Transcutaneous Auricular Vagus Nerve Stimulation-Paired Rehabilitation for Oromotor Feeding Problems in Newborns: An Open-Label Pilot Study

Abstract

Neonates born premature or who suffer brain injury at birth often have oral feeding dysfunction and do not meet oral intake requirements needed for discharge. Low oral intake volumes result in extended stays in the hospital (>2 months) and can lead to surgical implant and explant of a gastrostomy tube (G-tube). Prior work suggests pairing vagus nerve stimulation (VNS) with motor activity accelerates functional improvements after stroke, and transcutaneous auricular VNS (taVNS) has emerged as promising noninvasive form of VNS. Pairing taVNS with bottle-feeding rehabilitation may improve oromotor coordination and lead to improved oral intake volumes, ultimately avoiding the need for G-tube placement. We investigated whether taVNS paired with oromotor rehabilitation is tolerable and safe and facilitates motor learning in infants who have failed oral feeding. We enrolled 14 infants [11 premature and 3 hypoxic-ischemic encephalopathy (HIE)] who were slated for G-tube placement in a prospective, open-label study of taVNS-paired rehabilitation to increase feeding volumes. Once-daily taVNS was delivered to the left tragus during bottle feeding for 2 weeks, with optional extension. The primary outcome was attainment of oral feeding volumes and weight gain adequate for discharge without G-tube while also monitoring discomfort and heart rate (HR) as safety outcomes. We observed no adverse events related to stimulation, and stimulation-induced HR reductions were transient and safe and likely confirmed vagal engagement. Eight of 14 participants (57%) achieved adequate feeding volumes for discharge without G-tube (mean treatment length: 16 ± 6 days). We observed significant increases in feeding volume trajectories in responders compared with pre-stimulation (p < 0.05). taVNS-paired feeding rehabilitation appears safe and may improve oral feeding in infants with oromotor dyscoordination, increasing the rate of discharge without G-tube, warranting larger controlled trials.

Keywords: feeding; hypoxic–ischemic encephalopathy; pediatric rehabilitation; transcutaneous auricular vagus nerve stimulation; transcutaneous vagus nerve stimulation; vagus nerve stimulation.

Figure 1

Experimental overview.

Figure 2

(A) Auricular vagus nerve fibers (He et al., 2012). (B) Close-up photo of the left ear with attached custom, 3D-printed transcutaneous auricular vagus nerve stimulation (taVNS) electrodes attached. (C) Photo of the taVNS-paired feeding session with stimulation delivered concurrently with bottle feeding (written informed consent was obtained from the legal guardians for the publication of this image).

Figure 3

Box and whisker plots for heart rate (HR) data collected during taVNS and control feeds (min to max). (A) taVNS with these parameters induces immediate, safe reductions in HR that recover during feeding (n = 7, 39 total feedings in seven participants). For the 5-min epochs prior to perceptual threshold (PT) and during taVNS-paired feeding, HR was averaged in 60-s intervals for a total of 5 min. (B) The mean lowest HR during PT was calculated from real-time HR monitor recorded during onset of stimulation to determine the PT. taVNS induced significant reductions in HR compared with those in pre-stimulation baseline (p < 0.0001); however, these reductions recovered to baseline levels immediately during the taVNS-paired feeding. There was no significant reduction in HR during control feeds (feeding HR recorded without taVNS administered, n = 7, 19 feeds).

Figure 4

Reproducibility and reliability of individual HR change. (A) Individual HR change from baseline with onset of stimulation and during taVNS -paired feeding by individual subject. HR is averaged over all taVNS-paired feedings for each individual subject. (B,C) HR data from individual treatment sessions in two representative participants. HR changes are shown for each individual taVNS-paired feeding session over 5 min before and during taVNS-paired feedings and the lowest HR recorded during onset of stimulation with PT determination.

Figure 5

Daily PO intake feeding volumes in ml/kg/day for both responders (full PO feeds without G-tube) and non-responders (G-tube placement). The data demonstrate no significant difference in feeding trajectories between groups in the pre-stimulation phase but significant differences in trajectories between responders and non-responders upon initiation of taVNS-paired feeding.