neuroanatomy + Ix

Question 1

each lobe and their job (and what happens if it gets damaged)

Answer 1

• frontal: planning shit and Broca’s expressive speech. primitive reflexes and expressive dysphasia if lost.
• parietal: sensory shit and speech fluency. dysphasia / acalculia/agraphia, sensory loss.
• temporal: memory and Wernicke’s receptive aphasia.
• occipital: vision
• cerebellum: coordination

Question 2

diencephalic syndrome (Russell’s syndrome) - key features for exam

Answer 2

tumour in hypothalamic - optic - chiasmatic region
1) hperactivity and euphoric
2) munchies
3) but FTT and severely emaciated

+/- optic atrophy, nystagmus, tremor

Question 3

parinaud syndrome - key features for exam

Answer 3

1) upward gaze palsy
2) pupils dont respond to near light
3) nystagmus
4) eyelid retraction

Question 4

parinaud syndrome - key causes

Answer 4

1. pineal tumour
2. hydrocephalus
3. stroke
   …causing vertical gaze disturbance

Question 5

the cranial nerves and their functions

Answer 5

I = olfactory
II = optic
III = oculomotor
IV = trochlear
V = trigeminal: facial sensation, mastication muscles
VI = abducens
VII = facial: anterior 2/3 tongue, stapedius, facial movement, lacrimation and salivation
VIII = vestibulocochlear
IX = glossopharyngeal: posterior 1/3 tongue, swallowing, some salivation
X = vagus
XI = spinal accessory: SCM/trapezius
XII = hypoglossal: tongue

Question 6

what will the affected eye look like with the three oculomotor nerve palsies? which muscles do they therefore control?

Answer 6

III = down and out (inferior oblique, superior/inferior/medial recti)
IV = up and in (superior oblique)
VI = eye in (can’t abduct, lateral rectus)

Question 7

where do the cranial nerves exit?

Answer 7

Rule of 4’s:
a. 4 cranial nerves exit medulla = CNIX, X, XI, XII
b. 4 cranial nerves next the pons = CNV, VI, VII, VIII
c. 4 exit above the pons

Question 8

when does the paediatric brain fully myelinate?

Answer 8

2yo

Question 9

MRI sequences: T1 vs T2

Answer 9

T1 = structure, CSF black. grey is grey, white is white.
T2 = inflammation/oedema (T2 makes tea, so water will be white): CSF white. grey is grey, white matter is black.

Question 10

FLAIR sequence on MRI - used for?

Answer 10

suppresses CSF signal, so good to see inflammation close to CSF e.g. near ventricles

Question 11

DWI MRI - used for?

Answer 11

ischaemia - cellular swelling = lower diffusion coefficient

Question 12

diplopia: vertical, horizontal and oblique

Answer 12

horizontal = lateral/medial recti (CNVI)
vertical / rotational = CNIV
vertical = MR, SR, IR, IO = CNIII

Question 13

in diplopia, which image is the false one?

Answer 13

outermost one is the false one (regardless if vertical/horizontal)
- so if you cover the eye and the outermost one disappears, then the covered eye is the bad one. if you cover and the innermost one disappears, then the covered eye is the good one.

Question 14

monocular vs binocular diplopia

Answer 14

binocular - disappears when one eye is occluded
monocular - remains when good eye is occluded

binocular worse - suggests nerve problem (CN, NM, muscular)
monocular usually refractive problem only

Question 15

CNIII palsy signs

Answer 15

eye down and out
significant ptosis (levator palpebrae)
pupils stuck with light - no more parasympathetic

Question 16

head tilt test for which nerve palsy

Answer 16

CNIV
hypertropia worsens with ipsi head tilt, improves with contralat

Question 17

key features of bell’s palsy

Answer 17

• ipsi facial droop, unable to raise eyebrows / wrinkle forehead
• hyperacusis and altered taste
• pain (severe pain suggestive of VZV)
• recovery within 6 weeks

Question 18

bell’s palsy vs stroke

Answer 18

stroke causes contralateral mouth droop with upper half of face spared bc upper half of face is innervated by both sides of the cortex

bell’s causes ipsilateral facial paralyses bc its a peripheral nerve lesion

Question 19

red flags for facial weakness that suggest another cause aside from bell’s

Answer 19

<2yo
absence of recovery by 4 weeks
neuro deficits
sparing of forehead muscles
OM/parotitis/mastoiditis

Question 20

Mx for bell’s

Answer 20

eye care - lubricant, pad eye shut at night
pred for 10 days within 72h of onset

Question 21

most common causes of bell palsy

Answer 21

HSV
then VZV

Question 22

classic triad of horner’s syndrome

Answer 22

Ipsilateral:
1. minor ptosis (<2mm)
2. miosis
3. anhidrosis with 1st/2nd order lesions (not post-ganglionic or third order - these sweat fibres branch off earlier)

Question 23

pathogenesis of horner’s syndrome

Answer 23

caused by lesion anwhere along the oculosympathetic pathway:
1st order neuron e.g. tumour/syrinx/stroke: hypothal to cervical spinal cord
2nd order neuron e.g. pancoast tumour: along sympathetic trunk to ICA
3rd order e.g. ICA dissection: ICA through cavernous sinus > dilate eyes, muller muscle

Question 24

difference between horner’s and CNIII ptosis

Answer 24

horner’s is less severe bc it only affects muller’s muscle which has a minor role; CNIII affects levator palpebrae

Question 25

lesions from these result in what visual defects:
- optic chiasm
- occipital lobe
- parietal/ temporal lobe

Answer 25

• optic chiasm: bitemporal hemianopia
• occipital lobe: homonymous hemianopia (opp to defect)
• parietal/ temporal lobe: homonymous quadrantonopia (parietal lower defect, temporal upper

Question 26

erb vs klumpke’s palsy

Answer 26

erb: upper brachial plexus (C5+C6) = porter’s tip hand - adducted and medially rotated arm
klumpke: lower brachial plexus (C8+T1) = claw hand + horner’s

Question 27

which one thumb muscle does the ulnar nerve do that the median doesn’t?

Answer 27

adductor pollicis