RF treatment is carried out with the patient in the supine position. The fossa pterygopalatina is identified by lateral fluoroscopy. A line is drawn on the skin over the fossa, and the introduction point is chosen just below the arcus zygomaticus (Figure 1).
Figure 1. Radio-frequency treatment of the pterygopalatine ganglion: projection of the metal bar indicates the line over the fossa pterygopalatina.
Procedure
The surrounding skin is disinfected, anaesthetised and covered with sterile drapes. A 100-mm radio-frequency electrode with a 2-mm active tip is introduced slowly. The needle is carefully inserted in a superior and anterior direction towards the anterosuperior point of the fossa pterygopalatina, using lateral fluoroscopy (Figures 2 and 3).
Figure 2. Radio-frequency treatment of the ganglion pterygopalatinum: AP view.
The C-arm is now placed in an anteroposterior position; the tip of the canula should be lying just laterally to the nasal wall. The stylet is removed, and a thermocouple RF probe is positioned. The position of the electrode is confirmed by electrostimulation using 50 Hz. It is important to use a 2-mm active tip, otherwise damage can occur to the nervus maxillaries during the lesion. Generally, the patient feels paresthesia on the lateral side and back of the nose at a threshold of 0.4 V. No paresthesia should be felt in the soft palate or upper jaw since this indicates stimulation of the nervus maxillaris or its branches. After a limited amount of local anesthesia (maximum 1 ml), a lesion is carried out for 60 seconds at 80°C, and this lesion is repeated twice, during which the electrode is inserted further.
Figure 3. Radio-frequency treatment of the pterygopalatine ganglion: lateral view. Needle high in the fossa pterygopalatina.
Complications
- Total destruction of the PPG could result in dryness of the eyes. However, in normal conditions, RF treatment only aims at a partial lesion of the ganglion.
- A possible complication is hypesthesia of the palatum molle, which generally disappears after six to eight weeks.
- A further complication is nose bleeding and swelling of the cheek as the result of a hematoma.
- A bothersome complication is the accidental lesion of the nervus maxillaris, which can occur when the technique is not carried out properly.