Question

Fred fell from the garage roof when cleaning out the gutters after a storm. At the hospital doctors concluded that he had an Left T12 hemi-section.  

What pathway that would carry proprioceptive information and which side of the Fred's body would be effected. ?

Would Fred have voluntary movement of his lower limbs? consider both left and right sides?

Would Fred still have a knee jerk reflex?

Would Fred be able to perceive the reflex?

Describe the types of sensory modalities that may be influenced by this type of injury.

Answer 1

First, let us start from some facts:

Left T12 hemi-section will cause:

Loss of proprioception on the same side (right) (loss of dorsal columns)

Loss of pain and temperature on the opposite side of the lesion (left) (loss of spinothalamic tract)

Below the lesion, on the same side there will be spastic paralysis- UMN lesion

At the level of lesion on the same side there will be flaccid paralysis of the muscles supplied by the nerve injured- LMN lesion.

But note here, the lesion is situated below the entry of sensory fibers as well as the origin of anterior horn cells that innervate the upper limbs,

Therefore, no loss of sensation to the upper limbs will ensue, nor will there be an LMN or UMN paralysis of the upper limbs.

now, to summarise using above key points-

Pain and temperature loss in right leg of Freddy

Proprioception loss in his left leg

UMN on his left leg

Descending corticospinal tracts will be damaged so LMN loss will be there which used to control the muscles of left leg- hence flaccid paralysis of left leg.

This means NORMAL MOVEMENTS on the right leg.

Now coming to the reflexes, we know-

• Spastic paralysis- Brisk reflexes (UMN)
• Flaccid paralysis- sluggish or no reflex (LMN)

Knee reflexes are elicited by L3-L4, and below the lesion there is spastic paralysis therefore brisk reflexe in left leg.