Spinal Cord Injury Overview
Spinal cord injury is traditionally discussed in two phases: primary and secondary injury.

The primary injury refers to the initial physical trauma to the spine. That could be a car accident, diving accident, severe fall, or any other traumatic event.

During the primary injury, neurological injury (injury to the nerves and/or spinal cord) can occur from:

• physical compression of the spinal cord or nerves: Trauma can cause impact of bone, disc, and/or ligament against the tissues by narrowing the spinal canal or even dramatically changing its alignment. The nerves get pinched during the injury.
• stretching of the tissues: While complete transection, or severing of the cord, is rare, the spinal cord can be badly damaged with even the slightest trauma delivered directly to it.
• blood supply impairment: The injury may cut off or greatly reduce the blood supply to the spinal cord and nerves. The internal capillary network, or microscopic blood vessels, can be damaged almost instantaneously and cause immediate hemorrhage, or bleeding, into the cord.

Damage to the spinal cord can be seen on an MRI immediately following trauma.

The secondary injury is the cascade of events in the body after the initial trauma—the body's attempt to deal with the injury. In the seconds, hours, days, and weeks afterward, several factors play a role in the severity of the secondary injury. There is a surge of chemicals released by the body in response to trauma that causes inflammation, decreased spinal cord blood flow, and cell death.

Therapies to treat spinal cord injury are typically directed at one or more steps in this cascade. Typical goals of treatment are:

• decreasing inflammation
• slowing degradation and cell death
• increasing blood flow
• reducing scar formation

Initial treatment of the spinal cord injury is focused on stabilizing the injury. After that's been accomplished (as much as possible), there are two other treatment goals:

• transplanting nerves
• nerve regeneration

Evaluating Treatments for Spinal Cord Injury
Treatment of spinal cord injury aims to reduce the effects of primary and secondary injury. One of the initial treatments is to immobilize the spine to prevent further injury. This is typically done at the scene of the accident. This can be done with a hard collar or brace.

Additional treatments include IV fluids and medications to maintain blood pressure, plus the administration of oxygen. Treatment utilizing these techniques is fairly standard to deal with the primary injury.

However, there's a debate in the medical community when it comes to performing surgery and using neuroprotective agents (drugs used to protect nerves from further injury) immediately following the primary injury.

Surgery may be indicated to remove physical impingement on the nerves, restore blood flow, and provide room for subsequent inflammation (inflammation is one of the body's ways to heal itself). In certain cases, it can be argued that the risk of moving a patient, putting them to sleep, and subjecting them to surgery immediately after the primary injury is greater than potential benefits.

Surgery is sometimes done at a later date to restore alignment of the bone and correct bony deformity. This can be as important as the decompression (taking the pressure off the nerves) in maximizing a patient's rehabilitation. The stabilization from surgery can help a patient sit upright, perhaps walk, and maintain their weight on their trunk. It can also keep them from developing posture problems in the future.

Methylprednisolone, a steroid that's considered a neuroprotective agent, is the only drug treatment supported by the medical community for use immediately following the primary injury. In 1990, a multi-center trial of methylprednisolone showed that the steroid improved neurological function in a subset of patients who were given the drug within the first eight hours of injury. Based on this research, many physicians use this treatment.

However, aspects of the research have since been questioned, and there is still debate within the medical community regarding the effectiveness of methylprednisolone. To date, it has not been defined as a standard of care by any major medical associations (such as the American Association of Neurological Surgeons).

Research into Spinal Cord Injury Treatments
A number of other treatments have been proposed and proven successful in animal trials. Many medical treatments first go through animal trials before being tried on humans. However, replicating these benefits in human beings remains quite difficult. In fact, of the nearly 100 different treatments that have proven effective in animals, only methylprednisolone has demonstrated relatively consistent findings in humans.

There are several reasons why research for spinal cord injuries is difficult:

• Anatomical differences in rodent spinal cords: While rodents are typically used for most animal research, their spinal cord has innate pathways that can create stepping patterns in the legs without any signal from the brain. That is, they can learn to walk again even after severe spinal cord injury with no treatment. Human spinal cords lack this ability.
• Difference between an actual injury and a simulated one: Most clinical cases of spinal cord injury—that is, actual injuries—result in significant trauma to the bony spine and often have neurological compression far greater than that seen in most animal models during a simulated injury. Therefore, treatments may be effective in animal trials where there's less trauma to the bones and less nerve damage. Then, when the same treatments are tried for actual injuries, they may be less effective because the injury is much more severe.
  
  When testing spinal cord treatments, researchers often use moderate spinal cord injuries. However, most human injuries are so polarized that they are either too severe for any therapy or so mild that recovery occurs without treatment.
• Difficulties with doing the same experiments and research on animals and humans: A number of variables encountered in animal research often cannot be controlled in subsequent human studies. Different models of injury, occurring at different times and treated with different drugs on different schedules, all contribute to inconsistencies. This results in significantly differing accounts of the usefulness of a treatment when comparing the animal studies and the human ones.
  
  For example, treatments in laboratory animals are often initiated within one hour after injury, which is not feasible in many clinical settings. That's because typically, the first responders to accident scenes work to stabilize the patient, their airway, and spine before transporting them to an emergency room. Trying to replicate that procedure by using actual first responders is difficult to do in clinical studies.

Promising Treatments
Three of the most promising treatments in spinal cord injury are hypothermia, naloxone, and corticosteroids. All three of those showed good results in animal trials. However, there have been conflicting results in human trials. While there have been enough positive results to lead to further research, scientists and physicians remain far from developing a truly effective treatment for spinal cord injury.

Hypothermia treatment has drawn a lot of interest due to a publicized case of its use with Kevin Everett, a tight end with the Buffalo Bills, who suffered a spinal cord injury during a game in 2007. Unfortunately, despite its purported success in this case, other human studies of hypothermia treatment have failed to demonstrate a beneficial effect, and some fear the risks outweigh the benefits. For example, one of the researchers from The Miami Project to Cure Paralysis suggests that cooling "may reduce blood flow in the injury spinal cord and exacerbate secondary injury"( J Neurosurg Spine 2:308-318, 2005).

Additionally, most physicians cite Everett's good outcome as the result of a less severe injury and early decompression—not necessarily because of the hypothermia treatment.

Conclusion
Research into treating spinal cord injury remains a major focus in the medical community. While there has been some incremental progress, we've not yet seen the major breakthroughs that we all desire. However, with continued investigation, treatments for spinal cord injuries will continue to improve.