Abstract
ObjectivesHigh-pitched voice impairment (HPVI) is not uncommon in patients without recurrent laryngeal nerve (RLN) or external branch of superior laryngeal nerve (EBSLN) injury after thyroidectomy. This study evaluated the correlation between subjective and objective HPVI in patients after thyroid surgery.MethodsThis study analyzed 775 patients without preoperative subjective HPVI and underwent neuromonitored thyroidectomy with normal RLN/EBSLN function. Multi-dimensional voice program, voice range profile and Index of voice and swallowing handicap of thyroidectomy (IVST) were performed during the preoperative(I) period and the immediate(II), short-term(III) and long-term(IV) postoperative periods. The severity of objective HPVI was categorized into four groups according to the decrease in maximum frequency (Fmax): <20%, 20-40%, 40-60%, and >60%. Subjective HPVI was evaluated according to the patient’s answers on the IVST.ResultsAs the severity of objective HPVI increased, patients were significantly more to receive bilateral surgery (p=0.002) and have subjective HPVI (p<0.001), and there was no correlation with IVST scores. Among 211(27.2%) patients with subjective HPVI, patients were significantly more to receive bilateral surgery (p=0.003) and central neck dissection(p<0.001). These patients had very similar trends for Fmax, pitch range, and mean fundamental frequency as patients with 20-40% Fmax decrease (p>0.05) and had higher Jitter, Shimmer, and IVST scores than patients in any of the objective HPVI groups; subjective HPVI lasted until period-IV.ConclusionThe factors that affect a patient’s subjective HPVI are complex, and voice stability (Jitter and Shimmer) is no less important than the Fmax level. When patients have subjective HPVI without a significant Fmax decrease after thyroid surgery, abnormal voice stability should be considered and managed. Fmax and IVST scores should be interpreted comprehensively, and surgeons and speech-language pathologists should work together to identify patients with HPVI early and arrange speech therapy for them. Regarding the process of fibrosis formation, anti-adhesive material application and postoperative intervention for HPVI require more future research.
Highlights
Thyroid surgery is a precise operation that requires, to the greatest extent possible, the preservation of the function of adjacent nerves when removing thyroid lesions
The qualitative and quantitative information provided by Intraoperative neural monitoring (IONM) is far superior to visual identification of nerves alone, and standardized procedures and guidelines have been proposed in several studies, enabling more reliable recording of recurrent laryngeal nerve (RLN) status [3,4,5,6,7]
The cricothyroid muscle (CTM) innervated by the external branch of the superior laryngeal nerve (EBSLN) can lengthen the vocal fold and increase the fundamental frequency of vocal fold vibration to produce a higher-pitched voice; many studies have focused on the relationship between the EBSLN and High-pitched voice impairment (HPVI) [9, 10]
Summary
Thyroid surgery is a precise operation that requires, to the greatest extent possible, the preservation of the function of adjacent nerves when removing thyroid lesions. Intraoperative neural monitoring (IONM), as an adjunct technique for localizing and identifying the recurrent laryngeal nerve (RLN) and the external branch of the superior laryngeal nerve (EBSLN), has been widely studied and used in routine thyroid surgery [1, 2]. The qualitative and quantitative information provided by IONM is far superior to visual identification of nerves alone, and standardized procedures and guidelines have been proposed in several studies, enabling more reliable recording of RLN status [3,4,5,6,7]. Fibrosis may form between the strap muscles and laryngotracheal unit and impair the vertical movement [14], and may form in lateral extralaryngeal muscles when overtraction during the surgery. If fibrosis is formed between strap muscle and CTM, HPVI may be caused by limited movement of CTM
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
