Treatment of Sleep Apnea with Prosthetic Mandibular Advancement (PMA)

Transcription

1 ~ Sleep, 15(6): American Sleep Disorders Association and Sleep Research Society Treatment of Sleep Apnea with Prosthetic Mandibular Advancement (PMA) Yoichi Nakazawa, Tetsuro Sakamoto, Rika Yasutake, Ken Yamaga, Tatayu Kotorii, Yasushi Miyahara, Yuh Ariyoshi and Tadarilitsu Kameyama Departments of Neuropsychiatry and Oral Surgery, School of Medicine, Kurume University, Kurume, Japan Summary: Nine males with sleep apnea DOES syndrome and three males with sleep apnea DIMS syndrome were treated with prosthetic mandibular advancement (PMA). The method uses a prosthesis, which is designed to advance the mandible 3-5 mm to prevent upper airway occlusion during sleep. The apnea index in the obstructive-type apnea and the percentage of time spent in obstructive apnea decreased significantly with PMA. Although the apnea index showed merely a tendency to decrease in central apnea (p < 0.1), the percentage of time spent in central apnea decreased significantly with PMA. A marked improvement in sleep structures was observed with PMA; a significant increase was seen in total sleep time, percent slow wave sleep (SWS) and percent rapid eye movement (REM) sleep, and the time spent in intra-sleep awakening decreased remarkably. PMA had excellent effects on snoring, and daytime hypersomnolence was reduced in almost all patients. Moreover, a survey on the therapeutic effects of PMA on sleep apnea syndrome and problems associated with wearing PMA was performed with a questionnaire for the sample of nine DOES patients and an additional 22 patients who were treated over a long time. The therapeutic effects could be maintained without any problems in about 213 of these patients. The therapeutic mechanisms of PMA in its reduction of both obstructive and central apnea are discussed. Key Words: Obstructive apnea-central apnea-prosthetic mandibular advancement-sleep changes. Sleep apnea, particularly the obstructive type, frequently results in many complications, including cardiovascular disorders, daytime drowsiness and nocturnal insomnia (I). Although the first step in the treatment of obstructive sleep apnea is the removal of any obvious causes of upper airway obstruction, such causes are not detected in many cases. Accordingly, surgical (2) [tracheostomy, uvulopalatopharyngoplasty (UPPP)], mechanical [continuous positive airway pressure (CPAP) (3-5), diaphragm pacing (6), tongue-retaining device (TRD) (7)] and medical [respiratory stimulants (8), central stimulants (9), progesterone (10), acetazolamide (11)] treatments have been employed in these cases. However, many of these treatment modalities are cumbersome and frequently have associated problems for patients, while they show therapeutic effects on sleep apnea. In 1984, Meier-Ewert et al. (12) reported that use of a prosthesis designed to nonsurgically pull the mandible 3-5 mm forward markedly reduced the occur- Accepted for publication July Address correspondence and reprint requests to Dr. Y oichi Nakazawa, Department of Neuropsychiatry, School of Medicine, Kurume University, 67 Asahi-machi, 830 Kurume, Japan. 499 rence of obstructive sleep apnea by opening the oropharyngeal airway. They termed this therapy "prosthetic mandibular advancement (PMA)" (12-14). Similar treatment modalities have been independently developed for sleep apnea by some researchers (15-19) and have been shown to reduce obstructive sleep apnea. In this study, we tried to treat some patients with sleep apnea syndrome by PMA and found it to be therapeutically effective not only on obstructive apnea but also on central apnea. Although it has been reported that CPAP and TRD decreased both types of sleep apnea, the reduction of central apnea with PMA has not been reported so far. Accordingly, the fact that PMA reduced not only obstructive apnea but also central apnea in the present study may support the hypothesis of a developmental mechanism for central apnea proposed by Lowe et al. (18,20) and Issa and Sullivan (4). SUBJECTS AND METHODS The subjects included nine male outpatients with sleep apnea DOES syndrome (SASDOES) and three male outpatients with sleep apnea DIMS syndrome

