentional falls (203.9/100,000 population), which is at least three times the rate for any other age group.7 Moreover, falls may not only lead to TBI, but can also cause other injuries, such as hip fractures, which make independent living impossible. Approximately 5% to 10% of falls result in severe head injuries, joint distortions and dislocations, contusions, and lacerations; however, this rate is more than doubled among women who are 75 years of age or older.21
Because of the vulnerability of elders to falls and the increased incidence of TBI-related death in this population, the CDC recommends that elders maintain a regular physical activity program to improve lower body strength and balance and that the following precautions are taken to make living areas safer for senior citizens22:
• Remove hazards, such as throw rugs and clutter in walkways;
• Place nonslip mats in bathtubs and on shower floors, and install grab bars next to toilets and in tubs and showers;
• Install handrails on both sides of stairways;
• Improve lighting throughout the home.
In addition to obstacles and dangers in the environment, falls in elders may be due to certain comorbidities associated with advanced age, such as poor eyesight, impaired balance, and postural hypotension.14 Kannus and colleagues21 made several health-related recommendations for preventing falls in elders, including regular participation in strength and balance training programs, use of vitamin D and calcium supplements, reduction in the number and doses of psychotropic medications, use of hip protectors, and cataract surgery. They also acknowledged that environmental factors can be significant contributors to falls, and they recommended a professional home-hazard assessment and management for those with a history of falling.
Contradictory evidence exists on whether there is a direct correlation between outcome and comorbidities in elders; some reports noted that comorbidities increase mortality,3,4 whereas others did not observe such a relationship.23 Livingston and colleagues5 showed that the occurrence of cardiovascular, pulmonary, and diabetic comorbidities increase with age. Although only 6% of patients 19 to 29 years old in their study had such comorbidities, these conditions were present in 53% of those 60 years of age or older.5 As the number of comorbidities increase, so do the number of pharmacotherapies, which can also confer a greater risk of mortality. Studies have shown that iatrogenic coagulopathy with aspirin, clopidogrel, or warfarin increases the likelihood of death by 4.48 to 14.7 times over that in patients who are not receiving anticoagulation therapy.24,25
Neurosurgical Intervention
Mortality rates are high in older adults who sustain a TBI, especially in cases of severe TBI. When comparing the mortality rate following a severe TBI in individuals older than 60 years with that in patients 20 to 40 years old, Pennings and colleagues26 found that 79% of the older adults died in the hospital compared with 36% of younger patients. In addition, on the basis of the GCS, only one elder made a favorable recovery compared with 36% of younger individuals. Reports such as this lead to the question: Does surgery play a role in improving outcomes in elderly patients who sustain a TBI? According to Gan and colleagues,14 in cases when the presenting GCS score is poor and the patient has significant comorbidities, the potential outcome of treatment should be discussed with the patient’s family before further therapies are instituted.
Subdural hematomas are one of the more common intracranial hemorrhages and contribute to high mortality rates in all age groups. Mortality can be reduced and outcomes improved by rapid diagnosis and surgical evacuation; however, even after timely and satisfactory evacuation, outcomes are still worse in older patients (Figure).27 Cagetti28 evaluated the outcome of 28 patients older than 80 years who underwent surgical intervention to remove an acute subdural hematoma or an epidural hematoma. None of the patients with a GCS score of ≤11 survived, and only three patients who were operated on returned to their preinjury neurologic status.
Ethical Aspects of Treating TBI in Elders
Although research suggests that outcomes after TBI are poor in elderly patients, regardless of whether they undergo surgical intervention, the option of aggressive therapy is frequently offered to their families, who must then struggle with a difficult decision. If aggressive therapy is administered, patients who would have otherwise died may survive the initial stage of their head injury. Unfortunately, as in any intervention with a very limited chance of a good outcome, the concept of “risk of unacceptable badness” becomes pertinent.29
Unacceptable badness is defined as such a poor outcome (eg, vegetative state) that one would not want to experience it.
