Maxillary and mandibular nerve blocks are often performed for diagnostic and therapeutic purposes. We report the application of continuous maxillary and mandibular nerve blocks for intraoperative and postoperative analgesia in a patient scheduled for the excision of pleomorphic adenoma of the parotid gland.
A 68-yr-old 56-kg male patient with ischemic heart disease, intractable atrial fibrillation, and controlled hypertension with a pleomorphic adenoma of the parotid gland was scheduled for total parotidectomy. The patient’s difficult airway was Mallampatti grade III. The preoperative electrocardiogram (EEG) showed ST elevation in V1–V4 leads and left ventricular hypertrophy. Echocardiography revealed a markedly reduced left ventricular ejection fraction of 36% with significant regional wall motion abnormality in the anterior wall.
A regional anesthetic technique was selected because of the patient’s pulmonary and cardiac conditions, as well as his difficult airway.
The patient was familiarized with the visual analog scale pain scoring system technique (0–10 cm scale) and written informed consent for blocks was obtained.
Under aseptic technique, after local infiltration with lidocaine 1% at the midpoint of the zygomatic arch, a 16-gauge IV cannula was inserted at the midpoint of the lower margin of the zygomatic arch and advanced perpendicularly until it contacted the lateral pterygoid plate. For right maxillary nerve block, the cannula was then withdrawn slightly and advanced cephaloanteriorly 1 cm to enter the pterygopalatine fossa (Figure 1). The stylet was removed and an 18-gauge epidural catheter (Portex) was advanced 0.5 cm past the cannula tip. The cannula was removed, and the catheter was anchored and a filter was attached.
After negative aspiration, a 2-mL test dose of lidocaine 2% with epinephrine (1 in 200,000) was injected. As there was no evidence of intravascular injection, 8 mL of 0.25% bupivacaine was subsequently administered through the catheter.
To provide a right mandibular nerve block, a 16-gauge IV cannula was inserted to contact the lateral pterygoid plate. The depth of the pterygoid plate was noted, and the cannula was withdrawn and redirected slightly posteriorly (Fig. 2) to a position just behind the posterior border of the lateral pterygoid plate.
The cannula was advanced by a distance of 5 mm further, the stylet was removed, and an 18-gauge catheter was inserted 1.0 cm past the cannula tip and anchored. Injection of bupivacaine 0.25% 6 mL was performed through the catheter after a negative test dose.
The surgical field was evaluated for satisfactory anesthesia by pinprick. The patient was sedated with propofol 70 mg IV bolus followed by an infusion at a rate of 50 μg · kg−1 · min−1. Surgery was allowed to proceed.
The patient’s vital signs remained normal throughout surgery. The pattern of atrial fibrillation persisted but with no acute changes in the ECG. The patient was sedated but responding to verbal commands. The propofol infusion was stopped at the end of the surgery, the patient awoke completely pain-free.
In the evening, the visual analog scale score was 1. A top-up dose of 4 mL 0.25% bupivacaine was administered through each of the catheters at 8 pm (approximately 5.5 h after the initial bolus) when the visual analog scale score was 3.5 and repeated every 12 h for the next 72 h. The visual analog scale score noted throughout the 72-h postoperative period ranged between 1.5 and 3.0. The patient was fed by Ryle’s tube. Jaw opening was adequate and pain-free.
The two catheters were removed 72 h postsurgery approximately 4 h after the last injection with no evidence of any sensory or motor deficit or any local infection in the region.
In this patient, continuous maxillary and mandibular nerve blocks, using 0.25% bupivacaine injected via 18-gauge epidural catheters, provided adequate intraoperative and postoperative analgesia.
Continuous mandibular nerve blocks have been performed for postoperative analgesia after surgical repair of a fractured mandible (1) and for management of trigeminal neuralgia (2). Our patient is the first to receive continuous maxillary and mandibular nerve blocks for intraoperative anesthesia and postoperative analgesia.
In the past few years, continuous nerve blocks have enjoyed a significant surge of interest, especially for major shoulder procedures (continuous interscalene), for major surgeries of the upper extremity below the shoulder (continuous infraclavicular and axillary), and for major lower extremity surgery (continuous sciatic, femoral, and lumbar plexus blocks) (3). These techniques provide superior analgesia and encourage early mobilization and restoration of limb function.
When performing a maxillary nerve block, it must be considered that the pterygopalatine fossa is extremely vascular (1) as a result of pterygoid plexus of veins and that there is a possibility of intravascular injection or hematoma formation. We prefer the lateral extraoral approach for performance of mandibular block, as (1) it is more convenient to place a catheter by this approach.
Finally, proper caution must be exercised to prevent hematoma formation, infection, kinking, or obstruction of the catheter. It was important in our exercise to keep the catheter as close to the target nerve as possible to ensure a proper anesthetic effect. As in our patient there was a possibility that the catheter tip may have been displaced by chewing, jaw opening, and eating (2), proper position of the tip was confirmed by regular assessment of pain relief after the top-up dose.
In conclusion, continuous maxillary and mandibular nerve block is an excellent approach for obtaining adequate intraoperative and postoperative analgesia. However, a randomized trial is needed to determine the potential applications of this technique.