Tongue Base Reduction with Radiofrequency Tissue Ablation: Preliminary Results after Two Treatment Sessions

Transcription

1 SLEEP AND BREATHING VOL. 4, NO. 4, 2000 Tongue Base Reduction with Radiofrequency Tissue Ablation: Preliminary Results after Two Treatment Sessions BORIS A. STUCK, M.D., JOACHIM T. MAURER, M.D., and KARL HÖRMANN, M.D. ABSTRACT Over the last few years, different surgical techniques for the treatment of obstructive sleep apnea syndrome have been developed. While new methods for the treatment of velopharyngeal obstruction turned out to be safe and effective, treatment of hypopharyngeal obstruction due to tongue base hypertrophy has remained, in many aspects, an unsolved problem. Surgical techniques for partial resection of the tongue base (midline glossectomy, lingualplasty) are effective but very invasive procedures requiring temporary tracheotomy, and have high postoperative morbidity. A maxillofacial approach showed significant reduction in the Respiratory Disturbance Index (RDI), especially when bimaxillar osteotomies are performed. Along with the concerns of postoperative morbidity, these techniques require general anesthesia and hospitalization. Tongue base reduction with temperature-controlled radiofrequency tissue ablation was introduced in 1998, and has proven to be a safe and simple procedure. Significant reduction in RDI has been shown in the majority of the treated patients. This procedure does not require general anesthesia and has low postoperative morbidity. For curative results, tongue base reduction with radiofrequency requires multiple treatment sessions. The goal of the present study is to investigate the beneficial effect of increased amount of energy applied per treatment session, reducing the number of treatment sessions per patient. By delivering increased amounts of energy, a similar cure and/or responder rate with 2 treatment sessions, rather than 5 to 6 as published in earlier studies, was accomplished. Postoperative morbidity was similar to previously published results although there was a slight increase in postoperative complications. Apart from the reduced number of treatment sessions needed per patient, we also demonstrated the beneficial effect of prophylactic use of antibiotics in our study group. This more aggressive treatment scheme appears to be well tolerated by the patients and may be an effective means of reducing the overall number of treatments. KEYWORDS: obstructive sleep apnea syndrome, tongue base hypertrophy, radio frequency tissue ablation Nasal continuous positive airway pressure (ncpap) is still considered the gold standard in the treatment of obstructive sleep apnea syndrome (OSAS). Nevertheless, tremendous effort has been made to establish the use of different techniques for surgical treatment. 1 For the treatment of nasal obstruction, well known surgical procedures such as septoplasty or turbinate reduction are used, while new procedures have been developed for the treatment of velopharyngeal obstruction. Techniques such as laser assisted uvulopalatoplasty (LAUP), 2,3 uvulopalatopharyngoplasty (UPPP) 4 7 or the Sleep Disorders Center, Department of Otorhinolaryngology, Head and Neck Surgery, University Clinic, Mannheim, Germany Reprint requests: Dr. Boris A. Stuck, Universitäts HNO Klinik, Klinikum Mannheim, Mannheim, Germany. boris.stuck@hno.ma.uni-heidelberg.de uvulopalatal flap 8,9 have become widely used over the last couple of years. Surgical methods for the treatment of nasal or velopharyngeal obstruction are widely employed, but surgical treatment for hypopharyngeal obstruction due to tongue base hypertrophy remains an unsolved issue in many ways. TREATMENT OF HYPOPHARYNGEAL OBSTRUCTION The diagnosis of hypopharyngeal obstruction due to tongue base hypertrophy is made by clinical examination and cephalometry. Important aspects to consider are the presentation of the epiglottic vallecula at the laryngeal endoscopy and the posterior airway space (PAS) on the lateral cephalometric x-ray. Copyright 2000 by Thieme Medical Publishers, Inc., 333 Seventh Avenue, New York, NY 10001, USA. Tel. +1(212) ,p;2000,04,04,155,162,ftx,en;sbr00158x 155

