Posterior communicating artery aneurysm
PCOM. I kept forgetting this important to look for diagnosis. I have been reading this multiple times .
from http://neuroangio.org/anatomy-and-variants/posterior-communicating-artery/
Clinical signs
If the pupil is large on one side of the eye, Isolated cranial nerve III palsy
the parasympathetic fibres of the cranial nerves III are arranged on the outer surface as compared to the motor fibers. Therefore an external compression would cause dilated pupil but not in the case of medical cranial nerve III due to mononeuritis.
DrMKZ 
Love this ❤ http://www.misskymmiee.com
Miss_Kymmiee
July 15, 2016 at 7:36 pm
Add
If the pupil us affected then this suggest involvememt of the parasymphathetic nerve fibres that originate from the edinger westphal nuclues.
This often results from extrinsic compressive lesions as these autonomic fibreas are situated very superficially in the nerve trunk and if the pupil is affected it is temed surgical 3rd nerve palsy.
If spared termed medical 3rd nerve palsy
khairulorama
July 16, 2016 at 12:36 pm
Hello, I just found your website. I noticed you have a diagram above of the isloated 3rd nerve paralysis. Do you have a diagram of the 6th nerve paralysis? I was just diagnosed with this and I’d like to see this diagram to rule out things. Hoping you can help me? I would be so blessed with your help.
Thank you,
Cristina
Cristina
January 13, 2019 at 2:21 pm