2 500 Y. NAKAZA W A ET AL. FIG. 1. Side view of prosthesis. (SASDIMS). The age of the patients ranged from 22 to 58 years (mean = 46.7 ± 13.0). No obvious cause for the sleep apnea could be detected by various examinations at the Department of Otorhinolaryngology, Kurume University Hospital, Japan, in the nose, throat or lower jaw of any of the patients, except for one patient in whom moderate hypertrophy of both the adenoid and palatine tonsils was identified. The prosthesis (Fig. I) was made at the Department Table 1. Frequency of SA Apnea index Time spent in SA/TST(%) Mean duration of SA (seconds) " = not significant. Table 2. of Oral Surgery, Kurume University Hospital. The procedures for making the prosthesis are as follows. First, plaster figures of the maxilla and mandible are molded. Protective plates are then made by pressing 2-mm-thick plastic discs onto both plaster figures. After the protective plates are fitted to both the maxilla and mandible, the mandible is advanced 3-5 mm and is fixed in that position. Following fixation, the prosthesis is promptly made with acrylic dental resin in the patient's mouth. With the 3-5-mm anterior advancement, the mandible is positioned about 4 mm inferior to its position during normal closure. After the patient had become accustomed to the prosthesis, polysomnographic (PSG) recording was conducted using the prosthesis, and the data were compared to those obtained without the prosthesis for each patient. PSG and sleep record analysis were performed according to the manual by Rechtschaffen and Kales (21). The recordings of ventilation and respiratory movements were performed by thermistors attached under a nostril and by an abdominal wall strain gauge, respectively. Each episode of lapse of ventilation lasting longer than 10 seconds was regarded as an episode of sleep apnea. Hypopnea was differentiated from apnea and was not estimated in the study, although it was observed in some patients. Statistical analysis was performed using the Student's t test and Mann-Whitney U test. Changes in sleep apnea parameters with prosthetic mandibular advancement (PAM) Pre-PMA ± ± ± ± 5.2 Post-PMA 138.0± ± ± ±4.4(n= II) Effects a/prosthetic mandibular advancement (PMA) on each type 0/ sleep apnea Pre-PMA Post PMA Frequency of OSk' ± ± 94.1 Frequency of CSA 89.4 ± ± 38.9 Frequency of MSA 79.7 ± ± 52.1 OSA index 22.6 ± ± 12.5 CSA index 14.2 ± ± 5.5 MSA index 13.7 ± ± 8.8 Time spent in OSA/TST (%) 16.2 ± ± 9.4 Time spent in CSA/TST (%) 9.2 ± ± 3.2 Time spent in MSA/TST (%) 12.5 ± I\ ± 8.7 Duration of OSA (seconds) 24.9 ± 5.8 (n = 12) 22.6 ± 3.9 (n = II) Duration of CSA (seconds) 20.4 ± 5.4 (n = II) 18.1 ± 2.8 (n = 10) Duration of MSA (seconds) 32.8 ± 4.0 (n = II) 29.4±7.7(n=ll) a Abbreviations: OSA = obstructive apnea; CSA = central apnea; MSA = mixed apnea; = not significant. p <0.01 <0.01 <0.01 " p <0.05 <0.05 <0.05 Sleep. Vol. /5. No.6, 1992

3 ' TREATMENT OF SLEEP APNEA WITH PMA 501 * * ** ** _ pre PMA _ post PMA * : p < 0.05 * * : p < 0.01 TST % sws % REM FIG. 2.. Comparison of sleep structures obtained before and after PMA treatment. TST -total sleep time; TISA-time of intra-sleep awakenmg. RESULTS The effects of PMA on sleep apnea The mean sleep apnea values before and during treatment with PMA are presented in Table 1. A significant reduction was found in the mean frequency of total apnea (p < 0.01), mean total apnea index (p < 0.01) and mean percentage of time spent in apnea (time spent in apnea/total sleep time) (p < 0.01), but not in the mean duration of all apneic episodes. The effects of PM A on each type of sleep apnea were investigated and the results are presented in Table 2. Although the reduction in the frequency of all apnea did not reach a significant level (p < 0.1), a significant decrease was found in the obstructive apnea index (p < 0.05). The apnea indices of central and mixed types did show a tendency to decrease (p < 0.1). The percentage of time spent in each obstructive and central apnea was significantly reduced with PMA (p < 0.05), but the percentage of time in mixed apnea did not decrease. No significant changes were observed in the mean durations of each apnea type with PMA. The changes in sleep structures with PMA The results are indicated in Fig. 2. The mean total sleep time increased from ± 78.2 minutes to ± 74.6 minutes with PMA (p < 0.05). Likewise, the mean % slow wave sleep (SWS) (p < 0.05) and % rapid eye movement (REM) sleep (p < 0.01) increased with PMA. Conversely, the time of intra-sleep awakening was significantly reduced with PMA (p < 0.01). Changes in subjective symptoms and snoring with PMA The results are indicated in Table 3. Daytime sleepiness was improved by PMA in all but two patients. TISA Insufficient nocturnal sleep was