Spinal cord injury

Spinal cord injury
Specialty	Emergency medicine, neurosurgery

A spinal cord injury (SCI) is damage to the spinal cord that causes changes in its function. Injuries can occur at any level of the spinal cord and can be classified as complete injury, a total loss of sensation and muscle function, or incomplete, meaning some nervous signals are able to travel past the injured area of the cord. Depending on the location and severity of damage along the spinal cord, the symptoms can vary widely, from pain or numbness to paralysis to incontinence. The prognosis also ranges widely, from full recovery to permanent tetraplegia (also called quadriplegia) in injuries at the level of the neck, and paraplegia in lower injuries. Complications that can occur in the short and long term after injury include pressure sores, infections, muscle atrophy, and respiratory problems.

Usually the damage results from physical trauma such as car accidents, gunshots, falls, or sports injuries, but it can also result from nontraumatic causes such as infection, insufficient blood flow, or pressure from a tumor. Efforts to prevent SCI include individual measures such as using safety equipment and societal measures such as safety regulations in sports and traffic and improvements to equipment. Treatment of spinal cord injuries starts with stabilizing the spine and controlling inflammation to prevent further damage. Other interventions needed can vary widely depending on the location and extent of the injury, from bed rest to surgery. In many cases, spinal cord injuries require substantial, long-term physical and occupational therapy in rehabilitation, especially if they interfere with activities of daily living. Known since ancient times to be a catastrophic injury and long believed to be untreatable, SCI has seen great improvements in its care since the middle of the 20th century. Research into new treatments for spinal cord injuries includes controlled hypothermia, stem cell implantation, and wearable robotic exoskeletons.

Classification

Muscle strength score

Grade	Muscle function
0	No muscle contraction
1	Muscle flickers
2	Full range of motion with gravity eliminated
3	Full range of motion against gravity
4	Full range of motion against resistance
5	Normal strength

Spinal cord injury can be traumatic or nontraumatic, and can be classified into three types based on cause: mechanical forces, toxic, and ischemic (from lack of blood flow). The damage can also be divided into primary and secondary injury: the cell death that occurs immediately in the original injury, and biochemical cascades that are initiated by the original insult and cause further tissue damage. These secondary injury pathways include the ischemic cascade, inflammation, swelling, cell suicide, and neurotransmitter imbalances. They can take place for minutes or weeks following the injury.

The level of injury is determined by the part of the spinal cord that was damaged and corresponds to the nearest pair of spinal nerves that exit between the vertebrae. Thus injuries can be cervical 1–8 (C1–C8), thoracic 1–12 (T1–T12), lumbar 1–5 (L1–L5), or sacral (S1–S5). A person's level of injury is defined as the lowest level of full sensation and function. Paraplegia occurs when the legs are affected by the spinal cord damage (in thoracic, lumbar, or sacral injuries), and tetraplegia occurs when all four limbs are affected (cervical damage).

SCI is also classified by the degree of impairment. The International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI), published by the American Spinal Injury Association (ASIA), is widely used to document sensory and motor impairments following SCI. It is based on neurological responses, touch and pinprick sensations tested in each dermatome, and strength of the muscles that control key motions on both sides of the body.

ASIA Impairment Scale for classifying spinal cord injury

Grade	Description
A	Complete injury. No motor or sensory function is preserved in the sacral segments S4 or S5.
B	Sensory incomplete. Sensory but not motor function is preserved below the level of injury, including the sacral segments.
C	Motor incomplete. Motor function is preserved below the level of injury, and more than half of muscles tested below the level of injury have a muscle grade less than 3 (see muscle strength scores table).
D	Motor incomplete. Motor function is preserved below the level of injury and at least half of the key muscles below the neurological level have a muscle grade of 3 or more.
E	Normal. No motor or sensory deficits, but deficits existed in the past.

Complete and incomplete injuries

Level and completeness of injuries

	Complete	Incomplete
Tetraplegia	18.3%	34.1%
Paraplegia	23.0%	18.5%

In a "complete" spinal injury, all functions below the injured area are lost, whether or not the spinal cord is severed. An "incomplete" spinal cord injury involves preservation of motor or sensory function below the level of injury in the spinal cord. To be classed as incomplete, there must be some preservation of sensation or motion in the areas innervated by S4 to S5, i.e. voluntary external anal sphincter contraction. The nerves in this area are connected to the very lowest region of the spinal cord, and retaining sensation and function in these parts of the body indicates that the spinal cord is only partially damaged. This includes a phenomenon known as sacral sparing which involves the preservation of sensation in the sacral dermatomes, even though sensation may be more impaired in other, higher dermatomes below the level of the lesion. Sacral sparing has been attributed to the fact that the sacral spinal pathways are not as likely as the other spinal pathways to become compressed after injury due to the lamination of fibers within the spinal cord.

