Scalp nerve blocks for post craniotomy pain
Myron Yaster MD, Rita Agarwal MD, and Elliot J. Krane MD
We have been interested in post craniotomy pain and its treatment for a long time.1-4 In the past, many believed that because the brain does not have pain fibers, there was minimal pain associated with craniotomies. Furthermore, since the drugs used to treat pain, primarily the opioids, can produce sedation, nausea and vomiting and may alter the neurologic examination, pain treatment following neurosurgery was thought to be simply too dangerous and really unnecessary. Many studies demonstrated that this was simply untrue. Pain following craniotomy is common, usually severe, particularly following infratentorial craniotomy (the most common craniotomy in young children), and can be safely and effectively treated with opioids and acetaminophen.1-4
But what about scalp blocks?5-8 The use of scalp blocks for pain management has been described for several years, including as part of regimen used for awake craniotomy in children and adults.9 Neural blockade of the scalp is applicable for all intracranial procedures. Scalp blockade minimizes the hemodynamic response to surgical stimulus, it may decrease intraoperative anesthetic requirements, and it may reduce postoperative pain and analgesic consumption.10
In today’s PAAD, Xiong et al.11 investigated the analgesic effects of SNB in pediatric craniotomy patients by comparing preoperative versus postoperative administration on pain scores and cumulative opioid (sufentanil) dosing postoperatively. Myron Yaster MD
Original article
Xiong W, Wang Y, Li L, Li L, Feng Y, Liu Y, Liu B, Jin X. Effect of scalp nerve block on postcraniotomy analgesia in children: a randomized, controlled trial. BMC Anesthesiol. 2024 Nov 28;24(1):441. doi: 10.1186/s12871-024-02822-0. PMID: 39609724; PMCID: PMC11603626.
Xiong et al.11 in a prospective, randomized, blinded study “investigated the analgesic effects of preoperative scalp nerve blocks (SNB), postoperative SNB, and saline control injections in pediatric craniotomy patients. This investigation aimed to clarify the differences between SNB administered before or after surgery, shedding light on optimizing analgesic strategies in this vulnerable patient population.”
Scalp blocks consisted of 0.3% ropivacaine. “Specific blocking techniques included blocking the supraorbital nerve at the supraorbital notch (0.05 mL/kg) and adjusting the needle direction to the midline for supratrochlear nerve blocking (0.05 mL/kg); blocking the auriculotemporal nerve 1–1.5 cm anterior to the superior border of the pinna (0.05 mL/kg) and adjusting the needle direction to the lateral orbital rim for zygomaticotemporal nerve blocking (0.05 mL/kg); and blocking the greater and lesser occipital nerves at the medial 1/3 and lateral 2/3 along the superior nuchal line between the inion and mastoid process (0.1 mL/kg). The total blocking volume was recorded by the anesthesiologist who performed the SNB. Group N received an equivalent volume of saline for the block. (figure below)
Postoperatively, all patients were placed on PCA pumps containing sufentanil plus ondansetron (now there’s a good idea). For infants and pre-school children, the PCA pumps were activated by nurses (NCA) using a standard algorithm based on infant and child pain scales (FLACC) >3. A numeric Likert scale was used for the older subjects, who self-actuated the sufentanil/ondansetron pump (PCA). Basal infusions were not used for any of the subjects.
What did they find? “Total sufentanil use (µg·kg− 1) in the postoperative block group was both statistically and clinically relevantly lower than in the saline control group at every time point - 1 h, 2 h, 4 h, 24 h and 48 h (P < 0.001, 95% CI [-0.024 to -0.006], P < 0.001, 95% CI [-0.054 to -0.020], P < 0.001, 95% CI [-0.089 to -0.032],P < 0.001, 95% CI [-0.192 to -0.047]) and P = 0.010, 95% CI [-0.208 to -0.022] respectively.) Additionally, sufentanil use in the preoperative block group was statistically but not clinically significantly lower than that in the nonblocking control group at 1 h, 2h and 4h.
The authors also reported the results of pain scores, which were generally consistent with the findings above, but are less compelling in numbers and clinical relevance. First, the differences in scores, while statistically significant, do not rise to the magnitude of differences defined as clinically important according to standards used today in the pain literature; furthermore, postop pain scores are not that important within the context of pain management with NCA or PCA, in which expectations are that patients (or nurses) will titrate the PCA analgesic to similar levels of pain (e.g., the mean pain scores all were <3, but had very large SDs). Using NCA/PCA use as a surrogate measure of pain is the more accurate way to distinguish between treatment groups when comparing postoperative analgesia groups.
