The reliability of flexible nasolaryngoscopy in the identification of vocal fold movement impairment in young infants

Objective: Flexible nasolaryngoscopy (FNL) is considered the gold standard for evaluation of vocal fold mobility but there has been no data on the reliability of interpretation in the infant population. Visualization may be limited by excessive movement, secretions, or floppy supraglottic structures that prevent accurate diagnosis of vocal fold movement impairment (VFMI). We sought to evaluate the inter- and intra-rater reliability of FNL for the evaluation of VFMI in young infants.

Study type: Case-control.

Methods: Twenty infants were identified: 10 with VFMI and 10 normal as seen on FNL. Three pediatric otolaryngologists reviewed the video without sound and rated the presence and/or degree of vocal fold mobility. Twelve videos were repeated to assess intra-rater reliability.

Results: There was substantial agreement between the reviewers regarding the identification normal vs. any type of VFMI (kappa = 0.67) but only moderate agreement regarding the degree of vocal fold movement (kappa = 0.49). Intra-rater reliability ranges from moderate to perfect agreement (kappa = 0.48-1).

Conclusion: FNL in infants is an extremely challenging procedure. Clinically, physicians frequently use the quality of the cry and the past medical and surgical history to help make a judgment of vocal fold movement when the view is suboptimal. These other factors, however, may bias the interpretation of the FNL. Without sound, there is only moderate inter-rater and variable intra-rater reliability for the identification of degree of movement on FNL. Otolaryngologists must be cognizant of the limitations of FNL when using it as a clinical tool or as a "gold standard" against which other modalities are measured.