observed in two patients before treatment with PMA, and the sleeplessness disappeared with PMA and hypnotics. On the other hand, snoring was markedly improved with PMA in all patients, according to an estimation by the patients' family members. Subjective estimates in regard to the long-term wearing of PMA For this purpose, a questionnaire consisting of four questions was sent by mail to the nine patients and an additional 15 patients who were treated with PMA. They were requested to fill them out by answering the following questions: 1) Have you been using PMA up to now and how long have you been using it? 2) Do you think PMA is effective for snoring, periodic breathing and daytime hypersomnolence? 3) Did you feel any problems associated with wearing PMA? 4) Why did you stop using PMA if you were not wearing PMA? The questionnaire was collected from 21 patients, and the data are presented in Table 4. Table 3. Improved and unimproved symptoms with prosthetic mandibular advancement PMA Case Age Improved I 52 Insomnia 2 28 EDS," snoring 3 58 EDS, snoring 4 36 EDS, snoring 5 58 Snoring 6 57 EDS, snoring, insomnia 7 22 EDS, snoring 8 30 EDS, snoring 9 56 Insomnia b Snoring Insomnia," snoring EDS, snoring " EDS = excessive daytime somnolence. b Hypnotics intake. Not improved EDS EDS Sleep. Vol. 15. No

4 502 Y. NAKAZA W A ET AL. Table 4. Subjective estimates of long-term use of prosthetic mandibular advancement (PMA) 1. Have you been wearing PMA up to now, and how long have you been using it? Yes, every night Yes, frequently No 10 (48%) 4(19%) 7 (33%) Periods of wearing (months) Is PMA effective for snoring, periodic breathing and daytime' somnolence? Disap- No No peared Reduced change answer Snoring 0 11 (79%) 3(21%) 0 Periodic breathing 1 (7%) 11 (79%) 1 (7%) 1 (7%) Daytime somnolence 3(21%) 7 (50%) 4 (29%) 3. Did you feel any problems associated with wearing PMA? 14 patients who had been wearing PMA every night or frequently Gnathodynia 0 Occlusive disorder 3 (21%) Dullness of jaw 1 (7%) No problems 10 (71%) 7 patients who stopped wearing PMA Effective but cumbersome Gnathodynia Unable to wear No problems but ineffective " Because of an artificial tooth. 3 (43%) 2 (29%) 1 (14%)" 1 (14%) Ten patients (48% of 21 patients) had been using PMA every night for more than 4 months, and four patients (19% of2l patients) had been frequently wear ing it for more than 5 months. The effects of PMA estimated by patients or their family members on snor ing, periodic breathing and daytime hypersomnolence were analyzed for the 14 patients. Eleven patients re ported a reduction in snoring. Periodic breathing had disappeared in one patient and decreased in 11 pa tients. Daytime hypersomnolence had disappeared in three patients and decreased in seven. Problems as sociated with the long-term appliance of PMA were reported in six of the 14 patients. No one complained of gnathodynia, but one patient reported dullness of the temporomandibular joint. Of seven patients who had stopped wearing PMA, two abandoned it because of gnathodynia and three more stopped because the appliance was considered cumbersome, even though it decreased the symptoms of sleep apnea. DISCUSSION It is well known that sleep apnea syndrome often results in physical complications such as polycythemia and pulmonary and cardiovascular disorders. In more serious cases, cor pulmonale or right ventricular heart Sleep, Vol. IS, No.6, 1992 failure can be induced (1). In addition, patients with sleep apnea syndrome frequently complain of excessive daytime drowsiness and/or insufficient nocturnal sleep, which sometimes disturbs their social lives. For these reasons, an effective treatment for the syndrome is needed. All current treatments have some advantages but also have varying disadvantages, including respiratory infection following tracheostomy, necessity of using a complicated apparatus (CPAP, diaphragm pacing), expense of apparatus (CPAP), cumbersomeness ofthe apparatus (CPAP, tongue retaining device) and side effects (medication). In Japan, acetazolamide has been widely used since it was approved for use in the treatment of sleep apnea in However, some problems with its long-term administration, including lithogenesis (22) and progressive decrease in the therapeutic effect (11), remain. Because most patients require lifetime medication, drug safety is an important consideration and should not be ignored. PMA was introduced as a treatment for obstructive sleep apnea by Meier-Ewert et