A Brief history follows of radiofrequency and the application of Temperature Controlled Radiofrequency (TCRF) to the airway of patients with Sleep-Disordered Breathing (SDB) or more commonly known as Obstructive Sleep Apnea Syndrome.

An example of tongue base reduction is seen in this clip.

Previous Uses:

The advent of radiofrequency tissue volume reduction (RFTVR) is not new and has been extensively studied in many medical and surgical specialties. It has demonstrated acceptable feasibility, efficacy, safety, and reproducibility of its treatment results. RFTVR utilizes a low wave radiofrequency signal (456kHz) for therapeutic ablation of tissue in a minimally invasion fashion. The advantages of RFTVR over electrocautery and laser energy surgery reside in its precision in ablating tissues and in its control of operation. With RFTVR, the targeted tissue temperatures stay localized within a 60-90°C range thus limiting heat dissipation and damage to adjacent tissue. Electrocautery and laser temperatures are significantly higher (750-900°C) which result in significant heat propagation in excess of the desired therapeutic need. These differences allow for RFTVR to be more accurate, minimally invasive and less morbid without compromising treatment efficacy and durability.

RFTVR has been employed for precise tissue ablation in conditions affecting vital organs such as the central nervous system where accurate ablation of the abnormal tissue is mandatory while excess ablation is undesirable and dangerous.1 In cardiology, RFTVR is used for ablation of aberrant pathways in Wolfe-Parkinson-White syndrome.2 RFTVR is used in the treatment of patients with symptomatic benign prostatic hyperplasia (BPH) with excellent efficacy through a procedure named Trans-Urethral Needle Ablation (TUNA).3 In BPH, RFTVR is the only efficacious treatment modality available that can be performed as an office procedure under local anesthesia.4 RFTVR has also been used for the treatment of cancer in animals and humans.5-6

The first use of Temperature Controlled Radiofrequency (TCRF) in SDB

Our center was the first to investigate this technology to shrink the soft tissues of the upper airway in SDB. Since this technology had not previously been used for this purpose, a planned series of prospective studies that started with a porcine animal model was instituted.7 This study investigated the feasibility of RF tongue reduction for the future purpose of determining its clinical applications in SDB. For safety reasons the study was performed in stages and a temperature control algorithm was used. The last stage was a prospective investigation with histologic and volumetric analyses to establish outcomes. A homogeneous population of porcine animal models, including seven in stage one, and twelve in stage three (with controls), were used. Radiofrequency energy was delivered to the tongue tissue by a custom-fabricated needle electrode and RF generator (Somnus Medical Technologies Inc, Sunnyvale CA). Clinical outcomes as reported or published for new technologies and surgery: Histologic assessments done serially over time (1hr through 3 wks) showed a well circumscribed lesion with a normal healing progression and no peripheral damage to nerves. Volumetric analysis documented a very mild initial edematous response which promptly tapered at 24 hours. At 10 days after RF a 23% volume reduction was documented at the treatment site.

The second step was to apply this technology on the human palate, since the porcine study showed that predictable and safe energy levels could be delivered to the subsurface tissues.8 This investigation was structured to evaluate pain, swallowing, speech, edematous response, tissue shrinkage, sleep, snoring, and safety following RF treatment to the palate in 22 subjects with sleep-disordered breathing. It was a prospective non-randomized study. Polysomnography, radiographic imaging, and infrared thermography, along with questionnaires and visual analog scales, were used to evaluate the effects of RF treatment to the palate. Radiofrequency was delivered to the submucosa of the palate with a custom fabricated electrode. Reduction of snoring scores determined the end point of the study for each patient. Clinical outcomes as reported or published for new technologies and surgery: Neither speech nor swallowing were adversely affected. Pain was of short duration and was controlled with acetaminophen. There were no infections. Although there was documented edema at 24-48 hours there were no clinical airway compromises. Polysomnographic data showed improvement in esophageal pressure measurements of the mean nadir and the 95th percentile nadir (p=0.031, p=0.001) respectively, as well as the mean sleep efficiency index (p=0.002). Radiographic imaging showed a mean shrinkage of 5.5 mm ±3.7, (p=<0.0001). Subjective snoring scores fell by a mean of 77% (8.3 ±1.8 to 1.9±1.7, p=0.0001) accompanied by improved mean Epworth sleepiness scores (8.5±4.4 to 5.2 ±3.3, p=0.0001).

