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A spinal cord injury (SCI) refers to any injury to the spinal cord that is caused by trauma instead of disease. Depending on where the spinal cord and nerve roots are damaged, the symptoms can vary widely, from pain to paralysis to incontinence.Spinal cord injuries are described at various levels of "incomplete", which can vary from having no effect on the patient to a "complete" injury which means a total loss of function.
Treatment of spinal cord injuries starts with restraining the spine and controlling inflammation to prevent further damage. The actual treatment can vary widely depending on the location and extent of the injury. In many cases, spinal cord injuries require substantial physical therapy and rehabilitation, especially if the patient's injury interferes with activities of daily life.
Spinal cord injuries have many causes, but are typically associated with major trauma from motor vehicle accidents, falls, sports injuries, and violence. Research into treatments for spinal cord injuries includes controlledhypothermia and stem cells, though many treatments have not been studied thoroughly and very little new research has been implemented in standard care.
Classification
The American Spinal Injury Association (ASIA) first published an international classification of spinal cord injury in 1982, called theInternational Standards for Neurological and Functional Classification of Spinal Cord Injury. Now in its sixth edition, the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) is still widely used to document sensory and motor impairments following SCI.[4] It is based on neurological responses, touch and pinprick sensations tested in each dermatome, and strength of ten key muscles on each side of the body, including hip flexion (L2), shoulder shrug (C4), elbow flexion (C5), wrist extension (C6), and elbow extension (C7).[5] Traumatic spinal cord injury is classified into five categories on the ASIA Impairment Scale:
- A indicates a "complete" spinal cord injury where no motor or sensory function is preserved in the sacral segments S4-S5.
- B indicates an "incomplete" spinal cord injury where sensory but not motor function is preserved below the neurological level and includes the sacral segments S4-S5. This is typically a transient phase and if the person recovers any motor function below the neurological level, that person essentially becomes a motor incomplete, i.e. ASIA C or D.
- C indicates an "incomplete" spinal cord injury where motor function is preserved below the neurological level and more than half of key muscles below the neurological level have a muscle grade of less than 3, which indicates active movement with full range of motion against gravity.
- D indicates an "incomplete" spinal cord injury where motor function is preserved below the neurological level and at least half of the key muscles below the neurological level have a muscle grade of 3 or more.
- E indicates "normal" where motor and sensory scores are normal. Note that it is possible to have spinal cord injury and neurological deficits with completely normal motor and sensory scores.[4]
Dimitrijevic[6] proposed a further class, the so-called discomplete lesion, which is clinically complete but is accompanied by neurophysiological evidence of residual brain influence on spinal cord function below the lesion.
The spinal cord (highlighted in dark red) runs from the base of the brain down through
the spine in a person's back. It connects the brain to the nerves throughout the body.
Signs and symptoms
Signs recorded by a physician and symptoms experienced by a patient will vary depending on where the spine is injured and the extent of the injury. These are all determined by the area of the body that the injured area of the spine innervates. A section of skin innervatedthrough a specific part of the spine is called a dermatome, and spinal injury can cause pain, numbness, or a loss of sensation in the relevant areas. A group of muscles innervated through a specific part of the spine is called a myotome, and injury to the spine can cause problems with voluntary motor control. The muscles may contract uncontrollably, become weak, or be completely unresponsive. The loss of muscle function can have additional effects if the muscle is not used, including atrophy of the muscle and bone degeneration.
