<prompt> An 85-year-old man presents with a sudden onset of severe occipital headache and has vomited on two occasions since the headache began. He also complains of double vision. He has a history of hypeension. His examination findings are : - Glasgow Coma Scale 1515 - Mild neck stiffness noted - Power 55 in both upper and lower limbs. Where is the likely site of pathology?Anterior communicating aeryPosterior communicating aeryLenticulostriate aeryP1 Segment of Posterior cerebral aery  <response>: -Double vision and vomiting implies features of Raised ICP HTN -Mild neck stiffness indicates probability of SAH -Presence of ptosis ,since in the question eye is pulled laterally and down it means there is unopposed 6th nerve as the 3rd nerve is damaged. If Berry aneurysm ruptures into ACA : no cranial nerve palsy SAH w.r.t 3rd nerve palsy : PCA involvement HTN can lead to Charcot Bouchard Aneurysm can rupture-3rd nerve palsy Diagnosis: HTN with 3rd nerve palsy SAH : vascular malformation ruptured mc nerve involved in rupturedunruptured berry aneurysm is 3rd nerve as it runs adjacent to PCA 