Clinical applications of neuroanatomy

Question 1

How would lesions in one cerebral hemisphere present?

Answer 1

unilateral effects as only one hemisphere is affected

Question 2

How would lesions in the cerebellum present?

Answer 2

Discoordination but normal power

Question 3

If there is a lesion at the optic chiasm, what visual field defect would you expect?

Answer 3

• Bitemporal hemianopia (temporal field loss on both eyes)

Question 4

If there was a lesion before the optic chiasm what visual defect would you expect to see?

Answer 4

Monocular defect (vision loss on whole whole eye)

Question 5

If there was a lesion after the optic chiasm, what visual defect would you expect?

Answer 5

homonymous hemianopia (left = left visual field missing on both eyes)

Question 6

What effects would you expect to see in a third nerve palsy?

Where does the CN III nucleus sit?

Answer 6

Completely closed eyelid and deviation of the eye outward and downward. The eye cannot move inward or up, and the pupil is typically enlarged and does not react normally to light.

CN III nucleus sits in the brain stem and fibres move forward and go through the cavernous sinus.

Question 7

What is internuclear ophthalmoplegia?

What is the most common cause in young and old patients?

Answer 7

INO is caused by a lesion in the medial longitudinal fasciculus in the brain stem.

This leads to a disrupted communication between CN 3,4,6 causing weakness in adduction of the ipsilateral eye with nystagmus of the contralateral eye only when abducting.

• Young patients: multiple sclerosis
• Older patients: stroke

Question 8

What is lateral medullary syndrome?

Answer 8

Neurological disorder causing a range of symptoms due to ischaemia in the lateral part of the medulla oblongata in the brain stem.
The ischaemia is a result of a blockage most commonly in the vertebral artery or the posterior inferior cerebellar artery.

Question 9

What are the 4 symptoms of horner’s syndrome?

Answer 9

1. hypohydrosis
2. ptosis
3. miosis
4. enophthalmos

Question 10

Which ascending tract transmits pain, temperature and crude touch sensation from the skin to the somatosensory area of the thalamus?

Answer 10

Spinothalamic tract

Question 11

Where does the spinothalamic tract decussate?

Answer 11

Sensation in the limbs goes into the spinal cord and crosses over at the level of the spinal cord and then ascends on the opposite side

Question 12

In the spinothalamic tract, where is information sent to from the thalamus?

Answer 12

post central gyrus (primary sensory cortex)

Question 13

If there was a lesion in the brain stem, would you expect to see a loss of pain perception, crude touch and temperature sensation on the contralateral or ipsilateral side of the body?

Answer 13

Contralateral as the spinothalamic tract decussates at the level of the spinal cord

Question 14

With spinal cord hemisections, the loss of crude touch and proprioception is ipsilateral but pain perception is contralateral. What is this syndrome known as?

Answer 14

Brown-sequard syndrome.

Question 15

What information does the corticospinal tract carry?
What is this path involved in?
Where do they fibres decussate?

Answer 15

Carries motor information from the primary motor cortex (pre-central gyrus) in the brain to the muscles of the trunk and limbs.
It is involved in voluntary movements of muscles of the body.
85% of fibres decussate in the pyramids of the pons and descend as the lateral corticospinal tract. 15% continue as the anterior corticospinal tract.

Question 16

What effect would a lesion above or below the pyramidal decussation of the corticospinal tract have on motor deficits in the body?

Answer 16

Injury above pyramidal decussation: contralateral motor deficits
Injury below the pyramidal decussation: ipsilateral motor deficits.

Question 17

What effects would you expect from an UMN injury?

Answer 17

Spastic weakness when voluntary movement is attempted
Increased muscle spasticity
Exaggerated tendon reflexes
Positive pathological pyramidal signs (bakinski sign)

Question 18

What effects would you expect from a LMN injury?

Answer 18

flaccid weakness of the limb
loss of muscle tone
loss of tendon reflexes
atrophy of the muscle
fasciculation of the muscle

Question 19

What information does the dorsal column carry? From where to where?

Answer 19

The dorsal column is a sensory pathway of the CNS carrying sensation of fine touch, vibration, pressure, 2 point discrimination and proprioception (position) from the skin and joints.

Pyramids take information from the lower limbs

Olives take information from the upper limbs

From skin and joint -> medulla, pons, midbrain, thalamus and somatosensory post-central gyrus.

Question 20

Where do the fibres from the dorsal column decussate?

Answer 20

Brain stem - medulla

Question 21

What information does the corticopontine cerebellar tract transmit?

Answer 21

sensory from cortex to pons -> cerebellum through middle cerebellar peduncle

Question 22

What information does the vestibulocerebellar tract transmit?

Answer 22

information about balance, visual input through inferior cerebellar peduncle to flucolonodular lobe

Question 23

What symptoms would you expect from cerebellar tract lesion? (ipsilateral or contralateral)

Answer 23

ipsilateral symptoms as they cross over twice

Question 24

What information does the spinocerebellar tract transmit?

Answer 24

Originates in the spinal cord and terminates in the same side of the cerebellum carrying sensory info about postural adjustment, proprioception in skeletal muscles and joints to the cerebellum