I’ve had a long history of studying pain following craniotomy surgery.1-5 Indeed, while at Hopkins, the chair of the Department of Neurosurgery gave me a faculty appointment in his department in order to claim departmental credit for my study group’s publications!
Pain following craniotomy is much more common than neruosurgeons want to believe and is still often undertreated because of the long held belief that the brain has no pain fibers and can therefore not feel pain. Further, many neurosurgeons are afraid of using opioids in the treatment of post-craniotomy pain because they believe that opioids will interfere with the neuro exam and mask a postoperative catastrophe.
In today’s PAAD, Nassar et al.6 sought to determine if ultrasound guided blockade of the greater occipital nerve (GON) would improve pain control in children who underwent posterior fossa craniotomy. Blockade of this nerve is well known for this purpose but is usually performed blindly by either the anesthesiologist or neurosurgeon. The use of ultrasound to better identify the nerve is the new wrinkle in this study. I’ve asked Dr. Santhanam Suresh (“Suresh”), one of the world’s premier leaders in pediatric ultrasound and pain management, to assist. Myron Yaster MD
Original article
Nassar H, Sarhan K, Gamil M, Elgohary M, El-Hadi H, Mahmoud S. Ultrasound-guided Greater Occipital Nerve Block in Children Undergoing Posterior Fossa Craniotomy: A Randomized, Controlled Trial. J Neurosurg Anesthesiol. 2023 Jan 9. doi: 10.1097/ANA.0000000000000899. Epub ahead of print. PMID: 36728475.
“Brain tumors are the second most common childhood malignancy, with infratentorial tumors being the most prevalent type in children.”6 Posterior fossa surgery is more severely painful than supratentorial craniotomy and often requires opioids and scalp blocks in its treatment.”2,4,6,7 Nassar et al. “hypothesized that ultrasound-guided greater occipital nerve (GON) block is superior to conventional analgesic methods for the management of perioperative pain after posterior fossa surgery in children. This randomized controlled study aimed to assess the analgesic and hemodynamic profile of ultrasound-guided GON block in children undergoing posterior fossa craniotomy.”6
All patients received 2 micrograms/kg fentanyl at induction to facilitate tracheal intubation and 0.5 micrograms/kg to treat Increases in heart rate and/or systolic blood pressure more than 20% above baseline. Additionally, all patients received 15 mg/kg IV paracetamol (acetaminophen) 30 minutes before the end of surgery and IV dexamethasone 0.15 mg/kg 10 minutes before the end of surgery for postoperative nausea and vomiting prophylaxis. The greater occipital nerve blocks were placed by the anesthesia team aseptically after the induction of anesthesia and before the start of the surgical procedure.
“An ultrasound machine (M-Turbo TM) with a high-frequency linear probe (6 to 13 MHz) was used. The ultrasound probe was placed in the transverse plane at the level of the superior nuchal line, with the center of the probe 2 to 3 cm lateral to the external occipital protuberance. The GON was identified just medial to the pulsation of the occipital artery, and a 50 mm, 22 G block needle tip was advanced using an in-plane approach from lateral to medial until the tip was adjacent to the GON. After negative aspiration, 2 mL of 0.25% bupivacaine was injected. The procedure was repeated on the other side. Before the skin incision, the neurosurgeon infiltrated the scalp with lidocaine 1% and epinephrine 1:200,000 in control group patients, and with saline and epinephrine 1:200,000 in patients in the GON block group.”6
“In the ICU, pain was assessed using the objective pain scale. When patients first complained of pain (OPS score >2/8 or >3/10), intravenous paracetamol 15 mg/kg −1 was given and repeated every 6 hours. Persistent or breakthrough pain was managed with intravenous injection of ketorolac 0.5 mg/kg −1 (maximum per dose 15 mg) every 8 hours.”6
OK, what did they find? Pain scores in the ICU were lower in the GON block group at all measured time points compared to the control group and the “time to first analgesia request was 13.4±7.4 hours in the GON block group and 1.8±1.5 hours in the control group ( P <0.001). Cumulative intraoperative fentanyl consumption was lower in the GON block group than in the control group (2.68±0.53 μg/kg −1 vs 4.1±0.53 μg/kg −1 , respectively; P =0.0001).”6 Thus,
I (SS) switched to ultrasound guidance for this block many years ago and do it slightly differently than the authors of today’s PAAD and am attaching a YouTube video to better understand and visualize how to do this block. The advantage in using US guidance is the potential to block C3 at it root and cover the entire greater occipital nerve closer to its origin rather than peripherally where several branches could be missed. Moreover, it has been well studied and demonstrated. In addition, viewing the occipital artery, the vertebral artery and any other vascular structures will avoid complications of the occipital nerve block. This is a very useful technique both in the operating room for neurosurgical procedures as well as for managing chronic occipital pain or occipital neuralgia.
Send your thoughts and comments to Myron who will post in a Friday reader 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. Gottschalk A, Yaster M. The perioperative management of pain from intracranial surgery. NeurocritCare 2009;10(3):387-402.
3. 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.
4. 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.
5. 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.
6. Nassar H, Sarhan K, Gamil M, Elgohary M, El-Hadi H, Mahmoud S. Ultrasound-guided Greater Occipital Nerve Block in Children Undergoing Posterior Fossa Craniotomy: A Randomized, Controlled Trial. Journal of neurosurgical anesthesiology 2023 (In eng). DOI: 10.1097/ana.0000000000000899.
7. Thibault M, Girard F, Moumdjian R, Chouinard P, Boudreault D, Ruel M. Craniotomy site influences postoperative pain following neurosurgical procedures: a retrospective study. Canadian journal of anaesthesia = Journal canadien d'anesthesie 2007;54(7):544-8. (In eng). DOI: 10.1007/bf03022318.