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Radiofrequency Tissue Volume Reduction
Multilesion vs Single-Lesion Treatments for Snoring
Michael Ferguson, MD;
Timothy L. Smith, MD, MPH;
Adam M. Zanation;
Wendell G. Yarbrough, MD
Arch Otolaryngol Head Neck Surg. 2001;127:1113-1118.
ABSTRACT
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Objective To compare the safety and efficacy of single-lesion and multilesion
radiofrequency tissue reduction (RFTR) of the soft palate for the treatment
of snoring.
Design Prospective, nonrandomized clinical trial.
Setting University hospital outpatient clinic.
Patients Nonrandomized patients undergoing RFTR to treat socially unacceptable
snoring. Of 47 patients, 16 received single-lesion treatments and 31 received
multilesion treatments.
Intervention Soft-palate RFTR was performed using a radiofrequency generator. Patients
required 1 to 3 treatments based on improvement or withdrawal from the study,
and each received 1, 3, or 4 lesions per treatment. Patients who received
single-lesion therapy did not cross over into the multilesion group; however,
5 patients in the multilesion group received 4-lesion therapy after a treatment
with 3 lesions.
Main Outcome Measures Outcome measures were determined using visual analog scale questionnaires
assessing level of snoring (snoring index) and level of pain (pain index)
associated with the procedure. Adverse events and complications during treatment
were cataloged. Data were collected before the procedure, 6 weeks after each
treatment, and an average of 16 months after the last procedure.
Results Single-lesion and multilesion groups showed significant improvement
in snoring after RFTR treatments (P<.01 for both).
However, compared with the single-lesion group, the multilesion group required
fewer treatments (1.94 vs 2.38; P = .05) and was
more than twice as likely to be cured after 2 treatments (61% vs 25%; P = .02). A trend toward improved clinical outcomes with
increased number of lesions and total energy per treatment was observed when
patients treated with 1, 3, or 4 lesions were compared. The 4-lesion group
had the most pronounced improvement in snoring index score per treatment,
the lowest number of treatments required for cure, and the greatest percentage
of patients cured after 2 treatment sessions. Follow-up demonstrated minimal
relapse of snoring in the multilesion group at a mean of 16 months. Although
there was a statistically significant increase in pain in the multilesion
group vs the single-lesion group, this increase did not increase narcotic
use or time off work and was considered minimal by reporting patients.
Conclusion Multilesion RFTR using higher energy levels per treatment is safe and
has increased efficacy without increased complications relative to single-lesion
therapy.
INTRODUCTION
SNORING IS a ubiquitous problem in American society. Results of epidemiological
studies1-3 indicate
that approximately 30% of all women and more than 40% of all men habitually
snore. Furthermore, the percentage of the population that snores increases
with increasing age.4 The actual number of
snorers might be higher than reported because most snoring questionnaires
depend on patient awareness of their own snoring, and subjective snoring is
often grossly underreported.5 Snoring is classified
as a parasomnia, or an undesirable physical phenomenon that occurs primarily
during sleep6 and is commonly believed to be
a precursor to more severe forms of sleep-disordered breathing, such as upper
airway resistance syndrome, obstructive sleep hypopnea syndrome, and obstructive
sleep apnea (OSA) syndrome.
The physiologic mechanism of snoring involves a change during sleep
in the configuration of the collapsible regions of the upper airway, Because
these regions are the known culprits of snoring, surgical techniques have
traditionally focused on these anatomic areas for treatment. Uvulopalatopharyngoplasty
(UPPP) was first introduced as a treatment for OSA but was also found to be
effective for the treatment of snoring.7 The
need for general anesthesia and the significant morbidity associated with
UPPP led otolaryngologists to search for refinements of the surgical treatment
of snoring. Office-based laser-assisted uvulopalatoplasty (LAUP) was the first
adaptation to achieve acceptance as an alternate to traditional UPPP.8 Although it eliminates the need for general anesthesia,
postprocedure pain and the expense of LAUP have limited its widespread use.
