try this 1 - usmlegold

[ArchivalUser]

A 42-year-old woman comes to the emergency department complaining of double vision. She
has a long history of diabetes and occasionally suffers from blurred vision when
hyperglycemic. She reports being unable to keep her right eye open, a new problem that
developed over the last 24 hours. Past medical history is significant for poorly controlled
diabetes, diagnosed 2 years ago, and migraine headaches, which have been particularly
severe for the past 2 days. Family medical history is significant for diabetes, renal failure, and
heart disease. Examination reveals a droopy right eyelid and an inability to elevate, adduct,
and depress the right eye. The right pupil also appears dilated compared with the left pupil.
The left pupil shows no motility defects. Vision is 20/30 OD and 20/25 OS. Which of the
following is the most likely cause of her visual complaints?
A. Cavernous sinus thrombosis
B. Diabetic microvascular infarct
C. Hyperglycemia
D. Intracranial aneurysm
E. Ophthalmic migraine

[ArchivalUser]

B.

[ArchivalUser]

BB

[ArchivalUser]

no, thats not it

[ArchivalUser]

CNIII palsy, D??

[ArchivalUser]

bbb looks like a logical answer actually but does anyone know why its NOT B?

[ArchivalUser]

why?

[ArchivalUser]

D...posterior communicating artery aneurysm leading to III nerve palsy.

[ArchivalUser]

smart boys.....
answer is DDDDDDD

here's the explanation:

This is a medical emergency. An intracranial aneurysm can
compress the third cranial nerve, resulting in acute third nerve palsy. The recent severe
"migraines" probably represent sentinel or warning headaches caused by slow leakage
of blood. An angiogram and neurosurgical consult are appropriate immediate actions.
Incidentally, the family history of renal disease may represent polycystic kidney disease,
associated with berry aneurysms.
Cavernous sinus thrombosis (choice A) will often present with a swollen, protruding eye
and a retro-orbital headache. Expect fevers and the classic constellation of ptosis,
proptosis, chemosis, and ocular muscle paralysis beyond isolated CN III palsy.
Diabetic microvascular infarcts (choice B) often result in the development of a subacute,
not acute, third nerve palsy. Additionally, in diabetic third nerve palsy, pupillary findings
are usually absent. The sympathetic fibers, which run on the outside of the nerve and
have a separate blood supply, are usually spared in microinfarctions of the nerve.
However, in compression, such as from an aneurysm, the entire nerve is damaged,
including the sympathetic nervous tissue and blood vessels surrounding the nerve
sheath.
Hyperglycemia (choice C), if severe, can result in an increased intraocular osmolar
force, which distorts the shape of the lens. This usually results in blurred vision but does
not explain this patient's mechanical ocular findings.
Ophthalmic manifestations of a migraine (choice E) usually do not include acute third
nerve palsy.