Spinal cord injury

In a "complete" spinal injury, all functions below the injured area are lost, whether or not the spinal cord is severed.[9] An "incomplete" spinal cord injury involves preservation of motor or sensory function below the level of injury in the spinal cord.[18] To be classed as incomplete, there must be some preservation of sensation or motion in the areas innervated by S4 to S5,[19] e.g. voluntary external anal sphincter contraction.[18] 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. Incomplete injury by definition includes a phenomenon known as sacral sparing: some degree of sensation is preserved in the sacral dermatomes, even though sensation may be more impaired in other, higher dermatomes below the level of the lesion.[20] 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.[20]

Spinal cord injury without radiographic abnormality exists when SCI is present but there is no evidence of spinal column injury on radiographs.[21] Spinal column injury is trauma that causes fracture of the bone or instability of the ligaments in the spine; this can coexist with or cause injury to the spinal cord, but each injury can occur without the other.[22] Abnormalities might show up on magnetic resonance imaging (MRI), but the term was coined before MRI was in common use.[23]

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.[24] There is loss of sensation of pain, temperature, light touch, and pressure below the level of injury.[25] The spinal tracts that serve the arms are more affected due to their central location in the spinal cord, while the corticospinal fibers destined for the legs are spared due to their more external location.[25] The most common of the incomplete SCI syndromes, central cord syndrome usually results from neck hyperextension in older people with spinal stenosis. In younger people, it most commonly results from neck flexion.[26] The most common causes are falls and vehicle accidents; however other possible causes include spinal stenosis and impingement on the spinal cord by a tumor or intervertebral disc.[27]

Anterior spinal artery syndrome also known as anterior spinal cord syndrome, due to damage to the front portion of the spinal cord or reduction in the blood supply from the anterior spinal artery, can be caused by fractures or dislocations of vertebrae or herniated disks.[25] 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.[28][26] These differences are due to the relative locations of the spinal tracts responsible for each type of function.[25]

Brown-Séquard syndrome occurs when the spinal cord is injured on one side much more than the other.[29] It is rare for the spinal cord to be truly hemisected (severed on one side), but partial lesions due to penetrating wounds (such as gunshot or knife wounds) or fractured vertebrae or tumors are common.[30] On the ipsilateral side of the injury (same side), the body loses motor function, proprioception, and senses of vibration and touch.[29] On the contralateral (opposite side) of the injury, there is a loss of pain and temperature sensations.[27][29]Spinothalamic tracts are in charge for pain and temperature sensation and because these tracts cross to the opposite side and above the spinal cord there is loss on the contralateral side.[31]

Posterior spinal artery syndrome (PSAS), in which just the dorsal columns of the spinal cord are affected, is usually seen in cases of chronic myelopathy but can also occur with infarction of the posterior spinal artery.[32] This rare syndrome causes the loss of proprioception and sense of vibration below the level of injury[26] while motor function and sensation of pain, temperature, and touch remain intact.[33] Usually posterior cord injuries result from insults like disease or vitamin deficiency rather than trauma.[34] Tabes dorsalis, due to injury to the posterior part of the spinal cord caused by syphilis, results in loss of touch and proprioceptive sensation.[35]

Conus medullaris syndrome is an injury to the end of the spinal cord the conus medullaris, located at about the T12–L2 vertebrae in adults.[29] This region contains the S4–S5 spinal segments, responsible for bowel, bladder, and some sexual functions, so these can be disrupted in this type of injury.[29] In addition, sensation and the Achilles reflex can be disrupted.[29] Causes include tumors, physical trauma, and ischemia.[36] Cauda equina syndrome may also be caused by central disc prolapse or slipped disc, infections such as epidural abscess, spinal haemorrhages, secondary to medical procedures and birth abnormalities.[37]