A severe injury may also cause problems in parts of the spine below the injured area. In a "complete" spinal injury, all function below the injured area are lost. In an "incomplete" injury, some or all of the functions below the injured area may be unaffected. If the patient has the ability to contract the anal sphincter voluntarily or to feel a pinprick or touch around the anus, the injury is considered to be incomplete. The nerves in this area are connected to the very lowest region of the spine, the sacral region, and retaining sensation and function in these parts of the body indicates that the spinal cord is only partially damaged. An incomplete spinal cord injury involves preservation of motor or sensory function below the level of injury in the spinal cord.[8] This includes a phenomenon known as sacral sparing which involves the preservation of cutaneous sensation in the sacraldermatomes, even though sensation is impaired in the thoracic and lumbar dermatomes below the level of the lesion.[9] Sacral sparing may also include the preservation of motor function (voluntary external anal sphincter contraction) in the lowest sacral segments.[8] Sacral sparing has been attributed to the idea that the sacral spinal pathways are not as likely as the other spinal pathways to become compressed after injury.[9] The sparing of the sacral spinal pathways can be attributed to the lamination of fibers within the spinal cord.[9]
A complete injury frequently means that the patient has little hope of functional recovery.[citation needed] The relative incidence of incomplete injuries compared to complete spinal cord injury has improved over the past half century, due mainly to the emphasis on better initial care and stabilization of spinal cord injury patients.[10] Most patients with incomplete injuries recover at least some function.[citation needed]
In addition to sensation and muscle control, the loss of connection between the brain and the rest of the body can have specific effects depending on the location of the injury.
Determining the exact "level" of injury is critical in making accurate predictions about the specific parts of the body that may be affected by paralysis and loss of function. The level is assigned according to the location of the injury by the vertebra of the spinal column. While the prognosis of complete injuries are generally predictable since recovery is rare, the symptoms of incomplete injuries can vary and it is difficult to make an accurate prediction of the outcome.
| Segmental Spinal Cord Level and Function | |
|---|---|
| Level | Function |
| C1-C6 | Neck flexors |
| C1-T1 | Neck extensors |
| C3,C4,C5 | Supply diaphragm (mostly C4) |
| C5,C6 | Shoulder movement, raise arm (deltoid); flexion of elbow (biceps); C6 externally rotates the arm (supinates) |
| C6,C7 | Extends elbow and wrist (triceps and wristextensors); pronates wrist |
| C7,T1 | Flexes wrist |
| C7,T1 | Supply small muscles of the hand |
| T1-T6 | Intercostals and trunk above the waist |
| T7-L1 | Abdominal muscles |
| L1,L2,L3,L4 | Thigh flexion |
| L2,L3,L4 | Thigh adduction |
| L4,L5, S1 | Thigh abduction |
| L5,S1, S2 | Extension of leg at the hip (gluteus maximus) |
| L2,L3,L4 | Extension of leg at the knee (quadriceps femoris) |
| L4,L5,S1,S2 | Flexion of leg at the knee (hamstrings) |
| L4,L5,S1 | Dorsiflexion of foot (tibialis anterior) |
| L4,L5,S1 | Extension of toes |
| L5,S1,S2 | Plantar flexion of foot |
| L5,S1,S2 | Flexion of toes |
Cervical
Cervical (neck) injuries usually result in full or partial tetraplegia (Quadriplegia). However, depending on the specific location and severity of trauma, limited function may be retained.
- Injuries at the C-1/C-2 levels will often result in loss of breathing, necessitating mechanical ventilators or phrenic nerve pacing.
- C3 vertebrae and above : Typically results in loss of diaphragm function, necessitating the use of a ventilator for breathing.
- C4 : Results in significant loss of function at the biceps and shoulders.
- C5 : Results in potential loss of function at the shoulders and biceps, and complete loss of function at the wrists and hands.
- C6 : Results in limited wrist control, and complete loss of hand function.
- C7 and T1 : Results in lack of dexterity in the hands and fingers, but allows for limited use of arms.
Patients with complete injuries above C7 typically cannot handle activities of daily living and cannot function independently.[citation needed]
Additional signs and symptoms of cervical injuries include:
- Inability or reduced ability to regulate heart rate, blood pressure, sweating and hence body temperature.
- Autonomic dysreflexia or abnormal increases in blood pressure, sweating, and other autonomic responses to pain or sensory disturbances.
Thoracic
Complete injuries at or below the thoracic spinal levels result in paraplegia. Functions of the hands, arms, neck, and breathing are usually not affected.
- T1 to T8 : Results in the inability to control the abdominal muscles. Accordingly, trunk stability is affected. The lower the level of injury, the less severe the effects.
- T9 to T12 : Results in partial loss of trunk and abdominal muscle control.
Typically lesions above the T6 spinal cord level can result in Autonomic Dysreflexia.[11]
Lumbosacral
The effects of injuries to the lumbar or sacral regions of the spinal cord are decreased control of the legs and hips, urinary system, and anus.
