Incidence and Causes of Spinal Cord Injury

It is estimated that the incidence rate of spinal cord injury (SCI) in Canada is approximately 35 per million population. Based on Canada's current population, this translates into approximately 1,050 new injuries per year resulting in some level of permanent paralysis or neurological deficit.

When it comes to causes of SCI, an analysis of six years of data collected by CPA from 1983 to 1989 on more than 3000 new injuries tells us that vehicular accidents (car and motorcycle) were the leading cause of injury at 54.7%.  The second highest cause of injury was falls, including industrial accidents, which accounted for 17.7%.  Other causes included medical conditions, diving and sports injuries.

Anatomy of the Spine

There are three 'regions' to the spinal column:

Cervical Spine: There are seven cervical bones or vertebrae.  The cervical bones are designed to allow flexion, extension, bending, and turning of the head.  They are smaller than the other vertebrae, which allows a greater amount of movement.

Each cervical vertebra consists of two parts: 1) a body 2) a protective arch for the spinal cord called the neural arch.  Fractures or injuries can occur to the body, limb pedicles, or processes.  Each vertebra articulates with the one above it and the one below it.

Thoracic Spine: The thoracic spine attaches to the ribs in the chest region. There are 12 vertebrae in the thoracic region.  The spinal canal in the thoracic region is relatively smaller than the cervical or lumbar areas.  This makes the thoracic spinal cord at greater risk if there is a fracture.  The motion that occurs in the thoracic spine is mostly rotation (the ribs prevent bending to the side).  Only a small amount of movement occurs in bending forward and backward.

Lumbosacral Spine: The lumbar vertebrae are large, wide, and thick. There are five vertebrae in the lumbar spine.  The lowest lumbar vertebra, LS, articulates with the sacrum.  The sacrum attaches to the pelvis.  The main motions of the lumbar area are bending forward and extending backwards. Bending to the side also occurs.

Each portion of the spinal cord is divided into specific neurological segments:

The cervical spinal cord is divided into eight levels.  Each level contributes to different functions in the neck and the arms. Sensations from the body are similarly transported from the skin and other areas of the body from the neck, shoulders, and arms up to the brain.

In the thoracic region, the nerves of the spinal cord supply muscles of the chest that help in breathing and coughing.  This region also contains nerves in the sympathetic nervous system.

The lumbosacral spinal cord and nerves supply legs, pelvis, and bowel and bladder.  Sensations from the feet, legs, pelvis, and lower abdomen are transmitted through the lumbosacral nerves and spinal cord to higher segments and eventually the brain.

Consequences and Overview of SCI

Paralysis is caused by injury or disease to the spinal cord and the degree of paralysis depends upon the level of injury to the spinal cord.  An injury to the spinal cord can result in partial or total paralysis of two or four extremities, as well as loss of sensation and bowel and bladder control.

Many persons with a spinal cord injury still feel some sensation in the paralyzed parts of their body, or have some control of muscles below the level of injury.  This will often occur in the case of an incomplete injury where the spinal cord has been mashed or partially damaged from swelling and bruising. Nerve impulses may still travel through the spinal fibres left intact if the spinal cord has not been completely severed.  Consequences of an injury at a particular point on the spinal cord will vary from individual to individual.

Paraplegia is the paralysis of the lower extremities and part or all of the trunk muscles.  Usually there is a loss of sensation in paralyzed limbs and other effects such as muscle spasms, pain and loss of bowel and bladder control.  Paraplegia occurs when there is an impairment at or below the T1 Thoracic level.

Quadriplegia occurs when there is damage to the spinal cord in the Cervical region.  This will cause impairment to the hands and arms in addition to the effects of paraplegia.

Hemiplegia is the paralysis of one side of the body as a result of a stroke or traumatic brain injury and should not be confused with paraplegia or quadriplegia.  With paraplegia and quadriplegia the brain is not affected.  With hemiplegia, there may be an impairment of intellect, personality, speech or senses.

