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INTRODUCTION:

IN CONTRAST TO OBSTRUCTIVE SLEEP APNEA, NO GENERALLY ACCEPTED GOLD STANDARD IS AVAIL-ABLE FOR THE TREATMENT OF PRIMARY SNORING. IN addition to non-invasive treatment modalities such as intraoral devices, soft palate surgery has become a widespread treatment option. Due to its minimally invasive character, radiofrequency (RF) surgery of the soft palate has received increased attention. A recently published review of the literature demonstrated that all published trials document a significant improvement of primary snoring and minimal postoperative pain while postoperative com-plication rates were low in the majority of these studies.1 Nevertheless, the above mentioned review also pointed out the major limitation of these studies, namely the lack of control groups. Control groups are particularly important in studies in-vestigating therapeutic effects in primary snoring, as no reliable objective measurements are available and clinical efficacy is usu-ally assessed with bed-partner questionnaires. Aim of our study was to assess the efficacy of RF-surgery of the soft palate in the treatment of primary snoring in a random-ized, placebo-controlled trial.

METHODS

The study protocol was approved by the local ethics board of the Faculty of Clinical Medicine Mannheim of the University of Heidelberg; written informed consent was obtained from all the participating subjects. Patients with primary snoring between the age of 18 and 65 and a maximum BMI of 35 were included if they had complained about socially disruptive snoring and asked for surgical treat-ment. Non-invasive treatment alternatives including intraoral devices were offered to all our patients. Patients were only con-sidered for soft palate surgery if they were otherwise healthy and no professional voice users, if they were not complaining about excessive daytime sleepiness, and if obstructive sleep apnea had been ruled out with either polysomnography or ambulatory poly-graphic measurements. With respect to the polysomnographic or polygraphic results, a maximum apnea-hypopnea-index or oxy-gen desaturation index of 15 was used as inclusion criteria. Regarding the individual anatomy of our patients, RF-surgery of the soft palate was offered in those cases where a relevant ret-rolingual obstruction or significant tonsilar hypertrophy was ruled out with clinical assessment including rigid endoscopy (awake patient). Concerning the evaluation of retrolingual obstruction due to potential tongue base hypertrophy the appearance of the epiglottic vallecula at the laryngeal endoscopy was the main cri-teria. Patients with relevant uvular hypertrophy and patients with previous soft palate surgery were also excluded. As no gener-ally accepted objective airway assessment is available, the deci-sion whether patients were ultimately suitable for RF-soft palate surgery was based on subjective clinical assessment. As stated above, the inclusion criteria were in accordance with the criteria for RF soft palate surgery described in the literature. Patients received two consecutive sessions of either tempera-ture controlled RF-surgery (Somnoplasty®) or placebo on an out-

Radiofrequency Surgery of the Soft Palate in the Treatment of Snoring. A Placebo-Controlled Trial. Boris A. Stuck, MD; Alexander Sauter, MD; Karl Hörmann, MD; Thomas Verse, MD; Joachim T. Maurer, MD

Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital Mannheim, Mannheim, Germany

Study Objectives: Recent publications have demonstrated a reduction in snoring with radiofrequency (RF) surgery of the soft palate. Yet so far, all published data has been based on non-controlled trials.Design: Aim of this study was to assess the efficacy of RF surgery of the soft palate in a randomized, placebo-controlled trial.Setting: Outpatients department at university hospital, department of oto-rhinolaryngologyPatients: 26 patients with primary snoring (AHI<15, BMI<35).Interventions: Patients were treated with temperature-controlled RF sur-gery of the soft palate under local anesthesia. In accord with a random-ization protocol they received 2 sessions of RF surgery (total amount of energy: 3.300 Joule) or placebo (insertion of device needle without energy delivery).Measurements and Results: Snoring was evaluated by the bed part-

ner with 10 cm visual analogue scales. 23 patients completed the study; 12 received RF-surgery and 11 received placebo. Snoring scores did not change in the placebo group (8.4±1.6 to 8.0±2.3) while improving in the RF-group (8.1±1.3 to 5.2±2.4). The difference between the groups was statistically significant (p<0.05). Conclusion: RF-surgery was significantly better than placebo, although the reduction in snoring was only moderate in our group of patients. This study underlines the necessity for well-controlled clinical trials in the treat-ment of snoring.Keywords: Radiofrequency surgery, soft palate, snoringCitation: Stuck BA; Sauter A; Hörmann K et al. Radiofrequency surgery of the soft palate in the treatment of snoring. A placebo-controlled trial. SLEEP 2005;28(7): 847-850.