Step three used TCRF to treat the turbinates in subjects with nasal obstruction so commonly seen in sleep-disordered breathing, especially those on nasal CPAP.9 We prospectively evaluated the safety and effectiveness of radiofrequency for the treatment of nasal obstruction secondary to inferior turbinate hypertrophy. Twenty-two consecutive patients with nasal obstruction and associated inferior turbinate hypertrophy refractory to medical therapy were evaluated for RF. Clinical examinations, patient questionnaires and visual analog scales were utilized to assess treatment outcomes. Clinical outcomes as reported or published for new technologies and surgery: No adverse effects were encountered, including bleeding, crusting, dryness, infection, adhesion, or a worsening of obstruction. Mild edema was noted in all patients but was of short duration (24-48 hours). Post-treatment discomfort was well controlled with acetaminophen. At 8 weeks following treatment, nasal breathing improved in 21 of 22 patients, with a 58.5% reduction in severity and a 56.5% decrease in the frequency of nasal obstruction. A follow up study using a randomized double blind placebo controlled protocol evaluated the use of TCRF to shrink the turbinates of subjects using CPAP and having difficulty with nasal obstruction due to turbinate enlargements. All of these subjects had previously failed oral medication or topical sprays to the nose for the same problem.10

The last planned study was to apply this new technology to the tongue base in patients with SDB 11. This study investigates radiofrequency energy (RFe), as applied to the tongue base, for the purpose of assessing feasibility, safety and possible efficacy in the treatment of Sleep Disordered-Breathing (SDB). Eighteen patients with SDB were entered and completed the study. The disturbance index (RDI) was 39.6, with mean nadir oxygen (SaO2) of 81.9%. An RF mean respiratory electrode (Somnus Medical Technologies, Sunnyvale CA) delivered energy to the subsurface tongue base using local anesthetic. Polysomnography, quantitative speech and swallowing studies, questionnaires and visual analog scales (VAS) were used to assess outcomes. MRI imaging assessed changes in tongue volume. Clinical outcomes as reported or published for new technologies and surgery: Separate RFe treatments at 4 week intervals were given for a mean energy total of 8490 joules per patient. The post-treatment mean RDI was 17.8 and SaO2 nadir 88.3%. Weight increased slightly; speech and swallowing did not change. Questionnaires and VAS scores showed improvement in study variables. Tongue volume was reduced by a mean of 17%. Pain was controlled by Hydrocodone for 3-4 days. One infection was seen and resolved with I&D. This technology holds a promising new modality for the treatment of sleep-disordered breathing as long as it is used cautiously and the limits are expanded logically and supported by continued scientific research.

Since these early studies, we and others have published extensively on the uses and outcomes of TCRF for SDB.

Bibliography:

1. Sweet W, Wepsic J. Controlled thermocoagulation of trigeminal ganglion and rootlets for differential destruction of pain fibers. Part 1: Trigeminal neuralgia. J Neurosurg 1974;3:143-156
2. Jackman WM, Wang XZ, Friday KJ, et al. Catheter ablation of accessory atrioventricular pathways (Wolff-Parkinson-White syndrome) by radiofrequency current. N Engl J Med 1991;324:1605-11
3. Issa M, Oesterling J. Transurethral needle ablation (‘TUNA‘): an overview of radiofrequency thermal therapy for the treatment of benign prostatic hyperplasia. Current Opinion in Urology 1996;6:20-7.
4. Schulmun CC, Zlotta AR. Transurethral needle ablation of the prostate for treatment of benign prostate hyperplasia: early clinical experience. Urology 1995;45:28-33
5. LeVeen H, Wapnick S, Piccone V, et al. Tumor eradication by radiofrequency therapy. Response in 21 patients. JAMA 1976;253:2198-2200
6. McGahan J, Schneider P, Brock J, et al. Treatment of liver tumors by percutaneous radiofrequency electrocautery. Semin Interventional Radiology 1993;10(2):143-9.
7. Powell NB, Riley RW, Troell RJ, et al. Radiofrequency volumetric reduction of the tongue. A porcine pilot study for the treatment of obstructive sleep apnea syndrome. Chest 1997;111:1348-55
8. Powell N, Riley R, Troell, et al. Radiofrequency volumetric tissue reduction of the palate in subjects with sleep-disordered breathing. Chest 1998;113:1163-74
9. Li K, Powell N, Riley R, et al. Radiofrequency volumetric tissue reduction for treatment of turbinate hypertrophy-a pilot study. Otolaryngol Head Neck Surg, 1998, in press
10. Powell N, Zonato A, Weaver E, Li K, Troell R, Riley R, Guilleminault C. Radiofrequency Treatment of turbinate Hypertrophy in Subjects Using Continuous Positive Airway Pressure: A Randomized, Double-Blind, Placebo-Controlled Clinical Pilot Trial. The Laryngoscope, 2001;111;1783-90
11. Powell N, Riley R, Guilleminault C: Radiofrequency tongue base reduction in sleep-disordered breathing: A pilot study. Otolaryngol Head Neck Surg, 1999;120:656-64
12. Guilleminault C, Chervin R, Palombini L, Powell N. Radiofrequency (pacing and thermic effects) in the treatment of sleep-disordered breathing. Sleep. 2000 Jun 15;23 Suppl 4:S182-6
13. Riley RW, Powell NB, Li KK, Weaver EM, Guilleminault C. An adjunctive method of radiofrequency volumetric tissue reduction of the tongue for OSAS. Otolaryngology Head and Neck Surgery, 129(1): 37-42. 2003

Complete Radiofrequency Summary:

• Palate
• Turbinate
• Tongue