Detailed Description of SCI

The spinal cord is the "highway" through which motor and sensory information travels between the brain and body.  It contains spinal tracts (white matter) which surround central areas (gray matter) where most neuronal cell bodies are located.  Gray matter is organized into segments comprising sensory and motor neurons.  Nerves in the spinal cord connect to the body through nerve "roots" that exit the spinal column and supply the nerves in the legs, bladder, etc.

Each root receives sensory information from skin areas called dermatomes. Each root supplies nerve control to a group of muscles called a myotome. While a dermatome usually represents one specific skin area, most roots supply nerve control to more than one muscle, and most muscles are innervated by more than one root.

SCI affects conduction of sensory and motor signals across the site(s) of lesion(s).  By systematically examining the dermatomes and myotomes, health care practitioners can determine the cord segments affected by spinal cord injury.

Again, spinal cord injured patients are classified into two basic schemes:

Quadriplegia - if there is evidence of functional loss of motor and sensory function at or above the C8 neurological level with demonstrable loss in the upper extremities.

Definition of Quariplegia - impairment or loss of motor and/or sensory function in the cervical segments of the spinal cord due to damage of neural elements within the spinal canal.  Tetraplegia results in impairment of function in the arms as well as in the trunk, legs, and pelvic organs.  It does not include brachial plexus lesions or injury to peripheral nerves outside the neural canal.

Paraplegia - functional loss below the C8 level and represents a wide range of neuromuscular dysfunction.

Definition of Paraplegia - impairment of loss of motor and/or sensory function in the thoracic, lumbar or sacral (but not cervical) segments of the spinal cord, secondary to damage of neural elements within the spinal canal.  With paraplegia, arm functioning is spared but depending on the level of injury, the trunk, legs, and pelvic organs may be involved.

An injury is classified into two basic categories:

Incomplete - preserved motor or sensory function at the sacral levels
Complete - no functional motor or sensory preservation in the sacral segments

Functional Classification for Wheelchair Basketball

Wheelchair basketball attracts participants with various levels of physical ability.

The governing bodies involved in the promotion of the sport support a system that encourages and secures an opportunity for players at all levels of physical potential to participate in a wheelchair basketball game together.

Therefore, in order to ensure fair competitive opportunities for all athletes a classification system has evolved that recognizes the physical functional abilities of athletes and categorizes or assigns a classification to them.  It is important to note that the classification measures the players volume of action as opposed to his/her power, technique or ability.

The classification point value of the five players competing on the court is totalled, and may not exceed 14 points at any given time during international play (15 Points in CWBL Open, Junior, and Mini Basket Divisions, and 19.5 in the Women's Division).

There are two categories, Category A and Category B, which have led to the formation of the four classes 1, 2 and 3, 4.

CATEGORY A - This category is comprised of players who are not able to fix their pelvis, ie: complete paraplegics to lumbar 1 including those who have voluntary hip flexion with iliac psoas.

CLASS 1 - These athletes are not able to perform active rotation of the torso and lack abdominal muscles.  Generally speaking thoracic level 7 paraplegics and above.

CLASS 2 - These athletes have torso rotation, active stability and are generally speaking thoracic level 8 through lumbar 1 paraplegics.

CATEGORY B - This category is made up of players who are able to fix their pelvis and move their torso in the frontal and sagittal planes.

CLASS 3 - These athletes have mobility in the frontal plane and can therefore lean forward and return to an upright position without pushing off with their arms.  Generally speaking they could be categorized as lumbar 2 to lumbar 4 paraplegics.

CLASS 4 - These athletes have active mobility in the frontal and sagittal planes and can therefore lean at least to one side using hip abduction to maintain balance in the chair.  Generally speaking these athletes have lumbar 5 function or lower paraplegics.

* Special Note - In Canada, the CWBA has made a commitment to creating an inclusive environment in sport and therefore allow able bodied participation and quadriplegics.  An able bodied athlete is classified as a 4.5 whereas we have a 0.5 class that may apply to quadriplegics.