Delirium (confusion) after surgery is common and associated with a longer hospitl stay and increased hopsital cost. There is very little information available about how often delirium occurs and the complications associated with it. Elderly patients are at high risk for delirium after surgery. This research is being done to measure how often delirium after spine surgery occurs and to see if there are ways to predict if delirium will develop. The results from this study will provide important information on a possible mechanism and predictor of delirium.

Delirium (confusion) after surgery is common and associated with a longer hospitl stay and increased hopsital cost. This research is being done to measure how often delirium after spine surgery occurs and to see if there are ways to predict if delirium will develop. We hypothesize that impaired cerebral autoregulation may be a possible mechanism for postoperative delirium. We will measure intraoperative cerebral autoregulation and assess the relationship with postoperative dleirium. The results from this study will provide important information on a possible mechanism and predictor of delirium.

Inclusion Criteria:

1. ≥ 70 years old,
2. Undergoing any lumbar spine surgery, posterior cervical spine surgery, or anterior cervical spine surgery > 2 levels

Exclusion Criteria:

1. MMSE < 15
2. Delirium at baseline
3. Inability to speak and understand English
4. Severe hearing impairment, resulting in inability to converse.
5. Planned use of intraoperative ketamine
6. Planned use of intraoperative remifentanil, except for airway management pre-incision.
7. Arterial catheter not planned to be inserted

The study population is male and female subjects age 70 years and older that are having spine surgery.