INCOMPLETE TRANSECTION OF SPINAL CORD

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-SĂ©quard 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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