- Bowel and bladder function is regulated by the sacral region of the spine. In that regard, it is very common to experience dysfunction of the bowel and bladder, including infections of the bladder and anal incontinence, after traumatic injury.
- Sexual function is also associated with the sacral spinal segments, and is often affected after injury. During a psychogenicsexual experience, signals from the brain are sent to the sacral parasympathetic cell bodies at spinal levels S2-S4 and in case of men, are then relayed to the penis where they trigger an erection. A spinal cord lesion of descending fibers to levels S2-S4 could, therefore, potentially result in the loss of psychogenic erection. A reflexogenic erection, on the other hand, occurs as a result of direct physical contact to the penis or other erotic areas such as the ears, nipples or neck, and thus not involving descending fibers from the brain. A reflex erection is involuntary and can occur without sexually stimulating thoughts. The nerves that control a man's ability to have a reflex erection are located in the sacral nerves (S2-S4) of the spinal cord and could be affected after a spinal cord injury at this level.[12][13][14]
[edit]Other syndromes of incomplete injury
Central cord syndrome is a form of incomplete spinal cord injury characterized by impairment in the arms and hands and, to a lesser extent, in the legs. This is also referred to as inverse paraplegia, because the hands and arms are paralyzed while the legs and lower extremities work correctly.
Most often the damage is to the cervical or upper thoracic regions of the spinal cord, and characterized by weakness in the arms with relative sparing of the legs with variable sensory loss.
This condition is associated with ischemia, hemorrhage, or necrosis involving the central portions of the spinal cord (the large nerve fibers that carry information directly from the cerebral cortex). Corticospinal fibers destined for the legs are spared due to their more external location in the spinal cord.
Ischemia of the spinal cord is reduced blood flow to the spinal cord which is supplied by the anterior spinal artery and the paired posterior spinal arteries. This condition may be associated with arterioscleorosis, trauma, emboli, diseases of the aorta, and other disorders. Prolonged ischemia may lead to infarction of the spinal cord tissue.[15] Ischemia of the spinal cord affects its function and can lead to muscle weakness and paralysis. The spinal cord may also suffer circulatory impairment if the segmental medullary arteries, particularly the great anterior segmental medullary artery are narrowed by obstructive arterial disease. When systemic blood pressure drops severely for 3-6 min, blood flow from the segmental medullary arteries to the anterior spinal artery supplying the midthoracic region of the spinal cord may be reduced or stopped. These people may also lose sensation and voluntary movement in the areas supplied by the affected level of the spinal cord. [16]
This clinical pattern may emerge during recovery from spinal shock due to prolonged swelling around or near the vertebrae, causing pressures on the cord. The symptoms may be transient or permanent.
Anterior cord syndrome is often associated with flexion type injuries to the cervical spine, causing damage to the anterior portion of the spinal cord and/or the blood supply from the anterior spinal artery.[17] Below the level of injury motor function, pain sensation, and temperature sensation are lost. While touch, proprioception (sense of position in space), and sense of vibration remain intact.
Posterior cord syndrome can also occur, but is very rare. Damage to the posterior portion of the spinal cord and/or interruption to the posterior spinal artery causes the loss of proprioception and epicritic sensation (e.g.: stereognosis, graphesthesia) below the level of injury.[17] Motor function, sense of pain, and sensitivity to light touch remain intact.[17]
Brown-Séquard syndrome usually occurs when the spinal cord is hemisectioned or injured on the lateral side. True hemisections of the spinal cord are rare, while partial lesions due to penetrating wounds (e.g.: gunshot wounds or knife penetrations) are more common.[17] On the ipsilateral side of the injury (same side), there is a loss of motor function, proprioception, vibration, and light touch. Contralaterally (opposite side of injury), there is a loss of pain, temperature, and crude touch sensations.
Tabes Dorsalis results from injury to the posterior part of the spinal cord, usually from infection diseases such as syphilis, causing loss of touch and proprioceptive sensation.
Conus medullaris syndrome results from injury to the tip of the spinal cord, located at L1 vertebra.
