Spinal Cord Injury - Signs and Symptoms

Signs and Symptoms

Signs observed by a physician and symptoms experienced by a patient will vary depending on where the spine is injured and the extent of the injury. These are all determined by the area of the body that the injured area of the spine innervates. A section of skin innervated through a specific part of the spine is called a dermatome, and spinal injury can cause pain, numbness, or a loss of sensation in the relevant areas. A group of muscles innervated through a specific part of the spine is called a myotome, and injury to the spine can cause problems with voluntary motor control. The muscles may contract uncontrollably, become weak, or be completely unresponsive. The loss of muscle function can have additional effects if the muscle is not used, including atrophy of the muscle and bone degeneration.

A severe injury may also cause problems in parts of the spine below the injured area. In a "complete" spinal injury, all function below the injured area are lost. In an "incomplete" injury, some or all of the functions below the injured area may be unaffected. If the patient has the ability to contract the anal sphincter voluntarily or to feel a pinprick or touch around the anus, the injury is considered to be incomplete. The nerves in this area are connected to the very lowest region of the spine, the sacral region, and retaining sensation and function in these parts of the body indicates that the spinal cord is only partially damaged. An incomplete spinal cord injury involves preservation of motor or sensory function below the level of injury in the spinal cord. This includes a phenomenon known as sacral sparing which involves the preservation of cutaneous sensation in the sacral dermatomes, even though sensation is impaired in the thoracic and lumbar dermatomes below the level of the lesion. Sacral sparing may also include the preservation of motor function (voluntary external anal sphincter contraction) in the lowest sacral segments. Sacral sparing has been attributed to the idea that the sacral spinal pathways are not as likely as the other spinal pathways to become compressed after injury. The sparing of the sacral spinal pathways can be attributed to the lamination of fibers within the spinal cord.

A complete injury frequently means that the patient has little hope of functional recovery. The relative incidence of incomplete injuries compared to complete spinal cord injury has improved over the past half century, due mainly to the emphasis on better initial care and stabilization of spinal cord injury patients. Most patients with incomplete injuries recover at least some function.

In addition to sensation and muscle control, the loss of connection between the brain and the rest of the body can have specific effects depending on the location of the injury.

Determining the exact "level" of injury is critical in making accurate predictions about the specific parts of the body that may be affected by paralysis and loss of function. The level is assigned according to the location of the injury by the vertebra of the spinal column. While the prognosis of complete injuries are generally predictable since recovery is rare, the symptoms of incomplete injuries can vary and it is difficult to make an accurate prediction of the outcome.