Disclosure StatementThis was not an industry supported study. Dr. Hörmann has received re-search support and equipment, including treatment devices, from Gyrus ENT. Drs. Stuck, Sauter, Verse, and Maurer have indicated no financial conflicts of interest.

Submitted for publication December 2004 Accepted for publication March 2005Address correspondence to: Boris A. Stuck, MD, Department of Otorhino-laryngology, Head and Neck Surgery, University Hospital Mannheim, 68135 Mannheim, Germany; Tel: +49 (0) 621 383 1600; Fax:+49 (0) 621 383 3827; E-mail: boris.stuck@hno.ma.uni-heidelberg.de

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patient basis under local anaesthesia. The Somnus® radiofrequen-cy generator Model S2 (Gyrus ENT, Bartlett, USA) was used for the generation of temperature-controlled RF-energy. The surgical procedure itself was standardized. Three application sites were selected for the first session (600 Joule in the midline and two times 450 Joule approx. 1 cm lateral to the midline) and four ap-plication sites were chosen for the second session (4 times 450 Joule). In total, 3300 Joule were delivered in the RF-group. The target temperature was set to 85° C. Placebo treatment followed the same standardized protocol, in-cluding local anesthesia. In the placebo group, the device needle was inserted but no RF-energy was delivered. In both groups, patients did not receive any sedation or prophylactic antibiotics; corticosteroids were not used. Due to the local anesthesia and the minimal postoperative pain (minimal discomfort was also report-ed solely due to the insertion of the device needle), we do believe that patients were not able to determine whether they received RF-surgery or placebo. The procedure itself was performed by a single surgeon who was not the primary investigator; the surgeon adhered to a com-puter-generated randomization protocol. In accordance with an observer-blind study, the primary investigator was not informed about the results of the randomization process. The second session was performed 4 to 6 weeks after the first one. Follow up visits were scheduled 6 to 8 weeks after the second treatment session. Snoring was assessed with a 10 cm visual analogue scale.

“No snoring” and “excessive snoring, bed partner leaves the room”were used as anchors. Functional parameters such as speech, taste, swallowing and pharyngeal irritation were also assessed using standard 10 cm vi-sual analogue scales (VAS). No problems / not affected (0) and severe problem / severely affected (10) were used as anchors. Daytime sleepiness was assessed with the Epworth Sleepiness Scale.

STATISTICS

The statistical analysis was conducted at the Department of Statistics of the Faculty of Clinical Medicine Mannheim. The sample size for this study was calculated using the reported effects as summarized in our previously published review.1 Based on a 5% type I error (alpha-error) combined with a power of 90%, 12 patients per subgroup were considered as being necessary for the statistical analysis. In total, 26 patients were finally included in the trial in order to accommodate for possible drop-outs. Changes (after – before) in snoring and functional parameters (VAS) as well as in daytime sleepiness (ESS) results were calcu-lated. Differences between groups were analyzed with the help of a non-parametric approach (2-sample rank sum, U-test). A p-value of less than 0.05 was considered to be statistically signifi-cant. All computations were performed with the help of the SAS program (version 8.2).

