DISEASES OF SPINAL CORD
Syringomyelia
Syringomyelia is spinal cord disorder characterized by the presence of fluid-filled cavities in the spinal cord. Gray matter around the central canal is the most affected part. So the sensory disturbances are more pronounced than the motor disturbances.
Cause
Stringomyelia occurs due to the over growth of neuroglial cells in spinal cord accompanied by cavity formation and accumulation of fluid. Initially, a cavity appears in gray matter near the central canal of spinal cord. In later stages, the cavity extends and involves the surrounding white matter to a variable degree. The disease usually starts in one or two segments. Then, it extends up and down for considerable distances. Lower cervical and upper thoracic regions are affected the most.
Features
Characteristic features of this disease are the loss of pain and temperature sensations and muscular weakness. Severity of the loss of sensations depends upon the extent of disease in spinal cord.
Symptoms of syringomyelia:
1. If disease is only around central canal, there is loss of temperature, pain and crude touch sensations only. It is due to lesion of the fibers crossing through the anterior gray commissure. Fine touch sensation is not affected because the fibers of fine touch pathway are in the posterior white column.
2. If
lesion is unilateral, effect occurs only on the same side
3. If
disease extends to posterior gray horn, all the sensations are lost. Due to loss of pain and temperature sensations,
the affected part is not withdrawn either reflexly or
consciously from a
painful
stimulus. So, the affected persons become prone for injuries. Since, the injury
is not perceived
it leads
to severe damage to the tissues.
4. If anterior gray horn is affected,
there is flaccid paralysis of muscles. In later stages, both pyramidal
and extrapyramidal tracts
are also involved, if the disease spreads to white matter.
It causes spastic
paralysis of limbs, especially
in lower limbs, resulting in spastic paraplegia. Weakness
and wasting of
small
muscle of limbs occur. Winging of scapula and scoliosis (lateral curvature of spine) develops.
Tabes Dorsalis
Tabes dorsalis
is another disease of the spinal cord. It is a slowly progressive
nervous disorder affecting
both the
motor and sensory functions of spinal cord.
Cause
It occurs
due to the degeneration of posterior (sensory) nerve roots. It usually occurs
in syphilis.
Posterior
nerve roots are affected proximal to the posterior root ganglia. Ganglia are
not affected. Among
the fibers
of posterior root, the fibers of lateral division are affected much. Reason for
this type of selective degeneration is not known. Along with lateral fibers of
posterior root, the fibers in posterior white column of spinal cord are also
affected.
Features
In tabes dorsalis, both sensory
and motor functions are affected. Following are the features Sensations
1. During
the onset of degenerative changes, there is exaggeration of pain sensation
2. Then,
there is impairment and loss of all sensations
3. Loss of
sensations, particularly pain sensation leads to deformities of joint. There is
no proper support
and
movements at the joints become uncontrolled. It is called Charcot
joint.
4. Joints
enlarge due to inflammation by the development of osteoarthritis.
Reflexes
Both
superficial and deep reflexes are lost in tabes dorsalis mostly because of loss
of sensations.
Voluntary
movements
There is lack of
coordination of movements (ataxia). Normal
movements like walking also become clumsy. The gait is awkward. Every movement of the limb is exaggerated while walking. Patient keeps the leg apart, raises the leg very high and stamps it down forcibly. This is called
stamping gait.
Urinary
bladder
If sacral segments are
affected in tabes dorsalis, the smooth muscles of the urinary bladder become
hypotonic.
Micturition reflexes are lost. And the urinary bladder becomes atonic
bladder.
Multiple Sclerosis
Multiple
sclerosis (MS) is a chronic and progressive inflammatory disease
characterized by demyelination
in brain
and spinal cord. It affects the myelinated nerve fibers of brain, spinal
cord and optic nerve
and causes gradual destruction
of myelin sheath (demyelination). When the
disease progresses, there
is transection of axons in
patches throughout brain and spinal cord. The term sclerosis
refers to scars
(scleroses)
in the myelin sheath.
Cause
Cause of
multiple sclerosis is unknown. It is hypothesized that
multiple sclerosis occurs due to combination and interaction
of environmental factors (chemicals, bacteria and
virus) and genetic factors resulting in abnormal reactions of immune system.
During the process, the immune system attacks the myelin sheath.
Signs and
symptoms
Initial attack by multiple
sclerosis is often mild or asymptomatic. As the disease
progresses variety of
symptoms
start appearing. Symptoms become severe during further progress of the disease.
Common
initial symptoms:
1. Mild
disturbance in the sensations on face, arms and legs
2.
Weakness and disturbances in maintenance of posture
3. Double
vision followed by partial blindness.
Other
symptoms when the disease progresses:
1. Tremor,
fatigue and muscle spasms
2. Speech
difficulty
3.
Difficulty in performing day-to-day activities
4. Bowel
problems
5. Bladder
dysfunction
6.
Emotional outbursts like anxiety, anger and frustration
7.
Short-term memory loss
8.
Complete blindness
9.
Development of suicidal tendency.
Disk Prolapse
Intervertebral or spinal
disk is the cartilaginous structure of vertebral column that separates
each
vertebra.
It is made up of a tough outer fibrous layer and a soft inner part. Inner part
acts as a shock
absorber
and cushions the vertebrae while moving. A small gap in between the adjacent
vertebrae allows
nerve
roots to enter or leave the spinal cord. Rupture of disk is called disk
prolapse. During disk
prolapse, the soft inner
material bulges out through a weak area in the hard outer
layer. The bulged disk
material may irritate or
compress or damage the nerve root that passes through the gap between the
vertebrae.
Severity of the condition depends upon the degree of bulging.
Causes
1. Injury
to spinal cord, neck or back
2. Heavy
weight lifting
3. Sitting
for a long time
4. Sudden
violent twisting of the body involving spine
5. Aging:
Because of gradual degeneration of disk with age. After about 30 years of age,
the disk starts
dehydrating.
So it is more susceptible for rupture at the age of 30 to 40 years.
Symptoms
Symptoms of disk prolapse
include pain and weakness in the area of prolapse. Most
common area of disk prolapse is the lower part of
vertebral column. If it compresses the sciatic nerve, the symptoms become more severe. Pain spreads down the back of leg to ankle, heel or toes of foot. Lower limb cannot be lifted sometimes. There is numbness and tingling in the affected region. Sitting for long period aggravates the pain
and develops other symptoms such as sneezing,
coughing or voiding of urine. Prolonged compression of sciatic nerve leads to
weakness of leg muscles.
Next common area of
disk prolapse is the neck. In this case, the pain is felt in neck, shoulder blade
and armpit. If the
nerves supplying upper limbs are compressed, the pain spreads through the arm
up to
the fingers. It also
causes stiffness, weakness or tingling in the upper limbs. Even the movements
of fingers or arm are restricted
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