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.