Resolution of vocal fold immobility in preterm infants.

Introduction: Vocal fold immobility (VFI) is an important sequela of preterm birth due to patent ductus arteriosus (PDA) ligation and invasive ventilation. A minority of these patients experience VFI resolution. The purpose of this study is to determine factors associated with VFI resolution in preterm infants.

Methods: This is a case control study of preterm (<37 weeks gestation) infants admitted to a metropolitan Level IV neonatal intensive care unit from 2006 to 2012. All patients diagnosed with VFI by flexible nasolaryngoscopy were divided into 2 cohorts: those with and without laryngoscopic resolution of VFI during follow-up. Univariate and multivariate analyses were performed to determine factors associated with VFI resolution.

Results: Of 71 patients with VFI and adequate follow-up, 17 (23.9%) experienced resolution. Median (range) follow-up was 25.7 (0.4-91.3) months and time to resolution 4.4 (0.4-38.8) months. Compared to the ongoing-VFI cohort, those who experienced resolution had higher median gestational age (31 vs 25 weeks, p = 0.006) and birth weight (1550 vs 765 g, p = 0.02), and lower likelihood of undergoing PDA ligation (47.1% vs 77.8%, p = 0.02). On multivariate analysis, history of PDA ligation remained independently associated with a lower likelihood of VFI resolution (p = 0.02, OR 0.2, 95% CI 0.1-0.8). Among PDA ligation patients, birth weight >1000 g was more common in the resolution cohort compared to the ongoing-VFI cohort (62.5% vs 24.4%, p = 0.047).

Conclusion: While lower birth weight and gestational age are known risk factors for VFI following PDA ligation, in this study, these factors were also associated with a decreased likelihood of VFI resolution. Furthermore, PDA ligation appears to be a risk for both the development and persistence of VFI. This evidence should inform prognosis and intervention decisions for preterm infants with VFI.