2 156 SLEEP AND BREATHING VOL. 4, NO. 4, 2000 At present, only a few surgical interventions for hypopharyngeal obstruction have proven to be effective in OSAS. Treatment of hypopharyngeal obstruction can be done either by increasing the PAS with intraoral devices, by maxillofacial surgery, or by surgical reduction of the tongue base by partial resection. The use of surgical techniques is limited by their invasive character and associated postoperative morbidity. INCREASING POSTERIOR AIRWAY SPACE Increasing the PAS by using intraoral devices for mandibular advancement has been shown to have beneficial effects in multiple types of sleep disordered breathing (SDB) This technique is often limited by individual mandibular mobility or problems with the maxillomandibular joint, resulting in reduced patient compliance. Riley et al introduced maxillofacial surgery combined with hyoid suspension for the treatment of OSAS This procedure requires extensive experience with maxillofacial surgical techniques. Bimaxilliar advancement has also proven to be very effective in patients with OSAS Nevertheless, these techniques are invasive procedures, and are accompanied by hospitalization and high postoperative morbidity. Another surgical treatment introduced by Riley and his colleagues is the genioglossus advancement by mandibular osteotomy. 17,18 This technique has produced a significant reduction of the RDI in a selected patient population. Recently, preliminary results using tongue base suspension (the tongue base is mobilized and then fixed in position with a suture at the anterior intraoral mandible) have been published, indicating positive effects on SDB. 19 Prospective studies with a greater number of patients will provide more information in the near future about this relatively new technique. TONGUE BASE RESECTIONS Tongue base reductions with partial glossectomydecribed as midline glossectomy or lingualplasty-have been described by different authors These procedures may be combined with partial epiglottectomy. Significant reduction in RDI has been shown for different groups of patients. However, due to the invasive character and the associated postoperative morbidity, these techniques are not routinely used. TONGUE BASE REDUCTION WITH RADIOFREQUENCY TISSUE ABLATION The key principle of temperature controlled radio frequency tissue ablation (RFTA) is the submucosal delivery of controlled and monitored radiofrequency energy at 460KHz. This technique results in controlled and well defined coagulative lesions. Over a period of 4 to 6 weeks, progressive cicatric shrinking is followed by tissue volume reduction. In 1997, Powell and co-workers applied the radiofrequency tissue ablation in ENT surgery. 23 By reducing palatal tissue with temperature controlled RFTA, they demonstrated significant improvement in the snoring of patients with primary snoring. 24 Li and Utley have demonstrated the safety and efficacy of turbinate reduction with RFTA in patients with turbinate hypertrophy. 25,26 Because of the noninvasive character and the minimal postoperative morbidity, it has become widely used over the last few years for the treatment of turbinate hypertrophy. Powell et al adapted this method not only for palatal reduction for the treatment of habitual snoring, but also for tongue base reduction in obstructive sleep apnea syndrome. 23,27 In Powell s pilot study, he showed a significant reduction of the mean RDI from 39.5 to 17.8 events per hour in a group of 18 patients, with a 5.5 mean number of treatments. This method has proven to be save and simple. 27,28 The aim of our study was to investigate the safety and efficacy of temperature controlled RFTA in OSAS by delivering higher amounts of energy per treatment session and thereby possibly reducing the number of treatment sessions per patient. MATERIALS AND METHODS Study Design This study aimed to evaluate the safety and efficacy of tongue base reduction using temperature controlled RFTA for the treatment of OSAS. The preliminary results of the study demonstrate the treatment effect after 2 treatment sessions. The RDI and Epworth Sleepiness Scale are the treatment outcome measurements used to evaluate treatment efficacy. The study was approved and accepted by the local ethics commitee of the medical faculty of the University of Heidelberg. Patients Between August 1999 and June 2000, 40 tongue base reductions with RFTA were performed on 20 patients with OSAS at the University Hospital Mannheim. Four female and 16 male patients, diagnosed with OSAS and tongue base hypertrophy, were treated. The average patient age was 49.3 years 8.46 (age range from 33 to 64 years). Mean body mass index (BMI) was 29.2 kg/m (range from 24 to 33 kg/m 2 ). Five

