CNS Disorders tutorials Flashcards
How do you describe a lesion that results in loss of movement in one side of the body?
Verterbrae level (e.g T10) hemisection of the spinal cord on the (left/right) side.
Explain loss of motor function and fine touch in right leg due to lesion of spinal cord on right side?
Interrupts right lateral corticospinal tract projecting to ipsilateral motor neurones and right ascending dorsal columns tract from ipsilateral leg. Therefore, loss of function below the injury.
Explain loss of temperature and pain sensation in left leg due to lesion of spinal cord on the right side?
There is no loss of pain and temperature in the ipsilateral leg because the ascending spinothalamic tract crosses the midline within a few segments of the level of entry of the sensory information into the spinal cord. The spinothalamic tract from the contralateral leg will be interrupted by the lesion, hence the loss of pain and temperature sensation in that leg.
What determines if someone is to recover from a lesion?
If some parts of the pathways have only been temporarily affected. If the tracts are completely disrupted it is very unlikely that there will be any regeneration in the CNS.
What can help in recovery to lesion?
Synaptic plasticity.
Why may there be there may be segmental loss of pain and temperature ipsilaterally at the level of the injury?
Due to direct damage to the cord or nerve receiving the information.
How do you describe the location of the infarct that affects sensation on left hand side?
Right parietal cortex in or close to the primary somatosensory cortex, hence disturbance of sensation in left hand.
What can be prescribed to reduce jerking movements?
Anticonvulsants.
Why may an infarction of somatosensory cortex result in jerking movements?
Primary epileptic focus formed as a result of tissue damage in somatosensory cortex from stroke. Jerks caused by propagation of discharge to arm area of motor cortex in frontal lobe.
What happens if you don’t treat jerking movements due to stroke?
Seizures may spread to involve whole motor cortex and even propagate to other hemisphere to produce generalised seizures.
What would occur if there is a lesion in the dorsal root and why is this not as severe as other lesions?
Damage to dorsal root leads to loss of sensation in dermatome supplied by the corresponding spinal nerve. If only one root is affected its not severe lesion as there is considerable overlap of dermatome innervation by adjacent spinal nerves.
Why would occur if there is a lesion in the ventral root and why does this not lead to paralysis?
Damage to ventral root leads to weakness of muscles supplied by the corresponding spinal nerve. Most limb muscles are innervated by 2 or more spinal nerves therefore paralysis is unlikely unless all spinal roots are damaged.
What would occur if there is a lesion in the mixed spinal nerve?
Partial loss of sensation and muscle weakness.
What would occur if there is a lesion in the sensory nerve?
Leads to loss of sensation in the area of distribution of that peripheral nerve.
What would occur if there is a lesion in the motor nerve?
Damage to a motor nerve leads to weakness/paralysis of the muscle supplied by that peripheral nerve.
