Suprazygomatic Maxillary Nerve Block in Pediatric Tonsillectomy

Opioid-Free Pediatric Tonsillectomy With Intraoperative Maxillary Nerve Block Via Suprazygomatic Injection (OPTIMaS): A Randomized Controlled Triple-Blinded Trial

Tonsillectomies are among the most common surgical procedures performed in pediatric populations, with more than 14,000 procedures performed annually in Ontario, with more than 80% being performed to treat sleep-disordered breathing, including sleep apnea. Despite being a routine procedure, postoperative pain is a prevalent challenge following tonsillectomies, with significant pain lasting 7 to 10 days and peaking within the first 3 days following surgery. Effective pain management is critical not only to enhance patient comfort, but to ensure functional recovery, decrease the risk of post-surgical complications, and reduce the risk of hospital readmissions. The suprazygomatic maxillary nerve block (SZMN block) has become a promising alternative to opioids for the management of post-tonsillectomy pain. The SZMN block numbs the nerves in the facial region that would contribute to feeling pain following tonsillectomy. Although the SZMN block has been successful in adult tonsillectomies and pediatric cleft palate repairs, its success in pediatric tonsillectomies remains under investigation. This randomized controlled trial aims to evaluate the efficacy and safety of the SZMN block in pediatric tonsillectomy and adenotonsillectomy patients, through its role in providing pain management over 14 days following surgery. This study will be conducted at Victoria Hospital, London Health Sciences Centre.

Tonsillectomies are among the most common surgical procedures performed in pediatric populations, with more than 14,000 procedures performed annually in Ontario. Despite being a routine procedure, postoperative pain is a prevalent challenge following tonsillectomies, with significant pain lasting 7 to 10 days and peaking within the first 3 days following surgery. Effective pain management is critical not only to enhance patient comfort, but to ensure functional recovery, decrease the risk of post-surgical complications, and reduce the risk of hospital readmissions. More than 80% of tonsillectomies are performed to treat sleep-disordered breathing (SDB), an array of conditions including obstructive sleep apnea (OSA) that are characterized by abnormal respiratory patterns during sleep. Patients with these conditions often undergo an upregulation of central μ-opioid receptors due to chronic apnea, decreasing their response to hypercarbia and increasing opioid sensitivity. When opioids are administered for pain management, these patients are at a greater risk of hypoventilation and hypoxemia. Many nonopioid analgesics such as acetaminophen, non-steroidal anti-inflammatory drugs, and some corticosteroids provide varying degrees of efficacy in pain relief, acting more effectively in combination with other medications to maximize pain management while mitigating adverse effects.

The suprazygomatic maxillary nerve block (SZMN block) has become a promising alternative to systemic opioids for the management of post-tonsillectomy pain. The SZMN block targets the palatine branch of the maxillary nerve in the pterygopalatine fossa, providing partial analgesia to the adenoids while avoiding the glossopharyngeal nerve, thereby preserving airway reflexes and reducing the risk of respiratory compromise. Although the SZMN block has been successful in adult tonsillectomies and pediatric cleft palate repairs, its success in pediatric tonsillectomies remains under investigation. Reported complications are rare and easily managed, including perioperative bleeding and postoperative hematoma formation at the injection site. A recent randomized clinical trial by Lin et al. demonstrated the efficacy of the SZMN block in reducing opioid use and alleviating postoperative pain in pediatric patients during the immediate postoperative period, particularly the post-anesthesia care unit (PACU) stay and the first three days following surgery. However, its efficacy in pediatric tonsillectomy patients has not been evaluated over the initial 14-day postoperative period, during which patients commonly experience sustained, significant pain. The current investigation aims to evaluate the efficacy and safety of the SZMN block in pediatric tonsillectomy and adenotonsillectomy patients, through its role in providing pain management over 14 days following surgery.

Prior to enrollment in the study, informed consent will be sought from the parents/guardians of these children and assent will be obtained where appropriate. Upon enrollment in the study, patients will be randomized by a computer generated sequence into one of two study groups. The investigators, participants, and outcome assessors will be blinded to participant group assignment at the time of randomization and throughout treatment and assessment.

