Possible Clinical Evidence for a Glossopharyngeal Afferent Pathway in Human Hiccup Reflexes: A Report of Two Cases

Although hiccups are a reflex involving diaphragmatic contraction and glottic closure, the afferent pathway involved in humans remains unclear. We report the cases of two adult patients who developed hiccups during intravenous sedation for dental procedures. In both cases, midazolam administration immediately provoked persistent hiccups. Ultrasound-guided selective glossopharyngeal nerve block with local anesthetic resulted in immediate and complete hiccup cessation, allowing the uneventful continuation of dental procedures. Both patients had previously received midazolam without experiencing hiccups, suggesting that the drug alone was insufficient to trigger the response. Hence, reflex activation by pharyngeal stimulation from saliva or secretions may be necessary. These observations highlight a potentially under-recognized afferent pathway with diagnostic and therapeutic implications. The glossopharyngeal nerve contributes to hiccup generation in humans. Therefore, understanding hiccup pathophysiology may enable the management of underlying conditions in addition to symptom relief.