Spinal Cord Damage & Injury
The nervous system is divided into two major divisions: the peripheral nervous
system (PNS) and the central nervous system (CNS). The PNS is a network of
nerves throughout the body, handling everything from regulating the heart rate
to flexing the hand or foot. It also receives information, much of which is sent
to the brain such as pain and temperature. This information is analyzed and
coordinated by the CNS.|
The CNS is made up of the spinal cord, brain, and optic nerve. The spinal cord
runs from the base of the brain down the middle of the back and ends just above
the waist. It's made up of nerve cells (neurons) and long nerve fibers called
axons that relay all incoming information from the rest of the body to the brain
and all outgoing information from the brain to the rest of the body. Unlike the
nerves of the PNS, those in the CNS don't regenerate once they have been
injured. So when the spinal cord is injured, varying degrees of paralysis will
exist if these axons become destroyed.
The spinal column is made up of 33 vertebra and protect the spinal cord from
injury. If these bones are broken or damaged, paralysis isn't necessarily the
result once the bones are stabilized. Therefore, a person may break his or her
back or neck without suffering paralysis. It's when the damage reaches the
spinal cord that serious, long-term or permanent effects often result. The
extent and region of the body affected by this damage depends upon the region of
the spinal cord that is injured.
The spinal column and spinal cord consist of four regions, with each region
controlling a particular part of the body. These regions can be categorized even
further into 31 pairs of peripheral spinal nerves. These nerve pairs extend from
the spinal cord through spaces in the vertebra, connecting the spinal cord with
other nerves throughout the PNS. In general, the higher the spinal cord is
injured, the more severe the injury. The regions of the spine are numbered in
descending order from the brain.
Cervical Region (C1 to C8)
Located in the neck, this region controls the back of the
head, the neck, shoulders, arms, hands, and diaphragm
Thoracic Region (T1 to T12)
This region is located in the upper back and controls the
torso and parts of the arms
Upper Lumbar (L1 to L5)
Located in the middle of the back just below the ribs. The
upper lumbar region controls the hips and legs
Sacral Segments (S1 to S5)
Just below the upper lumbar region in the middle of the back. This region
controls movement in the groin, toes, and some parts of the legs
There are two types of spinal cord injuries:
complete and partial.
If a spinal cord injury is complete, there is no function below the point of injury. This
means a person will experience no sensation or voluntary movement and that both
sides of the body will usually be equally affected. A complete injury can result
in the paralysis of all four limbs (quadriplegia) or the lower half of the body
For partial injuries, a patient may be able to move one limb more than the other
or be able to feel more with one side than the other. The level of incomplete
injuries may vary from person to person, and can affect the body in different
ways. For example, a C-6 injury may result in having no hand control but having
wrist control. A C-5 injury may deprive a patient of wrist and hand control, but
not arm and shoulder control.
Aside from a loss of sensation and movement, those with a spinal cord injury may
also experience bladder and bowel complications. Spinal cord injuries often
affect fertility in males. If the spinal cord injury is high, such as C-1 or
C-2, a respirator or diaphragmatic pacemaker to breathe properly may be needed.
Other complications that may result from a spinal cord injury are an inability
to regulate blood pressure, low blood pressure, reduced control of body
temperature, an inability to sweat that occurs below the level of injury, and
chronic pain. Those with spinal injuries also have an increased susceptibility
to respiratory disease and autonomic dysreflexia.
Autonomic dysreflexia is primarily the result of the body being unable to
control the blood pressure. This is especially a concern for those who have a
spinal cord injury at T-6 or above. The signal responsible for "telling" the
blood vessels to relax can't be processed because of the injury. With autonomic
dysreflexia, these blood vessels intermittently remain constricted, thus
elevating the blood pressure and possibly leading to life-threatening
complications such as stroke. External methods of lowering the blood pressure to
a safe level are often necessary.
Typically when people think about multiple sclerosis (MS), the brain is usually
the focus. It's not uncommon with MS, however, to discover multiple silent brain
lesions on magnetic resonance imaging (MRI) and find a person afflicted with
only spinal cord problems due to the disease. Sometimes the symptomatic spinal
cord lesions are more difficult to identify on scans than some clinically quiet
but MRI evident brain lesions. About 90% of those with MS find that their spine
is involved at some point.|
As a central relay station for sensation, movement, balance and coordination for
so much of the body, the spinal cord is crucial for limb function and the
muscles involved in respiration.