Causes
Spinal cord injuries are most often traumatic, caused by lateral bending, dislocation, rotation, axial loading, and hyperflexion or hyperextension of the cord or cauda equina. Motor vehicle accidents are the most common cause of SCIs, while other causes includefalls, work-related accidents, sports injuries, and penetrations such as stab or gunshot wounds.[18] SCIs can also be of a non-traumatic origin, as in the case of cancer, infection, intervertebral disc disease, vertebral injury and spinal cord vascular disease.[19]
Men are at more risk for spinal cord injury than women.[20][21] More than 80% of the spinal cord injury patients are men.
Diagnosis
A radiographic evaluation using a x-ray, MRI or CT scan can determine if there is any damage to the spinal cord and where it is located. A neurologic evaluation incorporating sensory testing and reflex testing can help determine the motor function of a person with a SCI.
Management
Modern trauma care includes a step called clearing the cervical spine, where a person with a suspected injury is treated as if they have a spinal injury until that injury is ruled out. The objective is to prevent any further spinal cord damage. People are immobilized at the scene of the injury until it is clear that there is no damage to the highest portions of the spine.[25] This is traditionally done using a device called a long spine board and hard collar.
Once at a hospital and immediate life-threatening injuries have been addressed, they are evaluated for spinal injury, typically by x-ray or CT scan. Complications of spinal cord injuries include neurogenic shock, respiratory failure, pulmonary edema, pneumonia, pulmonary emboli and deep venous thrombosis, many of which can be recognized early in treatment and avoided. SCI patients often require extended treatment in an intensive care unit.[26]
Techniques of immobilizing the affected areas in the hospital include Gardner-Wells tongs, which can also exert spinal traction to reduce a fracture or dislocation.[27]
One experimental treatment, therapeutic hypothermia, is used but there is no evidence that it improves outcomes.[28][29] Maintaining mean arterial blood pressures of at least 85 to 90 mmHg using intravenous fluids, transfusion, and vasopressors to ensure adequate blood supply to nerves and prevent damage is another treatment with little evidence of effectiveness.
Surgery
Surgery may also be necessary to remove any bone fragments from the spinal canal and to stabilize the spine.[31] Inflammation can cause further damage to the spinal cord, and patients are sometimes treated with a corticosteroid drug such as methylprednisolone to reduce swelling. The drug is used within 8 hours of the injury.[23] This practice is based on the National Acute Spinal Cord Injury Studies (NASCIS) I and II, though other studies have shown little benefit and concerns about side effects from the drug have changed this practice.[32][33] A food dye, brilliant blue G, has also been shown to have some effect at reducing inflammation after spinal injury.[34][35]Methylprednisolone is not longer recommended in the treatment of acute spinal cord injury.
Steroids
High dose methylprednisolone may improve outcomes if given within 6 hours of injury.[37] However, the improvement shown by large trials has been small, and comes at a cost of increased risk of serious infection or sepsis due to the immunosuppressive qualities of high-dose corticosteroids. Methylprednisolone is not longer recommended in the treatment of acute spinal cord injury.
Rehabilitation
Main article: Rehabilitation in spinal cord injury
When treating a patient with a SCI, repairing the damage created by injury is the ultimate goal. By using a variety of treatments, greater improvements are achieved, and, therefore, treatment should not be limited to one method. Furthermore, increasing activity will increase his/her chances of recovery.[39]
The rehabilitation process following a spinal cord injury typically begins in the acute care setting. Physical therapists, occupational therapists, social workers, psychologists and other health care professionals typically work as a team under the coordination of a physiatrist to decide on goals with the patient and develop a plan of discharge that is appropriate for the patient’s condition.