Cauda equina syndrome (CES) results from a lesion below the level at which the spinal cord ends. Descending nerve roots continue as the cauda equina[34] at levels L2–S5 below the conus medullaris before exiting through intervertebral foraminae.[38] Thus it is not a true spinal cord syndrome since it is nerve roots that are damaged and not the cord itself; however, it is common for several of these nerves to be damaged at the same time due to their proximity.[36] CES can occur by itself or alongside conus medullaris syndrome.[38] It can cause low back pain, weakness or paralysis in the lower limbs, loss of sensation, bowel and bladder dysfunction, and loss of reflexes.[38] There may be bilateral sciatica with central disc prolapse and altered gait.[37] Unlike conus medullaris syndrome, symptoms often occur only on one side of the body.[36] The cause is often compression, e.g. by a ruptured intervertebral disk or tumor.[36] 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.[38]

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. People injured below level L2 may still have use of their hip flexor and knee extensor muscles.[44] Bowel and bladder function are regulated by the sacral region. It is common to experience sexual dysfunction after injury, as well as dysfunction of the bowel and bladder, including fecal and urinary incontinence.[9]

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 inability to control the abdominal muscles. Trunk stability may be affected; even more so in higher level injuries.[45] The lower the level of injury, the less extensive its effects. Injuries from T9 to T12 result in partial loss of trunk and abdominal muscle control. Thoracic spinal injuries result in paraplegia, but function of the hands, arms, and neck are not affected.[46]

One condition that occurs 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.[8][47] 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.[5] Signs and symptoms of AD include anxiety, headache, nausea, ringing in the ears, blurred vision, flushed skin, and nasal congestion.[5] It can occur shortly after the injury or not until years later.[5]

Other autonomic functions may also be disrupted. For example, problems with body temperature regulation mostly occur in injuries at T8 and above.[44] 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 maintaining muscle tone in the blood vessels.[5][47] Without the sympathetic input, the vessels relax and dilate.[5][47] 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.[48]

Spinal cord injuries at the cervical (neck) level result in full or partial tetraplegia (also called quadriplegia).[24] Depending on the specific location and severity of trauma, limited function may be retained. Additional symptoms of cervical injuries include low heart rate, low blood pressure, problems regulating body temperature, and breathing dysfunction.[49] 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.[9]

Complications of spinal cord injuries include pulmonary edema, respiratory failure, neurogenic shock, and paralysis below the injury site.

In the long term, the loss of muscle function can have additional effects from disuse, including atrophy of the muscle. Immobility can lead to pressure sores, particularly in bony areas, requiring precautions such as extra cushioning and turning in bed every two hours (in the acute setting) to relieve pressure.[51] In the long term, people in wheelchairs must shift periodically to relieve pressure.[52] 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.[53] Spasticity, the uncontrollable tensing of muscles below the level of injury, occurs in 65–78% of chronic SCI.[54] It results from lack of input from the brain that quells muscle responses to stretch reflexes.[55] It can be treated with drugs and physical therapy.[55] Spasticity increases the risk of contractures (shortening of muscles, tendons, or ligaments that result from lack of use of a limb); this problem can be prevented by moving the limb through its full range of motion multiple times a day.[56] Another problem lack of mobility can cause is loss of bone density and changes in bone structure.[57][58] 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.[59] Conversely, a poorly understood phenomenon is the overgrowth of bone tissue in soft tissue areas, called heterotopic ossification.[60] It occurs below the level of injury, possibly as a result of inflammation, and happens to a clinically significant extent in 27% of people.[60]

Muscle mass is reduced as muscles atrophy with disuse.

People with SCI are at especially high risk for respiratory and cardiovascular problems, so hospital staff must be watchful to avoid them.[61] Respiratory problems (especially pneumonia) are the leading cause of death in people with SCI, followed by infections, usually of pressure sores, urinary tract infections and respiratory infections.[62] Pneumonia can be accompanied by shortness of breath, fever, and anxiety.[24]

Another potentially deadly threat to respiration is deep venous thrombosis (DVT), in which blood forms a clot in immobile limbs; the clot can break off and form a pulmonary embolism, lodging in the lung and cutting off blood supply to it.[63] DVT is an especially high risk in SCI, particularly within 10 days of injury, occurring in over 13% in the acute care setting.[64] Preventative measures include anticoagulants, pressure hose, and moving the patient's limbs.[64] The usual signs and symptoms of DVT and pulmonary embolism may be masked in SCI cases due to effects such as alterations in pain perception and nervous system functioning.[64]

