Health

Presentation
Traumatic Spinal Cord Injury
Individuals who suffer a traumatic spinal cord injury usually have immediate loss of strength and/or numbness in the arms or legs depending on the location of the injury to the spinal cord. The severity of injury to the spinal cord will result in various degrees of weakness and numbness. Some individuals who suffer a severe injury to the spinal cord may have complete loss of movement and lack of sensation. Others sustaining a mild or moderate injury to the spinal cord may have minimal weakness and sensory loss. In addition, it is possible to have one side more affected than the other side and in a specific condition, the arms may be more affected than the legs. In general it is often possible to predict the area that will be involved with weakness and numbness based on the location of the spinal cord damage.

• Damage to the cervical spinal cord will result in weakness and/or numbness in the arms, trunk, and legs. 
• Injury to the thoracic spinal cord will result in normal movement and sensation of the arms and hands but decreased sensation and movement in the trunk and legs. The area of involvement of the trunk will depend on the location of the injury as will be described in the ASIA examination below.
• Damage to the spinal cord in the lumbar or sacral region will result in normal arm and trunk movement and sensation, but there will be weakness and/or numbness in the legs.

Non-traumatic Spinal Cord Injury
There are many conditions that can lead to injury to the spinal cord without a traumatic cause. Depending on the cause of the non-traumatic spinal cord injury, there may be multiple areas of injury to the spinal cord. Therefore, it is more difficult to anticipate the area or degree of weakness and numbness. For example, it is less likely that one specific area of the spinal cord will be injured. More commonly large or multiple areas of the spinal cord are actually damaged. The exception to this is a condition called Transverse Myelitis, which affects only a small portion of the spinal cord. It still follows, however, that involvement of the cervical spinal cord will likely lead to some involvement of the arms and legs, while involvement of the lowest part of the spinal cord will only lead to involvement of the legs.

Physical Examination
A general physical examination takes place, but the focus of this topic will be the neurological examination. A standardized and comprehensive neurological examination has been developed and is recommended by the International Standards for Neurological and Functional Classification of Spinal Cord Injury Patients. This is most commonly referred to as the American Spinal Injury Association (ASIA) examination.

This standardized examination tests two main categories: motor (movement or strength) and sensory (sensation or the ability to feel). The examination tests specific muscles and sensation in consistent and reproducible areas.

Motor Exam
The motor part of the examination tests 10 key muscles on each side of the body:

• C5 (biceps “elbow flexors”)
• C6 (wrist “wrist extensors”)
• C7 (triceps “elbow extensors”)
• C8 (end of middle finger “finger flexors”)
• T1 (little finger “finger abductors”)
• L2 (hip “hip flexors”)
• L3 (knee “knee extensors”)
• L4 (ankle “ankle dorsiflexors”)
• L5 (big toe “first toe extensors”)
• S1 (ankle (ankle plantar flexor”)

Sensory Exam
The sensory part of the examination tests 28 areas on each side of the body. This includes light touch (with a cotton swab) and pinprick (with the sharp point of a safety pin) of specific areas on the skin that are referred to as dermatomes. Each spinal nerve supplies an area or dermatome. For example, the C6 dermatome includes an area over the thumb and index finger that is responsible for sending messages of touch or pain up the nerve to the spinal cord at the C6 level and eventually to the brain. There is a map on the body that is fairly consistent from person to person. This allows someone to test specific areas and make determinations about whether that spinal nerve and the spinal cord are intact.

Rectal Exam
The rectal examination is very important and has both motor and sensory components. This area is innervated by the S4-5 dermatome and represents the very end of the spinal cord. Therefore, if there is any evidence of sensation or movement in this area, it demonstrates that some messages are making it all the way through the spinal cord. The sensory examination tests for any evidence of light touch, pinprick, or deep pressure during the rectal examination. The motor examination checks for any purposeful contraction of the rectum around the examiner’s gloved finger during the rectal examination. The examiner must be very careful to differentiate between involuntary (spasm or reflex contraction) and purposeful contraction. The examiner should ask the patient to contract his or her rectum around his finger on command several times before stating that voluntary rectal contraction was present. If any of the four tests (light touch, pinprick, deep pressure, voluntary anal contraction) are intact, then the patient is classified as an incomplete spinal cord injury and this is referred to as “sacral sparing.” If none of the four tests are intact, then the patient is classified as a complete spinal cord injury. This is the only way to determine a complete versus incomplete spinal cord injury.

SCI Level Determination
Sensory level: the sensory level is determined by identifying the lowest (high referring to the head and low referring to the toes) dermatome that has normal light touch and pinprick on both sides of the body.

