A majority of spinal cord injuries are due to injury to the vertebral column. This can include:
- Fracture of the bony material
- Dislocated joints
- Torn ligaments
- Herniated discs.
The injuries show the force and the direction of what happened, which in turn causes flexion, extension, rotation, and/or compressed spine, also makes the elements of the spine vulnerable. Most vertebral injuries in older people involve dislocation and fractures. The type of injury that occurred will tell if there will be a risk for more damage to the spinal cord.
The timeline of a spinal cord injury can be split into primary and secondary injury. Primary injury refers to the immediate effects of the trauma which may include compression, contusion, and a shear injury to the spinal cord. In the absence of part of the cord, or a frank hemorrhage (both of which are rare in non penetrating injuries), the cord may appear to be completely normal right after the event occurred. Penetrating injuries, such as a stabbing, or a gun shot wound, usually result in partial or complete transection of spinal cord. A remarkable action is when a spinal cord injury occurs following a gun shot wound that does not penetrate the spinal canal. The injury is therefore caused by kinetic energy caused by the bullet.
A secondary injury usually follows, starting within minutes and evolving over the course of hours after the injury occurred. The process that drives this is complex and not fully understood. The possible mechanisms are ischemia, hypoxia, edema, inflammation, troubling ion homeostasis, and apoptosis. The remarkable occurrence of secondary injuries is sometimes manifested clinically by neurological deterioration over the course of eight to twelve hours. This is in patients who present an incomplete cord syndrome first.
Within hours after the injury, spinal cord edema develops due to the secondary injuries. The edema peaks between day three and day six, and then begins to fade away after day nine. This is eventually replaced by a central hemorrhagic necrosis.
Clinical Presentation
A person who has an injury to the spinal cord will often experience pain at the site of the fracture, but not all do, and lack of pain does not rule out SCI. People with SCI often have related systematic and brain injuries that limit their ability to tell the doctor about any pain. Doctors find this to be an obstacle in evaluation of the patient, and the missed communication could affect the prognosis.
Almost half of the SCIs include the cervical cord and result in quadriparesis or quadriplegia. The seriousness of the cord syndromes is determined using the American Spinal Injury Association (ASIA) Scale or the Frankel scale:
Complete injury - (grade A) - There is a rostra zone of sensory, lower sensation in the next caudal level, and no sensation at all in all levels below, including none in the sacral segments, S4-S5. There will also be a lower muscle power in the level below the injury, followed by paralysis in the more caudal myotomes. Reflexes are nonexistent in the acute stage, and there is no response to stimulation, and muscle tone is flimsy. Men with TSCI may experience priapism. Urinary problems will happen.
Incomplete injury - (Grade B - D) - There are varying degrees of motor function in the muscles that are controlled by the spinal cord rear to the injury. Sensation is partly saved in areas below the injury. Typically sensation is saved over motor function because sensory tracts are in a less vulnerable place of the spinal cord. The anal sensation and bulbocavernosus reflex are usually there.
The occurrence of complete versus incomplete injuries has increased over the years because of improved care and systems that recognize the importance of immobilization after the injury occurs.
Transient paralysis and spinal shock - Following a spinal cord injury, there could be loss of all activity in the spinal cord. In men, especially those who have a cervical cord injury, priapism may occur. There could also be bradycardia and hypotension. This altered state could last for several weeks, which is why it is referred to as spinal shock. It is believed that function loss is due to the lack of potassium in the injured cells in the spinal cord. As the potassium levels increase, the shock wears off. Clinical manifestations will normalize somewhat, typically replaced by a spastic paresis that indicates more injuries to the spinal cord.
A transient paralysis accompanied with a full recovery occurs the most in young people with a sports related injury. These people should be fully evaluated for any underlying conditions before they engage in athletic activities.