Of the procedures employed, only the isolated interstitial radiofrequency treatments (RFT) and the SP implants can be regarded as minimally invasive techniques. Prerequisite for inclusion of the data into the following Table 10.1 is the application at least at the SP and TB, as well as the presentation of raw data for the calculation of the various parameters (Table 10.1).

A series of trials has been published regarding combined radiofrequency surgery at the TB and the SP. Steward et al. have treated a series of 29 patients with TB and SP radiofrequency surgery and have documented a statistically significant improvement in Apnea Hypopnea Index (AHI) and daytime somnolence [708]. The success rate was reported to be 59% (at least 50% reduction in AHI with postoperative values below 20). Comparable results have been published by Stuck et al. in 2004 where a statistically significant reduction in AHI and daytime somnolence was reported in a group of 20 patients [723]. Woodson et al. have published a remarkably designed trial comparing multilevel radiofrequency surgery at the TB and the SP with continuous positive airway pressure (CPAP) and placebo (sham-CPAP) [828]. Although the changes in the AHI in the radiofrequency group were not statistically significant compared to baseline and to placebo, subjective and functional outcome measures improved in statistical significance and there were no differences between the radiofrequency group and CPAP regarding these measure.

The data in the table are still very sparse. Yet we believe that it is possible to deduce two trends. On the one hand, the combined treatment of TB plus SP does not appear to significantly improve the results of an isolated TB treatment in respect to the AHI. In our clinical experience, the advantages of a combined treatment lie more in an additional effect upon the respiratory noises during sleep. We have recently been able to demonstrate [723] that the postoperative morbidity and complication rate after combined treatment and after isolated TB treatment are identical. Moreover, since the TB probes can also be used without difficulty at the SP, no significant further costs are created by an expansion of the therapy to the SP. Since snoring is frequently more of a burden to the patients than the health impediment caused by the often mild OSA, we almost exclusively perform combined treatments, even if the obstruction is assumed to be located solely at the TB.

Yet the relatively low success rate of the study by Fischer et al. [201] (RFT at the SP, TB and tonsils) is difficult to adequately interpret, since for other surgical procedures an unambiguously positive effect of tonsil reduction on the severity of the OSA has been demonstrated. The authors themselves use somewhat different success criteria and describe a success rate of 33%. According to our experience (Sect. 6.1.2) and that of other authors [495] RFT at the lymphatic tonsil tissue produces a pronounced volume effect; therefore we would have assumed a stronger effect on the AHI. Further studies will be needed to clarify this issue.

We see a second trend in the limitation of RFT to cases of mild OSA with an AHI of maximally 20. This trend is corroborated by the results of the currently single existing placebo-controlled study on this topic. Woodson et al. [828] treated 30 patients respectively either with CPAP, with combined RFT at SP and TB, and with a sham operation. Unfortunately, the authors did not provide any raw data; therefore, this study could not be included in Table 10.1. As expected, CPAP respiration was found to be superior to RFT, and RFT in turn superior to the sham operation. Yet in regards to the subjective results, which were measured with various validated test instruments for the assessment of life quality, no differences were found in the comparison of CPAP with RFT surgery. This means multilevel minimally invasive surgery is a valid option for selected patients with mild OSA with the understanding that they may require secondary treatment [214].

On the level of the SP, invasive therapy concepts include either a UPPP or an uvulopalatal flap. For the treatment of the hypopharyngeal obstruction different procedures have been recommended. Table 10.2 summarizes the existent data. In the case of a relevant clinical diagnosis, several authors additionally perform nasal surgery. Recently, we were able to demonstrate that additional nasal surgery does not have a positive effect on the severity of the OSA [766, 767]. This result is in line with the information we gathered in Chap. 4 in regards to isolated nasal surgery in the case of OSA.