Here, we showed that SPWFPP may be a surgical option for OSA patients with lateral pharyngeal wall collapse, and the therapeutic outcome of SPWFPP depended on the DISE findings of the patient. In particular, the surgical outcome of SPWFPP was not successful and AHI score was aggravated in OSA patients with lateral pharyngeal wall collapse combined with epiglottis narrowing. SPWFPP provides a favorable improvement of sleep parameters in mild OSA patients or patients with primary snoring who had lateral bulk around the posterior pillar and circumferential narrowing at the retropalatal level in our previous study 10. However, the present study showed that SPWFPP can be applied to OSA patients in whom lateral pharyngeal wall collapse is characteristic, especially in severe OSA patients.
The lateral pharyngeal wall is more collapsible when pressured by airflow in OSA patients than in healthy patients, and the lateral pharyngeal wall of OSA patients can be thicker than that in healthy patients, making it a predominant anatomic factor in airway narrowing in OSA patients 7,19. Lateral pharyngeal wall collapse in OSA patients contributes to induce airway resistance in the upper airway, causing aggravation of sleep parameters during sleep 5,20–22. Previous studies showed that lateral pharyngeal wall collapse–related airway resistance causes aggravated intermittent hypoxia and oxygen desaturation in OSA patients 3, and higher AHI was characteristic in OSA patients with only antero-posterior (AP) narrowing at the level of the soft palate 6,18. Our previous study also revealed that OSA patients with lateral pharyngeal wall collapse had markedly higher AHI and RDI than OSA patients with only AP narrowing 23. Therefore, adequate therapeutic options are needed to improve lateral pharyngeal wall collapse in sleep surgery for OSA patients. Clinical confirmation of SPWFPP is essential as an appropriate therapeutic option to maintain the tension or stability of the lateral pharyngeal wall.
SPWFPP appears to offer similar therapeutic benefits to relocation pharyngoplasty and expansion sphincter pharyngoplasty for OSA patients with lateral pharyngeal wall collapse by enhancing the stability of the posterior pillar. Exposing the palatopharyngeus muscle at the upper part of the posterior pillar in the supra-tonsillar area without requiring tonsillectomy has the advantage of manipulating the muscle away from other longitudinal pharyngeal muscles, preserving their function and avoiding the intra- and post-operative complications associated with tonsillectomy.
In our previous data, we recommended SPWFPP to mild, moderate, and severe OSA patients with more than 50% narrowing in their lateral pharyngeal wall and tonsil enlargement, and we expected greater tension required to improve lateral pharyngeal wall collapse 10. We found that SPWFPP yielded a 42.4% success rate and a 71.2% response rate in OSA patients with lateral pharyngeal wall collapse 10. SPWFPP provided higher success rates in mild and moderate OSA subjects, with 50% success in mild and 56.2% success in moderate OSA subjects, according to improved AHI score 10. Additionally, snoring intensity improved significantly 10. The success rate of SPWFPP was lower in severe OSA patients with lateral pharyngeal wall collapse 10. Therefore, we suggested SPWFPP as a favorable surgical technique to maintain pharyngeal tension in mild or moderate OSA patients with lateral pharyngeal wall narrowing and to provide good surgical outcomes in patients with primary snoring 10. SPWFPP has advantages in removing palatal redundancy while creating lateral pharyngeal wall tension with minimal complications.
The present study revealed that SPWFPP significantly decreased AHI score in severe OSA patients with lateral pharyngal wall collapse and improved sleep parameters in mild OSA patients. However, we noticed abrupt worsening of AHI scores in OSA patients after SPWFPP; this aggravation of post-operative AHI was predominant in mild and moderate OSA patients with lateral pharyngeal wall collapse. Notably, the factor found to be significantly influencing the deterioration of AHI was epiglottis collapse based on DISE findings. Considering the relatively high occurrence of epiglottis collapse in mild OSA patients compared with severe OSA patients, it can be inferred that epiglottis collapse does not affect the increase in AHI when lateral pharyngeal wall collapse exists in the palate of OSA patients, but it is thought to influence the increase in AHI when the narrowing of the palatal level is corrected.
In our previous study 10, the success rate of SPWFPP in OSA subjects with lateral pharyngeal wall narrowing was lower than that of relocation pharyngoplasty and ESP in severe OSA patients 6,7. We also suggested that SPWFPP might be a favorable surgical technique to maintain pharyngeal tension in mild or moderate OSA patients with lateral pharyngeal wall narrowing and can provide good surgical outcomes to subjects with primary snoring 10. Compared with other sleep surgeries to correct lateral pharyngeal wall collapse, SPWFPP does not include tonsillectomy and has a shorter operating time; therefore, post-operative pain and complications were significantly reduced. Therefore, we extended the application of SPWFPP to patients with severe OSA. The indications applied in the present study were BMI less than 30 kg/m2, soft palate webbing, tonsil size 1 or 2, and documented soft palatal and lateral pharyngeal wall collapse in DISE and endoscopic examination. The current clinical data showed a significant reduction of AHI in severe OSA patients and improved sleep parameters following SPWFPP in mild or moderate OSA patients. We inferred some reasons or causes of the different efficacies of SPWFPP by OSA severity. Less prominent epiglottis collapse and more severe palatal collapse might be the most adequate indication of SPWFPP, as we could find from the results of the distribution of palatal collapse grades and epiglottic collapse grades by OSA severities. In mild OSA patients, even if palatal webbing presents in the physical examination, SPWFPP may not be effective if DISE indicates less severe palatal collapse or the concurrence of epiglottis collapse. In contrast, in severe OSA cases, there is a higher possibility of coexistence of degenerative redundancy if there is palatal webbing. Therefore, it is advisable to consider SPWFPP when posterior pillar webbing is present in physical examination, especially in severe OSA patients. However, in mild OSA cases, it is crucial to perform DISE to confirm the presence of palatal collapse and check for epiglottic collapse before proceeding with surgery.
This study has several limitations. The main limitation is the small number of subjects in our study. We also excluded patients who underwent surgery including other multilevel operations. This was a retrospective study, and the subjective opinions of the patients about sleep quality or snoring were not included in our analysis. We are also planning a further prospective study using SPWFPP for patients who fit the indications described in this study and aim to compare the efficacy with other surgical techniques for patients in similar situations.