Efficacy of Liposomal Bupivacaine Scalp Nerve Block for Postoperative Pain Management After Supratentorial Craniotomy：a Randomized Controlled Trial

1. Background and Rationale:

Postoperative pain following supratentorial craniotomy is a significant clinical concern, often requiring opioid-based analgesia. However, opioid use in neurosurgical patients is limited by side effects such as sedation, respiratory depression, and nausea, which can obscure neurological assessment and delay recovery. Scalp nerve blocks (SNBs) with local anesthetics like bupivacaine are a well-established component of multimodal analgesia for craniotomy, targeting the primary sources of postoperative pain-the pericranial muscles and scalp tissues. While effective, conventional bupivacaine provides analgesia for only up to 6-8 hours, leaving patients with inadequate pain control during the critical 72-hour postoperative period.

Liposomal bupivacaine (LB) is an extended-release formulation designed to provide sustained analgesia for up to 72 hours. Its efficacy has been demonstrated in various surgical settings, but its application in neurosurgery, particularly for scalp nerve blocks, remains underexplored. This study aims to investigate whether a single preoperative scalp nerve block with liposomal bupivacaine can provide superior and prolonged analgesia compared to standard bupivacaine, thereby reducing opioid consumption and improving patient outcomes following craniotomy. 2. Objectives:

Primary Objective: To compare the efficacy of liposomal bupivacaine versus standard bupivacaine for scalp nerve blocks in controlling postoperative pain, as measured by the Numerical Rating Scale (NRS) at 2, 12, 24, 48, and 72 hours after surgery.

Secondary Objectives: