Instruct: Given a question, retrieve relevant passages that answer the question.
Query: Do brains heal themselves after strokes?
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.
Stroke symptoms typically start suddenly, over seconds to minutes, and in most cases do not progress further. The symptoms depend on the area of the brain affected. The more extensive the area of the brain affected, the more functions that are likely to be lost. Some forms of stroke can cause additional symptoms. For example, in intracranial hemorrhage, the affected area may compress other structures. Most forms of stroke are not associated with a headache, apart from subarachnoid hemorrhage and cerebral venous thrombosis and occasionally intracerebral hemorrhage.
In 1620, Johann Jakob Wepfer, by studying the brain of a pig, developed the theory that stroke was caused by an interruption of the flow of blood to the brain. After that, the focus became how to treat patients with stroke.
After an angiogram, a sudden shock can cause a little pain at the surgery area, but heart attacks and strokes usually don't occur, as they may in bypass surgery. A heart attack occurs when blood flow to a part of the heart is blocked, usually by a blood clot. Without oxygenated blood, the heart muscle begins to die. A stroke is a brain attack, cutting off vital blood flow and oxygen to the brain. Stroke happens when a blood vessel feeding the brain gets clogged or bursts. 
After a traumatic brain injury (TBI) or cerebrovascular accident (CVA), the brain undergoes several healing and re-organization processes, which may result in improved language function. This is referred to as spontaneous recovery. Spontaneous recovery is the natural recovery the brain makes without treatment, and the brain begins to reorganize and change in order to recover. There are several factors that contribute to a person's chance of recovery caused by stroke, including stroke size and location. Age, sex, and education have not been found to be very predictive.
These types of strokes include lacunar and other ischemic strokes and minor hemorrhages. They may also include leukoaraiosis (changes in the white matter of the brain): the white matter is more susceptible to vascular blockage due to reduced amount of blood vessels as compared to the cerebral cortex. These strokes are termed "silent" because they typically affect "silent" regions of the brain that do not cause a noticeable change in an afflicted person’s motor functions such as contralateral paralysis, slurred speech, pain, or an alteration in the sense of touch. A silent stroke typically affects regions of the brain associated with various thought processes, mood regulation and cognitive functions and is a leading cause of vascular cognitive impairment and may also lead to a loss of urinary bladder control.
As of 2011, there has been an effort to applying a rehabilitation robot connected to a non-invasive brain-computer interface to promote brain plasticity and motor learning following a stroke. Half of stroke survivors experience unilateral paralysis or weakness, and approximately 30-60% of them do not regain function. Typical treatment, post-stroke, involves constraint-induced movement therapy and robotic therapy, which work to restore motor activity by forcing the movement of the weak limbs. Current active therapy cannot be utilized by patients who suffer complete control loss or paralysis, and do not have any residual motor ability to work with.
Reperfusion injury plays a part in the brain's ischemic cascade, which is involved in stroke and brain trauma. Similar failure processes are involved in brain failure following reversal of cardiac arrest; control of these processes is the subject of ongoing research. Repeated bouts of ischemia and reperfusion injury also are thought to be a factor leading to the formation and failure to heal of chronic wounds such as pressure sores and diabetic foot ulcer. Continuous pressure limits blood supply and causes ischemia, and the inflammation occurs during reperfusion. As this process is repeated, it eventually damages tissue enough to cause a wound.
A stroke is the damage of a volume of brain tissue resulting from restricted blood supply, which is often a result of occluded blood vessels leading to the brain. Given the large number of brain areas involved in the motor skill acquisition, strokes affecting any of these areas can lead to deficits in motor skill consolidation. Therapies for stroke have focused on modified practice techniques to allow the reacquisition of important skills after the damage has occurred.
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.
Some treatments for stroke are time-critical. These include clot dissolution or surgical removal of a clot for ischaemic strokes, and decompression for haemorrhagic strokes. As stroke is time critical, hospitals and even pre-hospital care of stroke involves expedited investigations – usually a CT scan to investigate for a haemorrhagic stroke and a CT or MR angiogram to evaluate arteries that supply the brain. MRI scans, not as widely available, may be able to demonstrate the affected area of the brain more accurately, particularly with ischaemic stroke.