RESULTS

23 patients completed the protocol; 3 patients were not avail-able for follow-up. Mean age was 42.6±7.6 years (range: 27-60 years). 12 patients received RF-surgery according to the protocol, 11 received placebo. Mean snoring scores as assessed by the bed partner remained unchanged in the placebo group (mean score before surgery: 8.4 ± 1.6, after surgery: 8.0 ± 2.3), while it improved in the RF group from 8.1 ± 1.3 preoperative to 5.2 ± 2.4 postoperative. There was a statistically significant difference between the two groups re-garding the changes in snoring (p=0.045). Daytime sleepiness improved minimally in the control group (preoperative ESS 5.2 ± 3.1, postoperative ESS 4.3 ± 2.7) while it improved to a slightly greater extent in the RF group (perop-erative ESS 5.4 ± 4.6, postoperative ESS 3.9 ± 3.3). The differ-ences between the two groups were not statistically significant (p=0.77).Results of snoring and daytime sleepiness are shown in Figures 1 and 2 and in Table 1. All the other parameters (speech, taste, swallowing, pharyn-geal irritation) remained unchanged in both groups (all p>0.05, results see Table 2). DISCUSSION

The present study investigated the effects of RF-surgery of the soft palate in patients with primary snoring in a placebo-con-trolled setting. This is the first time that a placebo-controlled study design was used in RF-surgery. Due to the minimally-invasive character of the procedure and the minimal postoperative pain when used at the soft palate, patients were not able to distinguish between placebo and RF surgery, therefore, a placebo treatment was possible.

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Table 1—Results of visual analogue scales for daytime sleepiness and snoring before and after treatment

Number Group ESS pre ESS post Snore pre Snore post 1 Placebo 6 5 6.3 103 Placebo 7 4 10 9.46 Placebo 3 7 8.8 8.67 Placebo 11 10 9.7 9.88 Placebo 8 6 7.6 6.59 Placebo 2 3 5.8 4.114 Placebo 7 4 6.5 5.418 Placebo 6 2 8 4.919 Placebo 3 3 10 9.522 Placebo 4 3 9.5 1026 Placebo 0 0 10 10 MV±SD 5.2±3.1 4.3±2.7 8.4±1.6 8.0±2.3 2 RF-surgery 7 7 8.8 4.84 RF-surgery 3 3 9.6 1.15 RF-surgery 5 3 8.8 5.211 RF-surgery 7 4 10 3.512 RF-surgery 2 2 8 9.713 RF-surgery 14 9 8.2 4.217 RF-surgery 14 11 8.9 8.620 RF-surgery 1 1 7 6.521 RF-surgery 1 1 7.7 5.723 RF-surgery 2 1 5.8 6.624 RF-surgery 7 3 7.6 4.625 RF-surgery 2 2 6.3 2.3 MV±SD 5.4±4.6 3.9±3.3 8.1±1.3 5.2±2.4

MV: mean values; SD: standard deviation; RF: radiofrequency

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According to our results, two sessions of RF-surgery were sig-nificantly more effective than placebo in reducing socially dis-ruptive snoring as assessed by a bed partner questionnaire. Nev-ertheless, the postoperative snoring scores in the RF-group were not satisfying. With regard to the current literature, a reduction of snoring to a postoperative snoring score below 3 is regularly considered as a successful treatment.2-7 Only two patients of our patients were successfully treated according to this definition. With respect to the current literature, our data supports the idea that RF-surgery of the soft palate leads to a reduction of snor-ing. Nevertheless, our postoperative snoring scores are not in ac-cordance with most of the studies published and the results of our literature review.1 The postoperative score was comparable to selected studies only,8,9 where RF-surgery also lead to a signifi-cant reduction in snoring and was recommended as an effective procedure, although postoperative snoring scores were still at a relatively high level. This discrepancy can not be due to differences in the surgical protocol. Especially the total amount of energy applied and the total number of lesions were in accordance with the current litera-ture as summarized in our literature review.1 Since all the patients in the RF-group reported an improvement after the first procedure and only minimal additional effects after the second one, further RF-treatments were not routinely offered. Placebo-controlled trials have only rarely been conducted in the field of primary snoring,10,11 the study of Larrosa et al. for laser-assisted uvulopalatoplasty being the only one for surgical treatments. With regard to the inoffensive nature of primary snor-ing, controlled clinical trials are necessary to critically evaluate the efficacy of the numerous treatments available.