3 TONGUE BASE REDUCTION STUCK ET AL. patients had previous velopharyngeal surgery (tonsillectomy combined with a modified uvulaflap) without a sufficient reduction in the severity of their OSAS. The mean RDI was 28.0/h 11.2 (range 17.0 to 49.0). The mean lowest oxygen saturation (LSAT) was 79.3% 10.2 SD. All patients had a diagnosis of OSAS with an RDI of 15/h or greater. Male and female patients between the age of 18 and 65 were included if signs of tongue base obstruction were detected by clinical examination, laryngeal endoscopy, and cephalometry. Other sites of obstruction were ruled out by clinical assessment. Patients with an RDI greater than 60/h or an oxygen saturation less than 65% were excluded. Patients were required to use nasal CPAP for a minimum of one week after each treatment session. No surgical procedure apart from tongue base reduction was allowed during the time of the study. Methods At the baseline visit, all patients underwent intensive clinical examination, endoscopy, cephalometry, rhinomanometry, and allergometry. OSAS was diagnosed during two nights of standard polysomnography testing in the Sleep Disorders Center at the university ENT department in Mannheim according to the principles of the German Association of Sleep Medicine (DGSM). Monitoring included electroencephalograms, electrocardiograms, electrooculograms, chin and leg electromyograms, airflow, thoracic and abdominal efforts, snore microphone, and pulse oxymetry. Relevant symptoms associated with sleeping disorders, such as daytime sleepiness, were assessed with questionnaires (Epworth Sleepiness Scale [ESS]). Quality of life questionnaires were given before and after treatment (SF - 36 health survey). Functional parameters, such as snoring, speech, taste, swallowing and pharyngeal irritation, were assessed at baseline and four weeks after treatment using standard 10 cm visual analogue scales (VAS). The tongue base reduction procedure was performed under local anesthesia at the university ENT department Mannheim. Prilocain 1% with adrenalin 1: (Xylonest, ASTRA GmbH, Wedel, Germany) was used as local anesthetic after superficial cleaning of the tongue base mucosa with Hexetidin (Doreperol N, Dr. Rentschler, Laupheim, Germany). Midazolam (Dormicum, Hoffmann-La Roche, Grenzach-Whylen, Germany) was used for sedation under monitoring with ECG and pulse oxymetry. Nine to 17 ml of local anesthetic were used (mean 11.6 ml) and 3 to 10 mg of midazolam were needed for sufficient sedation (mean 5.8 mg). The standard dose was 10 ml of local anesthetic combined with 15 mg of midazolam. The model S2 Electrosurgical Generator (Somnus Medical Technologies, Sunnyvale, CA) was used for the production of temperature controlled radiofrequency energy. A special needle device was used for the treatment of the tongue base. Four application sites per treatment were chosen. The total amount of energy per treatment session was 2800 Joules (700 Joules/lesion). The target temperature was set to 85 C. Time needed per treatment session ranged from 8 to 26 minutes (mean 16.3 minutes). Nineteen treatments were performed under intravenous peri- and oral postoperative antibiotic prophylaxis with cefazolin 2g/ceruroxim 500 mg. Patients were kept overnight for postoperative monitoring. Perioperative pain was assessed using visual analogue scales. Follow-up visits for clinical examination were scheduled at day 1, day 7, and 1 month after surgery. Postoperative pain, dysphagia, and the need for analgesic medication were documented by the patients using standard 10 cm visual analogue scales and patient diaries. As anchors, no pain and severe pain were used. The second treatment session was performed 4 to 6 weeks after the initial treatment. Polysomnography was performed 4 to 6 weeks after the second treatment to assess changes in severity of SDB. RESULTS Postoperative Morbidity and Complications 157 No perioperative complications, especially bleeding or mucosal damage, occurred. Perioperative pain assessment showed good patients acceptance due to minimal perioperative pain (Fig. 1). Postoperative tongue swelling was mild (n = 25 treatments) to moderate (n = 15 treatments) one day after surgery. At the 1 week post treatment visit, tongue swelling was mild (n = 19) or absent (n = 17). Moderate postoperative tongue swelling at day 7 was noted after 4 treatments. No complications due to postoperative tongue swelling were reported. The results of visual analogue scales for postoperative pain are shown in Figure 2. Patients reported mild to moderate pain lasting for a mean of 3.8 days (range from 0 to 7 days), and the pain was controlled with nonsteroidal antiinflammatory drugs. Most patients returned to a diet of solid food after a mean of 2.5 days (range from 0 to 6 days). Ulceration of tongue base mucosa occurred in 2 cases but healed without any sequelae. During the first postoperative week, 4 additional hospital admissions due to more severe tongue swelling with dysphagia were seen. The symptoms were treated effectively with oral nonsteroidal antiinflammatory drugs, and intravenous corticosteroids and antibiotics. The patients were discharged after 1 (n = 3) to 2 (n = 1) days. One pa-

4 158 SLEEP AND BREATHING VOL. 4, NO. 4, 2000 FIG. 1. Paraoperative pain assessment by visual analogue scale (VAS). tient had a base of tongue infection at day 8 after his second treatment, requiring hospitalization, incision and drainage, and a temporary tracheotomy. The patient healed without further sequelae. According to the number of postoperative complications, there appears to be an overall complication rate of 18%, with 2.5% being severe complications. Periand postoperative antibiotic prophylaxis was used after treatment number 21 with significant reduction of postoperative complications. The post treatment complication rate was 5% without any severe complications in those patients that received peri- and post treatment antibiotics. Analyzing the visual analogue scales for functional parameters (speech, taste, swallowing, and pharyngeal irritation) at baseline visit and 4 weeks after the second treatment, no changes in these parameters were detected. Speech, taste and swallowing were not effected by tongue base surgery, and no pharyngeal irritation occurred. FIG. 2. Postoperative pain assessment by visual analogue scale (VAS), mean scores over one week.

