Traumatic brain injury, currently considered a singular event by the insurance industry and many health care providers, is instead the beginning of an ongoing process that impacts multiple organ systems and may cause or accelerate other diseases and disorders that can reduce life expectancy, according to research from the University of Texas Medical Branch at Galveston.
As such, traumatic brain injury should be defined and managed as a chronic disease to ensure that patients receive appropriate care and that future research is directed at discovering therapies that may interrupt the disease processes months or even years after the initiating injury, say co-authors Dr. Brent Masel, a clinical associate professor in UTMB's department of neurology and Dr. Douglas DeWitt, director of the Moody Center for Traumatic Brain & Spinal Cord Injury Research/Mission Connect and professor in the department of anesthesiology. Masel also serves as president and director of the Transitional Learning Center in Galveston, which for more than 25 years has provided survivors of brain injury with the special rehabilitation services they need to re-enter the community.
The literature review, which appears in the current issue of The Journal of Neurotrauma, examines 25 years of research on the effects of brain injury, including its impact on the central nervous system and on cognitive and motor functions.
Traumatic brain injury occurs when a sudden trauma causes damage to the brain and can be classified as mild, moderate or severe, depending on the extent of the damage. While many patients recover completely, more than 90,000 become disabled each year in the U.S. alone. It is estimated that more than 3.5 million Americans are presently disabled by brain injuries -- suffering lifelong conditions as a result.
"Traumatic brain injury fits the World Health Organization's definition of a chronic disease, yet the U.S. health care system generally views it as a one-time injury that heals the way a broken bone does," says Masel. "Only by reimbursing and managing brain injuries on par with other chronic diseases will patients get the long-term treatment and support they need and deserve."
The researchers add that re-classifying traumatic brain injury as a chronic disease may help to provide brain injury researchers with the additional funding required to investigate a potential cure.
Masel and DeWitt's review compiled extensive evidence that brain trauma initiates a disease process that severely affects cognitive function, physiological processes and quality of life. These effects can prevent patients from fully reentering society post-injury and may ultimately contribute to death months or years later. Specifically, traumatic brain injury is strongly associated with:
- Neurological disorders that reduces life expectancy, including epilepsy -- for which traumatic brain injury is the leading cause in young adults -- and obstructive sleep apnea, which is associated with reduced cognition and severe cardiac arrhythmias during sleep.
- Neurodegenerative disorders that lead to gradual declines in cognitive function after injury, including Alzheimer's dementia, Parkinson's disease and chronic traumatic encephalopathy (also known as "punch drunk" and characterized by disturbed coordination, gait, slurred speech and tremors). However, research shows that those who receive more therapy in the early post-injury months, irrespective of severity of injury and level of neuropsychological impairment, were less likely to show decline over the long-term. Age is also a factor in cognitive outcome after brain injury, with older patients showing greater decline.
- A host of neuroendocrine disorders, possibly caused by complex hormonal responses in the hypothalamic-pituitary system that ultimately lead to acute and/or chronic post-traumatic hypopituitarism -- the decreased secretion of hormones normally produced by the pituitary gland, which can result in several related conditions, including growth hormone deficiency and hypothyroidism.
- Psychiatric and psychological diseases, which are among the most disabling consequences of traumatic brain injury. Many individuals with mild brain trauma and the majority of those who survive moderate-to-severe brain injury are left with significant long-term neurobehavioral conditions. These range from aggression, confusion and agitation to obsessive-compulsive disorders, anxiety/mood/ psychotic disorders, major depression and substance abuse. It is also associated with high rates of suicide.
- Non-neurologic disorders, including sexual dysfunction, which affects 40-60 percent of patients; incontinence; musculoskeletal dysfunction, or spasticity that results in abnormal motor patterns that may limit mobility and independence; and metabolic dysfunction, as brain injury appears to impact the way the body absorbs, utilizes and converts amino acids, which play a critical role in brain function.
According to Masel and DeWitt, research suggests that the progression of symptoms seen in chronic traumatic brain injury patients may be due, in part, to defective apoptotic cell death -- a natural process in which cells die because they are genetically programmed to do so or because of injury or disease. It is possible that the abnormal apoptotic cell death is triggered by brain trauma, leading to an accelerated decline in cognitive function and development of disease.
"Media coverage of traumatic brain injury among soldiers and athletes, especially football players, has highlighted the serious health problems resulting from brain injury that are experienced later in life and helped raise awareness among the general public," says DeWitt. "But until traumatic brain injury is recognized as a chronic disease, research funding won't be adequate for the work that is needed to help patients minimize or avoid these outcomes."
- Brent E. Masel, Douglas S. DeWitt. Traumatic Brain Injury: A Disease Process, Not an Event. Journal of Neurotrauma, 2010; 27 (8): 1529 DOI: 10.1089/neu.2010.1358
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