Spinal cord injury without radiographic abnormality

Spinal column injury is trauma that causes fracture of the bone or instability of the ligaments in the spinal column; this can coexist with or result in injury to the spinal cord itself but each injury can occur without the other. Spinal cord injury without radiographic abnormality (SCIWORA) exists when SCI is present but no evidence of spinal column injury is present on radiographs. Abnormalities might show up on magnetic resonance imaging (MRI), but the term was coined before MRI was in common use.

Central cord syndrome

Incomplete lesions of the spinal cord: Central cord syndrome (top), Anterior cord syndrome (middle), and Brown-Séquard syndrome (bottom).

Central cord syndrome, almost always resulting from damage to the cervical spinal cord, is characterized by weakness in the arms with relative sparing of the legs, and spared sensation in regions served by the sacral segments. This is also referred to as inverse paraplegia. 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.

Anterior cord syndrome

Anterior cord syndrome is often associated with flexion type injuries to the cervical spine, causing damage to the front portion of the spinal cord and/or the blood supply from the anterior spinal artery. Below the level of injury, motor function, pain sensation, and temperature sensation are lost, while sense of touch and proprioception (sense of position in space) remain intact.

Brown-Séquard syndrome

Brown-Séquard syndrome occurs when the spinal cord is injured on one side much more than the other. True hemisections (cutting half) of the spinal cord are rare, but partial lesions due to penetrating wounds (such as gunshot wounds or knife penetrations) are more common. On the ipsilateral side of the injury (same side), the body loses motor function, proprioception, and senses of vibration and touch. On the contralateral (opposite side) of the injury, there is a loss of pain and temperature sensations. The loss on the contralateral side begins several dermatome sections below the level of injury. This discrepancy occurs because the lateral spinothalamic tracts ascend two or four segments on the same side before crossing.

Ischemia

Ischemia, or reduced blood flow to the spinal cord, may be associated with arteriosclerosis, trauma, emboli, diseases of the aorta, and other disorders. Prolonged ischemia may lead to infarction of the spinal cord tissue. When systemic blood pressure drops severely for 3–6 minutes, blood flow to the artery supplying the midthoracic region of the spinal cord may be reduced or stopped. This may cause a loss of sensation and voluntary movement in the areas supplied by the affected level of the spinal cord.

Other syndromes

Posterior cord syndrome can also occur, but is very rare. Damage to the posterior portion of the spinal cord and interruption to the posterior spinal artery cause the loss of proprioception and epicritic sensation (e.g.: stereognosis, graphesthesia) below the level of injury. Motor function, sense of pain, and sensitivity to light touch remain intact. Usually posterior cord injuries result from insults like disease or vitamin deficiency rather than trauma. Tabes dorsalis results from injury to the posterior part of the spinal cord, usually from infectious diseases such as syphilis, causing loss of touch and proprioceptive sensation.

Conus medullaris syndrome is an injury to the end of the spinal cord, located at about the T12–L2 vertebrae in adults. This region contains the S4–S5 spinal segments, which are responsible for bowel, bladder, and some sexual functions, so these can be disrupted in this type of injury. In addition sensation and the Achilles reflex can be disrupted. Cauda equina syndrome (CES) results from a lesion below the level at which the spinal cord splits into the cauda equina, at levels L2–S5 below the conus medullaris. It can cause low back pain, weakness or paralysis in the lower limbs, loss of sensation, bowel and bladder dysfunction, and loss of reflexes. CES can occur by itself or alongside conus medullaris syndrome. Since the nerves damaged in CES are actually peripheral nerves because they have already branched off from the spinal cord, the injury has better prognosis for recovery of function: the peripheral nervous system has a greater capacity for healing than the central nervous system.