Group 1: Participants will receive 15 mg/kg of Tylenol and 6 mg/kg of celecoxib (a nonsteroidal anti-inflammatory (NSAID drug) up to a maximum dose of 200 mg prior to the start of general anesthesia which will consist of gas or intravenous induction (2 mcg/kg fentanyl, 0.5 mg/kg dexamethasone). The SZMN block will be performed using 0.2 ml/kg bilaterally of 0.25% bupivacaine (MARCAINE) (cumulative dose 0.4 ml/kg) (local anesthetic), up to a maximum dose of 5 mL per side. The surgery (tonsillectomy or adenotonsillectomy) will then proceed according to standard of care practices.

Group 2: Participants will receive 15 mg/kg of Tylenol and 6 mg/kg of celecoxib (a nonsteroidal anti-inflammatory (NSAID drug) up to a maximum dose of 200 mg prior to the start of general anesthesia. which will consist of gas or intravenous induction (2 mcg/kg fentanyl, 0.5 mg/kg dexamethasone). The SZMN block will be performed using 0.2 ml/kg of saline (placebo) up to a maximum dose of 5 mL per side. The surgery (tonsillectomy or adenotonsillectomy) will then proceed according to standard of care practices.

SZMN Block: Participants will lie in the supine position, and anatomical landmarks including the posterior orbital rim and the zygomatic arch will be identified and marked. The skin will be prepared with chlorhexidine gluconate 2% in isopropyl alcohol 70%. The Pajunk SonoBlock II needle will be inserted between the angle made by the posterior orbital rim and zygomatic arch until contacting the greater wing of the sphenoid bone. The needle alignment will be adjusted obliquely forward and caudally to access the pterygopalatine fossa, and negative aspiration will be confirmed. Study group participants will receive 0.2 ml/kg of 0.25% bupivacaine, to a maximum dose of 5 ml per side, deposited on the maxillary bone surface. Control group participants will receive 0.2 ml/kg of saline, to a maximum dose of 5 ml, deposited on the maxillary bone surface.

Following the completion of surgery, participants will be transferred to the post-anesthesia care unit (PACU) for recovery. While in the PACU, participants will be assessed at two different time points for opioid consumption, side effects, recovery progress, and for early postoperative pain. Pain will be assessed using the FLACC (Face, Legs, Activity, Cry, Consolability) Pain Scale.. This scale is a validated pain assessment tool that allows for assessment of pain in children. Scores for each category are assigned on a scale of 0-2 and then added together to receive a final pain score out of 10 which is then interpreted to determine the severity of pain the patient is experiencing where 0 indicates no pain and 10 indicates severe pain.

After the participant is discharged from the hospital, the study team will call the participants' parents/guardians on days 1, 7, and 14 following surgery to conduct a phone follow up visit. During each phone call, parents/guardians will be asked to answer questions about their child's pain, side effects, ability to swallow, opioid use, other medications that are being taken, pain rating, and parental/guardian satisfaction with pain control. If the parents/guardians cannot be reached by telephone, the participant's medical record will be reviewed to determine if there were any complications requiring a readmission to hospital. This phone call will take approximately 5-10 minutes to conduct each time. Following completion of the telephone call on day 14 following surgery, the child's participation in this study will be concluded.

Inclusion Criteria:

1. Patients undergoing coblation intracapsular tonsillectomy or adenotonsillectomy for sleep apnoea.
2. Between 3-9 years old (inclusive).
3. Patient(s) and guardian(s) can consent to participate in the study.
4. Legal guardian(s) can read and write in English.

Exclusion Criteria:

1. Patient or legal guardian refusal to participate in the study.
2. Emergency surgery.
3. Allergies to local anesthetics.
4. Patients with coagulopathy.
5. Congenital facial abnormalities including (but not limited to) hemifacial microsomia, maxillary hypoplasia, Treacher-Collins syndrome, and Goldenhar syndrome.
6. Developmental delay or neurological impairment including (but not limited to) Trisomy 21, cerebral palsy, and autism spectrum disorder.
7. Previous airway surgery or a known or predicted airway difficulty.