Expert interpretation of modern noninvasive neuroimaging such as Computed tomography angiography (CTA) and magnetic resonance angiography (MRA), should detect nearly all aneurysms responsible for an isolated third nerve palsy 3) 4) 5) 6).
Although recent studies 9) have reported a risk of neurologic complications close to zero for diagnostic cerebral angiographies performed within a high volume neuro-interventional practice, the risk of neurologic complications following catheter cerebral angiography was once between 0.9 and 4% 10) and, therefore, algorithms trying to avoid routine catheter angiography, especially as a screening test, have been proposed in the past 11) 12) 13)
Recent publications have emphasized the importance of having presumed negative noninvasive vascular imaging studies reviewed by a skilled neuroradiologist before aneurysm is rejected as the cause of the third nerve palsy or before the patient undergoes catheter angiography 14).
1. if the p-comm is patent: determine if there is a “fetal circulation” where the posterior circulation is fed only through the p-comm
2. determine if the aneurysm fills from VA injection
If additional views are needed t o better demonstrate aneurysm
Try paraorbital oblique 55° away from inject ion side, center beam 1 cm posterior to inferior portion of lateral rim of ipsilateral orbit, orient x-ray tube 12° cephalad
One cannot accurately predict blood supply dominance of the posterior cerebral artery with CTA. Knowledge of the blood flow dominance is essential when clipping a posterior communicating artery aneurysm to avoid compromise in posterior circulation 15).