Evaluating mechanisms of postoperative delirium and cognitive dysfunction following elective spine surgery in elderly patients (CONFESS): study protocol for a prospective observational trial

Abstract

Background Elderly people are a rapidly growing proportion of the world's population that increasingly undergo major elective spine surgery. They are yet at particular high risk for postoperative delirium (POD), which is associated with longer hospital stays, higher costs, risk for delayed complications, long-term care dependency and cognitive dysfunction (POCD). It is insufficiently understood, which mechanisms and, particularly modifiable, risk factors contribute to the development of POD and POCD following these major but plannable surgeries. A better understanding thereof would help to adapt medical management and surgical strategies to individual risk profiles. Methods This is a single-center observational study that is jointly conducted by the departments of Neurosurgery, Neurology and Anesthesiology at a tertiary care hospital in Germany. All patients presenting to the neurosurgery outpatient clinic or ward for elective spine surgery are screened for eligibility. Inclusion criteria are age ≥ 60 years, indication for elective spine surgery, ability to give informed consent without assistance and speaking German natively. Exclusion criteria include presence of neurodegenerative disease, diagnosis of any psychiatric disease, medication with central nervous system activity (e.g. antidepressants, antipsychotics, sedatives), impossibility to participate in follow-up, participation in an interventional trial, presence of electronic or displaceable metallic implants and active neoplasm. All patients are evaluated for their preoperative cognitive abilities and physical, mental and social health and wellbeing. They additionally receive preoperative cerebrovascular ultrasound and structural and functional brain imaging. The immediate postoperative period includes screening for POD and the investigation of markers of (neuro‑)inflammation. Preoperative examinations are repeated three months postoperatively to investigate the presence of POCD and its mechanisms. Discussion This is the first study to prospectively evaluate risk factors for POD and POCD in spine surgery including comprehensive pre- and postoperative assessments of cognitive abilities, markers of (neuro‑)inflammation, cerebral vasculature and structural and functional neuroimaging. The identification of, possibly common, mechanisms underlying POD and POCD would be a major step towards the definition of effective interventional strategies early in or even before the postoperative period, including the adaptation of surgical strategies to individual risk profiles.