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.[24] The risk of UTI, likely the most common complication in the long term, is heightened by use of indwelling urinary catheters.[51] 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.[51] The use of intermittent catheterization to empty the bladder at regular intervals throughout the day has decreased the mortality due to kidney failure from UTI in the first world, but it is still a serious problem in developing countries.[59]

An estimated 24–45% of people with SCI have disorders of depression, and the suicide rate is as much as six times that of the rest of the population.[65] The risk of suicide is worst in the first five years after injury.[66] In young people with SCI, suicide is the leading cause of death.[67] Depression is associated with an increased risk of other complications such as UTI and pressure ulcers that occur more when self-care is neglected.[67]

Spine motion restriction 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 restricting further motion of the spine.[23] In the emergency setting, most people who has been subjected to forces strong enough to cause SCI are treated as though they have instability in the spinal column and have spinal motion restricted to prevent damage to the spinal cord.[94] 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.[9] High-speed vehicle crashes, sports injuries involving the head or neck, and diving injuries are other mechanisms that indicate a high SCI risk.[95] 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 spinal motion restricted.[96]

A rigid cervical collar is applied to the neck, and the head is held with blocks on either side and the person is strapped to a backboard.[94] Extrication devices are used to move people without excessively moving the spine[97] if they are still inside a vehicle or other confined space. The use of a cervical collar has been shown to increase mortality in people with penetrating trauma and is thus not routinely recommended in this group.[98]

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.[34] If these are all absent, no spinal motion restriction is necessary.[97]

If an unstable spinal column injury is moved, damage may occur to the spinal cord.[99] Between 3 and 25% of SCIs occur not at the time of the initial trauma but later during treatment or transport.[23] 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 adequately restrict motion of the spine. SCI can impair the body's ability to keep warm, so warming blankets may be needed.[96]

Initial care in the hospital, as in the prehospital setting, aims to ensure adequate airway, breathing, cardiovascular function, and spinal motion restriction.[100] Imaging of the spine to determine the presence of a SCI may need to wait if emergency surgery is needed to stabilize other life-threatening injuries.[101] Acute SCI merits treatment in an intensive care unit, especially injuries to the cervical spinal cord.[100] People with SCI need repeated neurological assessments and treatment by neurosurgeons.[102] People should be removed from the spine board as rapidly as possible to prevent complications from its use.[103]

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.[48] Thus it is important to maintain the blood pressure which may be done using intravenous fluids and vasopressors.[104] Vasopressors used include phenylephrine, dopamine, or norepinephrine.[1] Mean arterial blood pressure is measured and kept at 85 to 90 mmHg for seven days after injury.[105]

The CAMPER Trial led by Dr Kwon and subsequent studies by the UCSF TRACK-SCI group (Dhall) have shown that spinal cord perfusion pressure (SCPP) goals are more closely associated with better neurologic recovery than MAP goals. Some institutions have adopted these SCPP goals and lumbar CSF drain placement as a standard of care.[106] The treatment for shock from blood loss is different from that for neurogenic shock, and could harm people with the latter type, so it is necessary to determine why someone is in shock.[104] However it is also possible for both causes to exist at the same time.[1] Another important aspect of care is prevention of insufficient oxygen in the bloodstream, which could deprive the spinal cord of oxygen.[107] People with cervical or high thoracic injuries may experience a dangerously slowed heart rate; treatment to speed it may include atropine.[1]

The corticosteroid medication methylprednisolone has been studied for use in SCI with the hope of limiting swelling and secondary injury.[108] As there does not appear to be long term benefits and the medication is associated with risks such as gastrointestinal bleeding and infection its use is not recommended as of 2018.[1][108] Its use in traumatic brain injury is also not recommended.[103]

