Spinal Cord Injury (SCI)

SCI is typically caused by a traumatic blow to (or penetration of) the spine that fractures or dislocates vertebrae. The trauma causes the resulting bone fragments, material in the spinal discs, or ligaments to bruise or tear into spinal cord tissue, damaging it or, in some cases, severing the cord entirely and resulting in partial or complete paralysis. NICHD supports basic research related to SCI and promotes the development and application of devices, including prosthetics and wheelchairs, and the use of biomechanical modeling to improve the quality of life for people regardless of their injury.

About Spinal Cord Injury

What is SCI?

SCI is usually associated with what is commonly called a broken neck or broken back. Generally speaking, SCI is damage to the spinal nerves, the body's central and most important nerve bundle, as a result of trauma to the backbone.

Most cases of SCI take place when trauma breaks and squeezes the vertebrae, or the bones of the back. This, in turn, damages the axons—the long nerve cell "wires" that pass through vertebrae, carrying signals between the brain and the rest of the body. The axons might be crushed or completely severed by this damage. Someone with injury to only a few axons might be able to recover completely from their injury. On the other hand, a person with damage to all axons will most likely be paralyzed in the areas below the injury.1

An SCI is described by its level, type, and severity. The level of injury for a person with SCI is the lowest point on the spinal cord below which sensory feeling and motor movement diminish or disappear.

The level is denoted by the letter-and-number name of the vertebra at the injury site (such as C3, T2, or L4).

  • There are seven cervical vertebrae (C1 through C7), which are in the neck.
  • There are 12 thoracic vertebrae (T1 through T12), which are located in the upper back. There are five lumbar vertebrae (L1 through L5), which are found in the lower back.
  • Below those are five sacral vertebrae, which are fused to form the sacrum. Finally, there are the four vertebrae of the coccyx, or tailbone.1

There are two broad types of SCI, each comprising a number of different levels:

  • Tetraplegia (formerly called quadriplegia) generally describes the condition of a person with an SCI that is at a level anywhere from the C1 vertebra down to the T1. These individuals can experience a loss of sensation, function, or movement in their head, neck, shoulders, arms, hands, upper chest, pelvic organs, and legs.
  • Paraplegia is the general term describing the condition of people who have lost feeling in or are not able to move the lower parts of their body. The body parts that may be affected are the chest, stomach, hips, legs, and feet. The state of an individual with an SCI level from the T2 vertebra to the S5 can usually be called paraplegic.2

In addition, there are two degrees of SCI severity:

  • Complete injury is the situation when the injury is so severe that almost all feeling (sensory function) and all ability to control movement (motor function) are lost below the area of the SCI.
  • Incomplete injury occurs when there is some sensory or motor function below the damaged area on the spine. There are many degrees of incomplete injury.1

The closer the spinal injury is to the skull, the more extensive is the curtailment of the body's ability to move and feel. If the lesion is low on the spine, say, in the sacral area, it is likely that there will be a lack of feeling and movement in the thighs and lower parts of the legs, the feet, most of the external genital organs, and the anal area. But the person will be able to breathe freely and move his head, neck, arms, and hands. By contrast, someone with a broken neck may be almost completely incapacitated, even to the extent of requiring breathing assistance.3


  1. National Institute of Neurological Disorders and Stroke. Spinal cord injury: Hope through research. Retrieved June 19 , 2013 , from https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Hope-Through-Research/Spinal-Cord-Injury-Hope-Through-Research
  2. National Spinal Cord Injury Association. Understanding spinal cord injury. Retrieved May 21, 2012, from https://unitedspinal.org/what-is-spinal-cord-injury-disorder-scid/ external link
  3. Shepherd Center, KPKinteractive, American Trauma Society, National Spinal Cord Injury Association, & Christopher & Dana Reeve Foundation. Levels of Injury. Retrieved June 26, 2013, from https://www.spinalinjury101.org/details/levels-of-injury external link

What are the symptoms of SCI?