Theresa Jones has been awarded research funding for numerous research initiatives from the National Institute of Neurological Disorders and Stroke, the Department of Defense, and the National Institutes of Health. Some of these include "Cortical Stimulation to Enhance Experience-Dependent Plasticity After Stroke", "Cognitive Neurorehabilitation to Enhance Recovery After Stroke", "Neural Plasticity and Neurorehabilitation Following Traumatic Brain Injury", and "Cortical Stimulation to Enhance Recovery After Stroke". The most recent research topics for which she has been awarded funding include "Neural Mechanisms of Compensating for Brain Damage", "Neurovascular Mechanisms of Time-Dependencies in Stroke Rehabilitation", "Microscale Oxygenation Mapping During Stroke", "Optical Imaging of Baseline Blood Flow and Oxygen During Stroke", and "Cortical Stimulation to Enhance Motor Recovery Following Traumatic Brain Injury".
Villringer currently pursues the hypothesis that (maladaptive) brain plasticity is crucial for the development of vascular risk factors leading to stroke and for the (lack of) recovery after stroke, and that brain plasticity can be beneficially modified. For this purpose, he employs multimodal brain imaging to understand basic neurophysiological mechanisms underlying human brain plasticity in cortical and subcortical brain areas, and their interaction. Behavioral correlates include sensorimotor function, reaction to stress, and emotions. The clinical applications are (i) prevention of vascular risk factors (obesity, hypertension) and subsequent stroke, and (ii) recovery after stroke.
A watershed stroke or watershed infarct is defined as a brain ischemia that is localized to the vulnerable border zones between the tissues supplied by the anterior, posterior and middle cerebral arteries. The actual blood stream blockage/restriction site can be located far away from the infarcts. Watershed locations are those border-zone regions in the brain supplied by the major cerebral arteries where blood supply is decreased. Watershed strokes are a concern because they comprise approximately 10% of all ischemic stroke cases. The watershed zones themselves are particularly susceptible to infarction from global ischemia as the distal nature of the vasculature predisposes these areas to be most sensitive to profound hypoperfusion.
A neonatal stroke in the developing brain involves excitotoxicity, oxidative stress, and inflammation, which accelerate cell death through necrosis or apoptosis, depending on the region of the brain and severity of stroke. The pathophysiology of neonatal stroke may include thrombosis and thrombolysis, and vascular reactivity. Apoptosis mechanisms may have a more prominent role in developing an ischemic brain injury in neonatal humans than in adult brain ischemia, as a majority of cells die in the environment where edema developed after a neonatal stroke. There is an increased inflammatory response after hypoxia-ischemia, which corresponds to extensive neuronal apoptosis. Apoptosis involves the mitochondrial release of cytochrome c and apoptosis-inducing factor (AIF), which activate caspase-dependent and –independent execution pathways, respectively. Injury may also occur due to O accumulation via the production of O by microglia, a type of glial cell that are responsible for immune response in the CNS, but their role in injury after neonatal stroke is still relatively unknown. As observed by Alberi, "et al.", progressive atrophy in the ipsilateral hemisphere over three weeks after the stroke occurred, suggesting that a neonatal stroke has long-lasting effects on neuronal viability and the potential for a prolonged therapeutic window for alleviating the progression of cell death.
During an ischemic stroke, a lack of oxygen and glucose leads to a breakdown of the sodium-calcium pumps on brain cell membranes, which in turn results in a massive buildup of sodium and calcium intracellularly. This causes a rapid uptake of water and subsequent swelling of the cells. It is this swelling of the individual cells of the brain that is seen as the main distinguishing characteristic of cytotoxic edema, as opposed to vasogenic edema, wherein the influx of fluid is typically seen in the interstitial space rather than within the cells themselves. While not all patients who have experienced a stroke will develop a severe edema, those who do have a very poor prognosis.