Current investigations are examining the use of radiofrequency energy
to reduce the tissue volume of the soft palate as treatment for snoring. Earlier
studies9-10 in the fields of cardiology
and urology have demonstrated the soft tissue ablation capabilities of radiofrequency
energy. More recently, researchers in the field of otolaryngology have begun
to study the effectiveness of radiofrequency tissue ablation in the treatment
of snoring and sleep-disordered breathing. The first studies published demonstrated
tissue volume reduction in the soft palate of porcine models, and subsequent
human studies revealed statistically significant improvements in snoring.11-12 Studies conducted since these initial
works have corroborated these findings.13
Because the treatment is associated with little pain, criticisms of
the use of radiofrequency tissue reduction (RFTR) in the treatment of snoring
have revolved around expense and the necessity for multiple treatment sessions.
To date, published studies12-13
have examined the effects of a single-lesion technique in the treatment of
snoring. In an attempt to reduce the cost of the procedure and decrease the
number of treatment sessions, we altered the described technique by delivering
more energy per session through the creation of multiple palatal lesions.
The objective of this study was to compare the safety and efficacy of single-lesion
vs multilesion RFTR for the treatment of snoring.
MATERIALS AND METHODS
STUDY PROTOCOL
This prospective, nonrandomized clinical trial examined patients who
had undergone RFTR of the palate at 2 institutions to determine the effect
of single-lesion vs multilesion RFTR on snoring. Our hypothesis was that the
creation of multiple lesions using higher total energy per treatment session
would produce a more pronounced and earlier improvement in snoring, thus reducing
the number of treatments required, the length of time before achieving the
desired result, and, ultimately, the cost of the procedure. Specifically,
this study compares patients treated with a single lesion, 3 lesions, or 4
lesions during each therapy session.
PATIENTS
Patients enrolled in this study were nonrandomized individuals who elected
to undergo RFTR to treat their socially unacceptable snoring. Inclusion criteria
included bothersome snoring that disturbed the patient's bed partner. No patients
with symptoms suggestive of OSA (excessive daytime somnolence, witnessed apnea,
excessive sleep requirements, or morning headaches) were enrolled. All patients
were extensively screened for lack of risk factors suggestive of OSA in the
history or physical examination (body mass index [BMI, calculated as weight
in kilograms divided by the square of height in meters] >31; neck circumference  43
cm in men and 41 cm in women; maxillary or mandibular deficiency; cervical
scoliosis; telescoping of the uvular mucosa; lateral wall hypertrophy; rugae
of the posterior pharyngeal wall; and enlarged tonsils, adenoids, or both).
Patients who had any of these risk factors or a positive polysomnography (PSG)
study result indicative of OSA were excluded from the study. Tongue size was
assessed using the classification of Mallampati et al,14
with all patients determined to be either class 1 or class 2. Careful and
thorough informed consent was obtained from all patients regarding diagnostic
workup and treatment of snoring. Institutional review board–approved
informed consent was obtained from all participants who enrolled before Food
and Drug Administration approval of RFTR.
Patients undergoing single-lesion RFTR were treated with a single lesion
to the midline of the palate (see the "Procedure" subsection). Patients in
the multilesion group received either 3 or 4 lesions per treatment session.
Five patients in the multilesion group received 3-lesion therapy for their
first treatment and then received 4 lesions for additional treatment sessions.
POLYSOMNOGRAPHY
For our patient population in general, PSG is a covered health care
benefit only for patients who have overt signs and symptoms of OSA. By design,
this study population did not have signs and symptoms of OSA other than snoring,
and despite extensive counseling regarding the risks of OSA, many patients
made an informed decision not to undergo PSG. Reasons given by patients regarding
their decision to forego PSG related primarily to the expense, inconvenience,
and waiting time associated with the test. Twelve patients agreed to undergo
standard monitored overnight PSG before treatment. From these data, the apnea
index (apnea episodes per hour), hypopnea index (hypopnea episodes per hour),
respiratory disturbance index (apnea index + hypopnea index), and lowest arterial
oxygen saturation were determined.