CONCLUSION

RF-surgery of the soft palate for primary snoring is signifi-cantly more effective than placebo in reducing nightly snoring sounds. Nevertheless, snoring is not eliminated and only a moder-ate reduction could be achieved in our group of patients, although the sample size is relatively small which limits the significance of our conclusions. The costs of the procedure associated with single use devices are relatively high (250 Euro for a soft palate needle according to the distributor in Germany). Furthermore, a loss of efficacy over time has been documented at long term follow up studies. 2,8,12 The results of our study underline the necessity of well-con-trolled clinical trials to critically evaluate the various treatment options for primary snoring. REFERENCES

1. Stuck BA, Verse T, Hein G, Hörmann K, Maurer JT. Radiofrequen-cy surgery of the soft palate in the treatment of snoring – a review of the literature. Sleep 2004;27:551-5

2. Bäck LJ, Tervahartiala PO, Piilonen AK, Partinen MM, Ylikoski JS. Bipolar radiofrequency thermal ablation of the soft palate in habit-ual snorers without significant desaturations assessed by magnetic resonance imaging. Am J Respir Crit Care Med 2002;166:865-71

3. Blumen MB, Dahan S, Wagner I, De Dieuleveult T, Chabolle F. Radiofrequency versus LAUP for the treatment of snoring. Otolar-yngol Head Neck Surg 2002;126:67-73

4. Boudewyns A, Van De Heyning P. Temperature-controlled radio-frequency tissue volumetric reduction of the soft palate (Somno-plasty®) in the treatment of habitual snoring: Results of a European multicenter trial. Acta Otolaryngol 2000;120:981-5

5. Cartwright R, Venkatesan TK, Caldarelli D, Diaz F. Treatments for snoring: A comparison of Somnoplasty and an oral appliance. La-ryngoscope 2000;110:1680-3

6. Coleman SC, Smith TL. Midline radiofrequency tissue reduction of the palate for bothersome snoring and sleep disordered breathing: A clinical trial. Otolaryngol Head Neck Surg 2000;122:387-94

7. Emery BE, Flexon PB. Radiofrequency volumetric tissue reduc-tion of the soft palate: A new treatment for snoring. Laryngoscope 2000;110:1092-8

8. Bäck L, Palomaki M, Piilonen A, Ylikoski J. Sleep-disordered breathing: Radiofrequency thermal ablation is a promising new treatment possibility. Laryngoscope 2001; 111:464-71

9. Ferguson M, Smith TL, Zanation AM, Yarbrough WG. Radiofre-quency tissue volume reduction. Multilesion vs single-lesion treat-

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Table 2— Results of visual analogue scales for functional param-eters before and after treatment

Parameter [VAS] pre- post- pre- post- treatment treatment treatment treatment Placebo Placebo RF-group RF-groupspeech 1.0±1.4 0.7±1.1 0.4±0.8 0.3±0.5swallowing 0.3±0.6 0.3±0.5 0.4±0.6 0.4±0.5taste 0.4±0.5 0.4±0.6 0.3±0.7 0.3±0.4pharyngeal irritation 0.8±0.9 0.6±1.4 1.1±1.0 1.5±1.8

VAS: visual analogue scale; RF: radiofrequency; mean values ± SD

Figure 1—Pre- and Postoperative Snoring Scores in Both GroupsMean values ± SD, VAS: visual analogue scales

Figure 2—Pre- and postoperative scores for daytime sleepiness in both groupsMean values ± SD, ESS: Epworth Sleepiness Scale

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ments for snoring. Arch Otolaryngol Head Neck Surg 2001;127:312-8

10. Johnston CD, Gleadhill IC, Cinnamond MJ, Peden WM. Oral ap-pliances for the management of severe snoring: a randomized con-trolled trial. Eur J Orthod. 2001;23:127-34

11. Larrosa F, Hernandez L, Morello A, Ballester E, Quinto L, Montser-rat JM. Laser-assisted uvulopalatoplasty for snoring: does it meet the expectations? Eur Respir J. 2004;24:66-70

12. Li KK, Powell NB, Riley RW, Troell RJ, Guilleminault C. Radio-frequency volumetric tissue reduction of the palate: An extended follow-up study. Otolaryngol Head Neck Surg 2000;122:410-4

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