Works on risk analysis focused on activity in the operating room or in intensive care is rare. In fact, the operating room remains one of the units where the patient's medication management process is complex, which tends to increase the risk of ME as well as the severity of its consequences. In anesthesia, attention should be paid more specifically to errors during the preparation and administration of drugs, because these are actions that are performed many times every day. The analysis of this adverse event in our patient made it possible to classify this adverse event in the category of administrative errors. The administration of vancomycin should be done by slow infusion when it has been administered to our patient by direct intravenous route, this type of error is part of the volume or flow errors. Medication administration error can be prevented by providing coaching and continuing education for practitioners. It is also necessary to label the medication storage compartments of the anesthesia cart; the correct identification of drug ampoules and to ensure that there is only one packaging of the same product.

Vertebral arteries are usually paired major arteries of the neck. Typically, they originate from the subclavian arteries coursing superiorly along each side of neck, merging within the skull to form basilar arteries. Different variant anatomy including assymetry, complete or partial duplication, fenestration and variable origin have been explained in the literature. We have a case report of 54 year old gentle man who presented with acute headache and vomitting in our institute. CT angiogram revealed left posterior cerebral artery aneurysm causing subarachnoid hemorrhage. DSA further revealed bilateral vertebral arteries arising from the common carotid artery and left PCA aneurysm.