11b -
types of transection of SC
Spinal cord transections
can be divided into 3 types:
Complete transection,
Incomplete transection,
Hemisection of the spinal cord.
Causes
- Gun shot injury.
- Dislocation of the spine.
- Occlusion of the spinal blood vessel.
Commonest site of involvement is at the mid thoracic level.
It is a lesion involving one lateral half
of the spinal cord.
- Here, autonomic functions are usually normal.
- The other functional changes which takes place
can be divided into 3 categories:
2.changes at the level of
hemisection
- changes below the level
of hemisection
- changes above the
level of the hemisection
On the same side
- Sensory changes
- Fine touch,
- tactile localization and
- tactile discrimination,
- vibration sense and
- kinesthetic senses
is lost due to damage of the dorsal columns.
- Pain
- temperature and
- crude touch remain unaffected
as the spinothalamic tracts (anterior and lateral) carrying these sensations
cross to the opposite side and escape injury.
- Motor changes
- Extensive paralysis of upper motor neuron type due to damage of crossed pyramidal tracts.
- Since some fibers of direct pyramidal
tract of opposite side escape injury,
therefore, some muscles on
the same side of the lesion may not be paralyzed.
- Temporary loss of vasomotor tone due to damage to the descending fibers from the VMC in the medulla to the lateral horn cells.
-This leads to the dilatation of blood vessels and fall in BP. - Later, intact lateral horn cells start acting as supplementary VMC and tone returns.
On the opposite side
- Sensory changes
- Complete loss of pain,
- temperature and crude touch
due to damage
to the spinothalamic fibers
which come from the opposite side.
- Kinesthetic sensations, fine touch etc.
will persist because the
posterior columns of the opposite side are not damaged.
- Motor changes
Either no paralysis or paralysis of few muscles occurs (UMNL type).
This is due to possible involvement of some fibers of direct
pyramidal tracts of the same side when these fibers cross.
On the same side
- Sensory changes.
Complete anaesthesia occurs due to damage to the posterior nerve root,
posterior horn cells and
spinothalamic fibers
(which cross to the opposite side).
- Motor changes.
Complete lower motor neuron type paralysis is seen due to damage
to the anterior horn cells.
Complete and permanent vasomotor paralysis occurs due to
damage of the lateral horn cells.
On the opposite side
- Sensory changes.
Some loss of pain sensations due to injury of pain
fibers of spinothalamic tract which cross horizontally in the same
segment and may be caught in the lesion.
- Motor changes.
Nil or very slight due to damage of some pyramidal
tract of the same side.
On the same side
A band of hyperaesthesia present due to irritation of upper cut end of the damaged fibers.
On the opposite side
Hyperaesthesia may be referred.