Table of Contents
Causes of Quadriplegia
Quadriplegia (tetraplegia) is caused by damage to the cervical spinal cord segments at levels C1-C8. Damage to the spinal cord is usually secondary to an injury to the spinal vertebrae in the cervical section of the spinal column. The injury to the cellular structure of the spinal cord is known as a lesion and may result in the loss of partial or total function in all four limbs, the arms and the legs.
Typical causes of quadriplegia from damage to the spinal cord are trauma (such as car crash, fall or sports injury), disease (such as transverse myelitis or polio) or congenital disorders, such as muscular dystrophy. It is possible to injure the spinal cord without fracturing the spine, such as when a ruptured disc or bony spur on the vertebra protrudes into the spinal column.
The condition quadriplegia is also termed tetraplegia. Both terms mean “paralysis of four limbs”; tetraplegia is more commonly used in Europe than in the United States. In 1991, when the American Spinal Cord Injury Classification system was revised, it was recommended that the term tetraplegia be used to improve consistency (“tetra”, like “plegia”, has a Greek root, whereas “quadra” has a Latin root).
Symptoms of Quadriplegia
Upon visual inspection of a quadriplegic patient, the first symptom of quadriplegia is of motor or sensory impairment to the arms and legs. Function is also impaired in the torso. The loss of function in the torso usually results in a loss or impairment in controlling the bowel and bladder, sexual function, digestion, breathing and other autonomic functions.
Sensory loss can manifest itself as numbness, reduced sensation or sore burning neuropathic pain.
Quadriplegic symptoms show in different ways depending on the level of injury to the spinal cord. C1–C4 usually affects upper trunk control, respiratory control and arm sensation and movement more so than a C5–C7 injury. A common symptom of quadriplegia is to have or have had some kind of finger dysfunction.
A person with damage to the spinal cord at the cervical spinal cord segment C1 (the highest cervical vertebra, at the base of the skull) will probably lose function from the neck down and require permanent assistance with breathing in the form of a machine called a ventilator. A person with a C8 spinal cord injury may lose function from the chest down, but still retain use of the arms and much of the fingers.
The degree of the injury to the cellular structures of the spinal cord is very important. A complete severing of the spinal cord will result in complete loss of function from that spinal segment down. A partial severing or even bruising or swelling of the spinal cord results in varying degrees of mixed function and paralysis. A common misconception with quadriplegia is that the victim cannot move legs, arms or control any of the major bodily functions; this is often not the case. Some quadriplegic individuals can walk and use their hands as though they did not have a spinal cord injury, while others may use wheelchairs although they may still have function in their arms and mild finger movement, this is dependent on the degree of damage done to the spinal cord.
Spinal Nerves and Levels
The body is supplied by a particular level or segment of the spinal cord and its corresponding spinal nerve. Function below the level of spinal cord injury will be either lost or impaired.
This is approximately the same for every person:
Quadriplegia will result in complete loss or impaired function below the following cervical levels of injury.
C3,4 and 5 Supply the diaphragm (mostly C4) (the large muscle between the chest and the belly that we use to breath).
C5 also supplies the shoulder muscles (deltoid) and the muscle that we use to bend our elbow (biceps).
C6 Bends the wrist back (extension), and externally rotates the arm (supinates).
C7 Straightens the elbow and wrist (triceps and wrist flexors) straightens fingers, pronates wrist.
C8 Bends the fingers (flexion).
Injury below the cervical spinal segments will result in paraplegia.
Secondary Complications of Quadriplegia
Secondarily, because of a quadriplegic’s depressed physical functioning and immobility, they are often more susceptible to pressure sores, spasticity, osteoporosis and fractures, frozen joints, pneumonia, respiratory complications and infections, kidney stones, autonomic dysreflexia, deep vein thrombosis, and cardiovascular disease.
ASIA impairment scale
Spinal cord injuries are classified by the American Spinal Injury Association (ASIA) classification. The ASIA scale grades patients based on their functional impairment as a result of the injury, grading a patient from A to D.
A=Complete: no motor or sensory function is preserved in the sacral segments S4–S5.
B=Incomplete: sensory but not motor function is preserved below the neurological level and includes the sacral segments S4–S5.
C=Incomplete: Motor function is preserved below the neurological level, and more than half of key muscles below the neurological level have a muscle grade less than 3.
D=Incomplete: Motor function is preserved below the neurological level, and at least half of key muscles below the neurological level have a muscle grade of 3 or more.