Signs and symptoms

Actions of the spinal nerves

Level	Motor Function
C1–C6	Neck flexors
C1–T1	Neck extensors
C3, C4, C5	Supply diaphragm (mostly C4)
C5, C6	Move shoulder, raise arm (deltoid); flex elbow (biceps)
C6	externally rotate (supinate) the arm
C6, C7	Extend elbow and wrist (triceps and wrist extensors); pronate wrist
C7, T1	Flex wrist; supply small muscles of the hand
T1–T6	Intercostals and trunk above the waist
T7–L1	Abdominal muscles
L1–L4	Flex thigh
L2, L3, L4	Adduct thigh; Extend leg at the knee (quadriceps femoris)
L4, L5, S1	abduct thigh; Flex leg at the knee (hamstrings); Dorsiflex foot (tibialis anterior); Extend toes
L5, S1, S2	Extend leg at the hip (gluteus maximus); Plantar flex foot and flex toes

Further information: Dermatome (anatomy)

Signs (recorded by a clinician) and symptoms (experienced by a patient) vary depending on where the spine is injured and the extent of the injury. A section of skin innervated through 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. Thus a person with a lowered level of consciousness may show a response to a painful stimulus above a certain point but not below it. A group of muscles innervated through a specific part of the spine is called a myotome, and injury to the spinal cord can cause problems with motor control. The muscles may contract uncontrollably (spasticity), become weak, or be completely paralysed.

The specific parts of the body affected by loss of function are determined by the level of injury.

Lumbosacral

The effects of injuries at or above the lumbar or sacral regions of the spinal cord (lower back and pelvis) include decreased control of the legs and hips, genitourinary system, and anus. Bowel and bladder function are regulated by the sacral region. Thus it is very common to experience dysfunction of the bowel and bladder, including urinary and fecal incontinence, as well as sexual dysfunction after injury.

Thoracic

In addition to the problems found in lower-level injuries, thoracic (chest height) spinal lesions can affect the muscles in the trunk. Injuries at the level of T1 to T8 result in the inability to control the abdominal muscles. Accordingly, trunk stability is affected. The lower the level of injury, the less severe the effects. Injuries from T9 to T12 result in partial loss of trunk and abdominal muscle control. Thoracic spinal levels can result in paraplegia, but function of the hands, arms, neck, and breathing muscles are usually not affected.

One condition that can occur typically in lesions above the T6 level is autonomic dysreflexia (AD), in which the blood pressure increases to dangerous levels high enough to cause potentially deadly stroke. It results from an overreaction of the system to a stimulus such as pain below the level of injury because inhibitory signals from the brain cannot pass the lesion to dampen the excitatory sympathetic nervous system response. Signs and symptoms of AD include anxiety, headache, nausea, ringing in the ears, blurred vision, flushed skin, and nasal congestion. It can occur shortly after the injury or not until years later.

Another serious complication that can result from lesions above T6 is neurogenic shock, which results from an interruption in output from the sympathetic nervous system responsible for opposing the parasympathetic nervous system and maintaining muscle tone in the blood vessels, allowing them to relax and dilate. Neurogenic shock presents with dangerously low blood pressure, low heart rate, and blood pooling in the limbs—which results in insufficient blood flow to the spinal cord and potentially further damage to it.

Cervical

Spinal cord injuries at the cervical (neck) level, which account for almost 57% of spinal cord injuries, can result in full or partial tetraplegia (also called quadriplegia). However, depending on the specific location and severity of trauma, limited function may be retained.

Function after complete cervical spinal cord injury

Level	Respiratory function	Motor Function
C1–C4	Cannot breathe without mechanical ventilation	Full paralysis of the limbs
C5	Difficulty coughing, may need help clearing secretions	Paralysis of the wrists, hands, and triceps
C6		Paralysis of the wrist flexors, triceps, and hands
C7–C8		Some hand muscle weakness, difficulty grasping and releasing

Additional signs and symptoms of cervical injuries include low heart rate, low blood pressure, problems regulating body temperature, and breathing dysfunction. If the injury is high enough in the neck to impair the muscles involved in breathing, the person may not be able to breathe without the help of an endotracheal tube and mechanical ventilator.

Causes

Falling as a part of recreational activities can cause spinal cord injuries.

Spinal cord injuries are most often caused by physical trauma, including rotational force, axial loading, hyperflexion, or hyperextension of the cord or cauda equina. Traumatic SCI can be from stretching or twisting in addition, and can result in contusion, compression, or stretch injury. In the US, Motor vehicle accidents are the most common cause of SCIs; second are falls, then violence such as gunshot wounds, then sports injuries. Of all sports-related SCIs, shallow water dives are the most common cause; winter sports and water sports have been increasing as causes while association football and trampoline injuries have been declining. Hanging can cause injury to the cervical spine, as may occur in attempted suicide. Another potential cause of SCI is iatrogenic injury, caused by an improperly done medical procedure such as an injection into the spinal column.

