Question

1. A young man has suffered a spinal injury from being tackled while playing football. The doctor suspects he has a dislocated lumbar vertebra (just below the waist) that is compressing his spinal cord and that he will probably need surgery to restore normal function. To assess the extent of his problem, a number of tests are conducted:
   1. Knee jerk reflex – normal for both legs
   2. A prick to the bottom of the patient’s right foot produces a withdrawal of the right leg and an extension of the opposite leg and the patient says that he felt a sharp prick.
   3. A prick to the bottom of the patient’s left foot produces a withdrawal of the left leg and an extension the opposite leg but the patient does not feel the prick.
   4. The doctor tells the patient to lift his right leg and then his left leg – the patient does both tasks without difficulty.
   5. The doctor tells the patient to wiggle the toes on his right foot and his left foot – the patient cannot wiggle the toes of his right foot, but has no trouble wiggling the toes of his left foot.
   6. The doctor rubs an ice cube on the bottom of the patient’s feet and asks him to describe what he feels. The patient reports a smooth cold object when the ice cube is rubbed along the bottom of his right foot, but he only reports feeling a smooth object moving along the bottom of his left foot.

1. What is each test trying to assess - a spinal cord reflex, a sensory pathway, a motor pathway?   Provide specific names of pathways where appropriate.
2. What pathways were affected by his injury? Describe the basic features of these pathways including: the kind of information carried, where the information is coming from, where it is going to, the fiber type(s) involved, and where the major synapses/crossovers occur.

Answer 1

A) Knee jerk reflex is used to know about spinal cord injury especially lumbar injury.(patellar reflex)

Prick to the bottom is a sensory function and the withdrawal is due to spinal reflex action which includes sacral spinal(pain pathway)

Lifting up leg is to check motor function

Wiggling of toes are motor function

Rubbing of ice follows sensory pathway

B) as he was not able to feel the prick in right leg sole and was unable to wiggle the right time , his pain ascending pathway is disrupt which is a fast-sharp spinal pathway which is associated with S-1 spinal nerve. But he can feel slow thermal stimuli of ice on his right sole unlike left foot which is accociated with slow-chronic pain pathway, which mostly occurs due to chemical reaction of neurotransmitter and propireceptor along with temperature receptor.

Information carried are pain , thermal sensation and non discriminative touch and pressure. Information is registered from the different sensory fibres in skin as well as in muscle A-beta fibres, A-delta fibres and C fibres.

So this is how pain travels

Cervical spinal cord (dorsal ganglion root) - Cervical spinal cord(anterior commissure) - caudal medulla via anterolateral pathway - rostral medulla- pons( spinoreticular tract) - midbrain ( spinomesencphallic tract) - cerebrum (spinothalamic tract)