LVC Timing in Infant Pig Swallowing and the Effect of Safe Swallowing.
Andrew Gross, Jocelyn Ohlemacher, Rebecca German and 1 others
PMID 28780633WHAT IT FOUND
In infant pigs, unsafe swallows consistently showed delayed laryngeal vestibule closure and altered tongue and hyoid timing compared to safe swallows.
However, nerve damage itself did not change these closure timings, suggesting the mechanism for post-surgical aspiration remains unclear.
Key findings
01Laryngeal vestibule closure was significantly delayed in unsafe swallows (penetration or aspiration) compared to safe swallows, regardless of whether the recurrent laryngeal nerve was intact or lesioned.
02Lesion of the recurrent laryngeal nerve did not alter the timing of laryngeal vestibule closure or opening, indicating that the increased aspiration risk seen after such lesions is not caused by changes in these specific closure timings.
03Unsafe swallows were characterized by delayed posterior tongue movement to the caudal and dorsal positions, and delayed hyoid elevation, suggesting a breakdown in the coordination of oral and pharyngeal structures.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
This is an animal study using infant pigs, not human infants, so findings cannot be directly generalized to human patients. The sample size was very small (six pigs), although many swallows were analyzed. The study lesioned the right RLN, whereas human infant dysphagia often results from left RLN damage (e.g., after PDA closure). The study did not explain the mechanism by which RLN lesioning causes aspiration, as the expected changes in LVC timing were not observed post-lesion.
Declared interests
The study was supported by the National Institutes of Health (N.I.H., Extramural). No other conflicts of interest are explicitly stated in the provided text.
The easy way to misread this
Do not interpret these findings as evidence that laryngeal vestibule closure timing is the cause of aspiration in human infants with recurrent laryngeal nerve damage. The study showed that nerve lesion did not change closure timing, suggesting the mechanism for post-surgical aspiration in humans remains unclear and is not simply due to delayed closure.