VISUAL ANALOG SCALES
Snoring Index
Visual analog scale (VAS) questionnaires were used to evaluate the level
of snoring symptoms in each patient. Based on a 10-point scale, the questionnaires
were completed by each patient's bed partner before the first treatment and
6 weeks after treatment. In addition, patients and their bed partners were
seen in follow-up or contacted by telephone, and longer-term snoring index
(SI) scores were determined at periods ranging from 2 months to 26 months
after the procedure. The snoring scale ranged from a level 0 (no snoring)
to a level 10 (a partner leaving the room because of intolerable snoring).
A score less than 5 indicated that snoring was present but was not bothersome
to the bed partner, and in general this level of snoring correlated with patients'
desire for no further treatments.
Pain Index
A 10-point VAS was used to assess postprocedure pain, with 0 indicating
no pain and 10 indicating the worst pain ever experienced by the patient.
Patients assessed postprocedural pain at their first clinic visit after the
procedure.
STATISTICAL ANALYSES
GraphPad InStat (GraphPad Software Inc, San Diego, Calif) or Statview
(SAS Institute, Cary, NC) software and the unpaired t
test were used to compare single-lesion and 3- or 4-lesion groups for pain
or success rate after 2 treatment sessions. For analyses of patients receiving
multiple lesions, data for the 3- and 4-lesion groups were combined (including
5 patients who received both 3 and 4 lesions). As opposed to the multilesion
group, all analyses of the 3- and 4-lesion groups excluded the 5 patients
who received both 3 and 4 lesions. Two-tailed P .05
was considered statistically significant.
PROCEDURE
Soft-palate RFTR was performed on each patient using a radiofrequency
generator (Somnus Medical Technologies Inc, Sunnyvale, Calif). Probes designed
to deliver submucosal radiofrequency energy were used to treat the midline
and paramedian of the soft palate. Each electrode was supplied with an insulating
cover (Somnus Medical Technologies Inc) that allowed exposure of only 1 cm
of active electrode to avoid mucosal injury during treatment. After informed
consent was obtained, the soft palate was anesthetized with 14% benzocaine
topical spray, followed by submucosal injection of 1% lidocaine with 1:100 000
epinephrine in the proposed treatment area. No patients required use of sedatives
or additional pain medications to tolerate the procedure. Single-lesion treatments
were aimed at the midline region of the soft palate, midway between the hard
and soft palatal junction and the base of the uvula. Patients in the 3-lesion
group received treatments at the midline and lateral regions of the soft palate,
just above the superior pole of the tonsillar pillars. Patients in the 4-lesion
group received 2 paramedian lesions and 2 lateral lesions. Target levels for
tissue temperature and energy delivered were determined before initiation
of the procedure and were recorded immediately after the procedure. Tissue
temperature was regulated via feedback thermocouples in the tip of the electrode
and was maintained at 85°C by alterations in power determined automatically
by programs within the radiofrequency generator. After the procedure, patients
were observed in the outpatient clinic for approximately 10 minutes before
discharge.
FOLLOW-UP
Patients returned for a follow-up appointment 6 to 8 weeks after the
initial procedure and at that time completed questionnaires regarding pain
and snoring results. Further treatments were offered based on results from
the previous treatment. Patients who did not come to their follow-up appointment
and patients for whom longer follow-up data were needed were contacted by
telephone. Bed partners completed the SI and patients completed the pain index
and relayed information on any complications. Patients in this study received
a maximum of 3 treatment sessions at which 1, 3, or 4 lesions were created.
The treatment end point was either patient satisfaction (a score of 5
on the VAS) or patient withdrawal from the treatment protocol at their request.
Reasons for withdrawal and complications were documented.
