Spinal cord injury

A spinal cord injury (SCI) is damage to the spinal cord that causes temporary or permanent changes in its function. It is a destructive neurological and pathological state that causes major motor, sensory and autonomic dysfunctions.

Symptoms of spinal cord injury may include loss of muscle function, sensation, or autonomic function in the parts of the body served by the spinal cord below the level of the injury. Injury can occur at any level of the spinal cord and can be complete, with a total loss of sensation and muscle function at lower sacral segments, or incomplete, meaning some nervous signals are able to travel past the injured area of the cord up to the Sacral S4-5 spinal cord segments. Depending on the location and severity of damage, the symptoms vary, from numbness to paralysis, including bowel or bladder incontinence. Long term outcomes also range widely, from full recovery to permanent tetraplegia (also called quadriplegia) or paraplegia. Complications can include muscle atrophy, loss of voluntary motor control, spasticity, pressure sores, infections, and breathing problems.

In the majority of cases the damage results from physical trauma such as car accidents, gunshot wounds, falls, or sports injuries, but it can also result from nontraumatic causes such as infection, insufficient blood flow, and tumors. Just over half of injuries affect the cervical spine, while 15% occur in each of the thoracic spine, border between the thoracic and lumbar spine, and lumbar spine alone. Diagnosis is typically based on symptoms and medical imaging.

Classification

{| width="260px" style="text-align: center; margin-left: 15px; float:right;"

| style="border-bottom:0px;" |90px|alt=A human spinal column

| style="border-bottom:0px;" |182px|alt=A person with dermatomes mapped out on the skin

| colspan="2" |260px|alt=diagram of vertebrae and spinal nerves

| style="border-top:0px;" colspan="2"|The effects of injury depend on the level along the spinal column (left). A dermatome is an area of the skin that sends sensory messages to a specific spinal nerve (right).

| colspan="2" |Spinal nerves exit the spinal cord between each pair of vertebrae.

Spinal cord injury can be traumatic or nontraumatic,

Posterior spinal artery syndrome

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. This rare syndrome causes the loss of proprioception and sense of vibration below the level of injury while motor function and sensation of pain, temperature, and touch remain intact. Usually posterior cord injuries result from insults like disease or vitamin deficiency rather than trauma. Tabes dorsalis, due to injury to the posterior part of the spinal cord caused by syphilis, results in loss of touch and proprioceptive sensation.

Conus medullaris and cauda equina syndromes

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. 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. In addition, sensation and the Achilles reflex can be disrupted. Causes include tumors, physical trauma, and ischemia. 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.

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 at levels L2–S5 below the conus medullaris before exiting through intervertebral foraminae. 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. CES can occur by itself or alongside conus medullaris syndrome. It can cause low back pain, weakness or paralysis in the lower limbs, loss of sensation, bowel and bladder dysfunction, and loss of reflexes. There may be bilateral sciatica with central disc prolapse and altered gait.

Spinal cord injury locations

Cervical spine

thumb|Muscle mass is reduced as muscles atrophy with disuse.

{| class="wikitable" style="width: 100%; float: right;"

|+ Function after complete cervical spinal cord injury

! style="text-align:left;background-color:#ffc0c0;" | Level

! style="text-align:left;background-color:#ffc0c0;" | Motor Function

! style="text-align:left;background-color:#ffc0c0;" | Respiratory function

|C1–C4

|Full paralysis of the limbs

|Cannot breathe without mechanical ventilation

|C5

|Paralysis of the wrists, hands, and triceps

|rowspan="3"|Difficulty coughing; may need help clearing secretions

|C6

|Paralysis of the wrist flexors, triceps, and hands

| C7–C8

|Some hand muscle weakness, difficulty grasping and releasing

Spinal cord injuries at the cervical vertebrae (neck) level result in full or partial tetraplegia, also called quadriplegia. 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. 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. NHO the most frequent musculoskeletal complications of severe spinal cord injuries with reported incidence varying from 0.5 % to 53% but generally the reported incidence is between 6 and 25%. Recent metanalyses have has reported significant association with severity and completeness of the SCI, spasticity, presence of infections, presence of hip-pelvic trauma.