According to the American Association of Neurological Surgeons, there are many different symptoms or signs of SCI. Some of the more common signs of SCI include1:

  • Extreme pain or pressure in the neck, head, or back
  • Tingling or loss of sensation in the hand, fingers, feet, or toes
  • Partial or complete loss of control over any part of the body
  • Urinary or bowel urgency, incontinence, or retention
  • Difficulty with balance and walking
  • Abnormal band-like sensations in the thorax—pain, pressure
  • Impaired breathing after injury
  • Unusual lumps on the head or spine


  1. American Association of Neurological Surgeons. Spinal cord injury facts. Retrieved June 21, 2012, from https://www.aans.org/en/Patients/Neurosurgical-Conditions-and-Treatments external link

How many people are affected by SCI?

According to the National SCI Statistical Center, annually there are about 12,000 new cases of SCIs in the United States,1 which amounts to about 40 cases per million people. The last studies of the incidence of SCI were conducted in the 1990s, however, and so it is not known whether incidence has changed in recent years. In 2010, about a quarter of a million people in the United States were living with an SCI.

The majority of SCIs occur in young to middle-aged adults. From 1973 to 1979, the average age at injury was 28.7 years, and most injuries occurred between the ages of 16 and 30. However, demographic changes since the mid-1970s have resulted in an increase of 9 years in the median age of the U.S. population. Similarly, the average age for an SCI has increased over time. From 2005 to 2010, the average age was 40.7.2

Who is at risk for SCI?

SCIs are typically the result of accidents and therefore can happen to anyone.

Factors that increase the risk of SCI:

  • Driving or riding in a car. Using a seatbelt can reduce the possibility of an SCI by 60%; using a seatbelt plus having a functioning airbag can cut the odds of this injury by 80%.3,4
  • Being male. 80% of spinal cord injury patients are male.5
  • Operating machinery without using safety equipment6
  • Improper or unsafe use of a ladder, which can result in a fall from the ladder7
  • Using drugs or alcohol while driving, operating machinery, or playing sports8
  • Having arthritis, osteoporosis, or another bone or joint disorder9


  1. National Spinal Cord Injury Statistical Center. (2011). Spinal cord injury facts and figures at a glance. Retrieved May 22, 2012, from https://www.nscisc.uab.edu/PublicDocuments/nscisc_home/pdf/Facts%202011%20Feb%20Final.pdf external link (PDF 197 KB)
  2. National Spinal Cord Injury Statistical Center. (2011). Spinal cord injury facts and figures at a glance. Retrieved May 22, 2012, from https://www.nscisc.uab.edu/PublicDocuments/nscisc_home/pdf/Facts%202011%20Feb%20Final.pdf external link (PDF 197 KB)
  3. Clayton, B., MacLennan, P. A., McGwinn, G., Jr. Rue, L. W., III, Kirkpatrick, J. S. Cervical spine injury and restraint system use in motor vehicle collisions. Spine 2004 February;29(4):386-389.
  4. Thompson, W. L., Steill, I. G., Clement, C. M., Brison, R. J. (2009). Association of injury mechanism with the risk of cervical spine fractures. Canadian Journal of Emergency Medicine, 11(1):14-22.
  5. Centers for Disease Control and Prevention. (2010). Spinal Cord Injury (SCI): Fact Sheet. Retrieved June 21, 2012, from http://www.cdc.gov/TraumaticBrainInjury/scifacts.html
  6. Centers for Disease Control and Prevention. (2011). Machine safety. Retrieved June 26, 2012, from https://www.cdc.gov/niosh/topics/machine/default.html
  7. Hasler, R. M., Exadaktylos, A. K., Bouamra, O., Benneker, L. M., Clancy, M., Sieber, R. et al. (2011). Epidemiology and predictors of spinal injury in adult major trauma patients: European cohort study. European Spine Journal, 20(12):2174-2180.
  8. Beers, M. H., & Kaplan, J. L. (Eds.). (2006). The Merck manual of diagnosis and therapy. 18th ed. Whitehouse Station, NJ: Merck Sharp & Dohme Corp.
  9. PubMed Health. (2010). Spinal cord trauma. Retrieved June 26, 2012, from https://medlineplus.gov/ency/article/001066.htm

What causes spinal cord injury (SCI) and how does it affect your body?

