Wednesday, March 11, 2009

sudden onset of diplopia



Please examine the eyes of this 56-year-old Malay housewife with sudden onset of diplopia

features
•complete ptosis
•eye abducted and externally rotated downward
•normal pupils size and reactive to light


1.Has this patient a surgical or medical 3rd CN palsy?
She has a medical 3rd CN palsy because her pupils are not affected



2.What is the mechanism of a medical 3rd CN palsy.

The 3rd CN has dual blood supply.
The vasa vasorum supplies all but the pupillary fibres which is nourished by blood vessels arising from the pia mater. Thus microangiopathies eg. diabetes, PAN, sarcoidosis, HIV, and hypertension (so called medical 3rd CN palsy).
In contrast, surgical 3rd CN palsy is due to compression (tumor, posterior communicating artery aneurysm) or constriction (inflammation and fibrosis) and will produce a complete palsy.

3 comments:

Ibnu Shaukani on March 11, 2009 at 4:29 PM said...

features
•complete ptosis
•eye abducted and externally rotated downward
•pupils dilated and non-reactive to light

pupils dia dilated, n non-reactive to light..tp kenapa hang kata die punya pupils are not affected? ak kurang paham

pt ni mcm ada Adie's pupil (tonic pupil). sebab pupil die is unresponsive to direct n indirect light reflex..tp satu ja maklumat x cukup, pasal accomodation. kalau mata dia tunjuk slow pupillary constriction masa accomodation tu, sah dia Adie's pupil.

kalau Argyll-Robertson pupil, dia tak response pd both direct n indirect reflex jugak, tapi accomodation reflex dia adalah NORMAL. selalunya dlm syphilis, ada juga if ade lesion kt midbrain.

ainaa ismail on March 11, 2009 at 5:36 PM said...

owhyeah,azizi aku dah betulkan=p

in surgical 3rd cranial nerve palsy baru dilated and non reactive to light because dia kacau pupillary fiber,so parasympathetic tak bagus.

further reference rujuk xpress revision short case pasal approch to ptosis.senang nak paham.

Ibnu Shaukani on March 11, 2009 at 6:10 PM said...

owh, ok..so, medical x kacau parasymp, surgical kacau parasymp?

p/s: aku takde plak buku tu, rugi betul x beli.

 

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