Quadriplegia is caused by damage to the brain or 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 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, meaning the arms and the legs. An impairment in motor or sensory function of the lower extremities is known as paraplegia. Typical causes of quadriplegic from damage to the spinal cord are trauma (such as car crash, fall or sports injury).
Upon visual inspection of a quadriplegic patient, the first symptom of quadriplegic is 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. Furthermore, sensation is usually impaired in affected areas. This can manifest as numbness, reduced sensation or sore burning neuropathic pain.
Quadriplegic is defined in different ways depending on the level of injury to the spinal cord. C1-C4 usually affects arm sensation and movement more so than a C5-C7 injury; however, all quadriplegics 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 hands.
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.
Patients with C-1 and C-2 lesions may have functional phrenic nerves. In these cases, implanted phrenic nerve pacemakers can be used, and pacing of the diaphragms may be simultaneous or alternating. If secretions are not a problem, tracheostomies may be plugged or discontinued. Less equipment may be needed for C-1 and C-2 patients than for C-3 and C-4 patients.
C-5 Quadriplegics have functional deltoid and/or biceps musculature. They can internally rotate and abduct the shoulder, which causes forearm pronation by gravity. Wrist flexion is similarly produced. They can externally rotate the shoulder and cause supination and wrist extension. They can bend the elbow, but elbow extension can only be produced by gravity, or by forceful horizontal abduction of the shoulder and inertia or shoulder external rotation.
C-6 patients have musculature that permits most shoulder motion, elbow bending, but not straightening, and active wrist extension which permits tenodesis, opposition of thumb to index finger, and finger flexion. Wrist extensor recovery is common in C-6 patients, but its return can be delayed. Tenodesis orthoses support tenodesis training early in recovery. Wrist-driven flexor hinge splints permit pinching strength, needed for catheterization and work skills. Short opponens orthoses with utensil slots, writing splints, Velcro handles, and cuffs permit feeding, writing, and oral facial hygiene.
C-7 patients have functional triceps, they can bend and straighten their elbows, and they may also have enhanced finger extension and wrist flexion. As a result, they have enhanced grasp strength which permits enhanced transfer, mobility, and activity skills. They can turn and perform most transfers independently. They can propel a manual wheelchair on rough terrain and slopes, and may therefore not need a powered wheelchair. They may drive with a van and specialized equipment. They can perform most daily activities, they can cook and do light housework, and therefore they may live independently. They may, however, require assistance for bowel care and bathing.