DISEASES OF SPINAL CORD

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 Due to loss of pain and temperature sensations, the affected part is not withdrawn either reflexly or consciously from a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