Many with spinal cord problems and MS have numbness on one side of the body and
weakness on the opposite side. They may lose standing balance or have a gait
problem characterized by ataxia, such as the inability to walk a straight line.
Paralysis and loss of sensation of part of the body are common. This can include
total paralysis or numbness and varying degrees of movement or sensation loss.
Spinal cord lesions due to MS in the upper spine or neck (cervical region) can
cause cape like sensation loss in both shoulders and in the upper arms.
Quadriplegia is the great danger in cervical region MS. Anesthesia in a band
like distribution around the trunk can be experienced in those with mid spinal
cord inflammation and carry a chance that they could become paraplegic. All of
those with MS in the spinal cord can potentially have bladder or bowel control
problems. However, those with spinal cord MS of the lumbar region (the spinal
cord ends at the beginning of the lumbar spine) can have symptoms dominated by
retention of urine.
For those with MS, pain below the level of spinal cord involvement and sexual
problems were the greatest complaints, even when there were motor difficulties
in the limbs. Spinal cord induced pain is typically excruciating and often
shoots down the spine (Lhermitte's Sign) or to the limb that is involved due to
spinal cord damage.
Erectile dysfunction is common in men with spinal cord MS. Orgasmic and
fertility problems can strike both sexes with cord lesions. Spasticity is
another major problem for those with spinal cord problems of all types. The
increase in muscle tone from spasticity can also be painful and movement
Medication and certain devices such as spinal cord stimulators can be valuable
for many of these issues. Dyssnergia (movement incoordination) involves bladder
muscle difficulties due to cord MS. The incontinence and bladder emptying problems
that results can be treated with medication as well.
Therapeutic research in spinal cord disorders including MS involves
consideration for the transplantation of stem cells, the injection of nerve and
brain derived growth factors, and medicines that can provide the energy source
for spinal cord regrowth.
In addition, rehabilitation of the patient with spinal cord problems is critical
by way of special conditioning and strengthening programs.
In MS, an acute spinal cord attack is called Myelitis. Immunomodulator and
steroid therapy is often utilized with success with a dramatic reversal
possible. If the MS patient has persistent neurological signs and symptoms from
the spinal cord inflammatory attack, they are said to have a myelopathy.
Often the severity of MS is very much related to how bad the myelopathy is.
Progressive MS can be characterized by spinal cord shrinkage (atrophy) over
time. Reversal of this aspect of advancing MS remains a great challenge for
ongoing research. Defeating the immunological process that triggers both the
brain and spinal cord damage in MS is the best defense against the terrible
effects of spinal cord involvement in demyelinating disease.
Spinal Cord Lesions
There are several symptoms that show signs that there is damage in the spinal
cord. In the spinal cord the nerves that deal with the whole body run very close
together down the cord. A single lesion can cut across an area that affects a
large section of the body. One good sized lesion can essentially "cut off " the
body below it as if the spine had been severed. This is the worst case scenario
of the lesions of transverse myelitis, however, most lesions are not that large.
The areas that deal with the motor functions on one side, all run together and
the part of the cord that handles the sensory input is all on a different
section from the motor.
As the cord runs down the back, the nerves branch off and leave the cord, thus
becoming peripheral nerves. The nerves to the arms leave the cord in the
cervical spine. The nerves that control the muscles of the torso leave in the
lower cervical spine and the from the thoracic. The nerves to the legs travel on
through the cervical and upper thoracic to leave the spinal cord lower down.
Many of them stay in the spinal canal below where the spinal cord ends as a
loose-floating bundle of nerves called the "cauda equina" or horse's
tail. These nerves exit through the vertebra in the lumbar spine.
The greatest concern is the fact that the spinal cord is basically a bundle of
wires that are very small and compact. A single lesion in this area will affect
many nerves and the systems that they control. Unlike the brain where the damage
is more specific or precise, in the spine it essentially is more widespread. So
one good sized lesion can essentially "cut off " the body below it as if the
spine had been severed.
Typical Signs of a Spinal Cord Lesion
A specific or some combination of problems on the neurological exam can point to
a specific "level" of damage in the spinal cord where there must be a lesion.
Neurologists know that a lesion in the brain could not cause the same
combination of problems as a lesion in the spine. Numbness, paresthesias, and/or
weakness from one level on down is indicative of a cord lesion.
One of the difficulties with spinal lesions is that there can be indications
that a lesion definitely exists, but it may not be seen easily or at all on MRI.