Intractable Hemifacial Spasm Treated by Pulsed Radiofrequency Treatment
A 35-year-old woman developed MVD due to a left HFS 6 years ago, which was refractory to medical treatment. Results of preoperative brain magnetic resonance image and electromyography were normal. Surgery was successfully performed, and the postoperative findings revealed that the branch of the left anterior inferior cerebellar artery had been compressing the VII-VIII cranial nerve complex. The pateint did not show any specific symptoms for about 3 and a half years after MVD. But, the symptoms began to recur 1 year ago and she was medicated with 0.5 mg clonazepam for 3 months, and received two local botulinum toxin injections. No treatment effect occurred, so she visited our pain clinic. The patient was experiencing a twitch on the infraorbital area and chin when the HFS was severe, and spasm frequency was 3-4 Hz. Discomfort on the visual analogue scale (VAS) was 10/10. We initially attempted a left stellate ganglion block twice, but no effect was observed, Then, we performed a fluoroscope-guided left facial nerve block twice using 4 ml of 2% lidocaine, and 20 mg triamcinolone. No complications occurred, and the HFS symptoms were relieved for 4 days. Thus, we decided to perform PRF on the facial nerve. In the right lateral decubitus position, the patient's chin was slightly lifted, which exposed the mastoid process. Both sides of the mastoid process and mandible were superimposed on a lateral fluoroscope imaging view (). The skin was prepared with betadine and aseptic draping. We used a 10 cm, 22-G Sluijter-Mehta cannula needle with a 0.5 mm active tip and verified accurate needle position by fluoroscopy. A 5 mm skinwheal appeared from the mastoid process to the nose beginning at the needle entry point of the local anesthetic. We explored facial nerves with 50 Hz, 0.5 V sensory stimulation to the tongue and 2 Hz, 1.0 V motor stimulation to the left hemi face when the tip of the needle was positioned around the stylomastoid for amen. We administered three PRF pulses at 42℃ for 120 seconds after confirming that the needle tip was near the facial nerve. After the procedure, we injected 3 ml of 4% lidocaine mixed with 20 mg triamcinolone. The patient was symptom free for only 4 days, so we applied additional PRF treatments twice using the same method to obtain a longer effect. When the patient returned as an outpatient 1 week after the second PRF treatment, HFS frequency was improved to < 0.25 Hz, and subjective complaints improved on the VAS (2-3/10). The modified MacNab criteria at 1 week after the procedure were good. The patient was followed up at 3, 6, 9, and 12 months via telephone, and symptom relief was maintained continuously.