Supratentorial craniotomy, commonly performed for the excision of brain tumors, is a major neurosurgical procedure associated with significant nociceptive stimulation, particularly during scalp incision and cranial bone manipulation. Although general anesthesia is the standard approach, it may not sufficiently attenuate the hemodynamic response to noxious stimuli such as skull pinning and skin incision (1). These stimuli activate peripheral nociceptors, leading to sympathetic stimulation that can result in tachycardia, hypertension, and increased intracranial pressure—factors that may adversely affect surgical outcomes (2,3).

Scalp block, a regional anesthetic technique targeting six sensory nerves of the scalp, has been shown to provide effective analgesia for craniotomies (4). When administered preemptively—prior to the surgical incision—scalp block may not only reduce intraoperative autonomic responses but also prevent central sensitization and improve postoperative pain outcomes (5). Preemptive analgesia, a concept introduced to block the pain pathway before the initiation of the nociceptive stimulus, is increasingly recognized for its role in multimodal pain management (6).

Several studies have explored the utility of scalp blocks using local anesthetics such as bupivacaine and ropivacaine, with varying results in terms of hemodynamic stability and opioid-sparing effects (7,8). Despite its clinical relevance, there remains a need to further establish the analgesic efficacy and safety profile of preemptive scalp blocks in elective brain tumor surgeries.

This study aims to evaluate the clinical benefits of preemptive scalp block using bupivacaine in adult patients undergoing supratentorial brain tumor excision, focusing on intraoperative hemodynamic responses and postoperative analgesic outcomes.

The study included 60 adult patients aged between 18 and 60 years, classified as American Society of Anesthesiologists (ASA) physical status I or II, scheduled for elective supratentorial brain tumor excision under general anesthesia.

Inclusion and Exclusion Criteria

Patients with known allergies to local anesthetics, bleeding disorders, infection at the injection site, history of opioid dependence, or neurological deficits interfering with pain assessment were excluded. All enrolled patients underwent a thorough preoperative evaluation.

Randomization and Group Allocation

Participants were randomly assigned into two groups (n = 30 each) using a computer-generated random number table.

• Group A (Scalp Block Group): Received a preemptive bilateral scalp block with 0.25% bupivacaine (20 mL total), administered at six anatomical nerve sites (supraorbital, supratrochlear, auriculotemporal, zygomaticotemporal, greater occipital, and lesser occipital nerves) 10 minutes before skin incision.
• Group B (Control Group): Received the same volume of normal saline using the same technique.

Both the anesthesiologist performing the block and the observer recording data were blinded to the group allocation.

Anesthesia Protocol

All patients were premedicated with midazolam 0.03 mg/kg and fentanyl 2 µg/kg intravenously. General anesthesia was induced with propofol 2 mg/kg and rocuronium 0.9 mg/kg to facilitate endotracheal intubation. Anesthesia was maintained with sevoflurane (1–1.5 MAC) in a 50:50 oxygen-air mixture, with additional boluses of fentanyl as needed. Standard intraoperative monitoring included ECG, non-invasive blood pressure, pulse oximetry, capnography, and bispectral index (BIS).

Data Collection

Hemodynamic parameters (heart rate and mean arterial pressure) were recorded at baseline, before skin incision, and at 1, 5, 10-, 15-, 30-, and 60-minutes post-incision. Postoperative pain was assessed using the Visual Analog Scale (VAS) at 2, 4, 6, 12, and 24 hours after surgery. Rescue analgesia with intravenous tramadol 50 mg was administered if VAS exceeded 4, and the total consumption within the first 24 hours was recorded.

Statistical Analysis

Data were analyzed using SPSS version 25.0. Continuous variables were expressed as mean ± standard deviation, and categorical variables as frequencies and percentages. Intergroup comparisons were made using the unpaired t-test or chi-square test as appropriate. A p-value < 0.05 was considered statistically significant.

A total of 60 patients were enrolled and successfully completed the study, with 30 patients in each group. Both groups were comparable in terms of demographic characteristics such as age, sex, body weight, and duration of surgery (Table 1).

Hemodynamic Parameters

The mean heart rate (HR) and mean arterial pressure (MAP) at baseline were similar between the groups. However, Group A (Scalp Block) showed significantly lower HR and MAP following skin incision compared to Group B (Control). Notably, at 5 minutes post-incision, HR in Group A was 78.2 ± 6.3 bpm versus 90.5 ± 7.1 bpm in Group B (p < 0.001), and MAP was 82.6 ± 4.9 mmHg in Group A compared to 94.1 ± 5.7 mmHg in Group B (p < 0.001) (Table 2). This trend continued for up to 60 minutes post-incision.

Postoperative Pain Scores

VAS scores were significantly lower in Group A at all postoperative time intervals. At 4 hours postoperatively, the VAS was 3.1 ± 1.0 in Group A versus 5.4 ± 1.2 in Group B (p < 0.001). Similar differences were noted at 6, 12, and 24 hours (Table 3).

Analgesic Requirement

The total 24-hour postoperative tramadol requirement was significantly lower in the scalp block group (mean 75.0 ± 20.6 mg) compared to the control group (mean 145.2 ± 30.3 mg; p < 0.001) (Table 4).

Table 1: Demographic Characteristics of Study Participants

Table 2: Hemodynamic Changes at Skin Incision and Post-Incision Time Points

Table 3: Postoperative Visual Analog Scale (VAS) Scores

Table 4: Total Postoperative Tramadol Consumption in 24 Hours

These findings suggest that the preemptive scalp block significantly reduces intraoperative hemodynamic responses (Table 2), lowers postoperative pain intensity (Table 3), and decreases analgesic requirement (Table 4) in patients undergoing supratentorial brain tumor excision.