SCI can also be of a nontraumatic origin, as may occur in infection, intervertebral disc disease, and spinal cord vascular disease. Spontaneous bleeding can occur within or outside of the protective membranes that line the cord, and intervertebral disks can herniate. Congenital conditions and tumors that compress the cord can also cause SCI, as can vertebral spondylosis and ischemia. Multiple sclerosis is a disease that can damage the spinal cord, as can infectious or inflammatory conditions such as tuburculosis, herpes zoster or herpes simplex, meningitis, myelitis, and syphilis. In developed countries, the most common cause of nontraumatic SCI is degenerative diseases, followed by tumors; in many developing countries the leading cause is infection such as HIV and tuburculosis.

Prevention

Measures to prevent vehicle-related SCI include societal and individual efforts to reduce driving under the influence of drugs or alcohol, distracted driving, and drowsy driving. Other efforts include increasing road safety (such as adding lighting and marking hazards) and vehicle safety, both to prevent (such as routine maintenance and antilock brakes) and to mitigate the damage of crashes (such as head restraints, air bags, seat belts, and child safety seats). Falls can be prevented by making changes to the environment, such as nonslip materials and grab bars in bathtubs and showers, railings for stairs, and child safety gates for windows. Gun-related injuries can be prevented with conflict resolution training, gun safety education campaigns, and changes to gun technology to improve the safety of guns (such as trigger locks). Sports injuries can be prevented with changes to sports rules and equipment to increase safety, and education campaigns to reduce risky practices such as diving into water of unknown depth or head-first tackling in association football.

Diagnosis

X-rays (left) are more available, but can miss details like herniated disks that MRIs can show (right).

A radiographic evaluation using an X-ray, CT scan, or MRI can determine if there is any damage to the spinal cord and where it is located. X-rays, are commonly available and can detect instability or misalignment of the spinal column, but do not give very detailed images and can miss injuries to the spinal cord or displacement of ligaments or disks that do not have accompanying spinal column damage. Thus when X-ray findings are normal but SCI is still suspected due to pain or SCI symptoms, CT or MRI scans are used. CT gives greater detail than X-rays, but still does not give images of the spinal cord or ligaments; MRI shows body structures in the greatest detail.

Neurological evaluations to help determine the degree of impairment are performed initially and repeatedly in the early stages of treatment; this determines the rate of improvement or deterioration and informs treatment and prognosis. The ASIA Impairment Scale outlined above is used to determine the level and severity of injury.

Management

Prehospital treatment

Spine immobilization with a long spine board

The first stage in the management of a suspected spinal cord injury is geared toward basic life support and preventing further injury: maintaining airway, breathing, and circulation and immobilizing the spine. In the emergency setting, anyone who has been subjected to forces strong enough to cause SCI is treated as though they have instability in the spinal column and is immobilized to prevent damage to the spinal cord. Injuries or fractures in the head, neck, or pelvis as well as penetrating trauma near the spine and falls from heights are assumed to be associated with an unstable spinal column until it is ruled out in the hospital. Since head and spinal trauma frequently coexist, anyone who is unconscious or has a lowered level of consciousness as a result of a head injury is similarly immobilized. A rigid cervical collar is applied to the neck, and the head is held immobile with blocks on either side and the person is strapped to a backboard. An extrication device may be required to move the injured person without moving the spine if they are still inside a vehicle or other confined space. Modern trauma care includes a step called clearing the cervical spine, ruling out spinal cord injury if the patient is fully conscious and not under the influence of drugs or alcohol, displays no neurological deficits, has no pain in the middle of the neck and no other painful injuries that could distract from neck pain. If these are all absent, no immobilization is necessary. If an unstable spinal column injury is moved, damage may occur to the spinal cord. Between 3 and 25% of SCIs occur not at the time of the initial trauma but later during treatment or transport. While some of this is due to the nature of the injury itself, particularly in the case of multiple or massive trauma, some of it reflects the failure to immobilize the spine adequately.

SCI can impair the body's ability to keep warm, so warming blankets may be needed.