RESULTS
Forty-seven patients who underwent soft-palate RFTR were evaluated for
this study. Of these patients, 12 agreed to undergo overnight PSG before initiation
of RFTR treatments. The mean respiratory disturbance index score for patients
evaluated using PSG was 6.0 ± 4.3, and the lowest oxygen saturation
for individuals was greater than or equal to 87%. Of 47 patients in the study,
16 received single-lesion RFTR and 31 received multiple lesions. Of the 31
patients in the multilesion group, 19 had 3-lesion therapy only, 7 had 4-lesion
therapy only, and 5 received both 3 and 4 lesions at different treatment sessions.
When evaluating the data for comparison among treatment groups, the 5 patients
who received both 3- and 4-lesion therapy were excluded from the 3- and 4-lesion
groups but included in the multilesion group.
Single lesions were created midway between the hard and soft palatal
junction in the midline (see the "Materials and Methods" section) (Figure 1). In the single-lesion group, 11
patients were men and 5 were women (mean age, 44 years; mean BMI, 27.4) (Table 1). On average, each patient received
704 J per lesion, thus 704 J per treatment (Table 2). The average preoperative SI score was 8.94 on the VAS,
which equates to snoring heard in another room. An average of 2.38 procedures
of a maximum 3 were performed on this patient population, with snoring improvement
of 1.46 per treatment on the VAS. Of single-lesion patients, 25% obtained
a cure (SI score 5) after 2 treatment sessions (Table 2). Short-term follow-up demonstrated no decrease in efficacy
of the procedure at an average of 4 months after the last procedure.
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Figure 1. Single-lesion radiofrequency tissue
reduction. Submucosal delivery of a midline palatal lesion between the junction
of the hard and soft palates and the head of the uvula.
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Table 1. Patient Characteristics
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Table 2. Treatment Parameters and Results*
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The multilesion group, including all patients receiving either 3- or
4-lesion treatment (including 5 who received both 3- and 4-lesion treatments
at different treatment sessions), comprised 26 men and 5 women (Table 1). The average age of these patients was 53 years, and their
average BMI was 28.7. Nineteen patients received 3 lesions, 7 received 4 lesions,
and 5 received a combination of both. For 3-lesion treatments, lesions were
created at the midline and the lateral regions of the soft palate, just above
the superior pole of the tonsillar pillars. Patients in the 4-lesion group
received 2 paramedian lesions and 2 lateral lesions (see the "Materials and
Methods" section) (Figure 2). For
the multilesion group, an average of 1762 J was delivered per treatment (vs
704 J per treatment in the single-lesion group), with an average of 537 J
per lesion. In actual practice, more energy was delivered to the midline lesion
compared with the lateral lesions. The preprocedure SI score in the multilesion
group was higher than that in the single-lesion group (9.10 vs 8.94) and was
roughly equivalent to a bed partner's perception of intolerable snoring. Compared
with patients treated with single-lesion therapy, more improvement in snoring
per treatment session was noted (1.46 vs 2.14; P
= .20). The average number of treatment sessions was decreased in the multilesion
group compared with the single-lesion group (1.94 vs 2.38; P = .05). Likewise, the percentage of patients achieving an SI score 5
(indicating a clinical cure) after 2 treatments increased significantly compared
with the single-lesion group (61% vs 25%; P = .02).
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Figure 2. Four-lesion radiofrequency tissue
reduction. The typical paramedian and lateral location of 4-lesion radiofrequency
tissue reduction.
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Further analyses of the multilesion group revealed that 15 men and 4
women (mean age, 53 years; BMI, 28.5) comprised the 3-lesion group (Table 1). The 3-lesion data from the 5
patients receiving both 3 and 4 lesions are excluded from these analyses.
This group received, on average, 1580 J per treatment, with a mean of 527
J delivered to each lesion (Table 2).
After 2 treatment sessions, the percentage of patients obtaining a clinical
cure trended toward improvement relative to the single-lesion group (47% vs
25%; P = .18). In the 3-lesion group, 6 patients
(32%) withdrew from the study before 3 treatments without achieving a clinical
cure. These patients were considered failures in analyses of treatment efficacy.
Most commonly, patients who withdrew early did so because of a failure of
the first procedure to meet personal expectations of improved snoring.
