What is a Spinal Cord Injury?
Spinal Cord Injury Sections
Spinal Cord Injury Overview
A Spinal Cord Injury (SCI) is damage or trauma to
the spinal cord that
results in a loss or impaired function causing reduced mobility
or sensation. Common causes of damage are trauma (car accident, gunshot,
falls, sports injuries, etc.) or disease (Transverse Myelitis, Polio,
Spina Bifida, Friedreich's Ataxia, etc.). The spinal cord does not
have to be severed in order for a loss of function to occur.
In most people with SCI, the spinal cord is intact, but the cellular
damage to it results in loss of function. SCI is very different
from back injuries such as ruptured disks, spinal stenosis or pinched
nerves. The later involves musculoskeletal and peripheral nerve changes where as a spinal cord injury involves damage to the central nervous system.
It is possible for a person to "break their
back or neck" yet not sustain a spinal cord injury as long
as only the bones (the vertebrae)
around the spinal cord are damaged, but the spinal cord is not affected.
In such cases the person may not experience paralysis after the
vertebrae are stabilised. Fractured vertebrae and dislocated vertebrae can be stabilised using surgical management such as traction, vertebral fusion, fixation using titanium plates or rods and for less severe fractures of the vertebra bed rest.
What is the Spinal Cord?
The spinal cord is the major bundle of nerves that
carry nerve impulses to and from the brain to the rest of the body.
The brain and the spinal cord constitute the central nervous system.
Motor and sensory nerves outside the central nervous system constitute
the peripheral nervous system, and another diffuse system of nerves
that control involuntary functions such as blood pressure and temperature
regulation are the sympathetic and parasympathetic nervous systems.
The spinal cord is about 18 inches in length and
extends from the base of the brain surrounded by vertebral
bodies, extending vertically down the middle of the back, to about the waist. The nerves
that are situated within the spinal cord are called upper motor
neurons (UMN's) and their function is to carry the messages back
and forth from the brain to the spinal nerves along spinal tracts within the spinal cord responsible for specific functions.
The spinal nerves that branch out from the spinal cord to
parts of the body are peripheral nerves called lower motor neurons (LMN's). These spinal
nerves exit and enter at each vertebral level and communicate with
specific areas of the body. The sensory portions of the LMN carry
messages about sensation from the skin and muscles such as pain, temperature, joint position and information from organs to the brain. The motor portions
of the LMN send messages from the brain to the various body parts
to initiate actions such as muscle movement, gland functions and certain internal organ commands.
What are the Vertebrae?
The spinal cord is surrounded by rings of bone called
vertebra. These bones constitute the spinal
column (back bones). In general, the higher in the spinal
column the injury occurs, the more dysfunction a person will experience resulting in an increased level of paralysis.
The vertebra are named according to their location. The seven
vertebra in the neck are called the cervical vertebra. The top vertebra
is called C-1, the next is C-2, etc. Cervical SCI's usually cause
loss of function in the arms and legs, resulting in quadriplegia.
The twelve vertebra in the chest are called the thoracic vertebra.
The first thoracic vertebra, T-1, is the vertebra where the top
There are 5 lumbar vertebrae, and one fused sacral vertebra.
What are the Effects of a Spinal Cord Injury?
An injury to the spinal cord segments contained within the cervical spinal vertebrae C1-C7 usually result in paralysis of all four limbs to some degree. Injuries in the thoracic region usually affect the
chest and the legs and result in paraplegia. The vertebra in the
lower back between the thoracic vertebra, where the ribs attach,
and the pelvis (hip bone), are the lumbar vertebra. The sacral vertebra
run from the pelvis to the end of the spinal column. Injuries to
the five Lumbar vertebra (L-1 thru L-5) and similarly to the
five Sacral Vertebra (S-1 thru S-5) generally result in loss
of functioning in the hips, legs, bladder, bowel and sexual function.
The effects of SCI depend on the type of injury
and the level of the injury.
SCI can be divided into two types of injury - complete and incomplete.
A complete injury means that there is no function below the level
of the injury; no sensation and no voluntary movement. Both sides
of the body are equally affected. An incomplete injury means that
there is some functioning below the primary level of the injury.
A person with an incomplete injury may be able to move one limb
more than another, may be able to feel parts of the body that cannot
be moved, or may have more functioning on one side of the body than
the other. With the recent advances in medical intervention and treatment of acute SCI, incomplete
injuries are becoming more common. Since 2010, the most frequent spinal cord injury neurological classifications at time of discharge from a spinal injury center is incomplete tetraplegia (40.6%), followed by incomplete paraplegia (18.7%), complete paraplegia (18.0%) and complete tetraplegia (11.6%). It is estimated that less than 1% of individuals diagnosed with a spinal cord injury experienced a complete neurological recovery at the time of hospital discharge. Over the last 20 years, the incidence of individuals with incomplete tetraplegia has increased whilst complete paraplegia and complete tetraplegia have decreased.
Spinal Cord Injury Levels
The level of injury is very helpful in predicting
what parts of the body might be affected by paralysis and loss of
function. Remember that in incomplete injuries there will be some
variation in these prognoses.
Cervical (neck) injuries usually result in Quadriplegia/Tetraplegia.
Injuries to the spinal cord segments above the C4 level (C1,C2, C3) may result in the need of breathing aids such as mechanical ventilators or diaphragm pacemakers to stmulate the phrenic nerve to
initiate a persons
breathing due to weak innervation of the diaphragm. C-5 injuries often result in shoulder (deltoid) and
biceps control, but no control of the wrist or hand. C-6 injuries
generally yield wrist control (wrist extensors), but no finger hand
function. Individuals with C-7 and T-1 injuries can straighten their
arms (triceps) but still may have dexterity problems with the hand
and fingers. Injuries at the thoracic level and below result in
paraplegia, with the hands not affected. At T-1 to T-8 there is
most often control of the hands, but poor trunk control as the result
of lack of abdominal muscle control. Lower T-injuries (T-9 to T-12)
allow good truck control and good abdominal muscle control. Sitting
balance is very good. Lumbar and Sacral injuries yield decreasing
control of the hip flexors and legs.
Paralysis also has other effects as well as a loss
of sensation or motor function. Individuals with SCI also experience
other neurological changes. For example, the person may experience
dysfunction of the bowel and bladder. Sexual function
is frequently affected in men with SCI as they may have their fertility
affected due to the inability to attain an erection or achieve ejaculation, while women's fertility is generally not affected. Other effects of SCI may include
low postural blood pressure (Postural Hypotension), inability to
regulate blood pressure effectively , reduced control of body
temperature (poikilothermic), inability to sweat below the
level of injury, and chronic pain.
The above information has been written with reference from the following sources:
Sekhon, Lali H.S.; Fehlings, Michael G. (2001). "Epidemiology, Demographics, and Pathophysiology of Acute Spinal Cord Injury". Spine 26 (24 Suppl): S2–12. doi:10.1097/00007632-200112151-00002. PMID 11805601.
Alexander Vaccaro; Michael Fehlings (2010). Spine and Spinal Cord Trauma: Evidence-Based Management. Thieme Publishers. ISBN 9781604062229. Retrieved 2012-05-06.
Updated: May 2014
Support : Types
of Paralysis : Vertebral Column : Spinal
Cord : Myotomes & Dermatomes : Autonomic Dysreflexia : Spasticity
& Spasms : Temperature Regulation : Respiratory System : Pressure Sores : Spinal
Cord Injury Research : Definition
of a Wheelchair