Early hospital treatment

Initial care in the hospital, as in the prehospital setting, aims to ensure adequate airway, breathing, cardiovascular function, and spinal immobilization. Acute SCI merits treatment in an intensive care unit, especially injuries to the cervival spinal cord.

If the systolic blood pressure falls below 90 mmHg within days of the injury, blood supply to the spinal cord may be reduced, resulting in further damage. Thus it is important to maintain the blood pressure using a central venous catheter, intravenous fluids, and vasopressors, and to treat cases of shock. The treatment for shock from blood loss (hypovolemic shock) is different from that for neurogenic shock, and could harm people with the latter type, so it is necessary to first determine which type a person in shock has.

Surgery may be necessary between eight and 24 hours following SCI. The objective might be to stabilize the spine, or it may also be a way to relieve excess pressure on the cord or to put vertebrae back in their proper place. Surgery is also necessary when something is pressing on the cord, such as bone fragments, blood, material from ligaments or intervertebral discs, or a lodged object from a penetrating injury.

Surgery is controversial because it has potential complications (such as infection) and has not been conclusively shown to be more or less effective than a conservative, nonsurgical approach. In cases where a more conservative approach is chosen, bed rest, cervical collars, immobilizing devices, and optionally traction are used. Orthopedic specialists or neurosurgeons may opt to put traction on the spine to remove pressure from the spinal cord by putting dislocated vertebrae back into alignment. Gardner-Wells tongs are one tool used to exert spinal traction to reduce a fracture or dislocation and to immobilize the affected areas.

Steroids

Swelling can cause further damage to the spinal cord by reducing the blood supply and causing ischemia, which can give rise to an ischemic cascade with a release of toxins that damages neurons. Thus treatment is often geared toward limiting this secondary injury. People are sometimes treated with drugs to reduce swelling. Corticosteroid drugs such as methylprednisolone are commonly used within eight hours of the injury, but they are controversial because of their side effects. Studies have shown high dose methylprednisolone may improve outcomes if given within 6 hours of injury. However, the improvement shown by clinical trials has been inconclusive, and comes at the cost of increased risk of serious infection or sepsis, gastrointestinal bleeding, and pneumonia. Thus organizations that set clinical guidelines have increasingly stopped recommending methylprednisolone in the treatment of acute SCI.

Rehabilitation

Main article: Rehabilitation in spinal cord injury

SCI patients often require extended treatment in specialized spinal unit or an intensive care unit. The rehabilitation process typically begins in the acute care setting. Typically the inpatient phase lasts 8–12 weeks and then the outpatient rehabilitation phase lasts 3–12 months after that, followed by yearly medical and functional evaluation. Physical therapists, occupational therapists, nurses, 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 person’s condition. When treating a person with 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 chances of recovery.

Orthopedic devices such as ankle-foot orthoses can aid in walking.

In the acute phase physical therapists focus on the patient’s respiratory status, prevention of indirect complications (such as pressure ulcers), maintaining range of motion, and keeping available musculature active. Weak joints can be stabilized with devices such as ankle-foot orthoses and knee-AFOs, but walking may still require a lot of effort.

For people whose injuries are high enough to interfere with breathing, there is great emphasis on airway clearance during this stage of recovery. Following a spinal cord injury, the individual’s respiratory muscles may become weak, making the patient unable to cough effectively and allowing secretions to accumulate within the lungs. As SCI patients suffer from reduced total lung capacity and tidal volume, physical therapists teach SCI patients accessory breathing techniques (e.g. apical breathing, glossopharyngeal breathing, etc.) that typically are not taught to healthy individuals. Physical therapy treatment for airway clearance may include manual percussions and vibrations, postural drainage, respiratory muscle training, and assisted cough techniques. Patients are taught to increase their intra-abdominal pressure by leaning forward to induce cough and clear mild secretions. The quad cough technique is done with the patient lying on their back and the therapist applying pressure on the abdomen in the rhythm of the cough to maximize expiratory flow and mobilize secretions. Manual abdominal compression is another effective technique used to increase expiratory flow which later improves cough. Other techniques used to manage respiratory dysfunction include respiratory muscle pacing, use of a constricting abdominal binder, ventilator-assisted speech, and mechanical ventilation.

People with SCI may need to use specialized devices and to make modifications to their environment in order to handle activities of daily living and function independently. The Functional Independence Measure (FIM) is an assessment tool that aims to evaluate the function of patients throughout the rehabilitation process following a spinal cord injury or other serious illness or injury. It can track a patient's progress and degree of independence during rehabilitation.