In the acute phase physical therapists focus on the patient’s respiratory status, prevention of indirect complications (such as pressure sores), maintaining range of motion, and keeping available musculature active.[40] Also, there is great emphasis on airway clearance during this stage of recovery.[41] Following a spinal cord injury, the individual’s respiratory muscles become weak and, in turn, the patient is unable to cough.[42] This results in an accumulation of secretions within the lungs.[42] Physical therapy treatment for airway clearance may include manual percussions and vibrations, postural drainage,[41] respiratory muscle training, and assisted cough techniques.[42] With regards to cough techniques, patients are taught to increase their intra-abdominal pressure by leaning forward to induce cough and clear mild secretions.[42] The quad cough technique is done with the patient lying on their back and the therapist applies pressure on their abdomen in the rhythm of the cough to maximize expiratory flow and mobilize secretions.[42] Manual abdominal compression is another effective technique used to increase expiratory flow which later improves cough.[41] Other techniques used to manage respiratory dysfunction following spinal cord injury include respiratory muscle pacing, abdominal binder, ventilator- assisted speech, and mechanical ventilation.[42]
Depending on the Neurological Level of Impairment (NLI), the muscles responsible for expanding the thorax, which facilitate inhalation, may be affected. If the NLI is such that it affects some of the ventilatory muscles, more emphasis will then be placed on the muscles with intact function. For example, the intercostal muscles receive their innervation from T1 - T11, and if any are damaged, more emphasis will need to placed on the unaffected muscles which are innervated from higher levels of the CNS. As SCI patients suffer from reduced total lung capacity and tidal volume [43] it is pertinent that physical therapists teach SCI patients accessory breathing techniques (e.g. apical breathing, glossopharyngeal breathing, etc.) that typically are not taught to healthy individuals.
Outcome measures
The Functional Independence Measure (FIM) is an assessment tool that aims to evaluate the functional status of patients throughout the rehabilitation process following a stroke,traumatic brain injury, spinal cord injury or cancer.[44] Its area of use can include skilled nursing facilities and hospitals aimed at acute, sub-acute and rehabilitation care. It serves as a consistent data collection tool for the comparison of rehabilitation outcomes across the health care continuum.[44] Furthermore, it aims to allow clinicians to track changes in the functional status of patients from the onset of rehab care through discharge and follow-up. The FIM’s assessment of degree of disability depends on the patient’s score in 18 categories, focusing on motor and cognitive function. Each category or item is rated on a 7-point scale (1 = <25% independence; total assistance required, 7 = 100% independence).[44] As such, FIM scores may be interpreted to indicate level of independence or level of burden of care.
Prognosis
Spinal cord injuries frequently result in at least some incurable impairment even with the best possible treatment. In general, patients with complete injuries recover very little lost function and patients with incomplete injuries have more hope of recovery. Some patients that are initially assessed as having complete injuries are later reclassified as having incomplete injuries.
The place of the injury determines which parts of the body are affected. The severity of the injury determines how much the body will be affected. Consequently, a person with a mild, incomplete injury at the T5 vertebrae will have a much better chance of using his or her legs than a person with a severe, complete injury at exactly the same place in the spine.
Recovery is typically quickest during the first six months, with very few patients experiencing any substantial recovery more than nine months after the injury.[45]
Tetraplegia (quadriplegia)
The ASIA motor score (AMS) is a 100 point score based on ten pairs of muscles each given a five point rating. A person with no injury should score 100. In complete tetraplegia, a recovery of nine points on this scale is average regardless of where the patient starts. Patients with higher levels of injury will typically have lower starting scores.[45]
In incomplete tetraplegia, 46 percent of patients were able to walk one year after injury, though they may require assistance such as crutches and braces. These patients had similar recovery in muscles of the upper and lower body. Patients who had pinprick sensation in the sacral dermatomes such as the anus recovered better than patients that could only sense a light touch.
Paraplegia
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In one study on 142 individuals after one year of complete paraplegia, none of the patients where the initial injury was above the ninth thoracic vertebra (T9) were able to recover completely. Less than half, 38 percent, of the studied subjects had any sort of recovery. Very few, five percent, recovered enough function to walk, and those required crutches and other assistive devices, and all of them had injuries below T11. A few of the patients, four percent, had what were originally classified as complete injuries and were reassessed as having incomplete injuries, but only half of that four percent regained bowel and bladder control.[45]
Of the 54 patients in the same study with incomplete paraplegia 76 percent were able to walk with assistance after one year. On average, patients improved 12 points on the 50 point lower extremity motor score (LEMS) scale. The amount of improvement was not dependent on the location of the injury, but patients with higher injuries had lower initial motor scores and correspondingly lower final motor scores. A LEMS of 50 is normal, and scores of 30 or higher typically predict ability to walk.
