Types of Spinal Cord Injury | Levels and Classifications
Like so many things, spinal cord injuries are lumped into groups. These classifications are based on the location of the injury, cause of injury, level of motor impairment, degree of sensory impairment, and muscle strength.
Listed below are terms, classifications, and grading scales commonly used when discussing spinal cord injuries.
Traumatic vs. Non-traumatic SCI
A traumatic injury occurs when an outside force impacts the spinal cord. Traumatic injuries are a result of events like motor vehicle accidents, sports accidents, acts of violence, falls, etc. and can cause a contusion (bruise) or a laceration (cut) in the spinal cord.
A non-traumatic injury results from an illness or disease such as Multiple Sclerosis, arthritis, cancer, osteoporosis, etc., as well as from degeneration, inflammation, or abnormal development of the spinal cord.
Paraplegia or Quadriplegia
Paraplegia and quadriplegia (or Tetraplegia) differ in where the spinal cord is injured and the extremities affected.
A spinal cord injury below the first thoracic nerve results in paraplegia. This means the legs are affected and there is some degree of sensation and/or movement loss in those extremities. For some paraplegics, the degree of loss will go up into the abdomen and chest.
While the affected area can move up into the chest, paraplegics retain full use of their arms and hands.
Paraplegia also results in bladder, bowel and sexual dysfunction.
Not everyone's degree of loss will be the same. Some have a complete loss of sensation and/or movement while others experience only loss of movement or sensation or maybe both to varying degrees.
A spinal cord injury above the first thoracic nerve results in quadriplegia. This means the injury affects the legs and arms and there is some degree of sensory and or motor loss in all four limbs. This will range from mild loss to a complete loss of sensory and motor function.
The abdomen and chest muscles are affected. If the injury is very high up in the neck it will also affect a person's ability to breathe on their own, rendering them dependent on a ventilator.
Quadriplegia weakens the abdominal muscles and diaphragm making it difficult to cough and clear the chest.
Quadriplegia also causes bowel, bladder, and sexual dysfunction.
Complete or Incomplete SCI
Traumatic injuries to the spinal cord are classified as complete or incomplete depending on the amount of motor function (ability to move) and sensory perception (ability to feel sensations on the skin).
Incomplete Spinal Cord Injury
An incomplete injury means the body retains some combination of motor function and/or sensory perception below the level of injury.
The sacral 4th and 5th segments (S4-S5) and the pudendal nerve are also involved in this determination. Any sensory and/or motor function at these segments means a person is considered incomplete. This is normally tested by seeing if there is any anal sphincter sensation or motor control.
Complete Spinal Cord Injury
A complete injury indicates a total loss of motor and sensory function below the level of injury and at S4-S5. No function or sensation “down there” at the anal sphincter puts you in the complete category.
ASIA Impairment Scale
Spinal cord injuries are associated with an American Spinal Injury Association (ASIA) classification. This scale is a way for the medical community to grade the severity of motor and sensory loss. ASIA classifications or scores are as follows:
ASIA A - A complete loss of motor function and sensory perception as well as motor and sensory function at the S4-S5 segments. An ASIA A classification puts you in the complete category listed above.
ASIA B - Sensory perception but no motor function is preserved below the level of injury and at the S4-S5 segments. ASIA B classifications are considered incomplete.
ASIA D - Motor function is preserved below the level of injury and at the S4-S5 segments. At least half of key muscles below the level of injury have a Manual Muscle Test grade of 3 or higher.
ASIA E - These folks have a spinal cord injury but motor and sensory function are perceived as normal.
Manual Muscle Test
A Manual Muscle Test is a diagnostic procedure used to evaluate a person's ability to use specific muscles. These tests are valuable for evaluating a person's abilities and for planning therapies and rehabilitation.
Muscle strength is graded on a scale from 0 to 5.