Until recently, it has been difficult to predict outcomes after TBI, but investigators from the CRASH (Corticosteroid Randomisation After Significant Head Injury) study,30 a multicenter, randomized clinical evaluation of corticosterioids in TBI, have developed a validated prediction model that brings scientific evidence to bear on the ethical dilemmas of rescue and allows families and clinicians to avoid the trap of thinking that “any chance at life is better than none.”A prediction calculator derived from this model can be found online.31
In all cases of TBI, but especially when the patient is an elder, the responsible clinician or team will need to ask whether consideration should be given to not performing an interventional procedure because of the significant chance that the outcome will be poor and unacceptable to the patient.29 Healthcare providers need to help surrogate decision-makers for patients with severe TBI, most often close family members, feel comfortable not proceeding with a life-saving intervention, as these interventions are nonrestorative in the majority of cases, especially in elders.
Rehabilitation of Elders After TBI
Most studies report a poor response to and outcome after aggressive rehabilitation in elders who had a TBI.5,6,32 In one study, elderly patients with severe closed head injuries had a high rate of in-hospital mortality and those who survived their hospital stay did not show significant functional improvement.29 A study by LeBlanc and colleagues33 that compared functional outcomes of young, middle-aged, and elderly patients after their discharge from acute care facilities that provided treatment for TBI showed that a higher percentage of elders went to inpatient rehabilitation or long-term care facilities or died, whereas a higher percentage of young and middle-aged patients were discharged to home. Frankel and colleagues34 also found that older patients had significantly slower and more costly progress in inpatient rehabilitation and a significantly lower rate of discharge after TBI. Therefore, as the population ages, investment will be necessary to develop early rehabilitation services targeting the specific needs of the elderly patient with TBI.33
For the greatest benefit, rehabilitation should be initiated shortly after hospital admission, even while a patient is still in an intensive care setting. According to Flanagan and colleagues,3 the immediate goal of rehabilitation is to prevent complications associated with a prolonged period of immobilization, such as joint contracture, skin breakdown, venous stasis, and pulmonary compromise; thus, rehabilitation strategies should focus on treatments such as neuropsychologic, physical, occupational, and speech therapies.
Depression, which is more common in elders than in younger individuals after a TBI, can significantly interfere with rehabilitation. In a systematic review, Menzel35 found that the prevalence of depression in elders after TBI can range from 21% to 37%, which is also a notable increase from the prevalence of 1.8% to 8.9% found in elders without TBI. Cognitive impairment is prevalent after TBI and is easily confused with the diminished ability for thinking and concentration in the setting of major depression. Fann and colleagues36 noted that patients who sustain a TBI and have symptoms of depression typically attribute their cognitive impairments to their TBI, although these impairments may be a result of both TBI and depression. In their 8-week, nonrandomized, single-blind, placebo-controlled, run-in trial, neuropsychologic testing showed improvements in psychomotor speed, recent verbal memory, recent visual memory, and general cognitive efficiency following treatment of depression compared with baseline results. Improvements in self-perception of cognitive symptomatology were also observed. Studies in other medical and neurologic populations, such as patients with stroke, have shown similar results. Gan and colleagues14 reported that treating depression can be effective and can decrease functional impairment, somatic symptoms, and self-perception of the impairment.
Despite the known high prevalence of depression after TBI, surprisingly little research has addressed the efficacy of psychopharmacologic interventions for mood after TBI. The treatment of depression clearly has implications for the alleviation of the psychosocial and functional sequelae of brain injury, and screening, recognition, and treatment of depression should be undertaken in elders after a TBI to ensure the best outcome possible.
Conclusion
Despite the general improvement in outcomes after TBI over the past 50 years, the outcome for elderly patients remains poor. In fact, over the past 10 years, overall TBI-related mortality has increased in response to the increasingly aging population.37
Both operative and nonoperative treatment for elderly patients after head trauma cannot ameliorate outcomes. The treatment of TBI in elders can be intensive and of questionable benefit, and it often increases the emotional burden on patients’ families. The decision to provide or not provide treatment involves the consideration of many ethical questions. In view of the currently grim outlook on the recovery from TBI in elderly individuals, a reevaluation of clinical interventions and ethical guidelines as well as further research are necessary to help ensure that the best and most appropriate care will be provided for these patients in the future.
The authors report no relevant financial relationships.
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