Spinal Cord Injury
The human spinal cord is a bundle of nerve cells and fibres called axons that is approximately 18 inches long extending from the base of the brain to the lower back.
These axons are responsible for the communication systems of the body, which include sensory, motor, and autonomic functions. Axons are long, thin strings of nerve cell cytoplasm that carry electrical signals. The axons of nerve cells with similar functions run in groups or pathways. Some pathways carry sensory information up to the brain; others carry sensory information down from the brain to control the movements of the body. The spinal cord is surrounded by protective bones, 33 individual vertebrae called the vertebral column, or the spinal column, or the backbone.
The vertebrae have different names depending on their location:
- 7 cervical vertebrae located in the neck
- 12 thoracic vertebrae in the upper back
- 5 lumbar vertebrae in the lower back
- 5 fused sacral vertebrae in the hip area
- 4 fused vertebrae in the coccyx (tailbone)
The nerves that lie within the spinal cord are upper motor neurons (UMNs). Their function is to carry the messages back and forth from the brain to the spinal nerves along the spinal tract. The nerves that branch out from the spinal cord to the other parts of the body are called lower motor neurons (LMNs). These nerves exit and enter at each vertebral level and communicate with specific areas of the body. The sensory portions of the LMN carry messages about sensation from the skin and other body parts and organs to the brain. The motor portions of the LMN send messages from the brain to the various body parts to initiate actions such as muscle movement. “Spinal cord injury” (SCI) refers to any injury of the neural elements within the spinal cord. SCI can occur from either trauma or disease to the vertebral column or the spinal cord itself. Most spinal cord injuries are the result of trauma to the vertebral column. These injuries can affect the spinal cord’s ability to send and receive messages from the brain to the body systems that control sensory, motor, and autonomic function below the level of injury. Depending on the location and severity of the injury, the body can be affected in numerous ways. Typically, the nerves above the injury site continue to function as they always have and the nerves below the site do not. SCI is classified as “complete” when the nerve damage obstructs every signal coming from the brain to body parts below the injury. It is called “incomplete’ when only some of the signals are obstructed. In an incomplete injury, the messages that pass between the brain and the parts of the body depend on how many nerves remain undamaged. The level of injury is determined by which vertebrae have been injured. Generally, the closer the injury is to the brain, the greater the loss of function and feeling.
Paraplegia is loss of feeling and inability to move the lower part of the body. Tetraplegia, formerly called quadriplegia is loss of movement and feeling in both the upper and lower parts of the body.
Sometimes the spinal cord is only bruised or swollen after the initial injury and as the swelling goes down, the nerves begin to work again. Unfortunately, there are no tests to determine how may nerves, if any will work again. Generally, however, the longer there is no improvement, the less improvement will occur. In addition to movement and feeling, SCI affects other bodily functions, such as breathing, bowel and bladder control. It may also affect sexual function. The damage that occurs to spinal cord axons within the first few hours after injury is complex and occurs in stages. Normal blood flow is disrupted, which causes oxygen deprivation to some of the tissues of the spinal cord. Bleeding into the injured area leads to swelling, which can further compress and damage the axons. The chemical environment becomes destructive, due primarily to the release of highly reactive molecules known as free radicals. These negatively charged ions can break up cell membranes, thus killing cells that were not injured initially. Blood cells called macrophages that invade the site of injury to clean up debris may also damage uninjured tissue. Non-neuronal cells including astrocytes may divide too often, forming a scar that impedes the regrowth of injured nerve cell axons. Within weeks or months following injury, cysts often form at the site of injury and fill with cerebrospinal fluid, the clear, watery fluid that surrounds the brain and spinal cord.
Typically, scar tissue develops around the cysts, creating permanent cavities that can elongate and further damage nerve cells. In addition, nerve cell axons that were not damaged initially often lose their myelin, a white, fatty sheath that surrounds groups of axons to enhance the speed of nerve impulses. Scientists are trying to understand how this complex series of disruptive events occurs so they can find ways to prevent and treat it. They are also trying to identify treatments that will enhance some of the normal, but often limited kinds of recovery that can occur after a spinal cord injury. Another complication in spinal cord injury stems from the variety of nerve fibers and cell types that make up the tissue. The downward or descending pathways from the brain in the spinal cord carry nerve signals that control voluntary movements. The upward or ascending pathways carry sensory information–about touch, temperature, pain and body position–from the entire body to the brain. Researchers believe that the ascending and descending pathways, as well as different groups of nerve cells, called neurons in the spinal cord, may require individualized treatments to regenerate and regain their functions.
If you require assistance in dealing with the Insurance Corporation of British Columbia [ICBC] or any other personal injury matter, please contact us for information on our services or for specific advice about your potential claim. Hughes & Company Law Corporation has prepared these materials for general information purposes only and not for the purpose of giving legal advice. Every case is unique. Regardless of any similarity to your situation, the information on this web site should not be relied on in making any legal decision. Cedric Hughes and Hughes & Company Law Corporation are not by means of this web site giving legal advice or providing any other service and they are not responsible for any use made of this web site. Please contact us for specific legal advice.