Epidemiology
Spinal injury can occur without trauma. Many people suffer transient loss of function ("stingers") in sports accidents or pain in "whiplash" of the neck without neurological loss and relatively few of these suffer spinal cord injury sufficient to warrant hospitalization. The prevalence of spinal cord injury is not well known in many large countries. In some countries, such as Sweden and Iceland, registries are available. In the United States, the incidence of spinal cord injury has been estimated to be about 40 cases (per 1 million people) per year or around 12,000 cases per year.[46][47] The most common causes of spinal cord injury are motor vehicle accidents, falls, violence and sports injuries.[47] The average age at the time of injury has slowly increased from a reported 29 years of age in the mid-1970s to a current average of around 40. Over 80% of the spinal injuries reported to a major national database occurred in males.[48] In the United States there are around 250,000 individuals living with spinal cord injuries.[24][49] In China, the incidence of spinal cord injury is approximately 60,000 per year.
Research directions
Scientists are investigating many promising avenues for treatment of spinal cord injury. Numerous articles in the medical literature describe research, mostly in animal models, aimed at reducing the paralyzing effects of injury and promoting regrowth of functional nerve fibers.[51] Despite the devastating effects of the condition, commercial funding for research investigating a cure after spinal cord injury is limited, partially due to the small size of the population of potential beneficiaries.[citation needed] Some experimental treatments, such as systemic hypothermia, have been performed in isolated cases in order draw attention to the need for further preclinical and clinical studies to help clarify the role of hypothermia in acute spinal cord injury.[52] Despite the limitation on funding, a number of experimental treatments such as local spine cooling and oscillating field stimulation have reached controlled human trials,[53][54]
Advances in identification of an effective therapeutic target after spinal cord injury have been newsworthy, and considerable media attention is often drawn towards new developments in this area. However, aside from methylprednisolone, none of these developments have reached even limited use in the clinical care of human spinal cord injury in the U.S.[55]
Stem cells
Around the world, proprietary centers offering stem cell transplants and treatment with neuroregenerative substances are fueled by glowing testimonial reports of neurological improvement. It is also evident that when stem cells are injected in the area of damage in the spinal cord, they secrete neurotrophic factors, and these neurotrophic factors help neurons and vessels grow, thus helping repair the damage.[56][57][58] Bone Marrow Stem cells especially the CD34+ cells have been found to be relatively more in men compared to women in the reproductive age group among spinal cord injury patients.[21]
In 2009 the FDA approved the country's first human trial on embryonic stem cell transplantation into patients suffering from varying levels of traumatic spinal cord injury.[59] The trial however came to a halt in November 2011 when the company, which was financing the trial, announced the discontinuation of the trial due to financial issues.[60] It is important to note that only financial issues led to the trial being discontinued and not any scientific or ethical reasons.[61]
Other than stem cells, transplantation of tissues such as olfactory ensheathing mucosa have been shown to produce beneficial effects in spinal cord injured rats.[62]
Independent validation of the results of the various stem cell treatments is lacking.[63][64] However, current approaches on cell and tissue based therapies' for clinical application for spinal cord injury need to establish the underlying efficacy and mechanisms.
Engineering approaches
Recent approaches have used various engineering techniques to improve spinal cord injury repair. The general hypothesis of this is that bridging the lesion site using a growth permissive scaffold may promote axonal extension and in turn improve behavioral function. Engineered treatments are ideal for spinal cord injury repair because they do not induce an immune response like biological treatments and they are easily tunable and reproducible. In-vivo administration of hydrogels or self-assembling nanofibers has been shown to promote axonal sprouting and partial functional recovery.[65][66] In addition, administration of carbon nanotubes has shown to increase motor axon extension, decrease the lesion volume, and not induce neuropathic pain.[67] In addition, administration of poly-lactic acid microfibers has shown that topographical guidance cues alone can promote axonal regeneration into the injury site.[68] However, all of these approaches induced modest behavioral or functional recovery suggesting that further investigation is necessary.
BCI
Recent research shows that combining brain–computer interface and functional electrical stimulation can restore voluntary control of paralyzed muscles. A study with monkeys showed that it is possible to directly use commands from the brain, bypassing the spinal cord and enable limited hand control and function.