Radiofrequency Surgery of the Soft Palate in the Treatment

SLEEP DISORDERED BREATHING
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
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 treatment of snoring.
Keywords: Radiofrequency surgery, soft palate, snoring
Citation: 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.
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 otorhinolaryngology
Patients: 26 patients with primary snoring (AHI<15, BMI<35).
Interventions: Patients were treated with temperature-controlled RF surgery of the soft palate under local anesthesia. In accord with a randomization 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-
INTRODUCTION:
METHODS
IN CONTRAST TO OBSTRUCTIVE SLEEP APNEA, NO
GENERALLY ACCEPTED GOLD STANDARD IS AVAILABLE 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 complication 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 investigating therapeutic effects in primary snoring, as no reliable
objective measurements are available and clinical efficacy is usually 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 randomized, placebo-controlled trial.
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 treatment. Non-invasive treatment alternatives including intraoral
devices were offered to all our patients. Patients were only considered 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 polygraphic measurements. With respect to the polysomnographic or
polygraphic results, a maximum apnea-hypopnea-index or oxygen 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 retrolingual 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 criteria.
Patients with relevant uvular hypertrophy and patients with
previous soft palate surgery were also excluded. As no generally accepted objective airway assessment is available, the decision 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 temperature controlled RF-surgery (Somnoplasty®) or placebo on an out-
Disclosure Statement
This was not an industry supported study. Dr. Hörmann has received research 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 2005
Address correspondence to: Boris A. Stuck, MD, Department of Otorhinolaryngology, 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
SLEEP, Vol. 28, No. 7, 2005
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Placebo-Controlled RF-Surgery for Snoring—Stuck et al
patient basis under local anaesthesia. The Somnus® radiofrequency 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 application 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, including 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 reported 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 computer-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 visual 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.
Table 1—Results of visual analogue scales for daytime sleepiness
and snoring before and after treatment
23 patients completed the protocol; 3 patients were not available 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 regarding 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 (peroperative ESS 5.4 ± 4.6, postoperative ESS 3.9 ± 3.3). The differences 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, pharyngeal irritation) remained unchanged in both groups (all p>0.05,
results see Table 2).
Number Group
1
3
6
7
8
9
14
18
19
22
26
2
4
5
11
12
13
17
20
21
23
24
25
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 calculated. Differences between groups were analyzed with the help
of a non-parametric approach (2-sample rank sum, U-test). A pvalue of less than 0.05 was considered to be statistically significant. All computations were performed with the help of the SAS
program (version 8.2).
RESULTS
ESS pre ESS post Snore pre Snore post
Placebo
Placebo
Placebo
Placebo
Placebo
Placebo
Placebo
Placebo
Placebo
Placebo
Placebo
6
7
3
11
8
2
7
6
3
4
0
5
4
7
10
6
3
4
2
3
3
0
6.3
10
8.8
9.7
7.6
5.8
6.5
8
10
9.5
10
10
9.4
8.6
9.8
6.5
4.1
5.4
4.9
9.5
10
10
MV±SD
5.2±3.1
4.3±2.7
8.4±1.6
8.0±2.3
RF-surgery
RF-surgery
RF-surgery
RF-surgery
RF-surgery
RF-surgery
RF-surgery
RF-surgery
RF-surgery
RF-surgery
RF-surgery
RF-surgery
7
3
5
7
2
14
14
1
1
2
7
2
7
3
3
4
2
9
11
1
1
1
3
2
8.8
9.6
8.8
10
8
8.2
8.9
7
7.7
5.8
7.6
6.3
4.8
1.1
5.2
3.5
9.7
4.2
8.6
6.5
5.7
6.6
4.6
2.3
MV±SD
5.4±4.6
3.9±3.3
8.1±1.3
5.2±2.4
DISCUSSION
The present study investigated the effects of RF-surgery of
the soft palate in patients with primary snoring in a placebo-controlled 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.
MV: mean values; SD: standard deviation; RF: radiofrequency
SLEEP, Vol. 28, No. 7, 2005
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Placebo-Controlled RF-Surgery for Snoring—Stuck et al
Figure 2—Pre- and postoperative scores for daytime sleepiness in
both groups
Mean values ± SD, ESS: Epworth Sleepiness Scale
Figure 1—Pre- and Postoperative Snoring Scores in Both Groups
Mean values ± SD, VAS: visual analogue scales
CONCLUSION
Table 2— Results of visual analogue scales for functional parameters before and after treatment
Parameter [VAS]
pretreatment
Placebo
speech
1.0±1.4
swallowing
0.3±0.6
taste
0.4±0.5
pharyngeal irritation 0.8±0.9
postpretreatment treatment
Placebo RF-group
0.7±1.1
0.4±0.8
0.3±0.5
0.4±0.6
0.4±0.6
0.3±0.7
0.6±1.4
1.1±1.0
RF-surgery of the soft palate for primary snoring is significantly more effective than placebo in reducing nightly snoring
sounds. Nevertheless, snoring is not eliminated and only a moderate 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-controlled clinical trials to critically evaluate the various treatment
options for primary snoring.
posttreatment
RF-group
0.3±0.5
0.4±0.5
0.3±0.4
1.5±1.8
VAS: visual analogue scale; RF: radiofrequency; mean values ± SD
According to our results, two sessions of RF-surgery were significantly more effective than placebo in reducing socially disruptive snoring as assessed by a bed partner questionnaire. Nevertheless, 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 snoring. Nevertheless, our postoperative snoring scores are not in accordance 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 significant 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 literature 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 snoring, controlled clinical trials are necessary to critically evaluate
the efficacy of the numerous treatments available.
SLEEP, Vol. 28, No. 7, 2005
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