question: Why are our bodies so resilient and self healing yet damage to the brain is permanent?
comment: Our body is good at healing, but it’s rare that truly damaging injuries heal like new. Scar tissue, nerve damage, and other symptoms might last your entire life. Like the rest of our bodies, our brains can heal a truly vast amount and work around areas of damage... but only to a certain point. The brain is incredibly fragile and complex. Damage to it is not like breaking an arm.
passages: There are many misconceptions that revolve around brain injuries and brain damage. One misconception is that if someone has brain damage then they cannot fully recover. Recovery depends a variety of factors; such as severity and location. Testing is done to note severity and location. Not everyone fully heals from brain damage, but it is possible to have a full recovery. Brain injuries are very hard to predict in outcome. Many tests and specialists are needed to determine the likelihood of the prognosis. People with minor brain damage can have debilitating side effects; not just severe brain damage has debilitating effects. The side- effects of a brain injury depend on location and the body’s response to injury. Even a mild concussion can have long term effects that may not resolve. Another misconception is that children heal better from brain damage. Children are at greater risk for injury due to lack of maturity. It makes future development hard to predict. This is because different cortical areas mature at different stages, with some major cell populations and their corresponding cognitive faculties remaining unrefined until early adulthood. In the case of a child with frontal brain injury, for example, the impact of the damage may be undetectable until that child fails to develop normal executive functions in his or her late teens and early twenties.
   Section::::Prevention.
  
  Since primary injury occurs at the moment of trauma and is over so rapidly, little can be done to interfere with it other than prevention of the trauma itself. However, since secondary injury occurs over time, it can be prevented in part by taking measures to prevent complications such as hypoxia (oxygen deficiency). Furthermore, secondary injury presents opportunities for researchers to find drug therapies to limit or prevent the damage. Since a variety of processes occur in secondary injury, any treatments that are developed to halt or mitigate it will need to address more than one of these mechanisms.
   Prognosis worsens with the severity of injury. Most TBIs are mild and do not cause permanent or long-term disability; however, all severity levels of TBI have the potential to cause significant, long-lasting disability. Permanent disability is thought to occur in 10% of mild injuries, 66% of moderate injuries, and 100% of severe injuries. Most mild TBI is completely resolved within three weeks. Almost all people with mild TBI are able to live independently and return to the jobs they had before the injury, although a small portion have mild cognitive and social impairments. Over 90% of people with moderate TBI are able to live independently, although some require assistance in areas such as physical abilities, employment, and financial managing. Most people with severe closed head injury either die or recover enough to live independently; middle ground is less common. Coma, as it is closely related to severity, is a strong predictor of poor outcome.
   BULLET::::2. The cranial nerves III-XII emerge from the brainstem. These cranial nerves supply the face, head, and viscera. (The first two pairs of cranial nerves arise from the cerebrum).
  
  BULLET::::3. The brainstem has integrative functions being involved in cardiovascular system control, respiratory control, pain sensitivity control, alertness, awareness, and consciousness. Thus, brainstem damage is a very serious and often life-threatening problem.
  
  Section::::Function.:Cranial nerves.
   The central nervous system is protected by major physical and chemical barriers. Physically, the brain and spinal cord are surrounded by tough meningeal membranes, and enclosed in the bones of the skull and vertebral column, which combine to form a strong physical shield. Chemically, the brain and spinal cord are isolated by the blood–brain barrier, which prevents most types of chemicals from moving from the bloodstream into the interior of the CNS. These protections make the CNS less susceptible in many ways than the PNS; the flip side, however, is that damage to the CNS tends to have more serious consequences.
   Secondary injury is an "indirect" result of the injury. It results from processes initiated by the trauma. It occurs in the hours and days following the primary injury and plays a large role in the brain damage and death that results from TBI. Unlike in most forms of trauma a large percentage of the people killed by brain trauma do not die right away but rather days to weeks after the event. In addition, rather than improving after being hospitalized as most patients with other types of injuries do, about 40% of people with TBI deteriorate. This is often a result of secondary injury, which can damage neurons that were unharmed in the primary injury. It occurs after a variety of brain injury including subarachnoid hemorrhage, stroke, and traumatic brain injury and involves metabolic cascades.
   Brain injuries are very hard to predict in outcome. Many tests and specialists are needed to determine the likelihood of the prognosis. People with minor brain damage can have debilitating side effects; not just severe brain damage has debilitating effects. The side- effects of a brain injury depend on location and the body’s response to injury. Even a mild concussion can have long term effects that may not resolve.
  
