Discussion
This systematic review and metanalysis of seven and six studies, respectively, has three main findings. First, DISE-directed tongue surgery in children with persistent OSA (or surgically naive with small tonsils) reduces AHI by approximately 50%. The pre- and post-tongue surgery AHI decreased from 9.5 ± 12.1 to 4.2 ± 6.9 events/hr (p < 0.04) (Table 1) with an MD of -5.13 [95% CI -7.13, -3.13], Z-score 5.02 (P<0.00001) (Figure 2). There was moderate heterogeneity for AHI data largely owing to the heterogeneity of the patient population studied in Ulualp et al. This retrospective study assessed ten children with a broad BMI range and variable syndromic status. They found PSG parameters improved in both syndromic and non-syndromic patients after lingual tonsillectomy and tongue base reduction, but the majority of overweight and obese children did not experience normalization of parameters.16Post-operative PSG timelines were not consistently reported, but the studies that did reported an overall average of 2.1 months after surgery, which may not be enough time to permit healing leading to possible under or over-estimation of OSA.2
Second, DISE-directed surgery improves lowest oxygen saturation (LSAT) by almost 3%. The pre- and post-operative LSAT increased from 87.8 ± 5.7 to 90.1 ± 5.1% (p < 0.02) (Table 1) with a MD of 2.71 [95% CI 1.53, 3.89], Z score 4.51 (P<0.0001) (Figure 3). Similar to AHI, post-op LSAT may have continued to change as well since post-op PSG was completed on average less than 3 months after surgery, and no conclusion can be made about objective long-term outcome. He et al and Esteller et al did not report LSAT data so the LSAT analysis was lower in power compared to AHI but still included 264 patients.10,15 The LSAT data had moderate heterogeneity which appeared to stem from the small retrospective study published by Kanotra et al, but overall less heterogeneity compared to AHI and had a Cochrane Q statistic > 0.1, signifying heterogeneity may exist between studies rather than within each study. Kanotra et al evaluated five patients who underwent lingual tonsillectomy with epiglottopexy, and its primary objective was to assess swallowing outcomes. PSG data was available for four of the patients.11
Third, DISE-directed tongue surgery has an overall positive response rate. Nearly 70% of children either had an AHI reduction from moderate or severe to mild, reduced their AHI by 50%, or were completely cured of OSA. This collective evidence confirms the efficacy of the common clinical practice to use DISE to identify levels of obstruction and modify the surgical plan for children with persistent OSA, specifically for tongue surgery, which is an often-implicated site of obstruction especially in children with hypotonia or Down syndrome.