SCIs result from damage to the vertebrae, ligaments, or disks of the spinal column or to the spinal cord itself.

A traumatic SCI may stem from a sudden blow to the spine that fractures, dislocates, crushes, or compresses one or more vertebrae. Car crashes are the leading cause of SCI among people younger than 65. Falls cause most SCIs in persons age 65 and older.

Since 2005, SCI has been caused by1:

  • Car crashes (40.4%)
  • Falls (27.9%)
  • Violence, including gunshot wounds (15%)
  • Sport-related accidents (8%)
  • Other/unknown (8.5%)

What happens in your body when your spinal cord is injured?

When an SCI occurs, the spinal cord starts to swell at the damaged area, cutting off the vital blood supply to the nerve tissue and starving it of oxygen. This sets off a cascade of devastation that affects the entire body, causing the injured spinal tissue to die, be stripped of its insulation, and be further damaged by a massive response of the immune system.2

  • Blood flow. The sluggish blood flow at the injury site begins to reduce the flow of blood in adjacent areas, which soon affects all areas of the body. The body begins to lose the ability to self-regulate, leading to drastic drops in blood pressure and heart rate.
  • Flood of neurotransmitters. The SCI leads to an excessive release of neurotransmitters, or biochemicals that let nerve cells communicate with each other. These chemicals, especially glutamate, overexcite nerve cells, killing them through a process known as excitotoxicity. The process also kills the vital oligodendrocytes that surround and protect the spinal axons with the myelin insulation that allows the spinal nerves to transmit information to and from the brain.
  • Invasion of immune cells. An army of cells of the immune system speeds to the damaged area of the spine. While they help by preventing infection and cleaning up dead cellular debris, they also promote inflammation. These immune cells stimulate the release of certain cytokines that, in high concentrations, can be toxic to nerve cells, especially those needed to maintain the myelin sheath around axons.3
  • Onslaught of free radicals. The inflammation caused by cells in the immune system unleashes waves of free radicals, which are highly reactive forms of oxygen molecules. These free radicals react destructively with many types of cellular molecules, in the process severely damaging healthy nerve cells.
  • Nerve cell self-destruction. A normally natural process of programmed cell death, known as apoptosis, goes out of control at the injury site. The reasons are not known. Days or weeks after the injury, oligodendrocytes die from no apparent cause, reducing the integrity of the spinal cord.

Additional damage usually occurs over the days or weeks following the initial injury because of bleeding, swelling, inflammation, and accumulation of fluid in and around the spinal cord.


  1.   National Spinal Cord Injury Statistical Center. (2011). Spinal cord injury facts and figures at a glance. Retrieved May 21, 2012, from https://www.nscisc.uab.edu/PublicDocuments/nscisc_home/pdf/Facts%202011%20Feb%20Final.pdf external link (PDF 197 KB)
  2.   National Institute of Neurological Disorders and Stroke. (2012). Spinal cord injury: Hope through research. Retrieved May 22, 2012, from https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Hope-Through-Research/Spinal-Cord-Injury-Hope-Through-Research
  3.   Szalavitz, M. (2002). The Brain-Immunology Axis. Retrieved February 2022 from https://dana.org/brain-awareness-week/ external link

How is SCI diagnosed?

SCIs are not always immediately recognizable. The following injuries should be assessed for possible damage to the spinal cord1:

  • Head injuries, particularly those with trauma to the face
  • Pelvic fractures
  • Penetrating injuries in the area of the spine
  • Injuries from falling from heights

If any of these injuries occur together with any of the symptoms mentioned above (acute head, neck, or back pain; decline of feeling in the extremities; loss of control over part of the body; urinary or bowel problems; walking difficulty; pain or pressure bands in the chest area; difficulty breathing; head or spine lumps), then SCI may be implicated.2

A person suspected of having an SCI must be carefully transported—to prevent further injury the spine should be kept immobile—to an emergency room or trauma center. A doctor will question the person to determine the nature of the accident, and the medical staff may test the patient for sensory function and movement. If the injured person complains of neck pain, is not fully awake, or has obvious signs of weakness or neurological injury, diagnostic tests will be performed.

