[Study on changes of voice characteristics after adenotonsillectomy or adenoidectomy in children]

Objective: To study voice changes in children after adenotonsillectomy or adenoidectomy and the relationship with the vocal tract structure. Methods: Fifty patients were recruited in this study prospectively, aged from 4 to 12 years old with the median age of 6. They were underwent adenotonsillectomy or adenoidectomy in Beijing Tongren Hospital, Capital Medical University from July 2019 to August 2020. In the cases, there are 31 males and 19 females. Thirty-six patients underwent adenotonsillectomy and 14 patients underwent adenoidectomy alone. Twenty-two children (13 males, 9 females) with Ⅰ degree of bilateral tonsils without adenoid hypertrophy and no snoring were selected as normal controls. Adenoid and tonsil sizes were evaluated. Subjective changes of voice were recorded after surgery. Moreover, voice data including fundamental frequency(F0), jitter, shimmer, noise to harmonic ratio(NHR), maximum phonation time(MPT), formant frequencies(F1-F5) and bandwidths(B1-B5) of vowel/a/and/i/were analyzed before, 3 days and 1 month after surgery respectively.SPSS 23.0 was used for statistical analysis. Results: Thirty-six patients(72.0%,36/50) complained of postoperative voice changes. The incidence was inversely correlated with age. In children aged 4-6, 7-9, and 10-12, the incidence was 83.3%(25/30), 63.6%(7/11) and 44.4%(4/9) respectively. Voice changes appeared more common in children underwent adenotonsillectomy(77.8%,28/36) than in those underwent adenoidectomy alone(57.1%,8/14), but there was no statistical difference. After operation, for vowel/a/, MPT(Z=2.18,P=0.041) and F2(t=2.13,P=0.040) increased, B2(Z=2.04,P=0.041) and B4(Z=2.00,P=0.046) decreased. For vowel/i/, F2(t=2.035,P=0.050) and F4(t=4.44,P=0.0001) increased, B2(Z=2.36,P=0.019) decreased. Other acoustic parameters were not significantly different from those before surgery. The F2(r=-0.392, P =0.032) of vowel/a/and F2(r=-0.279, P=0.048) and F4 (r=-0.401, P =0.028) of vowel/i/after adenotonsillectomy were significantly higher than those of adenoidectomy alone. Half of patients with postopertive voice changes can recover spontaneously 1 month after surgery. Conclusions: Voice changes in children underwent adenotonsillectomy or adenoidectomy might be related to their changes in formants and bandwidths. The effect of adenotonsillectomy on voice was more significant compared with that of adenoidectomy alone. The acoustic parameters did not change significantly after surgery except MPT.