al. (12-14), who attempted to prevent upper airway occlusion by using a prosthesis to hold the mandible in a forward position. Similar treatment modalities have been independently developed by SolI and George (15), George (16), Bohnham et al. (17), Lowe et al. (18) and Schmidt-Nowara et al. (19). Their technique is based on the fact that sleep apnea frequently occurs in men with retrognathia or micrognathia, conditions that facilitate upper airway occlusion by backward movement of the tongue during sleep. As expected, they found that PMA provided excellent therapeutic effects on obstructive sleep apnea without unfavorable side effects. There was marked improvement in oxygen saturation, and snoring and daytime somnolence disappeared immediately. In the present study as well, we confirmed a significant decrease in obstructive apnea with PMA. These results indicate that PMA contributes to airway patency. Although the reduction of central apnea with PMA has not been reported so far, it is noteworthy that the percentage of time spent in central apnea was also significantly reduced by PMA, although the overall central apnea index showed only a tendency to decrease (p < 0.1). Issa and Sullivan (4,5) demonstrated that high pressure of CPAP prevented not only obstructive apnea but also central and mixed apnea and resulted in quiet breathing in all patients. On the other hand, Cartwright and Samelson (7) designed a device that holds the tongue slightly forward when negative pressure to one of its compartments is applied. This device, called a tongue-retaining device (TRD), is designed to advance the superior surface of the tongue away from the posterior pharyngeal wall. It has subsequently been found that not only obstructive but also central apnea is de- I i

5 TREATMENT OF SLEEP APNEA WITH PMA 503 creased considerably during use of the TRD. These results are consistent with those of the present study and suggest that both obstructive and central apnea share a common pathogenesis because modalities that maintain open upper airway are effective in both types of apnea. Although the causes of central apnea remain obscure, a mechanism that may induce central apnea has been experimentally demonstrated in humans and animals (23-28). Reflexes originating from the upper airway have been shown to alter the respiratory pattern in association with depth of anesthesia or sleep (27). If airway mucosa is stimulated by various stimuli during wakefulness or light anesthesia, a cough reflex is induced. However, an apneic reflex (central apnea) is induced by the same stimuli during sleep or deep anesthesia. Because upper airway occlusion occurs when the anterior wall of the oropharynx adheres to the posterior wall, central apnea results from obstructive apnea because receptors responsible for the reflex are stimulated. Actually, Issa and Sullivan (5) accounted for the reduction in all types of apnea by CPAP as follows: CPAP initially improves obstructive apnea by providing a pneumatic splint for the upper airway; this then induces secondary improvement and suppression of central apnea induced by reflective inhibition of respiration through activation of tracheal receptors during upper airway obstruction. Although the mechanisms by which PMA improves central apnea may be explained in the same way, the specific therapeutic mechanisms by which PMA suppresses obstructive apnea should be noted. PMA lowers the mandible about 4 mm, in addition to advancing the antherior pharyngeal wall. Lowe et al. (20) have demonstrated that, in man, voluntary or passive opening of the mandible produces definite enhancement of genioglossal EMG through activation of receptors located in the mandibular joint. Because the contraction of the genioglossal muscle opens the airway, this may also help to suppress/prevent airway obstruction. Subjective estimates regarding the long-term wearing of PM A suggest that the therapeutic effects of PM A on sleep apnea can be maintained in about 213 of patients without such problems as gnathodynia. Finally, we emphasize that PMA is simple and extremely easy for patients to use. Moreover, it is an important consideration that the cost ofthe prosthesis is very low ($5-6), and the prosthesis is light (15 g) and portable. Although the number of patients tested is limited in the present study, we think that PMA may be considered the treatment modality of choice for sleep apnea syndrome, except in serious cases. 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