Can someone explain these brain disorders? They are not in first aid, but I've gotten some NBME questions on them and they're included in the "4 and 5 star topics" of DIT. Thanks in advance.
Hey
So
Weber Syndrome happens when you have vascular damage to the vessels that supply the midbrain (post cerebral artery) and as a result you damage all the structures that are supplied by this artery:
1) CN 3: Therefore eye will look down and out. You'll have ptosis and no light/accomodation reflex (ipsilateral to damage)
2
) Corticospinal tract is also damaged as it passes through the midbrain so you'll spastic paresis on the contralateral side
3) The coritcobulbar pathway passes through the midbrain also so you'll get contralateral paralysis to the LOWER half of the face
Wallenberg Syndrome is when you damage blood supply to the LATERAL medulla (i.e. PICA)
1) You damage your
Nucleus ambigus: pt will complain of dysphasia, dysarhria
2) Damage the
Trigeminal nerve (note the trigeminal nucleus is in the pons but the pathway continues down the spinal cord so you'll find some fibers in the medulla laterally). Pt will complain of IPSILATERAL loss of sensation on the face
3)
Vestibular nuclei (at the pontomedullary junction): vertigo and nystagmus (area 8 will now make the eyes look AWAY from the lesion)
4)
Hornor's syndrome (you've interrupted the hypothalamic pathway)
5)
Spinothalamic/leminiscus pathway will also be knocked out so loss of pain, temp and sensations on the contralateral side.
Grestmann is actually kind of interesting: so if you have an infarct in the
LEFT middle cerebral artery in your dominant hemisphere and if the infarct was anywhere near "area 39" or angular gyrus in the parietal lobe you get this syndrome. It's basically when they can't process visual information that they get from the occiptal lobe but they're not actually blind. So they have "Alexia" which is when they can't see words AND agraphia (can't write). They also can't count or recognize their fingers so if they say dyscalculia they're kind of giving it away.
If the above happened in your "non-dominant" hemisphere (i.e. your right hemisphere) then you would get "Asomatognosia" which is when you don't recognize half of your body (that's that patient we're all so familiar with from psych who only dresses half of their body and draws 1/2 a clock).
