Pain Sucks: A Mechanistic Explanatory Model of Baroreceptor-Mediated Analgesia During Nonnutritive Sucking in Infants

Abstract Background: The analgesic effect of nonnutritive sucking (NNS) has been described in controlled neonatal studies, although its underlying mechanism remains incompletely understood. Independently, human experiments have shown that targeted activation of carotid baroreceptors can influence the processing of nociceptive stimuli. Established external neck-suction techniques further demonstrate that mechanical pressure changes in the surrounding cervical soft tissues can produce physiologically effective distension of the carotid sinus. Explanatory model: We propose a previously unexplored mechanical link between these fields of research: high-frequency, pulsatile negative intraoral pressure impulses during NNS may be transmitted through the pharyngeal and parapharyngeal soft tissues, thereby altering the local transmural loading of the carotid sinus. The resulting phasic activation of baroreceptor afferents could contribute to the observed neonatal analgesia through the nucleus tractus solitarii (NTS) and associated central networks. Evidence and outlook: Peak negative pressures of approximately −144 mmHg and active sucking frequencies of 2 Hz have been measured during NNS. The individual elements of the model are anatomically well characterized and experimentally accessible; the critical transmission pathway from the oral cavity remains to be verified. Simultaneous oropharyngeal pressure measurements, high-resolution ultrasonography, and autonomic recordings offer a comparatively accessible, stepwise approach to testing the hypothesis.