5 TONGUE BASE REDUCTION STUCK ET AL. Therapeutical Effects The therapeutic effects after 2 treatment sessions were assessed based on a reduction in RDI and on the Epworth Sleepiness Scores. The improvement in RDI after 2 treatment sessions for every patient is shown in Table 1 and Figure 3. According to the changes in RDI from night to night, which were seen routinely in polysomnographical studies, changes of RDI plus or minus 20% were defined as normal variations. Therapeutical success was defined as a reduction in RDI greater than 50%, with a postoperative RDI less than 20/h. According to these definitions, deterioration of sleep disordered breathing was seen in 2 patients (10%). One of these patients showed a dramatic increase in RDI without a significant increase in BMI. The cause of this deterioration is unclear but may be due to an increase in complaints of nasal obstruction of unknown cause. The RDI of 5 patients (25%) remained unchanged. Thirteen patients (65%) showed an improvement in their OSAS (a reduction of RDI > 20%, as stated above). Nine patients (45%) were cured (which means a reduction > 50% and a RDI < 20/h) after 2 treatment sessions. The therapeutic effects with changes in RDI are shown in Figure 4. Daytime sleepiness was measured with the Epworth Sleepiness Scale. Changes of up to 20% were stated as normal variations. Changes from baseline and after treatment number two showed deterioration of daytime sleepiness in 3 patients. Daytime sleepiness remained unchanged in 5 patients, while 12 patients (60%) reported a > 20% improvement in their daytime symptoms (Figs. 5 and 6). TABLE 1. Polysomnographical Results by Individual Patient Before Treatment After Second Treatment 159 Patient No. AI HI RDI AI HI RDI AI, Apnea Index; HI, Hypopnea Index; RDI, Respiratory Disturbance Index. One patient presented with a significant reduction in weight (minus 16 kg) accompanied with a massive reduction of RDI. In this patient, evaluation of therapeutical effect was, of course, difficult. In all the other patients, BMI remained unchanged. FIG. 3. Changes in Respiratory Disturbance Index (RDI) after two treatment sessions.

6 160 SLEEP AND BREATHING VOL. 4, NO. 4, 2000 FIG. 4. Therapeutical effect on Respiratory Disturbance Index (RDI) after 2 treatment sessions. DISCUSSION Tongue Base Reduction with Radiofrequency The comparison of these results with those of the pilot study of Powell et al is complicated by the lack of polysommnographical controls in the latter publication. 27 Powell et al performed sleep studies at the beginning and at the end of their treatment, but not between the treatment sessions. Powell and co-workers report a mean number of treatment sessions of 5.5, with a total amount of energy delivered per treatment session of 1543 Joules, compared to 2800 Joules in this study. They reported 7 cure responders out of the group total of 18 patients (38%) compared to a cure rate of 45% in our group, using a similar definition of cure (50% reduction of RDI and/or a RDI less than 20/h). Additionally, Powell et al. reported 14 responders (78%) in total, 2 nonresponders (11%), and 2 patients (11%) with deterioration of SDB (RDI increased > 20%). Compared to our results of 65% responders, the difference in the responders rate is clear, but not dramatic. A higher mean RDI at baseline in the study of Powell et al should be considered an influencing factor. Analyzing the visual analogue scales concerning postoperative morbidity, mean postoperative pain scores are slightly elevated in our study compared to Powell s results. Powell reported postoperative pain scores of 4.4 at day 1, tapering down to 0.8 at day 7. The duration for pain medication was 3 to 4 days. We report postoperative pain scores of 5.8 at day 1 and 1.5 at day 7; the mean duration for analgesics was 3.8 days. FIG. 5. Changes in Epworth Sleepiness Scale (ESS) after 2 treatment sessions.

