Aneurysmal subarachnoid hemorrhage (aSAH) is characterized by the rupture of an intracranial aneurysm and accumulation of blood in the subarachnoid space with 30 to 40% mortality rate. Amongst the survivors 40-50% suffers disability due to cognitive decline.Trends towards early surgery offers challenge to anesthesiologist to provide optimum brain relaxation and simultaneously maintaining stable hemodynamics. Anesthetic agents are administered to conduct smooth neurosurgical procedure. These agents may affect patient's cognitive function postoperatively.Currently most common anesthetic agents used are either intravenous hypnotic agents (propofol) or volatile inhalational agents (isoflurane/sevoflurane/desflurane). Provision of neuroprotection with propofol and volatile inhalational agents has been studied by various authors.Not many studies have been performed in patients undergoing aneurysmal clipping surgeries looking into effects of various anesthetic agents on intraoperative (I/O) brain condition, I/O hemodynamic and POCD.Thus present study is planned to compare propofol and desflurane for long term postoperative cognitive decline in patients undergoing surgery following aneurysmal subarachnoid hemorrhage.

100 patients will be randomized into two groups, Desflurane group (Group D) and Propofol group (Group P) using a computer generated algorithm. Written informed consent will be taken from all the patients.

Cognition assessed using MOCA (Montreal Cognitive Assessment)test. A preoperative assessment for establishing the patient's baseline performance. Surgery-related factors may affect test performance if performed too early to reduce possibility of confounding factors, we planned to conduct the test for POCD at the time of discharge of the patient after surgery. To compare long term protection provided by anesthetic agent cognitive functions were assessed at one month following surgery.

Cognitive functions will be assessed at following time period A) Preoperatively B) Postoperatively B1- At the time of discharge B2- 1month after discharge following surgery.

Biomarker levels S100B levels were also measured A) Preoperatively B) Intraoperatively - post clipping C) Postoperatively - 1hour after surgery

Inclusion Criteria:

1. Patients scheduled for aneurysmal SAH surgery with clinical and radiological evidence of cerebral aneurysm.
2. Age between 18 to 65 yrs.
3. World Federation of neurosurgery grade 1, 2.
4. American society of Anesthesia grade 1, 2 and 3.

Exclusion Criteria:

1. Co-morbidities other than hypertension and diabetes mellitus like cardiovascular disease and respiratory impairment.
2. Patients with known psychiatric disease.
3. History of drug abuse.
4. Low level of education (illiterate) or multiple failures in school.
5. Patients who are unconscious, intubated or tracheostomised even after two weeks following exposure to anesthesia will also be excluded from the study.
6. Intraoperative complications like massive blood loss, prolonged clipping time(>20minutes), severe intraoperative brain swelling precluding replacement of bone flap.
7. Patients with infectious diseases and respiratory complications.
8. Multiple surgeries.