Prognosis

Spinal cord injuries frequently result in at least some incurable impairment even with the best possible treatment. The best predictor of prognosis is the level and completeness of injury, as measured by the ASIA impairment scale. The neurological score at the initial evaluation done 72 hours after injury is the best predictor of how much function will return. Most people with ASIA scores of A (complete injuries) do not have functional motor recovery, but improvement can occur. Most patients with incomplete injuries recover at least some function. Chances of recovering the ability to walk improve with each AIS grade found at the initial examination; e.g. an ASIA D score confers a better chance of walking than a score of C. The symptoms of incomplete injuries can vary and it is difficult to make an accurate prediction of the outcome. A person with a mild, incomplete injury at the T5 vertebra 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. Of the incomplete SCI syndromes, Brown-Séquard and central cord syndromes have the best prognosis for recovery and anterior cord syndrome has the worst. In addition to the completeness and level of the injury, age and concurrent health problems affect the extent to which a person with SCI will be able to live independently and to walk. However in general people with injuries to L3 or below will likely be able to walk functionally, T10 and below to walk around the house with bracing, and C7 and below to live independently.

Most motor recovery occurs in the first year post-injury, but modest improvements can continue for years; sensory recovery is more limited. Recovery is typically quickest during the first six months; very few patients experience substantial recovery more than nine months after the injury. Spinal shock, in which reflexes are suppressed, occurs immediately after the injury and resolves largely within three months but continues resolving gradually for another 15. One important predictor of motor recovery in an area is presence of sensation there, particularly pain perception.

Sexual dysfunction after spinal injury is common. Problems that can occur include erectile dysfunction, loss of ability to ejaculate, insufficient lubrication of the vagina, and reduced sensation and impaired ability to orgasm. While sexual dysfunction is very common after SCI, many people learn ways to adapt their sexual practices so they can lead satisfying sex lives.

People with nontraumatic causes of SCI have been found to be less likely to suffer complete injuries and some complications such as pressure sores and deep vein thrombosis, and to have shorter hospital stays. Their scores on functional tests were better than those of people with traumatic SCI upon hospital admission, but the same upon discharge.

Tetraplegia

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.

In incomplete tetraplegia, 46% of patients were able to walk one year after injury, though they may require assistive devices 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

Holly Koester incurred a spinal injury as a result of a motor vehicle collision and is now a wheelchair racer.

In one study on 143 individuals after one year of complete paraplegia, none of the patients with an initial injury above the ninth thoracic vertebra (T9) were able to recover completely. Only 38% of the studied subjects had any sort of recovery. Only 5% recovered enough function to walk, and those required crutches and other assistive devices, and all of them had injuries below T11. 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.

Of the 54 people in the same study with incomplete paraplegia, 76% 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.

Complications

Complications of spinal cord injuries include neurogenic shock, respiratory failure, pulmonary edema, and paralysis below the injury site. In the long term, the loss of muscle function can have additional effects if the muscle is not used, including atrophy of the muscle. Immobility can also lead to pressure sores, particularly in bony areas, requiring precautions such as extra cushioning and turning the patient every two hours in the acute setting to relieve pressure. Another complication is pain, including nociceptive pain (indication of potential or actual tissue damage) and neuropathic pain, when nerves affected by damage convey erroneous pain signals in the absence of noxious stimuli. Spasticity, the uncontrollable tensing of muscles below the level of injury, occurs in 65–78% of chronic SCI. It results from lack of input from the brain that quells muscle responses to stretch reflexes. It can be treated with drugs and physical therapy. Contractures are shortening of muscles, tendons, or ligaments that result from lack of use of a limb; the problem can be prevented by exercises and devices to stretch the limb. Lack of mobility can also cause loss of bone density and changes in bone structure. Loss of bone density (bone demineralization), thought to be due to lack of input from weakened or paralysed muscles, can increase the risk of fractures. Conversely, another poorly understood phenomenon is the overgrowth of bone tissue in soft tissue areas called heterotopic ossification. It occurs below the level of injury, possibly as a ressult of inflammation, and happens to a clinically significant extent in 27% of people.

People with SCI are at especially high risk for respiratory and cardiovascular problems, so hospital staff must be watchful to avoid them. Respiratory problems (especially pneumonia) are the leading cause of death in people with SCI, followed by infections, usually of decubitus ulcers, urinary tract infections (UTIs) and respiratory infections. Pneumonia can be accompanied by shortness of breath, fever, and anxiety.