7 TONGUE BASE REDUCTION STUCK ET AL % 25% 60% improved unchanged deteriorated FIG. 6. Therapeutical effect on Epworth Sleepiness Scale (ESS) after 2 treatment sessions. The number of adverse events demonstrates a higher amount of postoperative adverse events in this study. Powell et al reported 3 complications out of 99 treatments (3%), compared to 7 out of 40 treatments (18%) in our study. This is due primarily to an increased number of mild complications. In both studies, one serious complication occurred, consisting of a tongue base infection. The increased number of adverse events in the presenting study may be due to the increasing amount of energy applied per treatment session, although we demonstrated a significant reduction in postoperative complications by the prophylactic use of antibiotics. Delivering higher amounts of energy and an increase in the number of lesions per treatment session do not appear to result in a dramatic increase in postoperative complications. Postoperative pain scores and the need for analgesic medication are similar to previously published data. 27 After 2 treatment sessions, we achieved similar cure and responder rates as Powell and his colleagues did. Methods of Tongue Base Resection Woodson et al report a modified technique, the lingualplasty, for midline glossectomyas as an effective alternative for the surgical treatment of OSAS in patients with hypopharyngeal obstruction. 22 Lingualplasty resulted in a 79% responder rate, defined as a RDI < 20/h. In contrast to these promising results, the invasive nature of lingualplasty limits the wide use of this technique. Tracheotomy was performed in all patients, with the procedure done under general anesthesia. Prolonged odynophagia in 3 patients resulted in high postoperative morbidity and postoperative pain. In the original 1991 publication of Fujita et al reporting on the efficacy of midline glossectomy, responder rates of 42% in a group of 12 patients were indicated. 20 Tonsillectomy was performed simultaneously in 7 of the 12 patients. Postoperative morbidity was not quantified and 3 postoperative complications (bleeding) occurred. Mickelson et al, in perfoming midline glossectomy combined with epiglottectomy, 21 could not demonstrate such a convincing reduction in RDI in their study with 12 patients. The cure rate was reported to be only 25%, with a mean RDI reduced from 48.9 to 35.7/h. Maxillofacial Surgery Preliminary results with a tongue-base suspension showed a reduction of mean RDI from 35 to 17/h in a group of 16 patients. 19 The advantage of this relativly new procedure is that it is minimally invasive. Experiences with a greater number of patients will give more detailed information about long term results and complication rates. However, this technique is performed under general anesthesia. Success rates of about 60% have been reported for inferior mandibular osteotomy and hyoid myotomy suspension, later called genioglossus advancement with hyoid myotomy (GAHM). 17,18 Lee et al report a cure rate of 69%, combining the genioglossus muscle advancement with the UPPP. 29 A more aggressive approach such as bimaxillar advancement may lead to better results, with success rates up to 100%. 18,16 Riley et al demonstrated maxillofacial surgery to be as effective as nasal CPAP in reducing relevant polysomnographical parameters. 14 CONCLUSION Minimally invasive procedures for the treatment of nasal or velopharyngeal obstruction have become available during the last few years. These procedures, like the UPPP, the uvulaflap, or RFTA for turbinate hypertrophy or velopharyngeal obstruction, often fail if the site of obstruction is primarily in the hypopharyngeal area. Tech-

8 162 SLEEP AND BREATHING VOL. 4, NO. 4, 2000 niques for the surgical treatment of hypopharyngeal obstruction are still invasive, leading to high postoperative morbidity and prolonged hospitalization. These techniques often require general anesthesia and temporary tracheotomy. Nevertheless, maxillofacial surgery has proven to be very effective in the treatment of SDB. Despite these problems, tongue base reduction with temperature-controlled radiofrequency has been successfully adapted into ENT surgery and has proven to be safe and effective. Powell et al. demonstrated a responder rate similar to the so-called stage one maxillofacial surgery (genioglossus advancement, hyoid myotomy) after 5.5 treatment sessions. The results of the present study demonstrate a cure rate of 45% (compared to 38% in the pilot study of Powell et al 27 ) after 2 treatment sessions by using higher amounts of energy delivered per treatment session (2800 J vs J). The advantages of RFTA for the treatment of tongue base hypertrophy are clear due to its minimally invasive character and this treatment does not require general anesthesia. Our experiences with a greater number of patients after this present study did not show any postoperative complications due to tongue swelling. As a result, we now perform temperature controlled RFTA as an outpatient procedure. Increasing the amount of energy per treatment session results in slightly higher postoperative pain scores and an increased number of mild postoperative complications. None the less, the amount of time an analgetic medication was used did not increase. The results of this study also demonstrate that the use of peri- and postoperative anitbiotic prophylaxis is required. Determining if additional therapeutic effects can be obtained by additional treatment sessions will be studied in the near future. REFERENCES 1. Hörmann K, Hirth K, Maurer JT. 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