Session 3.3 - Group Work Flashcards
1a) You help a plaster technician to apply a cast to a patient’s leg. He complains initially of some skin irritation but when you see him in fracture clinic the following day he states he feels comfortable, with no irritation.
What is the neurophysiological mechanism for this
phenomenon?
Rapidly adapting receptors adapt
1b) You help a plaster technician to apply a cast to a patient’s leg. He complains initially of some skin irritation but when you see him in fracture clinic the following day he states he feels comfortable, with no irritation.
Can you think of any everyday phenomena that can be
explained by this concept? This video might help
https://www.youtube.com/watch?v=MlCS0k16ESs
- Sitting in a chair
- Feeling your clothes
- Having a shower
2a) You are assisting in theatre with a resection of a brain tumour arising from the cerebral cortex. The neurosurgeon states that the patient’s sensory function in their right hand is likely to be impaired.
Ascertain as precisely as possible where in the brain the tumour is likely to be.
On the left-hand side in the post-central gyrus, superolaterally
2b) You are assisting in theatre with a resection of a brain tumour arising from the cerebral cortex. The neurosurgeon states that the patient’s sensory function in their right hand is likely to be impaired.
Why is the hand particularly vulnerable?
The hand occupies a large surface area in the cerebral cortex homunculus.
2c) You are assisting in theatre with a resection of a brain tumour arising from the cerebral cortex. The neurosurgeon states that the patient’s sensory function in their right hand is likely to be impaired.
Assuming the neurosurgeon’s prognosis is accurate, which modalities will be affected?
All of the modalities, because the lesion is in the cortex so you’ve lost everything
2d) You are assisting in theatre with a resection of a brain tumour arising from the cerebral cortex. The neurosurgeon states that the patient’s sensory function in their right hand is likely to be impaired.
Speculate on what other functions might be affected by the tumour or following the operation.
- Areas around the sensory cortex
- Motor affection
- Power of speech is close by
3a) A patient with diabetic neuropathy is found to have bilateral ‘glove and stocking’ paraesthesia in both hands and feet.
Can this pattern be explained by a single lesion affecting the sensory homunculus in the primary sensory cortex?
No, because the hands and feet are not adjcanet within the homunculus so they would need more than one nerve lesion. Secondally, it is bilateral, so it would need to be on both sides of the primary sensory cortex.
3b) A patient with diabetic neuropathy is found to have bilateral ‘glove and stocking’ paraesthesia in both hands and feet.
Further examination of the same patient reveals that they have complete sensory loss (all modalities) in the S1 dermatome on the right side.
Where is the S1 dermatome (can you answer this without looking it up?!)
Little toe and heel
Dorsum of the foot
3c) A patient with diabetic neuropathy is found to have bilateral ‘glove and stocking’ paraesthesia in both hands and feet.
Further examination of the same patient reveals that they have complete sensory loss (all modalities) in the S1 dermatome on the right side.
Which structure(s) might have been damaged to cause this isolated dermatomal loss? Draw a diagram showing these potential sites.
- Damage to the dorsal horn of the spinal root
- of the primary order neurone
- Dorsal root ganglion
Has to be more distal than the cord because we’ve lost all modalities - Spinal nerve
On the right side
3d) A patient with diabetic neuropathy is found to have bilateral ‘glove and stocking’ paraesthesia in both hands and feet.
Further examination of the same patient reveals that they have complete sensory loss (all modalities) in the S1 dermatome on the right side.
The patient is found to have weakness in plantarflexion?
Using this additional piece of information, state precisely where the lesion is.
The lesion would need to be at the S1 spinal nerve to affect both sensory and motor (it can’t be at the DRG)
4a) A vegan man is seen in the neurology outpatient department. His MRI scan of the cervical spinal cord on admission looked like this:
Label the images with anterior, posterior, superior,
inferior, left and right
Left: anterior (left), posterior (right)
Right: anterior (top), left (right), posterior (bottom), right (left)
4b) A vegan man is seen in the neurology outpatient department. His MRI scan of the cervical spinal cord on admission looked like this:
Which region of the cord has been affected?
C2-C4 posterior grey matter in the dorsal aspect - dorsal cord
(You can see the odontoid peg which is C2)
4c) A vegan man is seen in the neurology outpatient department. His MRI scan of the cervical spinal cord on admission looked like this:
Why is his dietary history important?
He doesn’t eat meat or dairy so he is lacking (deficient) in B12, iron and folate (and could therefore have megaloblastic anaemia)
Subacute combined degeneration of the cord
4d) A vegan man is seen in the neurology outpatient department. His MRI scan of the cervical spinal cord on admission looked like this:
Which cord levels have been affected?
C2-C4
4e) A vegan man is seen in the neurology outpatient department. His MRI scan of the cervical spinal cord on admission looked like this:
How might he have presented initially?
Posterior so sensory loss to C2-C4 dermatomes which is loss of sensation (paraesthesia) in the neck, upper torso and ears both anteriorly and posteriorly.
