Acute CN III palsy with ipsilateral pupil dilation is PCOM aneurysm until proven otherwise
Aneurysm compresses the outer fibers (pupillomotor) of CN III → dilation
In contrast to CN III palsy due to diabetes mellitus or hypertension in which pupil is spared
Aneurysm compresses the outer fibers (pupillomotor) of CN III → dilation
In contrast to CN III palsy due to diabetes mellitus or hypertension in which pupil is spared
Posterior Communicating Artery 
Basilar Artery Thrombosis
Truncus arteriosus
Posterior communicating artery 
Patent ductus arteriosus
Vertebral artery dissection
Takayasu arteritis
Myasthenia Gravis[1]