Scalp Nerve Block for Enhanced Pain Control and Analgesic Optimization in Elective Craniotomy: A Randomized Controlled Trial with Analgesia Nociception Index Monitoring

BACKGROUND: In patients who are candidates for craniotomy, scalp nerve blocks have been shown to be effective in relieving pain intensity as well as postoperative hemodynamic stability after surgery, but the results have been inconsistent. We aimed to assess the effect of scalp block on pain control, intraoperative drug use under Analgesia Nociception Index (ANI) monitoring, and postoperative pain in patients who were candidates for elective craniotomy. METHODS: In this randomized, single-blinded clinical trial study, candidates for craniotomy were randomly (using the block randomization method) divided into 2 groups before entering the operating room. The first group received a scalp block with bupivacaine (intervention), and the second group did not receive a scalp block (control) besides the routine anesthetic procedure in these patients. ANI, hemodynamic parameters, and the amounts of received remifentanil were conducted and compared. RESULTS: Patients under scalp block received less dosage of fentanyl than the nonscalp block group (mean = 57.14 +/- 15.59 mcg vs. 250.00 +/- 65.04 mcg, respectively). Similarly, the dose of remifentanil required in the scalp block group was less (mean = 3.04 +/- 1.95 mg and 5.54 +/- 2.57 mg, respectively). No difference was observed in hemodynamic parameters such as blood pressure and heart rate (before, during, and after surgery). However, the group receiving scalp block had higher ANI means than the control group. CONCLUSIONS: Scalp nerve block has an effective role in pain control (increasing ANI), consequently reducing the need for analgesic drugs such as fentanyl and remifentanil following craniotomy without changing the hemodynamic condition.