This study demonstrates that preemptive scalp block with bupivacaine significantly attenuates the hemodynamic response to noxious surgical stimuli and improves postoperative analgesia in patients undergoing supratentorial brain tumor excision. The findings align with previous research supporting the role of regional anesthesia techniques in reducing perioperative stress responses and enhancing patient comfort after craniotomy procedures (1,2).

The scalp is innervated by multiple sensory nerves, including branches of the trigeminal and cervical nerves, which can be effectively anesthetized by local infiltration at defined anatomical landmarks. Blocking these nerves before incision likely prevents the afferent transmission of nociceptive stimuli, reducing sympathetic activation and stabilizing cardiovascular parameters during surgery (3,4). In the current study, patients receiving scalp block exhibited significantly lower heart rates and mean arterial pressures following skin incision compared to the control group, supporting the effectiveness of this preemptive intervention in blunting acute nociceptive responses (Table 2).

Previous studies have demonstrated similar benefits. Pinosky et al. reported reduced hemodynamic fluctuations with the use of scalp block during skull pinning and craniotomy incision (5). Costello and colleagues also confirmed its utility as part of a balanced anesthetic regimen in neurosurgical patients (6). Moreover, the addition of regional blocks such as scalp infiltration has been shown to reduce intraoperative opioid requirements, contributing to more stable anesthetic planes and fewer postoperative complications like nausea and vomiting (7,8).

In our study, the postoperative pain scores assessed using the VAS were consistently lower in the scalp block group across all observed time points. This supports the concept of preemptive analgesia, which aims to prevent central sensitization and decrease the perception of postoperative pain (9). Several trials have emphasized that regional techniques initiated prior to tissue injury are more effective than those given afterward, particularly in surgeries associated with high pain intensity (10,11).

Additionally, total tramadol consumption over 24 hours was significantly reduced in the scalp block group. This opioid-sparing effect is clinically meaningful, as it reduces the risk of opioid-related adverse effects and promotes faster recovery and mobilization (12). Our findings are consistent with those of Bala et al. and Geze et al., who observed lower analgesic needs and better patient satisfaction with the use of scalp blocks in craniotomy patients (13,14).

The simplicity and safety profile of the scalp block technique also make it an attractive option in neurosurgical anesthesia. When performed correctly, complications such as hematoma, infection, or local anesthetic toxicity are rare. Furthermore, the time required to administer the block is minimal compared to the overall duration of surgery, making it a cost-effective and practical adjunct (15).

Limitations

of this study include a single-center design and a relatively small sample size. Moreover, the follow-up period for postoperative pain assessment was limited to 24 hours. Future research involving multicenter trials with larger cohorts and longer observation periods would help validate and generalize these findings.

In conclusion, preemptive scalp block with bupivacaine is a simple, safe, and effective method to attenuate the intraoperative stress response and improve postoperative pain outcomes in patients undergoing supratentorial brain tumor excision.

1. Bala I. Craniotomy under conscious sedation for intracranial lesions. J Neurosci Rural Pract. 2011;2(1):4–11.
2. Cormack JR, Orme RM, Costello TG. The role of regional anesthesia techniques in neurosurgery. Curr Opin Anaesthesiol. 2005;18(5):477–482.
3. Pinosky ML, Fishman RL, Reeves ST, et al. The effect of scalp block on the hemodynamic response to head pinning for craniotomy. Anesth Analg. 1996;83(6):1256–1261.
4. Geze S, Yilmaz AA, Tuzuner F. Preemptive scalp infiltration with local anesthetics in craniotomy patients. J Neurosurg Anesthesiol. 2009;21(2):186–189.
5. Costello TG, Cormack JR, Mather LE. The role of scalp block in neurosurgical procedures. Anaesthesia. 2006;61(6):561–562.
6. Nguyen A, Girard F, Boudreault D, et al. Scalp nerve blocks decrease the severity of pain after craniotomy. Anesth Analg. 2001;93(5):1272–1276.
7. Bala I, Bharti N, Madan R, et al. Effect of scalp block on postoperative pain and analgesic requirements in craniotomy patients. Indian J Anaesth. 2007;51(3):198–201.
8. Zuurmond WW, Langendijk PN, de Lange JJ. Preemptive analgesia with local anesthetics: the effect of wound infiltration on postoperative pain and opioid consumption. Anesth Analg. 1996;82(2):287–290.
9. Woolf CJ, Chong MS. Preemptive analgesia—treating postoperative pain by preventing the establishment of central sensitization. Anesth Analg. 1993;77(2):362–379.
10. Kissin I. Preemptive analgesia. Anesthesiology. 2000;93(4):1138–1143.
11. Gottschalk A, Berkow LC, Stevens RD, et al. Prospective evaluation of pain and analgesic use following major elective intracranial surgery. J Neurosurg. 2007;106(2):210–216.
12. D'Arcy Y. Opioid-sparing pain management strategies in surgical settings. Nurs Crit Care. 2015;10(3):12–18.
13. Bala I, Gupta B, Bhardwaj N. Scalp block for postoperative analgesia in craniotomy patients. J Anaesth Clin Pharmacol. 2010;26(4):515–518.
14. Geze S, Ciftci B, Tuzuner F. Evaluation of the efficacy of scalp block and local infiltration on postoperative analgesia in patients undergoing craniotomy. Neurosciences. 2012;17(3):220–224.
15. Venkatraghavan L, Luciano M, Manninen P, et al. Scalp block for craniotomy. J Neurosurg Anesthesiol. 2010;22(4):278–283.