The 4-lesion group included 6 men and 1 woman (Table 1). Their mean age was 52 years, and their mean BMI, 29.2,
was the highest of the 3 groups. Again, the 4-lesion data from the 5 patients
receiving both 3 and 4 lesions are excluded from analyses of this group. The
4-lesion group had the highest average total joules per treatment at 2420
(Table 2). Before intervention,
the 4-lesion group had the most bothersome snoring of any study group (SI
score, 9.25). The 4-lesion group also had the most pronounced improvement
in SI score per treatment session at 2.30. Increasing the number of palatal
lesions to 4 further reduced the average number of treatments necessary for
satisfactory snoring reduction (SI score 5) to 1.92. Despite the relatively
small number of patients in the 4-lesion treatment group (n = 7), the marked
increase in the percentage of patients cured after 2 treatment sessions remained
statistically significant compared with single-lesion patients (71% vs 25%; P = .04). No patients in the 4-lesion group withdrew before
completion of the study.
Extended follow-up of the multilesion patients at an average of 16 months
after the procedure revealed that the SI score had worsened by an average
of 0.2 points. This is equivalent to only a 2.9% worsening of snoring from
maximal improvement and was not statistically significant. Only 1 patient
reported a return to his preprocedure snoring baseline at extended follow-up,
with the remaining patients demonstrating little or no tendency toward relapse.
Because of the increased energy delivered with each treatment session
in the multilesion group, the possibility that postprocedure pain or complications
might be increased was evaluated. Although there was a statistically significant
increase in the average pain index score between the single-lesion and multilesion
groups (1.22 ± 1.29 vs 2.69 ± 1.52; P
= .04), the average pain index score for all patients regardless of the number
of lesions correlated with minimal pain (Table 2). No patients in either the single-lesion or multilesion
group required use of narcotic pain medication. Complications of RFTR were
uncommon in all treatment groups examined. Nearly all patients reported some
degree of palatal edema and an associated globus sensation that made sleep
uncomfortable. This sensation was worse on the day of the treatment and normalized
during the next 2 to 4 days. No palatal ulcerations or uvular slough were
seen. No patients reported dysphagia or odynophagia, and no patient refused
second or third treatments as a result of pain or complications. In addition,
no patient missed any days of work beyond the day of the procedure.
COMMENT
Initial management of obtrusive snoring frequently incorporates conservative
measures including diet modifications, weight loss, avoidance of alcohol and
sedatives, various dental appliances, external nasal dilator strips, and alterations
in sleep habits. Because behavioral modifications and nonprocedural remedies
are frequently unsuccessful, snorers often resort to surgical therapy. The
first surgical treatment commonly made available to the public was UPPP, introduced
by Fujita et al7 in 1981. Although designed
for treatment of OSA, UPPP is also effective in the treatment of snoring,
with most series reporting initial success rates of greater than 90%. The
drawbacks of UPPP include the requirement for general anesthesia and the association
with significant postoperative pain and complications. To avoid the requirement
for general anesthesia and hospital admission associated with UPPP, LAUP was
introduced by Kamami8 in 1990. However, after
the procedure, LAUP can be equally as painful as UPPP.15
In addition, LAUP can require multiple procedures for successful diminution
of snoring, and the cost might be equivalent to UPPP.
Recently, the use of radiofrequency energy for tissue volume reduction
has been developed for snoring treatment. Heat generated by temperature-controlled
radiofrequency energy denatures critical cellular proteins within a controlled
volume, causing cell loss resulting in scarring and contraction of the soft
tissue and subsequent improvement of upper airway obstruction.16
Submucosal delivery and temperature control of radiofrequency energy are thought
to be important in diminishing complications and postprocedure pain.
The goal of RFTR for the treatment of snoring has been to provide a
minimally invasive office-based therapy with results comparable to other available
procedures but with decreased morbidity and disruption of patients' normal
activities in the periprocedure period. On introduction of RFTR palatal therapy
for snoring, recommendations were to perform single palatal lesions at each
treatment session. Because the number of sessions necessary to obtain adequate
snoring reduction was excessive using the single palatal lesion technique,
we began treating with increased energies and multiple lesions in an attempt
to decrease the number of visits necessary for snoring reduction.