Another potentially deadly threat to respiration is Deep venous thrombosis (DVT), in which blood forms a clot in immobile limbs; the clot could break off and form a pulmonary embolism (PE), lodging in the lung and cutting off blood supply to it. DVT is an especially high risk in SCI, particularly within 10 days of injury, occurring in over 13% in the acute care setting. Preventative measures include anticoagulants, pressure hose, and moving the patient's limbs. The usual signs and symptoms of DVT and PT may be masked in SCI cases due to effects such as alterations in pain perception and nervous system functioning.

Urinary tract infection (UTI) is another risk that may not display the usual symptoms (pain, urgency and frequency); it may instead be associated with worsened spasticity. The risk of UTI, likely the most common complication in the long term, is heightened by use of indwelling urinary catheters, but catheterization may be necessary because SCI interferes with the bladder's ability to empty when it gets too full, which could trigger autonomic dysreflexia or damage the bladder permanently. The use of intermittent catheterization has decreased the mortality due to kidney failure from UTI in the first world, but it is still a serious problem in developing countries.

An estimated 24–45% of people with SCI suffer disorders of depression, and the suicide rate is as much as six times that of the rest of the population. Depression is associated with an increased risk of other complications such as UTI and pressure ulcers that occur more when self-care is neglected.

Epidemiology

SCI is present in about 2% of all cases of blunt force trauma. In 44% of SCI cases, other serious injuries are sustained at the same time; 14% of SCI patients also suffer head trauma or facial trauma.

Worldwide, the incidence (number of new cases) of SCI ranges from 10.4 to 59 people per million per year. In North America, about 39 people per every million incur SCI traumatically each year, and in Western Europe the incidence is 16 per million. 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. In China, the incidence is approximately 60,000 per year. The estimated prevalence (number of people living with SCI) ranges from 236 per million in India to 1800 per million in the US. In Western Europe the prevalence is 300 per million people and in North America it is 853 per million. In the United States there are betweem 225,000 and 296,000 individuals living with spinal cord injuries.

The average age at the time of injury has slowly increased from about 29 years in the 1970s to 41. Males account for four out of five traumatic spinal cord injuries. Most of these injuries occur in men under 30 years of age. The high numbers of adolescent injuries are attributable in a large part to traffic accidents and sports injuries. For people over 65, falls are the most common cause of traumatic SCI. In nontraumatic SCI, the gender difference is smaller, and the average age of occurrence is greater.

History

The ancient Egyptian Edwin Smith Papyrus is the earliest known description of SCI.

SCI has been known to be devastating for millenia; the ancient Egyptian Edwin Smith Papyrus from 2500 BC, the first known description of the injury, says it is "not to be treated". Hindu texts dating back to 1800 BC also mention SCI and describe traction techniques to straighten the spine. The Greek physician Hippocrates, born in the fifth century BC, described SCI in his Hippocratic Corpus and invented traction devices to straighten dislocated vertebrae. But it was not until Aulus Cornelius Celsus, born 30 BC, noted that a cervical injury resulted in rapid death that the spinal cord itself was implicated in the condition. In the second century AD the Greek physician Galen experimented on monkeys and reported that a horizontal cut through the spinal cord caused them to lose all sensation and motion below the level of the cut. The seventh-century Greek physician Paul of Aegina described surgical techniques for treatment of broken vertebrae by removing bone fragments, as well as surgery to relieve pressure on the spine. Little medical progress was made during the Middle Ages in Europe; it was not until the Renaissance that the spine and nerves were accurately depicted in human anatomy drawings by Leonardo da Vinci and Andreas Vesalius.

In 1762 a surgeon named Andre Louis removed a bullet from the lumbar spine of a patient, who regained motion in the legs. In 1829 the surgeon Gilpin Smith performed a successful laminectomy that improved the patient's sensation. However, the idea that SCI was untreatable remained predominant until the early 20th century. In 1934, the mortality rate in the first two years after injury was over 80%, mostly due to infections of the urinary tract and pressure sores. It was not until the latter half of the century that breakthroughs in imaging, surgery, medical care, and rehabilitation medicine contributed to a substantial improvement in SCI care. The relative incidence of incomplete compared to complete injuries has improved since the mid-20th century, due mainly to the emphasis on faster and better initial care and stabilization of spinal cord injury patients. The creation of emergency medical services to professionally transport people to the hospital is given partial credit for an improvement in outcomes since the 1970s. Improvements in care have been accompanied by increased life expectancy of people with SCI; survival times have improved by about 2000% since 1940.