Grading explanations listed below are adapted from Prohealthcareproducts.com
Grade 5 (Normal; 100%): A person is able to comfortably withstand pressure in the test position. They are able to complete the whole range of motion (movement) against gravity while the practitioner applies maximum resistance at the end-range of movement.
Grade 4 (Good; 75%): The person is able to successfully perform the test with moderate to strong pressure. They are able to complete the whole range of motion against gravity while the practitioner applies moderate resistance at the end-range of movement.
Grade 3+ (Fair+): The person can complete the motion against gravity with minimal resistance applied by the examiner at end-range.
Grade 3 (Fair; 50%): This is considered the mid-range grade in which a person can perform the movement without any additional pressure. The person can only complete the range of motion against gravity. When the practitioner applies force, the person cannot complete the test.
For example: when testing the strength of the left knee extensors (quadriceps femoris/quads) - if the client is able to straighten their leg fully from a seated position without force but gives way upon the application of force, the grade is considered 3.
Grade 2+ (Poor +): A person can move through 50% of a motion or less in an anti-gravity position or can hold a position against resistance in a position without gravity.
For example: when gravity is eliminated such as performing the motion in side-lying - if the client can perform the movement at full range of motion with ease but gives way immediately with the application of resistance, the grade is 2+.
Grade 2 (Poor;25%): A person can complete movement completely in a horizontal plane. Client cannot perform movements against gravity but can move once the pull of gravity is eliminated, as long as resistance is not applied.
Grade 1 (Trace): No visible movement of the tested body part is detected except a slight contraction. The person cannot move the body part at all, even without resistance or gravity. Upon closer examination, with palpation, the therapist will detect a slight muscle contraction.
Grade 0 (Zero; No trace): A complete lack of contraction by visual examination or with palpation.
What Part of the Body is Affected?
When a spinal cord is injured closer to the head it causes greater loss of function.
Shown below are a few diagrams indicating which functions originate from what areas of the spinal cord. Damage of the nerves in the spinal cord will affect all bodily functions below that spot.
For example, my injury is in my neck at the 4th through 7th vertebrae (C4-C7). I have fairly normal sensation and movement from the armpits to the top of my head but bodily functions listed below C4 are either impaired or do not work for me at all.
Nothing Is Written in Stone
As much as the medical field likes to categorize and label everything, even the classifications listed here are not clear-cut or black-and-white.
It's important to know that all spinal cord injuries are different. Even people with spinal cord injuries at the same level can have drastically different sensory and motor abilities.
Each person's recovery is also different.
When I was in rehabilitation doctors did not offer hope for recovery, especially past one year post-injury. I am now 10.5 years post-injury and I am still achieving improvements. I know many people who are 1-25 years post-injury who are also still making improvements and gaining abilities back.
While generalizations can be made, not enough known about the spinal cord to lump everyone, their recovery, and potential for recovery into highly defined categories.
My Personal Example
When I was injured in a vehicle accident in 2008 I sustained a complete cervical spinal cord injury at the 4th, 5th, 6th, and 7th vertebrae (C4-C7).
While in rehabilitation I could not even slide my arm on a table enough to bump a huge button an inch away. I could move my head - that was about it. The picture painted for me was very bleak.
Today while my right arm is still not very functional I have good range of motion with the shoulder and the bicep muscle is strong.
My left arm is even stronger and has full range of motion (more fluid and useful than my right); the bicep is very strong; there is a tinge of triceps muscle, and I have strong wrist extension. This wrist extension enables me to use a device called a tenodesis splint (I will write about that another time) which enables me to write, feed myself, pick up things, and if I so felt like it … pinch rear ends (who would ever suspect it was me). It's not pretty, but it sure helps me a lot!
My Purpose in Telling You This
Don’t get bogged down with what doctors or therapists say if it’s not what you want to hear. There is not enough known about this huge bundle of nerves called the spinal cord for them to know everything.
Work hard with what you do have and progress may still happen. It might be slow, but it can still happen. I am still considered a complete but my abilities have changed so much since those early days.
Yours can too!