  Section::::History.
   Brain healing
  
  Brain healing is the process that occurs after the brain has been damaged. If an individual survives brain damage, the brain has a remarkable ability to adapt. When cells in the brain are damaged and die, for instance by stroke, there will be no repair or scar formation for those cells. The brain tissue will undergo liquefactive necrosis, and a rim of gliosis will form around the damaged area.
  
  Section::::Scar formation.
   Section::::Epidemiology.
  
  TBI is a leading cause of death and disability around the globe and presents a major worldwide social, economic, and health problem. It is the number one cause of coma, it plays the leading role in disability due to trauma, and is the leading cause of brain damage in children and young adults. In Europe it is responsible for more years of disability than any other cause. It also plays a significant role in half of trauma deaths.
   In children with uncomplicated minor head injuries the risk of intra cranial bleeding over the next year is rare at 2 cases per 1 million. In some cases transient neurological disturbances may occur, lasting minutes to hours. Malignant post traumatic cerebral swelling can develop unexpectedly in stable patients after an injury, as can post traumatic seizures. Recovery in children with neurologic deficits will vary. Children with neurologic deficits who improve daily are more likely to recover, while those who are vegetative for months are less likely to improve. Most patients without deficits have full recovery. However, persons who sustain head trauma resulting in unconsciousness for an hour or more have twice the risk of developing Alzheimer's disease later in life.
   A large percentage of the people killed by brain trauma do not die right away but rather days to weeks after the event; rather than improving after being hospitalized, some 40% of TBI patients deteriorate. Primary brain injury (the damage that occurs at the moment of trauma when tissues and blood vessels are stretched, compressed, and torn) is not adequate to explain this deterioration; rather, it is caused by secondary injury, a complex set of cellular processes and biochemical cascades that occur in the minutes to days following the trauma. These secondary processes can dramatically worsen the damage caused by primary injury and account for the greatest number of TBI deaths occurring in hospitals.
   There are three main causes of CNS injury: stroke, traumatic brain injury (TBI), or developmental complications. Strokes are classified as either hemorrhagic (when a vessel is damaged to the point of bleeding into the brain) or ischemic (when a clot blocks the blood flow through the vessel in the brain). When a hemorrhage occurs, blood seeps into the surrounding tissue, resulting in tissue death, while ischemic hemorrhages result in a lack of blood flow to certain tissues. Traumatic brain injury is caused by external forces impacting the cranium or the spinal cord. Problems with CNS development results in abnormal tissue growth during development, thus decreasing the function of the CNS.
   The brain is protected by the skull, suspended in cerebrospinal fluid, and isolated from the bloodstream by the blood–brain barrier. However, the brain is still susceptible to damage, disease, and infection. Damage can be caused by trauma, or a loss of blood supply known as a stroke. The brain is susceptible to degenerative disorders, such as Parkinson's disease, dementias including Alzheimer's disease, and multiple sclerosis. Psychiatric conditions, including schizophrenia and clinical depression, are thought to be associated with brain dysfunctions. The brain can also be the site of tumours, both benign and malignant; these mostly originate from other sites in the body.
   TBI is a major cause of death and disability worldwide, especially in children and young adults. Males sustain traumatic brain injuries more frequently than do females. The 20th century saw developments in diagnosis and treatment that decreased death rates and improved outcomes.
  
  Section::::Classification.
  
