Procedures

The patient was placed in a supine position, monitored for vital signs, and administered oxygen through a nasal cannula. A positioning grid was placed on the affected cheek (Fig. 1), and a half-coronal CT scan was performed. The image was reviewed layer by layer to determine the location of the foramen rotundum (Fig. 2A); the target SPG was located caudally medial to the foramen rotundum (Fig. 2B).

The patient was positioned supine on the CT-fluoroscopy table. A positioning grid was placed over the cheek of the affected side

The location of the foramen rotundum (a), with the target nasopalatine ganglion located caudally medial to the FR (b)

The optimal puncture level was mapped using the CT built-in image processing software, while the puncture depth and angle were measured (Fig. 3A). Then, the puncture level and point were marked on the patient’s skin (Fig. 3B).

Design of the RF needle insertion route. The optimal puncture level was mapped using the CT built-in image processing software. Along the lateral wall of the maxillary sinus, a yellow line is drawn from the mid of the foramen rotundum canal to the point of skin entry. Then, the needle insertion depth (distance, 63.1 mm) and the puncture angle (the angle between the yellow line and the sagittal plane (a = 56.07) were measured. According to a, the puncture level and puncture point corresponding to the optimal puncture route are marked on the patient’s skin (b)

After routine disinfection of the towel, the skin and subcutaneous tissue were anesthetized with 2 mL of 1% lidocaine using a 27 G intradermal needle. Under CT guidance, the RF needle (specific model, 10 cm) was inserted and advanced according to predetermined parameters (angle, path, and depth). This process requires repeated correction of the puncture direction and path by CT scan to ensure the optimal puncture path is followed until the SPG target is reached (Fig. 4).

Under CT guidance, the RF needle is inserted and advanced according to predetermined parameters, a process that requires repeated correction of the puncture direction and path by CT scan to ensure consistency with the designed optimal puncture path until the target SPG is reached

After confirming the lack of evidence of blood, cerebrospinal fluid, or sensory abnormalities, sensory testing was performed via stimulation at 100 Hz and 500 ms pulse width to produce abnormalities at 0.1–0.5 V consistent with the patient's usual original pain site. The motor testing was performed by stimulating the probe at 2 Hz and 0.1–0.5 V to confirm that it was not in close proximity to other adjacent nerves, especially the trigeminal nerve V2 branch, and then 0.5 mL of 1% lidocaine was injected 2 min prior to RF. Subsequently, standard radiofrequency (RF) was performed continuously for 120 s at 90 °C under intravenous propofol anesthesia. Blood pressure, heart rate, electrocardiogram, and oxygen saturation were closely monitored during treatment. At the end of the procedure, the patient was transferred to the postoperative recovery room, and the scores were assessed and recorded. The patient’s vital signs were monitored for at least 4 h before discharge. The intra- and postoperative complications were recorded, and immediate and long-term outcomes were assessed during follow-up.