I don't think I've talked about this much on the blog, but I work in an inpatient rehabilitation center, and I'm the SLP on the Spinal Cord Team. We divide our patients into 3 main teams-- Stroke Team, Brain Injury Team, and Spinal Cord Injury Team. We get plenty of overflow from eachothers' caseloads, but mainly I see patients with high level spinal cord injuries. I see a lot patients who have tracheostomies and mechanical ventilators. A lot of AAC for these folks. Lots of swallowing assessment and therapy. Some cognitive therapy. It's an interesting little niche and sometimes my new student interns get thrown into this complex world with very little backgroud and instruction in it during grad school.
My awesome student Sarah Janis did a little "Into to Spinal Cord Injury" booklet for future students. I think I'll divide it into 2 or 3 posts. Here's the first section which covers the basics of the spinal cord and spinal cord injuries. Thanks for letting me share it, Sarah!
Spinal Cord and Spinal Cord Injury Student
By: Sarah Janis
General Spinal Cord Information
The spinal cord, which is part of the central nervous system (CNS), transmits sensory and motor signals between the brain and peripheral nervous system (PNS). Upper motor neurons travel from the brain through the spinal cord in tracts before synapsing with lower motor neurons at the level of the spinal nerve roots; the lower motor neurons then carry the signal to skeletal muscles.
The spinal cord is protected by the spinal column. The spinal column is comprised of 30 vertebrae separated by fibrous, fluid-filled sacs called discs, which act as shock absorbers, and connected with systems of ligaments. The thirty vertebrae are divided into five sections: cervical (7 vertebrae),
thoracic (12 vertebrae), lumbar (5 vertebrae), sacral (5 fused vertebrae), and coccyx (1 vertebra).
There are 31 pairs of lower motor neurons, or peripheral nerves, that originate in the spinal cord; these receive their names from the vertebrae through which they pass through. The 8 cervical nerves control the neck, arms, and hands; the 12 thoracic nerves control the trunk and upper abdominal muscles; the 5 lumbar nerves control the lower abdominal muscles and upper parts the legs; the 5 sacral nerves control the lower legs, bowel, bladder, and sexual function; the coccygeal nerve provides sensation to the bottom of the spinal column (see Figure 1).
Each peripheral nerve innervates a specific area of skin, known as a dermatome (see Figure 2). When a nerve is damaged, an individual loses sensation from that dermatome. Thus, testing the presence or absence of sensation in certain dermatomes can indicate the exact level of spinal cord damage.
Spinal Cord Injury (SCI)
Damage to the spinal cord, from injury or disease, impairs sensory and/or motor function at and below the level of damage. Thus, damage to a higher level of the spinal cord (i.e., a cervical injury vs. a thoracic or sacral injury) results in a greater loss of neural function. Depending on the injury,
individuals may experience a full or a partial loss of movement and/or sensation. Spinal cord injury often, but not always, results from trauma to the vertebral column as broken or displaced bone compresses, bruises, and/or tears the spinal cord. Damage can also occur as the result of loss of blood flow to the spinal cord. When spinal cord nerve cells are damaged, they can no longer carry messages between the brain and the rest of the body. Common causes of spinal cord injury include motor vehicle accidents (MVA), falls, sporting accidents, or gunshot wounds.
SCI Classification: Classification Categories/Levels
Spinal cord injuries are often classified by vertebral level, neurological level,
and severity. Vertebral level indicates which vertebra or vertebrae were
damaged. For example, an injury that causes the C5 vertebra to slip relative
to C4 may be called a C4/C5 injury because it compresses the C4 and C5
spinal cord. It is important to note, however, that the vertebral level does
not necessarily indicate which level of the spinal cord was damaged.
Classification according to neurological level indicates which level of the
spinal cord experienced neurological loss. This can be identified according to
(a) the first spinal cord segmental that shows sensory or motor loss
(commonly used by neurologists) or (b) the lowest level that shows normal
sensory and motor function (commonly used by physiatrists). For example,
using the lowest functional level classification, an individual with a C-5 injury
would have impaired function below the 5th cervical spinal cord segment.
Severity indicates how much sensory and motor function remain within the
Tetraplegia (formerly and still occasionally called quadriplegia) generally
describes a C1 to T1 injury that results in a loss of function in the head, neck,
shoulders, arms, and/or upper chest as well as the lower body. Paraplegia
generally describes a T2 to S5 injury that results in the loss of function in the
lower body, including the chest, stomach, hips, legs, and feet.
As an indication of severity, spinal cord injuries are classified as complete or
incomplete. A complete injury classification indicates that the individual has
no motor or sensory function in the S4-S5 (anal) area. Individuals with
complete injuries may, however, have some preserved motor or sensory
function between the injury level and S5; this is called the zone of partial
preservation (ZPP). An incomplete injury classification indicates at least
partial movement or sensation in the S4-S5 area; however, the amount of
functional movement/sensation remaining varies greatly according to the
extent and location of nerve damage. Note that the terms “complete” and
“incomplete” only refer to the functioning of the spinal cord, not extent of
physical damage to the cord.
The American Spinal Cord Injury Association (ASIA) developed a uniform
classification system, the ASIA Impairment Scale (AIS), which places SCIs into
one of five categories. Individuals are classified as follows:
A Complete – no sensory or motor function preserved in the sacral segments S4-5 B Sensory Incomplete – sensory but not motor function is preserved below the neurological level* and includes the sacral segments S4-5 (light touch or pin prick at S4-5 or deep anal pressure) AND no motor function is preserved more than three levels below the motor level** on either side of the body
C Motor Incomplete – motor function is preserved at the most caudal sacral segments for voluntary anal contraction (VAC) OR the patient meets the criteria or sensory incomplete status (sensory function preserved at the most caudal sacral segments (S4-S5) by LT, PP or DAP), and has some sparing of motor function more than three levels below the ipsilateral motor level on either side of
the body. (This includes key or non-key muscle functions to determine motor incomplete status.) For AIS C – less than half of key muscle functions below the neurological level of impairment have a muscle grade ≥ 3***.
D Motor Incomplete – motor incomplete status as defined above, with at least half
(half or more) of key muscle functions below the single NLI having a muscle grade
E Normal – If sensation and motor function as tested with the ISNCSCI are graded
as normal in all segments, and the patient had prior deficits, then the AIS grade is
E. Someone without an initial SCI does not receive an AIS grade.
*Neurological level indicates which level of the spinal cord was damaged
**Motor level is defined as the level at which the key muscle innervated by the segment has at least 3/5
of its normal strength. Sensory level is defined as the lowest spinal cord level that still has normal
pinprick and touch sensation.
***see ASIA examination protocol on pg. 6 for muscle grade scoring
SCI Classification: Physical Examination
Classification on the AIS is determined by a physical examination, which occurs between 72 hours and 7 days post injury. The purpose of the physical exam is to evaluate the extent of remaining motor and sensory function. Motor function is tested by instructing the individual to move certain key
muscles. Each key muscle is awarded a score from 0 to 5 with 0 indicating total paralysis and 5 indicating active movement against full resistance; these scores are especially important in determining sensory level and motor level and in differentiating AIS C and AIS D injuries.
Additionally, certain non-key muscles may be tested to differentiate AIS B and AIS C injuries. Sensory function is tested by administering different types of sensations (pinprick, touch, position of joints) to key sensory points. Sensory points are given a score between 0 and 2, with 0 indicating absent sensation and 2 indicating normal sensation.
In addition to the AIS physical examination, individuals may also undergo imaging procedures, such as x-ray or MRI, for visualization of the location and extent of damage. The following pages contain the ASIA examination for SCI classification.