Spinal Cord Injury Levels

The level of injury is very helpful in predicting what parts of the body might be affected by paralysis resulting in loss of function. Remember that in incomplete injuries there can be a wide variation in the prognoses.

Cervical (neck) injuries usually result in Quadriplegia/Tetraplegia. Injuries to the spinal cord segments above the C4 level (C1,C2, C3) may result in the need of breathing aids such as mechanical ventilators or diaphragm pacemakers. Diaphragm pacemaker devices may be required to stimulate the phrenic nerve to initiate a persons breathing due to weak innervation of the diaphragm. C5 injuries often result in shoulder (deltoid) and biceps control, but no control of the wrist or hand. C6 injuries generally yield wrist control (wrist extensors), but no finger hand function. Individuals with C7-T1 injuries can straighten their arms (triceps) but still may have dexterity problems with the hand and fingers.

It is interesting to note that in the cervical area of the spine the nerve roots exit the spinal column above the vertebra, except for C7 where a pair of nerve roots also exit both above and below the vertebra. This is why there are seven cervical vertebrae but eight pairs of cervical nerve roots, C1-C8. From T1 downwards all spinal nerves then exit the spinal column below the vertebrae.

Injuries at the thoracic level and below result in paraplegia, with the hands not affected. At T1 to T8 whilst there is good control of the hands, trunk control may vary as the result of lack of abdominal muscle control. Lower thoracic injuries (T9 to T12) allow good truck control and good abdominal muscle control. Sitting balance is very good. Lumbar and sacral injuries yield decreasing control of the hip flexors and legs.

To reference the spinal segments discussed above, the 5 spinal segments are:

Cervical segments: C1-C8
Thoracic segments: T1-T12
Lumbar segments: L1-L5
Sacral segments: S1-S5
1 coccygeal spinal nerve (sensation only).
Paralysis also has other effects as well as a loss of sensation or motor function. Individuals with SCI also experience other neurological changes. For example, the person may experience dysfunction of the bowel and bladder. Sexual function is frequently affected in men with SCI as they may have their fertility affected due to the inability to attain an erection or achieve ejaculation, while women’s fertility is generally not affected. Other effects of SCI may include low postural blood pressure (postural hypotension), inability to regulate blood pressure effectively , reduced control of body temperature (poikilothermic), inability to sweat below the level of injury, and chronic pain.

Symptoms

Your ability to control your limbs after spinal cord injury depends on two factors: the place of the injury along your spinal cord and the severity of injury to the spinal cord.

The lowest part of your spinal cord that functions normally after injury is referred to as the neurological level of your injury. The severity of the injury is often called “the completeness” and is classified as either of the following:

Complete. If almost all feeling (sensory) and all ability to control movement (motor function) are lost below the spinal cord injury, your injury is called complete.
Incomplete. If you have some motor or sensory function below the affected area, your injury is called incomplete. There are varying degrees of incomplete injury.
Additionally, paralysis from a spinal cord injury may be referred to as:

Tetraplegia. Also known as quadriplegia, this means your arms, hands, trunk, legs and pelvic organs are all affected by your spinal cord injury.
Paraplegia. This paralysis affects all or part of the trunk, legs and pelvic organs.
Your health care team will perform a series of tests to determine the neurological level and completeness of your injury.

Spinal cord injuries of any kind may result in one or more of the following signs and symptoms:

Loss of movement
Loss of sensation, including the ability to feel heat, cold and touch
Loss of bowel or bladder control
Exaggerated reflex activities or spasms
Changes in sexual function, sexual sensitivity and fertility
Pain or an intense stinging sensation caused by damage to the nerve fibers in your spinal cord
Difficulty breathing, coughing or clearing secretions from your lungs
Emergency signs and symptoms

Emergency signs and symptoms of spinal cord injury after an accident may include:

Extreme back pain or pressure in your neck, head or back
Weakness, incoordination or paralysis in any part of your body
Numbness, tingling or loss of sensation in your hands, fingers, feet or toes
Loss of bladder or bowel control
Difficulty with balance and walking
Impaired breathing after injury
An oddly positioned or twisted neck or back