only a small decrease in the risk of stroke. to be beneficial, the complication rate of the surgery should be kept below 4%. even then, for 100 surgeries, 5 people will benefit by avoiding stroke, 3 will develop stroke despite surgery, 3 will develop stroke or die due to the surgery itself, and 89 will remain stroke-free but would also have done so without intervention. diet nutrition, specifically the mediterranean-style diet, has the potential for decreasing the risk of having a stroke by more than half. it does not appear that lowering levels of homocysteine with folic acid affects the risk of stroke. women a number of specific recommendations have been made for women including taking aspirin after the 11th week of pregnancy if there is a history of previous chronic high blood pressure and taking blood pressure medications during pregnancy if the blood pressure is greater than 150 mmhg systolic or greater than 100 mmhg diastolic. in those who have previously had preeclampsia other risk factors should be treated more aggressively. previous stroke or tia keeping blood pressure below 140/90 mmhg is recommended. anticoagulation can prevent recurrent ischemic strokes. among people with nonvalvular atrial fibrillation, anticoagulation can reduce stroke by 60% while antiplatelet agents can reduce stroke by 20%. however, a recent meta-analysis suggests harm from anticoagulation started early after an embolic stroke. stroke prevention treatment for atrial fibrillation is determined according to the cha2ds2–vasc score. the most widely used anticoagulant to prevent thromboembolic stroke in people with nonvalvular atrial fibrillation is the oral agent warfarin while a number of newer agents including dabigatran are alternatives which do not require prothrombin time monitoring. anticoagulants, when used following stroke, should not be stopped for dental procedures. if studies show carotid artery stenosis, and the person has a degree of residual function on the affected side, carotid endarterectomy (surgical removal of the stenosis) may decrease the risk of recurrence if performed rapidly after stroke. management ischemic stroke aspirin reduces the overall risk of recurrence by 13% with greater benefit early on. definitive therapy within the first few hours is aimed at removing the blockage by breaking the clot down (thrombolysis), or by removing it mechanically (thrombectomy). the philosophical premise underlying the importance of rapid stroke intervention was summed up as time is brain! in the early 1990s. years later, that same idea, that rapid cerebral blood flow restoration results in fewer brain cells dying, has been proved and quantified. tight blood sugar control in the first few hours does not improve outcomes and may cause harm. high blood pressure is also not typically lowered as this has not been found to be helpful. cerebrolysin, a mixture of pig-derived neurotrophic factors used to treat acute ischemic stroke in many asian and european countries, does not improve outcomes and may increase the risk of severe adverse events. thrombolysis thrombolysis, such as with recombinant tissue plasminogen activator (rtpa), in acute ischemic stroke, when given within three hours of symptom onset, results in an overall benefit of 10% with respect to living without disability. it does not, however, improve chances of survival. benefit is greater the earlier it is used. between three and four and a half hours the effects are less clear. the aha/asa recommend it for certain people in this time frame. a 2014 review found a 5% increase in the number of people living without disability at three to six months; however, there was a 2% increased risk of death in the short term. after four and a half hours thrombolysis worsens outcomes. these benefits or lack of benefits occurred regardless of the age of the person treated. there is no reliable way to determine who will have an intracranial bleed post-treatment versus who will not. in those with findings of savable tissue on medical imaging between 4.5 hours and 9 hours or who wake up with a stroke, alteplase results in some benefit. its use is endorsed by the american heart association, the american college of emergency physicians and the american academy of neurology as the recommended treatment for acute stroke within three hours of onset of symptoms as long as there are no other contraindications (such as abnormal lab values, high blood pressure, or recent surgery). this position for tpa is based upon the findings of two studies by one group of investigators which showed that tpa improves the chances for a good neurological outcome. when administered within the first three hours thrombolysis improves functional outcome without affecting mortality. 6.4% of people with large strokes developed substantial brain bleeding as a complication from being given tpa thus part of the reason for increased short term mortality. the american academy of emergency medicine had previously stated that objective evidence regarding the applicability of tpa for acute ischemic stroke was insufficient. in 2013 the american college of emergency medicine refuted this position, acknowledging the body of evidence for the use of tpa in ischemic stroke; but debate continues. intra-arterial fibrinolysis, where a catheter is passed up an artery into the brain and the medication is injected at the site of thrombosis, has been found to improve outcomes in people with acute ischemic stroke. endovascular treatment mechanical removal of the blood clot causing the ischemic stroke, called mechanical thrombectomy, is a potential treatment for occlusion of a large artery, such as the middle cerebral artery. in 2015, one review demonstrated the safety and efficacy of this procedure if performed within 12 hours of the onset of symptoms. it did not change the risk of death, but reduced disability compared to the use of intravenous thrombolysis which is generally used in people evaluated for mechanical thrombectomy. certain cases may benefit from thrombectomy up to 24 hours after the onset of symptoms. craniectomy strokes affecting large portions of the brain can cause significant brain swelling with secondary brain injury in surrounding tissue. this phenomenon is mainly encountered in strokes affecting brain tissue dependent upon the middle cerebral artery for blood supply and is also called "malignant cerebral infarction" because it carries a dismal prognosis. relief of the pressure may be attempted with medication, but some require hemicraniectomy, the temporary surgical removal of the skull on one side of the head. this decreases the risk of death, although some people – who would otherwise have died – survive with disability. hemorrhagic stroke people with intracerebral hemorrhage require supportive care, including blood pressure control if required. people are monitored for changes in the level of consciousness, and their blood sugar and oxygenation are kept at optimum levels. anticoagulants and antithrombotics can make bleeding worse and are generally discontinued (and reversed if possible). a proportion may benefit from neurosurgical intervention to remove the blood and treat the underlying cause, but this depends on the location and the size of the hemorrhage as well as patient-related factors, and ongoing research is being conducted into the question as to which people with intracerebral hemorrhage may benefit. in subarachnoid hemorrhage, early treatment for underlying cerebral aneurysms may reduce the risk of further hemorrhages. depending on the site of the aneurysm this may be by surgery that involves opening the skull or endovascularly (through the blood vessels). stroke unit ideally, people who have had a stroke are admitted to a "stroke unit", a ward or dedicated area in a hospital staffed by nurses and therapists with experience in stroke treatment. it has been shown that people admitted to a stroke unit have a higher chance of surviving than those admitted elsewhere in hospital, even if they are being cared for by doctors without experience in stroke. nursing care is fundamental in maintaining skin care, feeding, hydration, positioning, and monitoring vital signs such as temperature, pulse, and blood pressure. rehabilitation stroke rehabilitation is the process by which those with disabling strokes undergo treatment to help them return to normal life as much as possible by regaining and relearning the skills of everyday living. it also aims to help the survivor understand and adapt to difficulties, prevent secondary complications, and educate family members to play a supporting role. stroke rehabilitation should begin almost immediately with a multidisciplinary approach. the rehabilitation team may involve physicians trained in rehabilitation medicine, neurologists, clinical pharmacists, nursing staff, physiotherapists, occupational therapists, speech-language pathologists, and orthotists. some teams may also include psychologists and social workers, since at least one-third of affected people manifests post stroke depression. validated instruments such as the barthel scale may be used to assess the likelihood of a person who has had a stroke being able to manage at home with or without support subsequent to discharge from a hospital. stroke rehabilitation should be started as quickly as possible and can last anywhere from a few days to over a year. most return of function is seen in the first few months, and then improvement falls off with the "window" considered officially by u.s. state rehabilitation units and others to be closed after six months, with little chance of further improvement. however, some people have reported that they continue to improve for years, regaining and strengthening abilities like writing, walking, running, and talking. daily rehabilitation exercises should continue to be part of the daily routine for people who have had a stroke. complete recovery is unusual but not impossible and most people will improve to some extent: proper diet and exercise are known to help the brain to recover. spatial neglect the current body of evidence is uncertain on the efficacy of cognitive rehabilitation for reducing the disabling effects of neglect and increasing independence remains unproven. however, there is limited evidence that cognitive rehabilitation may have an immediate beneficial effect on tests of neglect. overall, no rehabilitation approach can be supported by evidence for spatial neglect. automobile driving the current body of evidence is uncertain whether the use of rehabilitation can improve on-road driving skills following stroke. there is limited evidence that training on a driving simulator will improve performance on recognizing road signs after training. the findings are based on low-quality evidence as further research is needed involving large numbers of participants. yoga based on low quality evidence, it is currently uncertain whether yoga has a significant benefit for stroke rehabilitation on measures of quality of life, balance, strength, endurance, pain, and disability scores. yoga may reduce anxiety and could be included as part of patient-centred stroke rehabilitation. further research is needed assessing the benefits and safety of yoga in stroke rehabilitation. action observation physical therapy for upper limbs low-quality evidence suggests that action observation (a type of physiotherapy that is meant to improve neural plasticity through the mirror-neuronal system) may be of some benefit and has no significant adverse effects, however this benefit may not be clinically significant and further research is suggested. cognitive rehabilitation for attention deficits the current body of scientific evidence is uncertain on the effectiveness of cognitive rehabilitation for attention deficits in patients following stroke. while there may be an immediate effect after treatment on attention, the findings are based on low to moderate quality and small number of studies. further research is needed to assess whether the effect can be sustained in day-to-day tasks requiring attention. motor imagery for gait rehabilitation the latest evidence supports the short-term benefits of motor imagery (mi) on walking speed in individuals who have had a stroke, in comparison to other therapies. mi does not improve motor function after stroke and does not seem to cause significant adverse events. the findings are based on low-quality evidence as further research is needed to estimate the effect of mi on walking endurance and the dependence on personal assistance. physical and occupational therapy physical and occupational therapy have overlapping areas of expertise; however, physical therapy focuses on joint range of motion and strength by performing exercises and relearning functional tasks such as bed mobility, transferring, walking and other gross motor functions. physiotherapists can also work with people who have had a stroke to improve awareness and use of the hemiplegic side. rehabilitation involves working on the ability to produce strong movements or the ability to perform tasks using normal patterns. emphasis is often concentrated on functional tasks and people's goals. one example physiotherapists employ to promote motor learning involves constraint-induced movement therapy. through continuous practice the person relearns to use and adapt the hemiplegic limb