In short, the take home message is that postoperative scalp blocks provide superior analgesia, therefore you or the neurosurgeon should perform scalp blocks after the craniotomy is completed and the skin is closed.
But this publication does raise unanswered questions: Did the authors block all those nerves for every case, regardless of the location of the incision? Or were blocks targeted to the surgical location? Did they block both sides of the head for one sided surgery? Oddly, these details are missing from the Methods. And most importantly, are there differences in block effects for posterior fossa craniotomies versus frontal craniotomies? Posterior fossa surgery, which is far more common in children, is significantly more painful given the trauma to the upper neck muscles and fascial layers, and blood in the posterior fossa CSF, and these sources of pain are not going to respond to occipital nerve blocks at the nuchal ridge. Having studies nearly 300 subjects, it seems to us that these investigators could/should have analyzed these two groups separately.
What do you think? Do you or do your surgeons perform these blocks routinely in your practice? Tell us of your experience and roadblocks that you have had to overcome. If you (versus the neurosurgeon) performs the block do you routinely use ultrasound for localization of the nerves? If you do them, what do you usually use? Would additives prolong the duration of the blocks?
For those interested in learning more, there are 2 excellent reviews by Suresh and Voronov on head and neck blocks with indications, dosing, photos and diagrams.12,13
Send your comments to Myron who will post in a Friday readers response.
References
1. Gottschalk A, Berkow LC, Stevens RD, et al. Prospective evaluation of pain and analgesic use following major elective intracranial surgery. JNeurosurg 2007;106(2):210-216.
2. Morad AH, Winters BD, Yaster M, et al. Efficacy of intravenous patient-controlled analgesia after supratentorial intracranial surgery: a prospective randomized controlled trial. JNeurosurg 2009.
3. Morad A, Winters B, Stevens R, et al. The efficacy of intravenous patient-controlled analgesia after intracranial surgery of the posterior fossa: a prospective, randomized controlled trial. AnesthAnalg 2012;114(2):416-423.
4. Maxwell LG, Buckley GM, Kudchadkar SR, et al. Pain management following major intracranial surgery in pediatric patients: a prospective cohort study in three academic children's hospitals. Paediatric anaesthesia 2014;24(11):1132-40. (In eng). DOI: 10.1111/pan.12489.
5. Gottschalk A, Yaster M. The perioperative management of pain from intracranial surgery. NeurocritCare 2009;10(3):387-402.
6. Papangelou A, Radzik BR, Smith T, Gottschalk A. A review of scalp blockade for cranial surgery. Journal of clinical anesthesia 2013;25(2):150-9. (In eng). DOI: 10.1016/j.jclinane.2012.06.024.
7. Gottschalk A, Berkow LC, Stevens RD, et al. Prospective evaluation of pain and analgesic use following major elective intracranial surgery. Journal of neurosurgery 2007;106(2):210-6. (In eng). DOI: 10.3171/jns.2007.106.2.210.
8. Pinosky ML, Fishman RL, Reeves ST, et al. The effect of bupivacaine skull block on the hemodynamic response to craniotomy. Anesthesia and analgesia 1996;83(6):1256-61. (In eng). DOI: 10.1097/00000539-199612000-00022.
9. McDougall RJ, Rosenfeld JV, Wrennall JA, Harvey AS. Awake craniotomy in an adolescent. Anaesthesia and intensive care 2001;29(4):423-5. (In eng). DOI: 10.1177/0310057x0102900416.
10. Nguyen A, Girard F, Boudreault D, et al. Scalp nerve blocks decrease the severity of pain after craniotomy. Anesthesia and analgesia 2001;93(5):1272-6. (In eng). DOI: 10.1097/00000539-200111000-00048.
11. Xiong W, Wang Y, Li L, et al. Effect of scalp nerve block on postcraniotomy analgesia in children: a randomized, controlled trial. BMC anesthesiology 2024;24(1):441. (In eng). DOI: 10.1186/s12871-024-02822-0.
12. Suresh S, Voronov P. Head and neck blocks in children: an anatomical and procedural review. Paediatric anaesthesia 2006;16(9):910-8. (In eng). DOI: 10.1111/j.1460-9592.2006.02018.x.
13. Suresh S, Voronov P. Head and neck blocks in infants, children, and adolescents. Paediatric anaesthesia 2012;22(1):81-7. (In eng). DOI: 10.1111/j.1460-9592.2011.03701.x.