Surgery may be necessary, e.g. to relieve excess pressure on the cord, to stabilize the spine, or to put vertebrae back in their proper place.[105] In cases involving instability or compression, failing to operate can lead to worsening of the condition.[105] Surgery is also necessary when something is pressing on the cord, such as bone fragments, blood, material from ligaments or intervertebral discs,[109] or a lodged object from a penetrating injury.[88] Although the ideal timing of surgery is still debated, studies have found that earlier surgical intervention (within 12 hours of injury) is associated with better outcomes.[110] This type of surgery is often referred to as "Ultra-Early", coined by Burke et al. at UCSF. Sometimes a patient has too many other injuries to be a surgical candidate this early.[105] Surgery is controversial because it has potential complications (such as infection), so in cases where it is not clearly needed (e.g. the cord is being compressed), doctors must decide whether to perform surgery based on aspects of the patient's condition and their own beliefs about its risks and benefits.[111] Recent large-scale studies have shown that patients who do undergo earlier surgery (within 12–24 hours) experience significantly lower rates of life-threatening complications and spend less time in hospital and critical care.[112][113] However, in cases where a more conservative approach is chosen, bed rest, cervical collars, motion restriction devices, and optionally traction are used.[114] Surgeons may opt to put traction on the spine to remove pressure from the spinal cord by putting dislocated vertebrae back into alignment, but herniation of intervertebral disks may prevent this technique from relieving pressure.[115] Gardner-Wells tongs are one tool used to exert spinal traction to reduce a fracture or dislocation and to reduce motion to the affected areas.[116]

SCI patients often require extended treatment in specialized spinal unit or an intensive care unit.[117] The rehabilitation process typically begins in the acute care setting. Usually, 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.[8] Physical therapists, occupational therapists, recreational therapists, nurses, social workers, psychologists, and other health care professionals work as a team under the coordination of a physiatrist[9] to decide on goals with the patient and develop a plan of discharge that is appropriate for the person's condition.

An Orthopedic device like this also known as a drop foot orthosis has only one functional element for lifting the forefoot in order to compensate for a weakness in the dorsiflexors. If other muscle groups, such as the plantar flexors, are weak, additional functional elements must be taken into account. An ankle-foot orthoses (AFO) of the drop foot orthosis type is therefore not suitable for the care of patients with weakness in other muscle groups.

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.[118]

For people whose injuries are high enough to interfere with breathing, there is great emphasis on airway clearance during this stage of recovery.[119] Weakness of respiratory muscles impairs the ability to cough effectively, allowing secretions to accumulate within the lungs.[120] As SCI patients have reduced total lung capacity and tidal volume,[121] physical therapists teach them accessory breathing techniques (e.g. apical breathing, glossopharyngeal breathing) that typically are not taught to healthy individuals. Physical therapy treatment for airway clearance may include manual percussions and vibrations, postural drainage,[119] respiratory muscle training, and assisted cough techniques.[120] Patients are taught to increase their intra-abdominal pressure by leaning forward to induce cough and clear mild secretions.[120] The quad cough technique is done lying on the back with the therapist applying pressure on the abdomen in the rhythm of the cough to maximize expiratory flow and mobilize secretions.[120] Manual abdominal compression is another technique used to increase expiratory flow which later improves coughing.[119] Other techniques used to manage respiratory dysfunction include respiratory muscle pacing, use of a constricting abdominal binder, ventilator-assisted speech, and mechanical ventilation.[120]

The amount of functional recovery and independence achieved in terms of activities of daily living, recreational activities, and employment is affected by the level and severity of injury.[122] 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.[123] It can track a patient's progress and degree of independence during rehabilitation.[123] 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 to function independently. Weak joints can be stabilized with devices such as ankle-foot orthoses (AFOs) or knee-ankle-foot orthoses (KAFOs), but walking may still require a lot of effort.[124] Increasing activity will increase chances of recovery.[125]

Patient after incomplete paraplegia (lesion height L3) with a knee-ankle-foot orthosis (KAFO) with an integrated stance phase control knee joint.

For treatment of paralysis levels in the lower thoracic spine or lower, starting therapy with an orthosis is promising from the intermediate phase (2–26 weeks after the incident).[126][127][128] In patients with complete paraplegia (ASIA A), this applies to lesion heights between T12 and S5. In patients with incomplete paraplegia (ASIA B-D), orthoses are even suitable for lesion heights above T12. In both cases, however, a detailed muscle function test must be carried out to precisely plan the construction with an orthosis.[129]