Full recovery is common with proper treatment. Pulmonary laceration usually heals quickly after a chest tube is inserted and is usually not associated with major long-term problems. Pulmonary lacerations usually heal within three to five weeks, and lacerations filled with air will commonly heal within one to three weeks but on occasion take longer. However, the injury often takes weeks or months to heal, and the lung may be scarred. Small pulmonary lacerations frequently heal by themselves if material is removed from the pleural space, but surgery may be required for larger lacerations that do not heal properly or that bleed.
Domed labels are much more permanent than many other labels and do not show wear; the clear polyurethane substance, even after curing (hardening), is self-healing. Minor scratches or cuts heal themselves and the label looks like new once again.
Unlike many effects of stroke, where the clinician is able to judge the particular area of the brain that a stroke has injured by certain signs or symptoms, the causation of apraxia is less clear. A common theory is that the part of the brain that contains information for previously learned skilled motor activities has been either lost or cannot be accessed. The condition is usually due to an insult to the dominant hemisphere of the brain. More often this is located in the frontal lobe of the left hemisphere of the brain. Treatment of acquired apraxia due to stroke usually consists of physical, occupational, and speech therapy. The Copenhagen Stroke Study, which is a large important study published in 2001, showed that out of 618 stroke patients, manual apraxia was found in 7% and oral apraxia was found in 6%. Both manual and oral apraxia were related to increasing severity of stroke. Oral apraxia was related with an increase in age at the time of the stroke. There was no difference in incidence among gender. It was also found that the finding of apraxia has no negative influence on ability to function after rehabilitation is completed. The National Institute of Neurological Disorders and Stroke (NINDS) is currently sponsoring a clinical trial to gain an understanding of how the brain operates while carrying out and controlling voluntary motor movements in normal subjects. The objective is to determine what goes wrong with these processes in the course of acquired apraxia due to stroke or brain injury.
The National Institutes of Health Stroke Scale has been repeatedly validated as a tool for assessing stroke severity and as an excellent predictor for patient outcomes. Severity of a stroke is heavily correlated with the volume of brain affected by the stroke, strokes effecting larger portions of the brain tend to have more detrimental effects. NIHSS scores have been found to be reliable predictors of damaged brain volume, with a smaller NIHSS score indicating a smaller lesion volume
Cedar Lake Ballet Company made a ballet about "My Stroke of Insight" called "Orbo Novo". The piece's title is drawn from a 1493 reference to North America by Spanish historian Pietro Martire d'Anghiera. But the "new world" that Cherkaoui is exploring is current theories about the brain, and the text that the 17 dancers speak during the first moments of the 75-minute work comes from "My Stroke of Insight", neuroanatomist Jill Bolte Taylor's uncanny recollection of her stroke. The choreography is based on the ramifications of a single resonant idea: the duality between rationality (the left brain) and instinctive, sensual responses (the right brain); between control and the lack of it; between balance and instability, solitude and society. "Thus were the dancers speaking Taylor's words (“My spirit soared free like a great whale gliding through the sea of silent euphoria”), while they physically embodied brain waves and misfiring synapses, with a nod, perhaps, to the double helix: rubbery splayed limbs; über-arched backs; ever-rippling torsos." “‘Orbo Novo’ is a humorous and insightful take on (Taylor’s) story,” said dancer Jubal Battisti. “It has a lot to do with the hemispheres of the brain switching between left and right and what that reveals.”
