section of nerve. the best non-invasive test for bpi is magnetic resonance imaging (mri). mri aids in the assessment of the injuries and is used to provide information on the portion of the plexus which cannot be operatively explored (the rootlets and roots). in addition, assessment of the cervical cord, post-traumatic changes in soft tissues and associated injuries (e.g. fractures, cuff tears, etc.) may be appreciated. although superior to nerve conduction studies, ultrasound and other tests, conventional mri has a poor specificity (72%) meaning that the false-positive rate is high and surgeons can't rely upon the test to guide treatment. consequently, the future of peripheral nerve mr imaging (including imaging brachial plexus injuries) is likely to be based on diffusion-weighted imaging, such as diffusion tensor techniques, which are of significant potential clinical utility and can enable the production of easily interpreted 3d reconstructions of the spinal cord and brachial plexus such as this. several weeks/months after bpi, emg examination can provide additional information about whether the muscle is denervated. these examinations are painful, highly user-dependent and lack normal values so cannot be relied upon. classification the severity of brachial plexus injury is determined by the type of nerve damage. there are several different classification systems for grading the severity of nerve and brachial plexus injuries. most systems attempt to correlate the degree of injury with symptoms, pathology and prognosis. seddon's classification, devised in 1943, continues to be used, and is based on three main types of nerve fiber injury, and whether there is continuity of the nerve. neurapraxia: the mildest form of nerve injury. it involves an interruption of the nerve conduction without loss of continuity of the axon. recovery takes place without wallerian degeneration. axonotmesis: involves axonal degeneration, with loss of the relative continuity of the axon and its covering of myelin, but preservation of the connective tissue framework of the nerve (the encapsulating tissue, the epineurium and perineurium, are preserved). neurotmesis: the most severe form of nerve injury, in which the nerve is completely disrupted by contusion, traction or laceration. not only the axon, but the encapsulating connective tissue lose their continuity. the most extreme degree of neurotmesis is transsection, although most neurotmetic injuries do not produce gross loss of continuity of the nerve but rather, internal disruption of the nerve architecture sufficient to involve perineurium and endoneurium as well as axons and their covering. it requires surgery, with unpredictable recovery. a more recent and commonly used system described by the late sir sydney sunderland, divides nerve injuries into five degrees: first degree or neurapraxia, following on from seddon, in which the insulation around the nerve called myelin is damaged but the nerve itself is spared, and second through fifth degree, which denotes increasing severity of injury. with fifth degree injuries, the nerve is completely divided. treatment treatment for brachial plexus injuries includes orthosis/splinting, occupational or physical therapy and, in some cases, surgery. some brachial plexus injuries may heal without treatment. many infants improve or recover within 6 months, but those that do not, have a very poor outlook and will need further surgery to try to compensate for the nerve deficits. the ability to bend the elbow (biceps function) by the third month of life is considered an indicator of probable recovery, with additional upward movement of the wrist, as well as straightening of thumb and fingers an even stronger indicator of excellent spontaneous improvement. gentle range of motion exercises performed by parents, accompanied by repeated examinations by a physician, may be all that is necessary for patients with strong indicators of recovery. the exercises mentioned above can be done to help rehabilitate from mild cases of the injury. however, in more serious brachial plexus injuries surgical interventions can be used. function can be restored by nerve repairs, nerve replacements, and surgery to remove tumors causing the injury. another crucial factor to note is that psychological problems can hinder the rehabilitation process due to a lack of motivation from the patient. on top of promoting a lifetime process of physical healing, it is important to not overlook the psychological well-being of a patient. this is due to the possibility of depression or complications with head injuries. rehabilitation there are many treatments to facilitate the process of recovery in people who have brachial plexus injuries. improvements occur slowly and the rehabilitation process can take up to many years. many factors should be considered when estimating recovery time, such as initial diagnosis of the injury, severity of the injury, and type of treatments used. some forms of treatment include nerve grafts, medication, surgical decompression, nerve transfer, physical therapy, and occupational therapy. therapy physical and occupational therapy is important when dealing with a brachial plexus injuries. one of the main goals of rehabilitation is to prevent muscle atrophy until the nerves regain function. electrical stimulation is an effective treatment to help patients reach this fundamental goal. exercises that involve shoulder extension, flexion, elevation, depression, abduction and adduction facilitate healing by engaging the nerves in the damaged sites as well as improve muscle function. stretching is done on a daily basis to improve or maintain range of motion. stretching is important in order to rehabilitate since it increases the blood flow to the injury as well as facilitates nerves in functioning properly. a study has also shown that a sensory-motor deficit in the upper limbs after a brachial plexus injury can affect the corporal balance in the vertical positioning. examined patients had a lower score in the berg balance scale, a greater difficulty in maintaining in the unipodal stance during one minute and leaned the body weight distribution to the side affected by the lesion. patients also exhibited a greater variability in the postural oscillation, evaluated by the directional stability index. the results alert the clinical community about the necessity to prevent and treat secondary effects of this condition. epidemiology brachial plexus injury is found in both children and adults, but there is a difference between children and adults with bpi. adults bpi traumatic event the prevalence of brachial plexus injuries in north american adults in the 1900s was about 1.2%. bpi is most commonly found in young healthy adults, from ages 14 to 63 years old, with 50% of patients between 19 and 34 years old. 89% of bpi patients are male. the rate of brachial plexus injury has been increasing. children incidence of obpp obpp, also known as obstetrical brachial plexus palsy, occurs primarily in young children at a rate of 0.38 to 1.56 per 1000 live births depending on the type of care and the average birth weight of infants in different regions of the world. for example, a study in the united states showed and incidence of obpp of about 1.51 cases per 1000 live births, in a canadian study, the incidence was between 0.5 and 3 injuries per 1000 live births, a dutch study reported an incidence of 4.6 per 1000 live births. the risk of bpi at birth is highest for infants weighing more than 4.5 kg at birth born to diabetic women. type of delivery also affects the risk of bpi. brachial plexus injury risks for newborns are increased with gained birth weight, birth delivery where a vacuum is assisted, and not being able to handle glucose. traumatic injuries motorcycles and bpi bpi has shown to occur in 44% to 70% of traumatic injuries, such as motorcycle accidents, sporting activities, or workplace accidents. with 22% being motorcycle injuries and about 4.2% having plexus damage. people who have accidents with riding motorcycles and snowmobiles have higher risks of getting a bpi and with ihg-injury injuries such as motorcycle accidents, root avulsion from the spinal cord is the most common pattern of injury (~72% prevalence of at least 1 root avulsion) which requires surgery to reanimate the arm. prognosis the site and type of brachial plexus injury determine the prognosis. avulsion and rupture injuries require timely surgical intervention for any chance of recovery. equally, reconstruction of elbow flexion in patients with pan-plexus injuries should be performed as soon as possible, because delays lead to worse motor outcomes. most closed infra-clavicular injuries due to shoulder dislocation are managed non-operatively initially and data shows that most fail to recover sensory function but recover some motor function. for milder injuries involving buildup of scar tissue and for neurapraxia, the potential for improvement varies, but there is a fair prognosis for spontaneous recovery, with a 90–100% return of function.