- Spinal cord injury occurs when the spinal cord or the nerves at the end of the spinal canal are damaged and causes changes to how the body works.
- Spinal cord injury may cause changes in strength, sensation, bladder, bowel and other functions below the injury.
- There are many different types of spinal cord injury and the effects of the injury can be very different from one person to the next.
- The amount of function affected largely depends on where the injury occurs and how severe the damage is.
- Health providers use a standardized physical exam called the International Standards for Neurological Classification of Spinal Cord Injury exam to determine the level of injury and whether the injury is complete or incomplete. This is referred to as the AIS classification.
SCI can be a life-changing injury. It can affect many different body systems and often causes permanent changes to strength, sensation, and other functions below the injury. There are many different types of spinal cord injury and the effects of the injury can be very different from one person to the next.
SCI can have many causes, which are commonly divided into traumatic or non-traumatic causes.
Traumatic spinal cord injury
Traumatic spinal cord injury is damage to the spinal cord that is caused by direct trauma from an outside force. This is usually caused by a sudden blow to the spine (such as something falling on the spine), compression of the spine (from the force of a car of a car accident, for example) or a penetrating injury (such as a gunshot wound).
Although a large force is usually needed to damage the spine, smaller forces can also cause traumatic injuries in people with certain medical conditions. For example, people with osteoporosis have weak bones that can break from lesser forces, such as a fall from a standing position.
Non-traumatic spinal cord injury
Non-traumatic spinal cord injury is damage to the spinal cord that is caused by anything other than direct trauma. This includes complications from an illness, degeneration of the spine from arthritis, or certain conditions that people are born with (like spina bifida). Non-traumatic injuries often develop gradually over time, compared to the sudden onset of traumatic injuries.
Common causes of spinal cord injury
|Traumatic spinal cord injury||Non-traumatic spinal cord injury|
Spinal cord injury can cause a wide range of different signs and symptoms. The effects of the injury can be very different from one person to the next, depending on the person and the characteristics of the injury. Symptoms can be temporary or permanent and may change over time.
The earliest period after a spinal cord injury often involves a phase of shock. This is usually a temporary period that resolves after a few days or weeks.
After shock resolves, the longer-lasting symptoms of spinal cord injury may be experienced. These may include the following symptoms.
Changes in sensation
Changes in sensation occur below the spinal cord injury. This may include total or partial loss of sensation as well as abnormal sensations like tingling, numbness, or pain.
The amount of sensation affected depends on whether the injury is complete or incomplete and the level of the injury. Each level of injury causes changes to the sensation in a specific area of the body. For example, an injury at C3 affects sensation from the neck down, whereas an injury at L1 affects sensation of the legs and groin.
People with incomplete spinal cord injuries may have only parts of their sensation below the injury affected. Those with complete injuries may also have some sensation in select areas below the injury, which are called zones of partial preservation.
Changes in strength and muscle control
Changes to the strength and control of the muscles also happens below the injury. This can include both paralysis (loss of movement) and weakness of the muscles.
The amount of strength and movement affected depends on whether the injury is complete or incomplete and the level of injury. Each level of injury affects specific muscles. For example, an injury at C3 can cause paralysis from the neck down, whereas an injury at L1 can cause paralysis of the hips and legs.
People with incomplete injuries may have strength in some of the muscles below the injury.
Changes in breathing
People who have cervical and thoracic spinal cord injuries may experience problems with breathing. This is because the diaphragm (the main muscle of breathing), as well as the muscles of the neck, chest, and abdomen are needed to breathe and cough normally. This can affect the ability to breathe, cough, and clear mucus from the lungs without assistance.
Injuries at C5 and above affect the diaphragm and sometimes people with injuries at these levels cannot breathe long-term without the support of a ventilator or other device. People with lower cervical and thoracic injuries may also experience problems breathing because they cannot control other important muscles of the neck and rib cage that help with breathing and coughing.
Changes in bladder function
There are a number of changes to bladder function after spinal cord injury, including inability to control urination. Many people will use catheters and other treatments to control their bladder functions after spinal cord injury, which may predispose them to developing urinary tract infections if not done carefully.