In comparison to monolinguals, bilinguals have shown to have a better recovery after stroke. As with Alzheimer's patients, bilingual patients who have suffered an ischemic stroke have shown to have a better cognitive outcome which researchers believe is due to a higher cognitive reserve. This increase of cognitive reserve might be attributed to the increase of grey matter in bilingual individuals. Since bilingual individuals have to constantly change and inhibit a language, the brain is more used to brain training and has been able to optimize better the space it uses. Brain training has led researchers to believe is a factor that helps stroke patients recover faster and better. Bilingual individuals then are able to benefit more from rehabilitation after stroke compared to monolingual patients because the brain has a higher plasticity ability that allows for a better remodeling of the brain after stroke. Stroke patients (bilinguals) with aphasia also perform better in other cognitive tasks that measure attention and ability to organize and retrieve information. This is attributed again to the increase of grey matter since it is involved in cognitive control and higher cognitive functions that are more present in bilinguals. This is relevant since in some patients the automatization of language is impaired, highly correlated to basal ganglia lesions and anterior parietal cortex. Although it is uncommon for patients to lose automatization of the first language, basal ganglia lesions have been correlated to loss of automatization of language, which fits with the role of basal ganglia in automatized motor and cognitive performance. This is more evident with patients who have acquired a second language at a later age since studies suggest that late bilingual aphasics' syntactic judgment abilities may be more impaired for the second language. Acquisition of language at a later age changes the mapping of language in the brain since the languages do not overlap. This difference in mapping seems to be a contributing factor in recovery for patients with bilingual aphasia since there are second language-restricted zones that are dedicated to the first language.
How to Differentiate from Other Types of Aphasia.The most common cause of Wernicke's aphasia is stroke. Strokes may occur when blood flow to the brain is completely interrupted or severely reduced. This has a direct effect on the amount of oxygen and nutrients being able to supply the brain, which causes brain cells to die within minutes. The primary classifications of stroke are hemorrhagic (ruptured blood vessel), or ischemic (blood clot reduces or completely stops blood flow). Two of the most common types of hemorrhagic stroke are subarachnoid hemorrhage and intracerebral hemorrhage. Subarachnoid hemorrhage is when an artery near the surface of the brain bursts causing blood to leak into the space between the brain and skull. Meanwhile intracerebral hemorrhage occurs when a blood vessel inside the brain bursts, causing spillage into surrounding brain tissue. Three main causes of these hemorrhagic strokes are hypertension (uncontrolled high blood pressure), aneurisms (weak spots in blood vessel walls), and arteriovenous malformations (rupture of abnormal tangle of thin-walled blood vessels). As previously noted the other major classification for a stroke is an ischemic stroke. The ischemic strokes, which are the most common form of stroke, are further broken down and can be classified as embolic or thrombotic. Embolic strokes occur when a blood clot forms away from the brain, typically in the heart. A small portion of this clot breaks away and travels through the blood vessels until eventually reaching a small enough vessel in the brain that it can no longer pass through, causing a blockage. Thrombotic strokes on the other hand are due to the formation of a blood clot directly formed in one of the arteries that supply the brain. In general, stroke is the number one leading cause of disability worldwide.,
Air pollution is known to affect small and large blood vessels throughout the body.
High levels of air pollution are associated with increased risk of strokes and heart attacks. By permanently affecting vascular structures in the brain, air pollution can have serious effects on neural functioning and neural matter. In dogs air pollution shows to cause damage to the CNS by altering the blood–brain barrier, causing neurons in the cerebral cortex to degenerate, destroying glial cells found in white matter, and by causing neurofibrillary tangles. These changes can permanently alter brain structure and chemistry, resulting in various impairments and disorders. Sometimes, the effects of neural remodeling do not manifest themselves for a prolonged period of time.
Brain implants, often referred to as neural implants, are technological devices that connect directly to a biological subject's brain – usually placed on the surface of the brain, or attached to the brain's cortex. A common purpose of modern brain implants and the focus of much current research is establishing a biomedical prosthesis circumventing areas in the brain that have become dysfunctional after a stroke or other head injuries. This includes sensory substitution, e.g., in vision. Other brain implants are used in animal experiments simply to record brain activity for scientific reasons. Some brain implants involve creating interfaces between neural systems and computer chips. This work is part of a wider research field called brain-computer interfaces. (Brain-computer interface research also includes technology such as EEG arrays that allow interface between mind and machine but do not require direct implantation of a device.)