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March 2023BACKGROUND
Vocal fold immobility (VFI) can cause significant morbidity for pediatric patients, including respiratory distress, poor airway protection resulting in aspiration and recurrent respiratory tract infections, and dysphonia. The most common etiology of VFI is an iatrogenic injury during cardiovascular surgery, though VFI may follow prolonged intubation, thyroid surgery, or other cervical or thoracic surgeries and can also be idiopathic, congenital, or neurologic in etiology.
The gold standard in the evaluation of VFI in children is awake flexible fiberoptic laryngoscopy (FFL). Over the past decade, ultrasound (US) has gained increasing attention as a modality for assessing vocal fold mobility in children, especially as a screening exam prior to FFL (Ann Otol Rhinol Laryngol. 2021;130:292-297; Int J Pediatr Otorhinolaryngol. 2017;100:157-159).
BEST PRACTICE
Although FFL remains the standard, US is emerging as an adjunct in the evaluation of VFI in children. As FFL is poorly tolerated in some patients, US may be used to narrow the focus of FFL to only patients at high risk for abnormal findings. When vocal fold mobility as assessed by FFL is indeterminate due to poor visualization, US may be used as a secondary modality. US is valuable as a screening tool, especially in cases where FFL is not available or safe, including in patients with tenuous cardiorespiratory status. Becoming facile at performing and interpreting US is easy for an examiner familiar with laryngeal anatomy. This may allow for pre- and postoperative evaluations of vocal fold mobility in patients undergoing procedures that place the recurrent laryngeal nerves at risk, such as cardiothoracic or cervical surgeries, especially when it may not be feasible for an otolaryngologist to be available to perform screening FFL. US may be used as surveillance in patients with known VFI. Whenever possible, FFL should be used to confirm VFI detected in US and to assess for other laryngeal pathology. Although the studies comparing FFL and US have been prospective and, at times, blinded, the studies are very small. There is an opportunity to report on large-scale screening programs comparing FFL and US implemented at pediatric tertiary care centers.