These tests may include3:

  • A CT ("cat") scan. This approach uses computers to form a series of cross-sectional images that may show the location and extent of the damage and reveal problems such as blood clots (hematomas).
  • An MRI (magnetic resonance imaging) scan. An MRI machine "takes a picture" of the injured area using a strong magnetic field and radio waves. A computer creates an image of the spine to reveal herniated disks and other abnormalities.
  • A myelogram. This is an X-ray of the spine taken after a dye is injected.
  • Somatosensory evoked potential (SSEP) testing or magnetic stimulation. Performing these tests may show if nerve signals can pass through the spinal cord.
  • Spine X-rays. These may show fracture or damage to the bones of the spine.

On about the third day after the injury, doctors give patients a complete neurological examination to diagnose the severity of the injury and predict the likely extent of recovery. This involves testing the patient's muscle strength and ability to sense light touch and a pinprick. Doctors use the standard ASIA (American Spinal Injury Association) Impairment Scale for this diagnosis. X-rays, MRIs, or more advanced imaging techniques are also used to visualize the entire length of the spine.

The ASIA Impairment Scale has five classification levels, ranging from complete loss of neural function in the affected area to completely normal4:

  • A: The impairment is complete. There is no motor or sensory function left below the level of injury.
  • B: The impairment is incomplete. Sensory function, but not motor function, is preserved below the neurologic level (the first normal level above the level of injury) and some sensation is preserved in the sacral segments S4 and S5.
  • C: The impairment is incomplete. Motor function is preserved below the neurologic level, but more than half of the key muscles below the neurologic level have a muscle grade less than 3 (i.e., they are not strong enough to move against gravity).
  • D: The impairment is incomplete. Motor function is preserved below the neurologic level, and at least half of the key muscles below the neurologic level have a muscle grade of 3 or more (i.e., the joints can be moved against gravity).
  • E: The patient's functions are normal. All motor and sensory functions are unhindered.

To illustrate, a person classified as C-level on the ASIA scale functions better than a person at the B level. Time was, a patient might have been labeled a C4 quadriplegic. Today, however, using the ASIA scale, the classification might be C4 ASIA A tetraplegic. Regarding muscle-strength grades, zero is the lowest, corresponding to complete absence of muscle movement. Five is the highest, representing full, normal strength.5,6


  1. National Institute of Neurological Disorders and Stroke. (2012). Spinal cord injury: Hope through research. Retrieved June 26, 2012, from https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Hope-Through-Research/Spinal-Cord-Injury-Hope-Through-Research
  2. University Specialty Clinics. (n.d.). Spinal cord injury. Retrieved June 26, 2012, from http://neurosurgery.med.sc.edu/patientcare/spinal_cord_injury.asp
  3. PubMed Health. (2010). Spinal cord trauma. Retrieved June 26, 2012, from https://www.ncbi.nlm.nih.gov/pubmedhealth/PMHT0030151/
  4. The Spinal Cord Injury Zone. (2009). What is ASIA impairment scale. Retrieved June 26, 2012, from http://www.spinalcordinjuryzone.com/answers/9243/what-is-asia-impairment-scale external link
  5. Shepherd Center. (n.d.) Diagnosing the severity of a SCI. https://spinalcordinjuryzone.com/answers/9243/what-is-asia-impairment-scale external link
  6. Radiopaedia. (n.d.). ASIA impairment scale. Retrieved June 26, 2012, from https://radiopaedia.org/articles/asia-impairment-scale-for-spinal-injury?lang=us external link

What are the treatments for spinal cord injury (SCI)?

Unfortunately, there are at present no known ways to reverse damage to the spinal cord. However, researchers are continually working on new treatments, including prostheses and medications, which may promote regeneration of nerve cells or improve the function of the nerves that remain after an SCI.

SCI treatment currently focuses on preventing further injury and empowering people with an SCI to return to an active and productive life.

At the Scene of the Incident

Quick medical attention is critical to minimizing the effects of head, neck, or back trauma. Therefore, treatment for an SCI often begins at the scene of the injury.

