INCOMPLETE TRANSECTION OF SPINAL CORD
If spinal cord is gravely
injured, but does not suffer complete division, the condition is called as
incomplete transection.
Symptoms of
Incomplete Transection
After incomplete transection
of the spinal cord, all the three stages of complete
transection occur.
1. Stage
of spinal shock
2. Stage
of reflex activity
3. Stage
of reflex failure.
1. Stage of Spinal
Shock
Features
are similar to those of complete transection.
2. Stage of Reflex Activity
Features of this stage:
i. Tone
returns to extensor muscles first and not to the flexor muscles. This is
because, in incomplete
transection, some of the
descending fibers in lateral column of cord, especially vestibulospinal and reticulospinal tracts may escape the injury. So, some
connections persist between brainstem and spinal cord.
Fibers of vestibulospinal and reticulospinal tracts mainly reinforce the
activity of extensor motor neurons.Because of this, there is
extensor hypertonia and so, the lower limbs are
extended at hip and knee with toes pointing slightly
downwards. This condition is known as paraplegia in extension.
ii.
Stretch reflex reappears first. Flexor reflexes return later. Philipson reflex (clasp-knife reflex)
can be
elicited.
iii. In
the upper limb, some resistance is offered when the arm is flexed at elbow
joint passively.
That is,
the arm cannot be flexed. This resistance is offered because of the stretch
reflex developed
in the
triceps muscle. However, if forearm is flexed forcefully, the resistance to
flexion is abolished
suddenly,
leading to quick flexion of arm. This is called the Philipson reflex or clasp-knife reflex.
iv. Mass
reflex, which is produced in complete transection, does not occur in
incomplete transection
of spinal
cord.
3. Stage of Reflex Failure
Features
are similar to those of complete transection.
HEMISECTION OF SPINAL
CORD – BROWNSÉQUARD SYNDROME
Lesion
involving one lateral half of the spinal cord is called hemisection . It can
occur due
to injury
during accidents. It can also be produced experimentally in animals.
Symptoms of
Hemisection of Spinal Cord
Signs and symptoms, which
occur after hemisection of the spinal cord, constitute
Brown-Séquard syndrome. If the hemisection is due to injury, spinal shock occurs immediately. Muscles loose the tone and become flaccid. The reflexes are abolished. In case the patient survives,
this stage gradually passes off and certain signs and
symptoms develop. Effects are seen below the level
of lesion and at the level of lesion. Effects in these areas differ on the same side and opposite side. There are changes in sensory and motor functions.
EFFECTS OF
HEMISECTION OF SPINAL CORD BELOW THE LEVEL OF LESION
On the Same Side
Sensory
changes
1. On the
same side below the level of lesion, following sensations are lost because
these sensations
are carried by the uncrossed fibers of tracts of Goll and Burdach:
i. Fine
touch
ii.
Tactile localization
iii.
Tactile discrimination
iv.
Sensation of vibration
v.
Conscious kinesthetic sensation
vi.
Stereognosis.
2. Some
sensations are not affected because these sensations are carried by crossed fibers of
spinothalamic
tracts. These sensations are:
i. Crude
touch
ii. Pain
iii.
Temperature.
Motor
changes
Motor
changes resemble the effects of upper motor neuron lesion.
1. Muscle
tone increases, leading to spastic paralysis
2.
Rigidity of limbs occurs
3. Muscle
wastage does not occur
4.
Superficial reflexes are lost
5. Babinski
sign is positive
6. Deep
reflexes are exaggerated
7. Fall in
blood pressure because of loss of vasomotor tone.
On the Opposite Side
Sensory
changes
1. On the
opposite side, below the level of lesion, the following sensations are
lost completely because,
these sensations are
carried by crossed spinothalamic tracts
i. Crude touch
ii. Pain
iii. Temperature.
2. Following sensations
are not affected because, these sensations are carried by uncrossed tracts
of Goll and Burdach:
i. Fine touch
ii. Tactile localization
iii. Tactile
discrimination
iv. Sensation of
vibration
v. Conscious
kinesthetic sensation
vi. Stereognosis.
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