Previous studies have demonstrated the effectiveness of radiofrequency
energy for the treatment of snoring; however, no study to date, to our knowledge,
has detailed the ability to improve the treatment outcome by alterations in
the RFTR procedure.12-13 Our results
show a statistically significant improvement in the percentage of multilesion
patients cured after 2 procedures (61%) compared with the single-lesion group
(25%). In addition, although there was no significant difference between the
3- and 4-lesion patients, the improvement seen in the 4-lesion group relative
to the 3-lesion group and the significant difference between the single- and
4-lesion patients point to a clear trend toward increased efficacy with lesion
number and total energy delivered. Likewise, the improvement in the SI score
per procedure showed a clear trend correlating with increased number of lesions
and increased energy delivered per treatment. The 4-lesion group had the highest
total energy delivered and demonstrated the largest improvement in SI score
per treatment session. In addition, the 4-lesion group had the lowest number
of treatments performed per patient. Pain after the procedure was significantly
greater in patients treated with multiple lesions but was still considered
minimal by patients and was controlled with use of nonprescription analgesics.
The increased pain observed with increased number of lesions and total energy
delivered did not result in unplanned time away from work.
These data suggest that multilesion RFTR will result in a successful
outcome after 2 treatment sessions for most patients. In addition, delivery
of increased numbers of lesions was safe and was not associated with increased
complications. Although not directly evaluated in this study, decreased numbers
of treatment sessions until cure likely translate directly into less time
away from work, less visits to the physician, and a less costly health care
experience compared with single-lesion RFTR treatments.
Patient selection might directly impact the effectiveness of RFTR treatment
of snoring. It is likely that RFTR therapy for snoring might be less successful
in patients with concomitant OSA, but because of our attempt to exclude patients
with OSA and the inability to attain PSG on all patients, we could not evaluate
this variable. Although it would have been preferable to obtain sleep studies
on all patients interested in snoring therapy, we found that certification
and payment through third-party payers for PSG in this selected group of snorers
with no other indicators of OSA was constraining.
Evaluation of long-term snoring results after UPPP17
or LAUP18 has revealed that snoring can recur
over time after these procedures. Similarly, with single-lesion RFTR of the
palate for snoring, an extended follow-up study19
revealed a significant relapse rate. With mean follow-up of 14 months, the
authors found that 41% of their patients treated with single-lesion RFTR had
relapse in snoring. For the entire cohort of 22 patients, the authors found
that SI score increased 98% during follow-up.19
These authors suggested that the effectiveness in snoring reduction provided
by RFTR diminishes over time and therefore patients might need to expect to
undergo further "tune-up" treatments.19 Although
our study was not designed to examine extended-term efficacy, we found that
patients in the multilesion group followed up for a mean of 16 months had
only a 2.9% increase in their SI score. These data contrast with the 98% increase
in SI score seen by Li and colleagues19 and
suggests that multilesion RFTR snoring therapy might provide longer-lasting
results than single-lesion therapy. Longer-term evaluation of our patients
treated with single lesions is needed for direct comparison. In addition,
further studies examining patients who received multiple lesions will be needed
to determine the long-term effectiveness of multilesion vs single-lesion therapy.
AUTHOR INFORMATION
Accepted for publication March 20, 2001.
Corresponding author and reprints: Wendell G. Yarbrough, MD, Department
of Otolaryngology/Head and Neck Surgery and Department of Biochemistry and
Biophysics, University of North Carolina School of Medicine, Neurosciences
Hospital, CB 7600, UNC Hospitals, Chapel Hill, NC 27599-7600 (e-mail:
wgy{at}med.unc.edu).