Emergency personnel typically:

  • Immobilize the spine as gently and quickly as possible using a rigid neck collar and a rigid carrying board
  • Use the carrying board to transport the patient to the hospital

In the Emergency Room

Once the patient is at the hospital, health care providers focus on:

  • Maintaining the person's ability to breathe
  • Immobilizing the neck to prevent further spinal cord damage

Health care providers also may treat an acute injury with:

  • Surgery. Doctors may use surgery to remove fluid or tissue that presses on the spinal cord (decompression laminectomy); remove bone fragments, disk fragments, or foreign objects; fuse broken spinal bones; or place spinal braces.1
  • Traction. This technique stabilizes the spine and brings it into proper alignment.
  • Methylprednisolone (Medrol). If this steroid medication is administered within 8 hours of injury, some patients experience improvement. It appears to work by reducing damage to nerve cells and decreasing inflammation near the site of injury.
  • Experimental treatments. Scientists are pursuing research on how to halt cell death, control inflammation, and promote the repair or regeneration of nerves.2 See "Is there a cure for SCI?"

People with SCI may benefit from rehabilitation, including3,4:

  • Physical therapy geared toward muscle strengthening, communication, and mobility
  • Use of assistive devices such as wheelchairs, walkers, and leg braces
  • Use of adaptive devices for communication
  • Occupational therapy focused on fine motor skills
  • Techniques for self-grooming and bladder and bowel management
  • Coping strategies for dealing with spasticity and pain
  • Vocational therapy to help people get back to work with the use of assistive devices, if needed
  • Recreational therapy such as sports and social activities
  • Improved strategies for exercise and healthy diets (obesity and diabetes are potential risk factors for persons with SCI)
  • Functional electrical stimulation for assistance with restoration of neuromuscular function, sensory function, or autonomic function (e.g., bladder, bowel, or respiratory function).5


  1. PubMed Health. (2010). Spinal cord trauma. Retrieved June 27, 2012, from https:// www.ncbi.nlm.nih.gov/pubmedhealth/PMHT0030151/
  2. National Institute of Neurological Disorders and Stroke. (2012). Spinal cord injury: Hope through research. Retrieved May 22, 2012, from https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Hope-Through-Research/Spinal-Cord-Injury-Hope-Through-Research
  3. National Institute of Neurological Disorders and Stroke. (2012). Spinal cord injury: Hope through research. Retrieved May 22, 2012, from https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Hope-Through-Research/Spinal-Cord-Injury-Hope-Through-Research
  4. Tator, C. H., & Benzel, E. C. (Eds.). (2000). Contemporary management of spinal cord injury: From impact to Rehabilitation, 2nd ed. Rolling Meadows, IL: American Association of Neurological Surgeons.
  5. Evans, R. W., Wilberger, J. E., & Bhatia, S. Traumatic disorders. In: Goetz, C. G. (Ed.). (2007). Textbook of clinical neurology (3rd ed.), chap. 51. Philadelphia, PA: Saunders Elsevier.

What conditions are associated with SCI?

SCI is associated with many secondary conditions that have significant impacts on medical rehabilitation management, long-term outcome, and quality of life.

  • Secondary conditions associated with SCIs include1,2:
    • Breathing problems
    • Bowel and bladder problems, including overactive bladder and incontinence
    • Heart problems
    • Pressure sores
    • Sexual function problems
    • Pain
    • Blood clots
    • Impaired muscle coordination (or spasticity)
    • Pneumonia
    • Autonomic dysreflexia (or hyperreflexia), which causes a potentially lethal increase in blood pressure
    • Increased likelihood of certain cancers, including bladder cancer


  1. McKinley, W. O., Tewksbury, M. A., & Godbout, C. J. (2002). Comparison of medical complications following nontraumatic and traumatic spinal cord injury. The Journal of Spinal Cord Medicine, 25(2):88-93.
  2. Gunduz, H. & Binak, D. F. (2012). Autonomic dysreflexia: An important cardiovascular complication in spinal cord injury patients. Cardiology Journal, 19(2):215-219.
top of pageBACK TO TOP