Endoscopic classification of pharyngeal stenosis pattern in obstructive sleep apnea hypopnea syndrome
Abstract
Abstract Twenty-one patients with obstructive sleep apnea–hypopnea syndrome (OSAHS) were classified into three categories according to their pharyngeal stenosis patterns during sleep, as determined from endoscopic findings: (i) a falling type (n = 6); (ii) an all-round type (n = 11); and (iii) a bilateral type (n = 4). In all patients with the bilateral type, the palatine tonsils were hypertrophied, and the apnea–hypopnea indexes (AHI) were improved markedly by surgery. Conversely, the AHI of patients with the falling and all-round types were reduced by a smaller percentage. Surgical therapy is only to be recommended to patients with OSAHS whose pharynx is bilaterally stenotic.
INTRODUCTION
In order to improve the treatment efficacy of upper airway surgery in treating obstructive sleep apnea– hypopnea syndrome (OSAHS), the detailed examination of upper airway morphology is very important. With regard to this issue, selection of the surgical method according to the site of obstruction has been considered generally to be the best approach. However, the sites of pharyngeal obstruction do not remain constant overnight.1 Taking this problem into account, we would like to propose a new classification of the pharynx by using endoscope during sleep, and have investigated the relationship between the treatment outcomes of upper airway surgery for each stenosis pattern.
SUBJECTS AND METHOD
Twenty-one patients with OSAHS who had undergone surgery at Tottori University Hospital between 1996 and 2000 were selected as subjects. Those patients with nasal disease or with a weight change of more than 5 kg at the time of polysomnography (PSG) after the surgery were excluded from the study. Endoscopic examination during sleep was performed prior to surgery, and PSG was performed both before and at least 6 months after surgery. The periods to PSG after surgery in the falling, all-round, and bilateral types were 12.5 ± 8.6 months, 11.7 ± 7.3 months, 10.8 ± 3.6 months, respectively. There were no significant differences between the three groups.
For evaluation of the upper airway, the patients were put to sleep with an intravenous injection. Judging from the endoscopic findings, the stenosis patterns of the pharynx were classified into three categories: (i) falling type (n = 6), in which the soft palate and tongue sank due to gravity; (ii) all-round type (n = 11), in which the submucosa of the pharynx looked very thick, whereby two out of these 11 patients had their hypertrophied tonsils covered in thick mucosa; and (iii) bilateral type (n = 4), which included three patients with hypertrophy of the palatine tonsils and another with enlarged tonsils buried in the arch of the palate. Tonsillectomy without uvulo-palato-pharyngo-plasty (UPPP) was performed on two patients with the bilateral type and on two patients with the all-round type. Laser-assisted uvulo-plasty was performed on one patient with the all-round type, and tonsillectomy and UPPP were performed simultaneously on all the other 16 patients.
The clinical backgrounds among the aforementioned three groups were compared. A comparison of the before- and after-surgery apnea–hypopnea indices (AHI) was also made, and the reduction rate of the AHI (reduced AHI/AHI before surgery) was calculated.
RESULTS
Subjects’ age, body mass index (BMI) and the period to PSG after surgery are reported in Table 1. Although the group with bilateral type includes the most obese patient as well as the youngest patients in the three categories, no statistical difference was observed.
| Falling type (n = 6) | All-round type (n = 11) | Bilateral type (n = 4) | All patients (n = 21) | |
|---|---|---|---|---|
| Age (years) | 48.8 ± 16.5 | 45.4 ± 10.0 | 28.5 ± 9.1 | 43.4 ± 13.7 |
| Body mass index (kg/m2) | 26.8 ± 2.7 | 27.7 ± 3.7 | 30.7 ± 4.4 | 27.8 ± 3.5 |
The reduction rate of the AHI in all patients (n = 21) was 46.0%. The bilateral type group showed the most severe OSAHS before surgery. However, this group showed a general reduction from 72.2(/h) to 5.8(/h) (92.0%), whereas the AHI of the groups with falling type and all-round type did not show as much reduction (21.6%, 42.7%, respectively) (Table 2).
| Before | After | Significance* | Reduction rate of AHI | |
|---|---|---|---|---|
| Falling type (n = 6) | 38.1 ± 16.3 | 29.1 ± 18.7 | NS | 21.6 ± 48.2% |
| All-round type (n = 11) | 49.1 ± 28.2 | 30.7 ± 24.9 | P = 0.007 | 42.7 ± 35.5% |
| Bilateral type (n = 4) | 72.2 ± 20.4 | 5.8 ± 1.2 | P = 0.06 | 92.0 ± 9.5% |
- * Significant according to Wilcoxon’s signed-ranks test; NS, not significant.
DISCUSSION
The study’s results suggest that surgical treatment in patients with bilateral type may be more effective than other forms of therapy, even in cases of severe OSAHS. These results are in agreement with a previous report in which tonsillectomy was found to be very effective in treating patients with hypertrophy of the tonsils.2 This finding might come from the morphological characteristics of the patients with bilateral type in whom the obstructed site is only located in the tonsils and other parts remain unobstructed. Conversely, in the groups with both falling type and all-round type, surgical treatment might not be effective. Accordingly, nasal continuous positive airway pressure or an oral appliance should be recommended for these groups. In conclusion, endoscopic the stenosis pattern of the pharynx provides a helpful indicator when selecting a surgical method for patients with OSAHS.