Motor level: the motor level is determined by identifying the lowest (C5 is higher than C7, cervical is higher than thoracic, which is higher than lumbar) muscle that is able to move through full range of motion against gravity with the muscle above it in number (C5 is above the C6) being completely normal in strength.

Neurological level:  the neurological level of injury is most commonly referred to by patients and their physicians. For example, an individual will say, “I'm a C6.” This is specifically referring to the neurological level and not the sensory level or motor level. The sensory level and motor level are used together to help determine the neurological level of injury.

The neurological level is determined by the lowest level where both motor and sensory are intact on both sides of the body. For example, an individual may be classified as a right C5 motor, right C6 sensory, left C6 motor, left C5 sensory. In this case, the neurological level of injury would be a C5, because this is the lowest level on both sides that is normal.

ASIA Impairment Scale
The ASIA Impairment Scale has transformed over time and was initially called the Frankel Scale. This scale classifies complete and incomplete spinal cord injuries. It further breaks down and defines an ‘incomplete” spinal cord injury. Before describing the ASIA Impairment Scale, we must first define how muscle grading is determined.

Muscle strength is graded from 0 to 5.
0 = no movement or contraction
1 = trace (very slight movement or contraction)
2 = able to move through full range of motion without gravity (example: holding an arm parallel with the ground and flexing the elbow parallel to the ground through full range of motion)
3 = able to move through full range of motion against gravity (holding the arm straight down to the ground and flexing the elbow through full range of motion)
4 = able to resist some force of the examiner, but not normal strength
5 = normal strength

ASIA Impairment Scale (2000 version)
A–complete: no motor or sensory function in the rectal area (S4-S5)
B–incomplete: sensory is present but no motor function below the neurological level of injury
C–incomplete: motor function is intact to some degree below the neurological level of injury. This is determined if more than half of the key muscles below the neurological level have a muscle grade less than three (3/5)
D–incomplete: motor function is intact to some degree below the neurological level of injury. This is determined if at least half of the key muscles below the neurological level have a muscle grade of three or more (3/5)
E–incomplete: motor and sensory functions are normal.

Putting it all together
Physicians, health care professionals, family and patients can use a short phrase to describe their medical diagnosis. This is very helpful because any person who understands this terminology can then immediately understand what areas are weak and/or numb and to what degree this occurs. By knowing this, a physician can accurately determine what level of function can be expected and what equipment will be needed. For example, C7 ASIA A will tell the physician that the patient has complete use of his arms but limited finger dexterity and no movement of the legs. This also would allow someone to determine equipment needs as well as appropriate bowel and bladder needs. This C7 ASIA A tetraplegia will be able to transfer independently from bed to wheelchair and back. They will be able to perform activities of daily living independently with equipment. All of this information about functional abilities and equipment can be inferred from someone’s ASIA score.

“Incomplete Syndromes” of Spinal Cord Injury

All incomplete spinal cord injuries by definition have “sacral sparing” as described above during the rectal examination. All of the incomplete syndromes of spinal cord injury occur in the specific patterns because of the way that the nerve fibers that travel up and down the spinal cord are arranged.

The nerve fibers within the spinal cord are consistently located in specific areas that are grouped by their function. For example, the nerve fibers in the spinal cord that control the arms and upper body are located closer to the center of the spinal cord. The nerve fibers to the legs are located more outward in the spinal cord and outside of the fibers of the arms. In addition, nerve fibers that carry the sensation of pain and temperature are located specifically in one area of the spinal cord, and fibers carrying the sensation of vibration are located in the back part of the spinal cord.

Central Cord Syndrome:
This is a condition where the upper extremities (arms) are more affected or weaker then the lower extremities (legs). This is sometimes referred to as the upside-down paraplegic. This condition is associated with a cervical injury. This syndrome usually occurs because of hyperextension (extreme bending of the neck with the head moving backwards) of the neck. As individuals get older the bone on the vertebrae develops extra growth and a ligament that travels down the spinal column on the backside of the spinal cord begins to thicken. The spinal cord travels between this area of vertebrae with extra bone growth and the thickened ligament. When the neck hyperextends, these two structures move closer together and temporarily pinch or compress the spinal cord. When this happens the forces meet in the middle of the spinal cord where the nerve fibers to the arms and upper body travel. This causes the central cord syndrome.

Patients with central cord syndrome usually have a good prognosis for walking. A central cord syndrome can affect the legs, but to a lesser degree than the arms. Recovery of strength usually occurs with the legs first, then the bladder and eventually the arms. Recovery of strength in the arms usually occurs with the muscles that are closer to the body; last to recover are the fine motor movements of the hand.

