Clinical trial NCT03727464: Memory Priming in General Anesthesia
Official title: Memory Priming for Abstract and Concrete Words in General BIS Guided Propofol vs. Sevoflurane Anesthesia
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Unconscious (Psychology)
Keywords: Memory priming
Anesthesia
Language processing
Abstract and Concrete words
Neural correlates
Lead sponsor: Fondazione I.R.C.C.S. Istituto Neurologico Carlo Besta
Sponsor class: OTHER
Collaborators: name: University of Milano Bicocca
First posted: 2018-11-01
Enrollment: 102
Sex: ALL
Minimum age (years): 18
Maximum age (years): 65
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Allocation: RANDOMIZED
Intervention model: PARALLEL
Primary purpose: BASIC_SCIENCE

Brief summary: Memory priming under general anesthesia is a phenomenon of incredible interest in the study of consciousness and unconscious cognitive processing, and for clinical practice.

However results from anesthesiological literature are divergent and methodologies vary.

To overcome these limits, the present study aims at better defining the phenomenon of memory priming under general anesthesia, manipulating as experimental variables both the anesthetic drug used and the stimuli primed.

Detailed description: Some patients may develop serious psychological sequelae after surgical intervention under general anesthesia due to implicit memory formation of intraoperative events.

A number of studies in the field of anesthesiology have tried to better define the phenomenon of implicit memory in general anesthesia, with conflicting results. While some studies demonstrated the existence of unconscious memory formation also under adequate general anesthesia (BIS ranging 40-60), others state that implicit memory formation is possible only during light sedation, and that, therefore, traumatic disorders due to unconscious intraoperative memories are imputable to inadequate anesthesiological intraoperative management. The methodologies used by these studies, however, are very heterogeneous, and often inaccurate from a cognitive point of view. Data from cognitive neuroscience, in fact, demonstrate that different linguistic material, e.g. abstract and concrete words, are processed and retrieved via different networks in the brain. Then, since different anesthetics are known to target different areas of the brain, it is assumable that implicit memory formation is influenced both by the specific drug used and by the type of stimuli primed.

Therefore in this experiment, the investigators aim at testing implicit memory for different word category, abstract vs. concrete words, in patients undergoing either propofol or sevoflurane general anesthesia. Also, a very strict methodology was used both for the construction of the stimuli and the stimulation and testing procedure, in order to maximize the priming effect and exclude the risk of false positive results. The investigators hypothesize that, considering the existing data on propofol and sevoflurane effects on the brain, and the known neural correlates for abstract and concrete word processing, the priming effect would be different for abstract and concrete words between patients under propofol or sevoflurane anesthesia.

Eligibility criteria: Inclusion Criteria:

* patient undergoing general anesthesia for back surgery
* American Society of Anesthesiology (ASA) physical status classification I or II
* Italian native speaker
* right handed (assessed with the Edinburgh Handedness Inventory)
* not to suffer from memory deficits, hearing impairment or any other medical/psychiatric condition that could affect the memory performance or hearing

Exclusion Criteria:

* to develop a postoperative cognitive dysfunction or delirium or any other medical complication that could prevent the memory testing or that could affect memory performance

Primary outcomes:
measure: Implicit score
timeFrame: 24 hours
Secondary outcomes:
measure: Explicit recall of intraoperative words
timeFrame: before discharge from the Recovery Room and at 24 hours
measure: Explicit recall of intraoperative events
timeFrame: before discharge from the Recovery Room and at 24 hours
measure: Target hits
timeFrame: 24 hours
measure: Nontarget hits
timeFrame: 24 hours
Other outcomes:
Locations:
city: Milan
country: Italy
facility: Fondazione IRCCS Istituto Neurologico Carlo Besta
Study officials:
affiliation: Fondazione IRCCS Istituto Neurologico Carlo Besta
name: Eleonora F Orena, PhD
role: PRINCIPAL_INVESTIGATOR
References:
citation: Orena EF, Landucci F, Ayadi R, Caldiroli D, Papagno C. Propofol and sevoflurane affect intra-operative memory formation of words differently: A prospective cohort study. Eur J Anaesthesiol. 2021 Mar 1;38(Suppl 1):S50-S57. doi: 10.1097/EJA.0000000000001417.