Lecture 45: Injuries of the Spinal cord

Question 1

Describe the motor and sensory deficits after a Hemisection of the spinal cord (brown sequard syndrome)

Answer 1

Motor:
Loss of corticospinal, rubrospinal tract below lesion level
On same side of lesion
- loss of voluntary motor function in limb (s),
- hyperactive reflexes: (increased excitability due to imbalance of inputs from reticulospinal and vestibulospinal inputs)

Sensory: (loss below level of lesion)
On same side: Loss of fine tactile and proprioception lost.
On Opposite side of lesion: Loss of pain and temperature sensation

Question 2

What happens during the first 1-3 days after a complete lesion at a spinal cord level and why : motor, sensory, autonomic etc

Answer 2

Goes into Spinal shock: a period of areflexia due to loss of excitatory inputs from Reticulospinal and vestibulospinal tracts
Below lesion
Motor: Flaccid paralysis- complete loss of tone. No reflexes at all
Sensory: Total anaesthesia
Autonomic:
- Dilation of blood vessels-> BP decrease (loss of CVS medulla input)
- Thermal sweating is absent
- SM of bladder and bowels atonic; bladder distends with urinary flow
-sexual organ dysfunction

Question 3

In the days/weeks following complete spinal cord lesion what are the symptoms of Recovery: motor, sensory, autonomic

Answer 3

Motor:

• recovery of muscle tone (voluntary movement absent), - hyperactive muscle stretch reflex (spasticity/clonus)
• extensor plantar reflex

Sensory
- Paresthesia: abnormal sensations from affected area- eg. burning, due to reorganisation of synapses

Autonomic:
-Increase in BP and variable autonomic dysreflexia: even if can send info to medulla there is loss of baroreceptor reflex afferents- more pronounced if lesion higher than T1 (no more symp to the heart)

• Spontaneous reflex emptying of rectum and bladder

Question 4

What are the 2 mechanisms behind the recovery phase of complete spinal cord injury

Answer 4

1. Sprouting of presynaptic axon terminals and formation of new synapses from remaining nerve cells
2. Denervation super sensitivity: increased receptor expression in post synaptic membrane to try increase sensitivity

Question 5

Where will the complete spinal cord lesion be to cause paraplegia vs quadraplegia

Answer 5

Paraplegia: T8
Quadraplegia: C1-C4;

Question 6

What is the respiratory management for quadriplegic patients

Answer 6

If lesion is above C3-5 (phrenic nerve) then it is likely that positive pressure ventilation is required

If phrenic nerve is still intact, electrode can be implanted on free nerves to radio transmitter for rhythmic activation for contraction of diaphragm = breathing pacemaker

Question 7

What are the 2 movement help for paraplegic patients

Answer 7

1. Parastep: microcomputer controlled system for evoking coordinated muscle contraction for flexors/extensors to enable walking to prevent atrophy
2. ReWalk: Exoskeleton with crutches to walk

Question 8

What are some potential future treatments for paraplegic/quadraplegics

Answer 8

• Neutralising antibodies to a growth-inhibiting myelin-associated-glycoprotein
• TIssue bridges with peripheral nerves (nerve grafts), Schwann cells, olfactory ensheathing glia cells
• Neurotrophin 3

More dodgy

• Tissue bridges with fetal spinal cord
• Embryonic neural stem cells