Cleft lip and palate (CLP) is one of the most common congenital malformations and requires repeated surgical correction during childhood. Surgical repair is often associated with significant postoperative pain, traditionally managed with morphine, which carries a risk of undesirable side effects. The suprazygomatic maxillary nerve block (SZMNB) has been shown to provide effective analgesia and may reduce the need for opioids.

Routine use of SZMNB was introduced at the pediatric surgery unit at Karolinska University Hospital in late 2017. A before-and-after evaluation project based on retrospective chart review was initiated in 2018 but was not completed due to the COVID-19 pandemic.

The aim of this project is to investigate whether the introduction of SZMNB has reduced postoperative morphine requirements and opioid-related side effects, and whether this has resulted in shorter hospital stays (earlier discharge) after cleft palate repair.

Scientific background and rationale Cleft lip and palate (CLP) is one of the most common congenital malformations and often requires repeated surgical corrections during childhood. These procedures are associated with considerable postoperative pain that may delay recovery and prolong hospital stay. Traditionally, systemic analgesics (opioids, NSAIDs, and acetaminophen given intravenously or orally) have been used, but these are often insufficient or associated with adverse effects.

Peripheral nerve blocks have become an established and effective method to optimize pain control and reduce side effects in many surgical procedures. The suprazygomatic maxillary nerve block (SZMNB) is a well-described technique that can provide efficient analgesia in cleft palate surgery. Previous studies have demonstrated its safety and analgesic benefits.

Objectives and hypothesis The aim of this study is to evaluate the effectiveness and patient benefits of introducing routine SZMNB as an adjunct to standard analgesic therapy in children undergoing cleft palate surgery at Astrid Lindgren Children's Hospital, Karolinska University Hospital.

Hypothesis: SZMNB provides superior postoperative pain control and shorter hospital stay compared with conventional systemic analgesia alone.

Study design and methods This is a retrospective observational study based on chart review of patients aged 3 months-15 years who underwent cleft palate surgery at Astrid Lindgren Children's Hospital during 2017-2018. No intervention will be performed.

Data will be collected from medical records, including demographics (age, sex, weight), surgical procedure, perioperative and postoperative analgesic regimen (type, dose, timing), presence of SZMNB, pain scores when available, and any recorded adverse effects (nausea, sedation, etc.).

Outcome measures Primary outcome: Length of hospital stay, defined as time from arrival in the recovery unit to the time of discharge documentation.

Secondary outcomes: Total postoperative opioid consumption, need for supplemental analgesia, and frequency of opioid-related side effects (e.g., nausea, sedation).

Statistical analysis Pseudonymized data will be analyzed descriptively and comparatively using standard statistical methods. Results will be presented in tables and figures. Manuscript preparation and analysis will be conducted at Karolinska Institutet, and the results will be submitted for publication in a peer-reviewed journal.

Clinical significance Peripheral nerve blocks such as SZMNB may reduce opioid requirements, shorten hospital stay, and improve recovery in children after cleft palate surgery. This project aims to quantify these effects within our institution. Demonstrated benefits could support wider implementation of SZMNB, improve care efficiency, and enhance the quality of postoperative recovery for affected children.

criteria for participating in the study

• children aged 3 months to 15 years.
• Underwent cleft palate (LKG) surgery between 2017-2018.
• Available and complete medical records including perioperative notes, anesthesia documentation, and discharge summaries.
• Received either standard systemic analgesia alone (2017) or standard analgesia plus suprazygomatic maxillary nerve block (SZMNB) (2018).

Exclusion Criteria: not fulfilling inclusion cirteria

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The study population consists of children aged 3 months to 15 years who underwent cleft palate (LKG) surgery at Astrid Lindgren Children's Hospital, Karolinska University Hospital, during 2017-2018.

All patients received general anesthesia with standard perioperative monitoring and multimodal analgesia. In 2018, a suprazygomatic maxillary nerve block (SZMNB) was introduced as a routine adjunct to systemic analgesia. The study includes two cohorts: one before (2017) and one after (2018) the implementation of SZMNB. Data are collected retrospectively from medical records without any additional interventions.

This study involves retrospective analysis of patient medical records. Due to Swedish and EU data protection regulations (GDPR), individual participant data cannot be shared publicly. Only aggregated, de-identified summary data will be presented in publications.