Brown-Séquard Syndrome:
This is also referred to as a hemisection of the spinal cord. “Hemi” means half and “section” means cut. Therefore, when talking about a spinal cord injury, hemisection means that half of the spinal cord is not damaged or not working properly. This is most commonly reported to occur after damage from shrapnel or a knife stab wound to the spinal cord. This condition can also occur after fracture of the vertebrae or the growth of tumor into the left or right side of the spinal cord. Understanding the anatomy of the spinal cord and where nerves travel is important to understanding why this injury causes the specific physical findings.

Patients with a Brown-Séquard Syndrome have loss of strength on one side of the body with absence of vibratory sense (tuning-fork) and proprioception (knowing where a part of the body is in space or “position sense”). For example, the leg that is weak will also not be able to feel the vibration of a tuning-fork and cannot tell when the leg is moved in different directions. In addition, the leg that is not weak will not have the ability to feel pain and temperature (hot or cold differentiation).

Patients with Brown Séquard Syndrome have the best prognosis with regards to walking again. Of all the incomplete syndromes, Brown Séquard Syndrome has the highest percentage of normal recovery of bowel and bladder function.

Anterior Cord Syndrome:
This is an injury to the anterior (front) two-thirds of the spinal cord. It can occur because of fractured vertebrae or disc material traveling into the front part of the spinal cord. Another common cause of anterior cord syndrome is damage to the anterior spinal artery which supplies blood to the anterior two-thirds of the spinal cord.

Anterior Cord Syndrome is similar to a spinal cord injury except that there is preserved sensation of light touch, deep pressure, vibration and proprioception (position sense). This condition has a poor prognosis for recovery.
Posterior Cord Syndrome:
This is the least common injury of all of the incomplete syndromes. Posterior Cord Syndrome occurs when an object is pushed into the back part of the spinal cord. This back part of the spinal cord is the area that controls the vibration sense and position sense. In the pure definition of posterior cord syndrome, there is intact strength, pain and temperature sensation, but no vibration sense and position sense. Walking is very difficult in this condition because of the lack of position sense. In this situation, the patient must be looking down at his legs and feet to make sure they are in the proper position or he is likely to fall.

Work-up:
The work-up for a spinal cord injury includes the physical examination and imaging. A detailed physical examination performed using the ASIA examination is very accurate and has been shown to be more useful in determining long-term prognosis and functional outcome then any available test. Imaging of the spinal cord injured patient often includes x-rays, CT scans, and MRI. Other electrical tests (i.e., somatosensory evoked potentials) have been studied but are uncommonly done or necessary.

Imaging is crucial to help determine the location and severity of damage to the spinal column that supports and protects the spinal cord. This also helps determine the need and approach to surgical stabilization. Possible imaging techniques will now be described.

Plain film radiography (x-ray)
X-ray of the spine is often the initial study recommended and performed in any individual who is suspected of having a spinal cord injury or damage to the spinal column. These x-rays are usually done from the side which is referred to as a “lateral” view and straight over the patient from front to back, which is referred to as an “AP or anteroposterior.” These two x-rays allow assessment of the bone alignment from one vertebra to another and often show areas of fracture or broken bone. The vertebrae are aligned in a continuous and smooth line in the normal spine. If there is evidence of one vertebra being considerably offset compared to the other, then there is a consideration for damage to the ligaments that connect one vertebra to another.

If the x-ray is normal but significant neck pain still exists, often the next step is to perform a “functional x-ray.” This includes flexion and extension (bending forward and backwards) of the spine during an x-ray. If there is a significant movement of one vertebra compared to the other, this is suggestive of a possible tear of the ligament connecting to vertebrae.

Computed tomography (CT scan)
CT scans are very useful for identifying broken bone in the vertebra that is difficult to see with plain film x-ray. In addition, the computer is able to create three-dimensional pictures which is very helpful to see how the vertebrae are arranged in comparison to each other and other structures.

Magnetic Resonance Imaging (MRI)
An MRI is often used in addition to x-rays and CT scans because it is better able to identify damage to the spinal cord, ligaments and disk. Another very important benefit of the MRI is the ability to distinguish different types of injury to the spinal cord. The MRI can identify whether the injury to the spinal cord is from swelling or bleeding. This has some importance in determining the prognosis of the injury; a study
(by Kulkarni et al) showed that recovery of function was much better for a spinal cord injury with swelling compared to blood.