Post-hospitalization behavioral changes are common in children after surgery and general anesthesia and may persist for varying durations depending on individual and perioperative factors. The Post-Hospitalization Behavior Questionnaire (PHBQ) is a well-validated instrument widely used to evaluate negative postoperative behavioral changes in pediatric patients following hospitalization or surgical procedures. Although early postoperative behavioral disturbances have been extensively studied, most research has focused on short-term outcomes within the first weeks after surgery, while long-term behavioral outcomes remain insufficiently investigated.

Processed electroencephalography (pEEG) monitoring provides an objective method for assessing anesthetic depth during surgery. Parameters such as the Patient State Index (PSI) and Spectral Edge Frequency 95 (SEF95) allow dynamic evaluation of cortical activity and may help optimize anesthetic administration by preventing excessively deep or inadequate anesthesia. Improved anesthetic depth management may theoretically influence postoperative recovery and behavioral outcomes.

In the initial randomized study, early postoperative behavioral assessments were obtained within the first postoperative month using the Post-Hospitalization Behavior Questionnaire (PHBQ). In the present follow-up study, children will be contacted again 12-24 months after surgery to evaluate long-term behavioral outcomes. PHBQ scores at long-term follow-up will be compared between children who previously received EEG-guided anesthesia and those managed with standard anesthesia without processed EEG monitoring. By examining both early and long-term behavioral outcomes, this study aims to determine whether intraoperative EEG-guided anesthesia management influences postoperative behavioral changes in the pediatric population.

Postoperative behavioral disturbances are frequently observed in children following hospitalization, anesthesia, and surgical procedures. These behavioral changes may include anxiety, sleep disturbances, separation difficulties, regression, aggression, or withdrawal. In pediatric patients, such behavioral disturbances may negatively affect family dynamics, social functioning, and psychological well-being. Therefore, evaluating postoperative behavioral outcomes represents an important component of pediatric perioperative care.

The Post-Hospitalization Behavior Questionnaire (PHBQ) was first developed in 1966 by Vernon, Schulman, and Foley to assess behavioral changes in children following hospitalization. Since its introduction, PHBQ has become one of the most widely used and validated instruments for evaluating postoperative behavioral disturbances in pediatric populations. The questionnaire consists of 27 items designed to compare the child's current behavior with their behavior prior to hospitalization. These items assess behavioral changes across six domains: general anxiety and regression, separation anxiety, eating disturbances, aggression toward authority, apathy or withdrawal, and sleep-related anxiety. Each item is scored on a five-point Likert scale, resulting in a total score ranging from 27 to 135, where higher scores indicate greater behavioral change.

The definition of negative postoperative behavioral changes (PONB) varies across studies. Kain and colleagues defined PONB as the presence of a negative behavioral response in at least one PHBQ item. In contrast, other investigators have adopted more stringent definitions. Faulk and colleagues suggested that deterioration in at least seven PHBQ items should be considered clinically significant behavioral change. Similarly, Stargatt et al., in a large cohort study involving more than one thousand children, also defined clinically relevant postoperative behavioral disturbances as worsening in seven or more questionnaire items. These variations highlight the complexity of evaluating behavioral outcomes in pediatric populations and suggest that postoperative behavioral disturbances may be more prevalent than previously recognized.

Most studies evaluating postoperative behavioral changes using the PHBQ have focused primarily on early postoperative periods, typically within the first weeks or the first month after surgery. However, several studies have shown that certain behavioral changes-particularly sleep disturbances, separation anxiety, and withdrawal behaviors-may persist for several months following surgery. Despite these findings, studies examining behavioral outcomes beyond the first postoperative year remain extremely limited. Consequently, the long-term psychological impact of pediatric anesthesia and surgery remains incompletely understood.

Appropriate management of anesthetic depth during pediatric anesthesia is an important factor in optimizing perioperative outcomes. Excessively deep anesthesia may increase exposure to anesthetic agents, while inadequate anesthesia may lead to physiological stress responses or intraoperative awareness. Processed electroencephalography (pEEG) monitoring provides a real-time and objective assessment of brain activity and anesthetic depth during general anesthesia.

Among pEEG-derived parameters, the Patient State Index (PSI) is commonly used to estimate the depth of anesthesia. PSI values range from 0 to 100, with values between 25 and 50 generally considered indicative of an appropriate level of anesthesia for surgical procedures. Another parameter, Spectral Edge Frequency 95 (SEF95), represents the frequency below which 95% of the electroencephalographic power spectrum is contained and provides additional information regarding cortical activity and anesthetic effects on brain function. Previous studies have demonstrated that pEEG monitoring may contribute to improved anesthetic titration and more stable intraoperative anesthesia management.

In the initial randomized clinical study, children undergoing surgery lasting longer than one hour under general anesthesia were randomized to receive either EEG-guided anesthesia management or standard anesthesia management without processed EEG monitoring. Early postoperative behavioral assessments were obtained within the first postoperative month using the PHBQ.

The present study represents a long-term follow-up of this randomized cohort. Children from the original study population will be contacted 12-24 months after surgery, and long-term behavioral outcomes will be reassessed using the PHBQ. This design allows evaluation of both early postoperative behavioral changes and long-term behavioral outcomes. PHBQ scores obtained at long-term follow-up will be compared between children who previously received EEG-guided anesthesia and those who received standard anesthesia management.

By investigating the relationship between intraoperative anesthetic depth monitoring and both early and long-term behavioral changes, this study aims to provide new insights into the potential influence of EEG-guided anesthesia on postoperative neurobehavioral outcomes in pediatric patients.

Inclusion Criteria:

• Children aged 3-10 years
• Surgical duration longer than 1 hour
• Patients undergoing urology, plastic surgery, or pediatric surgery procedures
• Availability of early postoperative PHBQ data
• Verbal consent from parents or legal guardians for participation in the follow-up telephone interview

Exclusion Criteria:

• Patients with neuromotor developmental abnormalities
• History of epilepsy or antiepileptic medication use
• Patients requiring postoperative intensive care unit admission
• Emergency surgical procedures
• Inability to contact the family or refusal of verbal consent for the telephone interview
• Patients who underwent another surgical procedure between the initial surgery and the follow-up period

Although EEG electrodes were applied in all participants, processed EEG values were not visible to the anesthesia team in the standard anesthesia group, and anesthetic management was performed according to conventional clinical parameters.