Observational prospective pilot study to analyze the trajectory of neuroinflammatory protein expression in cerebrospinal fluid (CSF) in relation to systemic compartment in patients undergoing thoracic aortic surgery.

The aim of this study is to identify and unravel the biochemical (neuroinflammatory) pathways involved in postoperative delirium.

Patient undergoing thoracic aortic surgery will have an external lumbar drain (ELD) in situ on the day before surgery. This ELD remains in place during and three days after surgery to reduce the risk on periprocedural spinal cord ischemia. Paired measurements of CSF and blood will be analyzed.

Major (cardiovascular) surgery is frequently associated with cerebral dysfunction postoperatively. Major surgical procedures account for substantial systemic inflammatory activation. Interestingly, animal models have shown that surgery rather than anaesthetics trigger a neurocognitive decline. An increase of pro-inflammatory cytokines and activation of immune cells mediate this post operative cognitive decline. There is growing support that systemic inflammation can activate the innate immune system of the brain leading to inflammation in the brain ('neuroinflammation'). This neuroinflammation is suggested to play a pivotal role in postoperative delirium and postoperative cognitive decline due to surgery-related systemic inflammation. However little evidence is available on the extend of the neuroinflammation and which biochemical pathways are dysregulated in the brain after surgery.

Thoracic aortic surgery offers the unique opportunity to study the trajectory of protein expression in CSF prior to and after surgery in a non-invasive matter. It is standard of care that an external lumbar drain (ELD) is placed the day prior to surgery and this ELD will remain in place during three postoperative days.

To advance the understanding of the impact of major surgery to the brain, the investigators wish to study the trajectory of protein expression prior to and after thoracic aortic surgery.

Inclusion Criteria:

• Competent patients ≥ 18 years
• Patients who will undergo thoracic aortic surgery and will therefore receive an external lumbar drain as a standard of care procedure.

Exclusion Criteria:

• Patients with meningitis/encephalitis/brain abscess within the last 6 months
• Patients with other neurological conditions: brain injury (acute stroke, brain trauma or cerebral haemorrhage) within the last 3 months, known brain tumours, neurodegenerative disease or known pre-existing cognitive impairment (to a degree that would be compatible with mild cognitive impairment or more).
• Brain or spinal surgery within the last 3 months
• Active infection <2 weeks before surgery
• Patients who object against storage of their body material for scientific reasons

Adult patients undergoing thoracic aortic surgery who will therefore receive an external lumbar drain as a standard of care procedure.