The underlying mechanism by which NHO forms is not fully understood but has been studied in a mouse model of SCI-induced NHO. Neurogenic heterotopic ossficiation is thought to be caused by abnormal muscle repair following trauma. During normal muscle repair, muscle stem cells divide and differentiate to regenerate muscle fibres. This process is controlled by inflammatory cells and support muscle cell growth. A key step during normal muscle repair is the programmed cell death (apoptosis) triggered inflammatory cells to prevent the development of muscle fibrosis. However, following a spinal cord injury, fibro-adipogenic progenitors fail to undergo apoptosis and instead accumulate and differentiate into bone forming osteoblasts. The spinal cord injury stimulates the adrenal glands to release the glucocorticoid corticosterone into the circulation. Excessive corticosterone causes an exaggerated inflammation response in the injured muscle with excessive release of oncostatin M and interleukin-1β. Oncostatin M and interleukin-1 bind to their cognate receptors OSMR and IL1R1 expressed by muscle fibro-adipogenic progenitors which in turn promote their proliferation and osteogenic differentiation. In support of this model, treatment with glucocorticoid receptor antagonists such as mifepristone or relacorilant or conditional deletion of the glucocorticoid receptor gene strongly inhibit the development of NHO after SCI in this mouse model. This mechanism also explains why infections, particularly with gram-negative bacteria, are associated with higher incidence of NHO in victims of traumatic brain and spinal cord injuries. Lipopolysaccharides from gram-negative bacteria worsen NHO by binding to their receptor Toll-like receptor 4 expressed by macrophages and muscle fibro-adipogenic progenitors and further increase oncostatin M and interleukin-1β release by macrophages.

Causes

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

Spinal cord injuries are most often caused by physical trauma. Forces involved can be hyperflexion (forward movement of the head); hyperextension (backward movement); lateral stress (sideways movement); rotation (twisting of the head); compression (force along the axis of the spine downward from the head or upward from the pelvis); or distraction (pulling apart of the vertebrae). Traumatic SCI can result in contusion, compression, or stretch injury. Pre-existing asymptomatic congenital anomalies can cause major neurological deficits, such as hemiparesis, to result from otherwise minor trauma.

In the U.S., motor vehicle accidents are the most common cause of SCIs; second are falls, then violence such as gunshot wounds, then sports injuries. Another study from Asia, found that the most common cause of the SCI is fall (31.70%) from various sites such as fall from roof-tops (9.75%), electric pole (7.31%), fall from tree (7.31%) etc. Whereas road traffic accidents count for 19.51%, firearm injuries (12.19%), slipped foot (7.31%) and sports injuries (4.87%). As a result of injury, 26.82%In some countries falls are more common, even surpassing vehicle crashes as the leading cause of SCI. The rates of violence-related SCI depend heavily on place and time. 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. Military conflicts are another cause, and when they occur they are associated with increased rates of SCI.

A radiographic evaluation using an X-ray, CT scan, or MRI can determine if there is damage to the spinal column and where it is located.

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 spinal motion restriction is necessary.

If an unstable spinal column injury is moved, damage may occur to the spinal cord. 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. However it is also possible for both causes to exist at the same time. 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.

Surgery

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. 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.

However, in cases where a more conservative approach is chosen, bed rest, cervical collars, motion restriction devices, and optionally traction are used. 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. 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.

For people whose injuries are high enough to interfere with breathing, there is great emphasis on airway clearance during this stage of recovery. 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.

Prognosis

thumb|Holly Koester, who incurred a spinal injury as a result of a motor vehicle collision, is now a [[wheelchair racer.]]

Spinal cord injuries generally 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.

| label1 = 0–15

| value1 = 3.0

| label2 =16–30

| value2 =42.1

| label3 =31–45

| value3 =28.1

| label4 =46–60

| value4 =15.1

| label5 =61–75

| value5 =8.5

| label6 =76+

| value6 =3.2

Worldwide, the number of new cases since 1995 of SCI ranges from 10.4 to 83 people per million per year. It was not until the second 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.

Research directions

thumb|Human bone marrow derived [[mesenchymal stem cells seen under phase contrast microscope at 63-times magnification)]]

Scientists are investigating various avenues for treatment of spinal cord injury. Therapeutic research is focused on two main areas: neuroprotection and neuroregeneration. showing that after 90 days, 2 out of 4 subjects had already improved two motor levels and had thus already achieved its endpoint of 2/5 patients improving two levels within 6–12 months. Six-month data was expected in January 2017.

Another type of approach is tissue engineering, using biomaterials to help scaffold and rebuild damaged tissues. and in some cases to enable walking to some degree bypassing the injury.

In 2014, Darek Fidyka underwent pioneering spinal surgery that used nerve grafts, from his ankle, to bridge the gap in his severed spinal cord and olfactory ensheathing cells (OECs) to stimulate the spinal cord cells. The surgery was performed in Poland in collaboration with Prof. Geoff Raisman, chair of neural regeneration at University College London's Institute of Neurology, and his research team. The OECs were taken from the patient's olfactory bulbs in his brain and then grown in the lab, these cells were then injected above and below the impaired spinal tissue.

In March 2025, researchers reported that a paralyzed man stood for the first time after being injected of neural stem cells to treat his spinal cord injury. The first-of-its-kind study, which is not yet peer-reviewed, is encouraging scientists to consider if reprogrammed stem cells can be used in the future to treat people who are fully paralyzed. Reprogrammed cells are adult cells that are reverted to an embryonic-like state, from which they can be coaxed to develop into other cell types.

References

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Bibliography

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