Vocal acoustic changes before and after adenotonsillectomy in a 3-year-old: a 6-month single-case longitudinal analysis

Abstract Background Adenotonsillar hypertrophy is a major cause of pediatric sleep disorders and may also contribute to voice disorders; however, the acoustic features underlying these voice disorders remain unclear due to several factors, including scarcity of objective pediatric acoustic data, insufficient consideration of the recovery period of postoperative pharyngeal pain, and insufficient investigation into the effects of vocal abuse and fatigue. In this prospective, single-case study, acoustic analyses were conducted twice daily from the preoperative phase up to 6 months postoperatively to evaluate voice changes associated with adenotonsillar hypertrophy and adenotonsillectomy, including those influenced by vocal abuse and fatigue. Case presentation A 3-year-old boy presented with habitual snoring and obstructive sleep apnea (OSA) due to adenotonsillar hypertrophy. His sustained vowel phonations were collected for 10 days preoperatively and for 5 consecutive days at 1, 3, and 6 months postoperatively. His voices were recorded twice daily—once in the morning (AM, ≥ 30 min after waking) and once in the evening (PM, before dinner/bath)—and subjected to acoustic analysis using the Multi-dimensional Voice Program (MDVP, model 5105). Then, the average fundamental frequency (F0), standard deviation of F0 (STD), jitter percent (Jitt), shimmer percent (Shim), noise-to-harmonic ratio (NHR), F0-tremor and amplitude-tremor intensity index (FTRI and ATRI), degree of subharmonics (DSH), and degree of voiceless (DUV) were measured. Results Although significant differences were observed in F0 at both AM ( p = 0.014) and PM ( p = 0.019) evaluations, and in NHR and DSH during the PM evaluation were observed over time (NHR, p = 0.017; DSH, p = 0.011), post hoc Holm’s analysis revealed no significant differences between each time period. No significant changes were observed in the other parameters across the time points (Friedman test). In contrast, analysis of diurnal variation between AM and PM at each measurement point (Wilcoxon test) revealed a significant deterioration in preoperative DSH in PM relative to AM (median; AM = 0.25%; PM = 1.51%; p = 0.033). These findings suggest that adenotonsillar hypertrophy contributes to vocal abuse and fatigue and that adenotonsillectomy improves pediatric OSA and promotes voice development. However, as this is a single-case study, certain limitations, such as ambient noise and other potential confounding factors, must be considered during result interpretation. The findings are exploratory and warrant further investigation.