  Traumatic brain injury is defined as damage to the brain resulting from external mechanical force, such as rapid acceleration or deceleration, impact, blast waves, or penetration by a projectile. Brain function is temporarily or permanently impaired and structural damage may or may not be detectable with current technology.
   In TBI, primary injuries result immediately from the initial trauma. Primary injury occurs at the moment of trauma and includes contusion, damage to blood vessels, and axonal shearing, in which the axons of neurons are stretched and torn. The blood brain barrier and meninges may be damaged in the primary injury, and neurons may die. Cells are killed in a nonspecific manner in primary injury. Tissues have a deformation threshold: if they are deformed past this threshold they are injured. Different regions in the brain may be more sensitive to mechanical loading due to differences in their properties that result from differences in their makeup; for example, myelinated tissues may have different properties than other tissues. Thus some tissues may experience more force and be more injured in the primary injury. The primary injury leads to the secondary injury.
    Although the brain and spinal cord are surrounded by tough membranes, enclosed in the bones of the skull and spinal vertebrae, and chemically isolated by the blood–brain barrier, they are very susceptible if compromised. Nerves tend to lie deep under the skin but can still become exposed to damage. Individual neurons, and the neural circuits and nerves into which they form, are susceptible to electrochemical and structural disruption. Neuroregeneration may occur in the peripheral nervous system and thus overcome or work around injuries to some extents, but it is thought to be rare in the brain and spinal cord.
   Section::::Damage on a cellular level.
   Another approach to brain function is to examine the consequences of damage to specific brain areas. Even though it is protected by the skull and meninges, surrounded by cerebrospinal fluid, and isolated from the bloodstream by the blood–brain barrier, the delicate nature of the brain makes it vulnerable to numerous diseases and several types of damage. In humans, the effects of strokes and other types of brain damage have been a key source of information about brain function. Because there is no ability to experimentally control the nature of the damage, however, this information is often difficult to interpret. In animal studies, most commonly involving rats, it is possible to use electrodes or locally injected chemicals to produce precise patterns of damage and then examine the consequences for behavior.
   Findings on the frequency of each level of severity vary based on the definitions and methods used in studies. A World Health Organization study estimated that between 70 and 90% of head injuries that receive treatment are mild, and a US study found that moderate and severe injuries each account for 10% of TBIs, with the rest mild.
   BULLET::::- Brain death is the irreversible loss of measurable brain function, with loss of any integrated activity among distinct areas of the brain. Breathing and heart function must be maintained with assistive devices.
  
  Disorders of consciousness affect a significant number of people who suffer severe TBI; of those with severe TBI discharged from a hospital, are in a vegetative state, and of this number only half regain consciousness within one to three years.
  
  Section::::Cognitive deficits.
   About 90% of patients who are single when injured are still single five years after the injury. There is a high incidence of divorce and separation after an injury, though this decreases beyond the first year after injury.
  
  Many catastrophic spinal cord injury patients improve their education. Immediately after injury, the average level of education is below that of the general population; fifteen years after injury, it is above that of the general population.
  
  Survivors of catastrophic injury may also have catastrophic facial injuries, such as fractured facial bones, particularly those from events associated with ice hockey, cycling, and snowmobiling.
   The central nervous system (CNS), which includes the brain and spinal cord, is a sensitive system with limited capacity for regeneration. In that regard, the concept of "immune privilege" within the CNS was once thought to be critical in limiting inflammation. The blood–brain barrier plays an important role in maintaining the separation of CNS from the systemic immune system but the presence of the blood–brain barrier, does not, on its own, provide immune privilege. It is thought that immune privilege within the CNS varies throughout the different compartments of the system, being most pronounced in the parenchyma tissue or "white matter".
   Changes in personality are common in cases of traumatic brain injury involving the frontal lobes, the most famous example of this is the case of Phineas Gage who survived having a tamping iron shot through his head in a railway construction accident.
  
  Declines from premorbid levels of intelligence and other cognitive functions are observed in stroke, traumatic brain injury, and dementia as well as in mental illnesses such as depression and schizophrenia.
   Primary and secondary brain injury are ways to classify the injury processes that occur in brain injury. In traumatic brain injury (TBI), primary brain injury occurs during the initial insult, and results from displacement of the physical structures of the brain. Secondary brain injury occurs gradually and may involve an array of cellular processes. Secondary injury, which is not caused by mechanical damage, can result from the primary injury or be independent of it. The fact that people sometimes deteriorate after brain injury was originally taken to mean that secondary injury was occurring. It is not well understood how much of a contribution primary and secondary injuries respectively have to the clinical manifestations of TBI.
   Robert A. Stern, one of the scientists at the Boston University CTE Center, said in 2015 that "he expected a test to be developed within a decade that will be able to diagnose C.T.E. in living people".
  
  Section::::Prevention.
  
  Investigators have demonstrated that immobilizing the head during a blast exposure prevented the learning and memory deficits associated with CTE that occurred when the head was not immobilized. This research represents the first case series of postmortem brains from U.S. military personnel who were exposed to a blast and/or a concussive injury.
  
presuppositions: Damage to the brain is permanent. Human bodies are resilient and self-healing.
corrections: While the brain is incredibly fragile and complex, it can heal damage to a certain point. Human bodies are not so resilient and self-healing to the extent that they can heal entirely like new.
raw_presuppositions: Damage to the brain is permanent. Human bodies are resilient and self-healing.
raw_corrections: While the brain is incredibly fragile and complex, it can heal damage to a certain point. Human bodies are not so resilient and self-healing to the extent that they can heal entirely like new.