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.
1 comments:
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.
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