Shown here is the nervous system, containing the brain, spinal cord and peripheral nerves.
Credit: The BioDigital HumanTM developed by NYU School of Medicine and BioDigital Systems LLC
The spinal cord is a bundle of nerves that extends from the brain and runs down the middle of the back. It sends signals to and from the brain and the rest of the body. It is a soft tissue surrounded and protected by the vertebrae in the spine.
A spinal cord injury is caused by damage to any part of the spine, including to the vertebrae, ligaments or disks, or the spinal cord itself. Spinal cord injuries can cause permanent loss of function below the level of the injury, including paralysis.
The incidence of spinal cord injury among survivors is about 40 cases per million in the United States, or about 12,000 new cases per year, according to the National Spinal Cord Injury Statistical Center (NSCISC). Estimates of the number of people in the United States living with spinal cord injuries range from 238,000 to 332,000.
A sudden blow to the spine that fractures, dislocates, crushes or compresses the vertebrae can cause traumatic spinal cord injuries. A gunshot or knife wound can also cut the spinal cord. During the weeks following the injury, bleeding, swelling, inflammation and fluid buildup in or near the spinal cord often cause further damage.
Diseases such as arthritis, cancer, inflammation, infections or degeneration of spinal disks can cause nontraumatic spinal cord injuries.
NSCISC lists the following causes of spinal cord injury since 2010:
- Motor vehicle accidents (36.6 percent)
- Falls (28.5 percent)
- Violence (14.3 percent)
- Sports (9.2 percent)
- Other/Unknown (11.4 percent)
Spinal cord injury levels
Spinal cord injuries vary in their location and severity. The "level" of injury refers to the lowest part of the spinal cord with normal function. Higher-level injuries affect the arms, hands, trunk, legs and pelvic organs, whereas lower-level injuries affect only the legs, pelvic organs and trunk. These can result in paralysis of all four limbs (tetraplegia or quadriplegia) or paralysis of the lower limbs (paraplegia).
The severity of the injury is classified as either complete, in which nearly all movement and sensation below the level of the injury is lost, or incomplete, in which some residual movement and sensation remains.
Symptoms of spinal cord injury include:
- loss of movement
- loss of sensation (sense of touch, heat or cold)
- loss of bowel or bladder control
- exaggerated reflexes or spasms
- changes in sexual function or sensitivity
- pain or stinging due to nerve damage
- difficulty breathing, coughing, or clearing the throat
Emergency symptoms of an injury include:
- severe pain or pressure in the neck, head or back
- weakness, lack of coordination or paralysis of part of the body
- numbness, tingling or loss of feeling in the hands and feet
- loss of bladder or bowel control
- difficulty walking or balancing
- difficulty breathing after the injury
- a twisted neck or back
People with these symptoms should seek immediate medical attention.
Treatment options are limited, but prosthetic technologies and therapeutic drugs that may help nerve cells regenerate or improve how well remaining nerves function are being developed.
Immediately after an accident, emergency responders immobilize the spine using a stiff neck collar and carrying board in order to transport the patient. Emergency treatment involves maintaining breathing ability, preventing shock, keeping the neck immobilized, and preventing complications such as blood clots.
Once a patient is diagnosed with a spinal cord injury, they may receive medications, such as Methylprednisolone (Medrol), which can cause mild improvement in some patients, if taken within eight hours of injury. Doctors may use traction (often by attaching metal braces and weights to the skull to prevent it moving) to stabilize the spine and/or realign it. Surgery may be needed to remove fragments of bone, herniated disks, fractured vertebrae or foreign objects, or to stabilize the spine to minimize pain or future deformity.
A variety of experimental treatments may also be available.
A team of therapists and specialists work with patients during their early stages of recovery. Physical therapists focus on having the patient maintain and strengthen existing muscle function, while occupational therapists, rehab psychologists and others help the patient learn basic tasks and new skills.
Modern technology can provide some independence to individuals living with spinal cord injury. Assistive equipment includes wheelchairs, computer adaptations, electronic aids, robotic gait training and electrical stimulation.
Researchers are currently developing neural prostheses, known as brain-computer interfaces. These systems use electrodes on the scalp or implanted in the brain, which record electrical signals from neurons and translate them into control of a computer or prosthetic limb. The technology is still in its early stages, however, and not available for general use.