Research directions

Scientists are investigating various 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. Neuroprotection is another research direction. One experimental treatment, therapeutic hypothermia, is used in treatment but there is no evidence that it improves outcomes. Some experimental treatments, including systemic hypothermia, have been performed in isolated cases in order to draw attention to the need for further preclinical and clinical studies to help clarify the role of hypothermia in acute spinal cord injury. Despite limited funding, a number of experimental treatments such as local spine cooling and oscillating field stimulation have reached controlled human trials.

Inflammation and glial scar are considered important inhibitory factors to neuroregeneration after SCI. However, aside from methylprednisolone, none of these developments have reached even limited use in the clinical care of human spinal cord injury in the US.

Stem cells

When stem cells are injected in the area of damage in the spinal cord, they secrete neurotrophic factors, and these factors help neurons and blood vessels to grow, thus helping repair the damage. Stem cells harvested from the bone marrow, the most common type used in SCI, have been shown in experiments to help repair nervous tissue, regrowing axons and replacing myelin. In 2009 in the US, 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. The trial however came to a halt in November 2011 when the company financing the trial announced its discontinuation due to financial issues. There were not scientific or ethical reasons for the discontinuation. Hundreds of stem cell studies have been done in humans, with promising but inconclusive results.

Transplantation of tissues such as olfactory ensheathing cells from the olfactory bulbs has been shown to produce beneficial effects in spinal cord injured rats. Trials have also begun to show success when olfactory ensheathing cells are transplanted into humans with severed spinal cords. People have recovered sensation, use of formerly paralysed muscles, and bladder and bowel function after the surgeries.

Independent validation of the results of the various stem cell treatments is lacking. 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 is that bridging the lesion site using a growth permissive scaffold may help axons grow and thereby improve behavioral function. Engineered treatments are ideal for spinal cord injury repair because they do not induce an immune response as biological treatments may, 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. In addition, administration of carbon nanotubes has shown to increase motor axon extension and decrease the lesion volume, without inducing neuropathic pain. In addition, administration of poly-lactic acid microfibers has shown that topographical guidance cues alone can promote axonal regeneration into the injury site. However, all of these approaches induced modest behavioral or functional recovery suggesting that further investigation is necessary.

Exoskeletons

The technology for creating powered exoskeletons, wearable machinery to assist with walking movements, is currently making significant advances. There are products available, such as the Ekso, which allows individuals with up to a C7 complete (or any level of incomplete) spinal injury to stand upright and make technologically assisted steps. The initial purpose for this technology is for functional based rehabilitation, but as the technology develops, so will its uses.

Functional electrical stimulation (FES) uses coordinated electric shocks to muscles to cause them to contract in a walking pattern. While it can strengthen muscles, a significant downside for the users of FES is that their muscles tire after a short time and distance. One research direction combines FES with exoskeletons to minimize the downsides of both technologies, supporting the person's joints and using the muscles to reduce the power needed from the machine, and thus its weight.

Brain–computer interface

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.

Spinal cord implants

Spinal cord implants, such as e-dura implants, designed for implantation on the surface of the spinal cord, are being studied for paralysis following a spinal cord injury. Human studies have not yet been done.

E-dura implants are designed using methods of soft neurotechnology, in which electrodes and a microfluidic delivery system are distributed along the spinal implant. Chemical stimulation of the spinal cord is administered through the microfluidic channel of the e-dura. The e-dura implants, unlike previous surface implants, closely mimic the physical properties of living tissue and can deliver electric impulses and pharmacological substances simultaneously. Artificial dura mater was constructed through the utilization of PDMS and gelatin hydrogel. The hydrogel simulates spinal tissue and a silicone membrane simulates the dura mater. These properties allow the e-dura implants to sustain long-term application to the spinal cord and brain without leading to inflammation, scar tissue buildup, and rejection normally caused by surface implants rubbing against nerve tissue.

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External links

• Spinal cord injury at Curlie
• Cochrane Injuries Group, systematic reviews on the prevention, treatment and rehabilitation of traumatic injury
• Spinal Cord Infarction: Lamination of Fibers