According to the World Health Organization, a stroke, also known as a cerebrovascular accident (CVA), is a sudden ischemic or hemorrhagic interruption in the blood flow supplying oxygen and nutrients to brain tissue. This event results in brain cell death and, consequently, partial loss of neurological function . The occurrence of strokes has been progressively increasing. Currently, stroke is "the leading cause of adult disability in Western countries"  and one of the most common causes of death in the world . The majority of people with stroke live with long-term disabilities leading to serious social and economic impacts. It is estimated that the direct and indirect cost of stroke care for the 6.5 million people living with the disability in the United States  was $73.7 billion for 2010 . According to "Tracking Heart Disease and Stroke in Canada" for 2009, stroke and heart diseases cost more than $22.2 billion annually . These numbers will continue to rise as the population ages and people live longer.
Depending on the magnitude and severity of the problem, people with stroke experience a variety of motor, sensory, and cognitive disabilities. A majority of patients have impaired upper-limb (UL) motor function following stroke and have difficulty in independently performing activities of daily living (ADL) [7-8]. Therefore, one of the challenging aspects of stroke rehabilitation is UL intervention. Studies have shown that only 6 to 10 percent of people with stroke who have severe paralysis achieve a full recovery by 6 months , and only 18 percent of them regain full UL function . While the initial degree of stroke and paresis severity is a good predictor of UL function recovery [7,11-12], task-specific, high-intensity exercises in an active, functional, and highly repetitive manner over a large number of trials have been shown to enhance motor recovery, even in chronic stages of stroke . Studies on the dose-response relationship in stroke rehabilitation have shown that more intensive therapy is associated with enhanced rate of motor recovery; additionally, no ceiling effect for intensity of therapy has been observed [14-16]. Despite these findings, traditional therapies are still not delivered more intensively or frequently, often because of cost and labor limitations . In addition, traditional "hands-on" interventions can, at times, result in repetitive strain injuries and excessive fatigue for therapists, thus leading to possible failure in delivery of highly intensive and repetitive training . Moreover, major intra- and interindividual variability exists in the application of manual therapy, leading to inconsistent outcomes.
One of the novel and rapidly expanding technologies in poststroke rehabilitation for enhancing the recovery process and facilitating the restoration of function is robot-assisted therapy (RT). Rehabilitation robotics has some advantages over conventional treatment approaches. Advanced and intelligent robotic devices are able to provide consistent training and to measure performance with high reliability and accuracy . Most importantly, robots may allow patients to train more independently and with less supervision from a therapist .
Compared with the research and development in conventional therapy (CT) techniques, the cost, effort, and time required for the research and development in rehabilitation robotics are significantly higher. Therefore, an important element in further development of therapeutic robots and RT programs is determining whether RT is more effective than CT, based on the scientific evidence extracted from the literature. A systematic review is a rigorous methodology for gathering, synthesizing, and evaluating available scientific evidence . Therefore, the main objective of this article was to systematically analyze the literature to find evidence regarding the effectiveness of RT compared with CT in improving motor recovery and functional abilities of the paretic UL of patients with stroke. …