Bowel problems are also common after spinal cord injury and can include an inability to control bowel functions (bowel incontinence), constipation, and other problems. Many people use a personalized bowel routine, which is a schedule that keeps bowels moving at a regular rate (using special foods or supplements), to maintain healthy bowel function after spinal cord injury.
Changes in control of blood pressure and heart rate
The autonomic nervous system is part of the nervous system that controls the unconscious functions of the internal organs like the heart and circulation (blood vessels). Spinal cord injury can cause changes to how the autonomic nervous system functions, which may alter the body’s ability to control blood pressure, temperature, and heart rate, as well as cause conditions like orthostatic hypotension (a sudden drop in blood pressure when moving into an upright position) and autonomic dysreflexia.
Changes in sexual function
Changes in sexual function are also common after spinal cord injury. This may include difficulties with orgasm, ejaculation, and erection. These changes depend on the individual and their particular injury.
Complete spinal cord injury
A complete spinal cord injury is when there is a total loss of strength and sensation below the spinal cord injury. This must include complete loss of movement or sensation of the anus (S4 and S5).
In some cases, people with complete injuries may still have some areas of strength or sensation below level of injury (but not including S4 and S5). These areas are known as zones of partial preservation.
Incomplete spinal cord injury
Incomplete injuries can have very different symptoms depending how much and in what way the injury has affected the spinal cord. These have traditionally been described as different ‘syndromes’, but more often now are best described by the characteristics of the person’s unique symptoms.
You may hear your healthcare providers use these terms:
|Syndrome||Area of spinal cord injury||Key Symptoms|
|Central cord syndrome||Central areas of the cervical spinal cord||
|Brown-Séquard syndrome||One half of the spinal cord (the right or left side)||
|Conus medullaris syndrome||The end of the main part of the spinal cord and the start of the ’cauda equina’||
|Cauda equina syndrome||The nerves in lowest part of the spinal canal once the ’true’ spinal cord has ended||
Neurological level of injury is the lowest level of the spinal cord that has normal function, which is confirmed using strength and sensation tests. Level of injury is an important classification that, together with whether the injury is complete or incomplete, can be used to describe how much physical function a person is likely to have.
The International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) exam (often called the American Spinal Injury Association (ASIA) exam) is a physical exam that is used to classify spinal cord injuries. It determines both the neurological level of injury and the completeness of the injury.
During this exam, a health provider such as a doctor or physiotherapist will carefully test for sensation and strength at specific points on the body and use the exam findings to determine the characteristics of the injury. These tests include:
- Testing for “light touch” sensation (if you can feel the touch of a cotton swab or tissue and whether it feels normal)
- Testing for “pin prick” sensation (if you can feel whether the touch of a safety pin is sharp or dull and whether it feels normal)
- Testing for muscle strength of specific muscles (if you can resist against certain movements applied by the health provider)
- Testing for movement and sensation of the anus. This is a very important test because it is the only way we can determine if a person’s injury is complete or incomplete). It is testing the last nerves to leave the spinal cord (S4 and S5).
ASIA Impairment Scale (AIS)
The ASIA Impairment Scale (AIS) describes the completeness of the injury. This scale identifies whether a person has any movement or sensation in the lowest levels of the spinal cord (S4 and 5) and what movement or sensation they have below the neurological level of injury. If you are interested in learning how healthcare providers are trained to do the test, you can visit http://asialearningcenter.com/.
|A, Complete||No sensation or movement below the injury, including around the anus (S4 and 5)|
|B, Sensory Incomplete||There is sensation, but not movement below the injury, including around the anus (S4 and 5)|
|C, Motor Incomplete||There is movement, but not sensation below the level of injury and more than half of the muscles below the injury are quite weak|
|D, Motor Incomplete||Movement is present below the injury and at least half of muscles below the injury have close to normal strength|
|E, Normal||Sensation and movement are normal|
Spinal cord injury is a relatively rare condition. Although estimates vary by country and study, it is estimated 86,000 people were living with SCI in Canada in 2010. New injuries were estimated to be 4,300 per year in 2010.
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