From the Division of Otolaryngology/Head and Neck Surgery, Department
of Surgery (Drs Ferguson and Yarbrough and Mr Zanation), the Department of
Biochemistry and Biophysics (Dr Yarbrough), and the Lineberger Comprehensive
Cancer Center (Dr Yarbrough), University of North Carolina School of Medicine,
Chapel Hill; and the Department of Otolaryngology, Medical College of Wisconsin,
Milwaukee (Dr Smith).
REFERENCES
| |
1. Lugaresi E, Cirignotta F, Coccagna G, Paina C. Some epidemiological data on snoring and cardiocirculatory disturbances. Sleep. 1980;3:221-224.
ISI
| PUBMED
2. Lugaresi E, Cirignotta F, Montagna P, Sforza E. Snoring: pathogenic, clinical, and therapeutic aspects. In: Kryger MH, Roth T, Dement WC, eds. Principles
and Practices of Sleep Medicine. Philadelphia, Pa: WB Saunders Co;
1994:621-629.
3. Young T, Palta M, Demsey J, Skatrud J, Weber S, Badr S. The occurrence of sleep-disordered breathing among middle-aged adults. N Engl J Med. 1993;328:1230-1235.
FREE FULL TEXT
4. Norton PG, Dunn EV. Snoring as a risk factor for disease: an epidemiological survey. Br Med J (Clin Res Ed). 1985;291:630-632.
5. Hoffstein V, Mateikas S, Anderson D. Snoring: is it in the ear of the beholder? Sleep. 1994;17:522-526.
ISI
| PUBMED
6. Thorpy MJ. Classifications of sleep disorders. In: Kryger MH, Roth T, Dement WC, eds. Principles
and Practices of Sleep Medicine. Philadelphia, Pa: WB Saunders Co;
1994:426-436.
7. Fujita S, Conway W, Zorick F, et al. Surgical correction of anatomical abnormalities in obstructive sleep
apnea syndrome: uvulopalatopharyngoplasty. Otolaryngol Head Neck Surg. 1981;89:923-934.
ISI
| PUBMED
8. Kamami YV. Laser CO2 for snoring: preliminary results. Acta Otorhinolaryngol Belg. 1990;44:451-456.
PUBMED
9. 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;324:1605-1611.
ABSTRACT
10. Issa M, Osterling J. Transurethral needle ablation (TUNA): an overview of radiofrequency
thermal therapy for the treatment of benign prostatic hyperplasia. Curr Opin Urol. 1996;6:20-27.
11. 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;111:1348-1355.
FREE FULL TEXT
12. Powell NB, Riley RW, Troell RJ. Radiofrequency volumetric tissue reduction of the palate in subjects
with sleep-disordered breathing. Chest. 1998;113:1163-1174.
FREE FULL TEXT
13. 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;122:387-395.
PUBMED
14. Mallampati SR, Gatti SP, Gugino LD. A clinical sign to predict difficult intubation: a prospective study. Can Anaesth Soc J. 1985;32:429-434.
ISI
| PUBMED
15. Troell RJ, Powell NB, Riley RW, Li KK, Guilleminault C. Comparison of postoperative pain between laser-assisted uvulopalatoplasty,
uvulopalatopharyngoplasty, and radiofrequency volumetric tissue reduction
of the palate. Otolaryngol Head Neck Surg. 2000;122:402-409.
FULL TEXT
|
ISI
| PUBMED
16. Smith TL, Smith JM. Radiofrequency electrosurgery. Oper Tech Otolaryngol Head Neck Surg. 2000;11:66-70.
17. Levin BC, Becker GD. Uvulopalatopharyngoplasty for snoring: long-term results. Laryngoscope. 1994;104:1150-1152.
PUBMED
18. Wareing MJ, Callanan VP, Mitchell DB. Laser assisted uvulopalatoplasty: six and eighteen month results. J Laryngol Otol. 1998;112:639-641.
PUBMED
19. Li KK, Powell NB, Riley RW, Troell RJ, Guilleminault C. Radiofrequency volumetric reduction of the palate: an extended follow-up
study. Otolaryngol Head Neck Surg. 2000;122:410-414.
PUBMED
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