Chapter 18 – Hiccup

Publisher Summary This chapter presents a study on hiccup. Hiccup is a forceful, involuntary inspiration commonly experienced by fetuses and newborns and to a lesser extent by children and adults. It usually presents in otherwise healthy subjects as an annoyance for short periods. Hiccup consists of a periodic, synchronous, myoclonic contraction of the diaphragm and inspiratory intercostal musculature. Generally, glottal closure follows in 35 ms, stopping the air exchange abruptly and producing the typical "hic". Hiccups are most likely to occur during the period of maximal inspiration, because lung inflation inhibits vagal mucosal and laryngotracheal afferents, which are known to inhibit hiccups. In contrast to the protection reflexes like vomiting or coughing, hiccup has no physiological relevance. Three hypotheses regarding the pathophysiology of hiccups have been proposed so far. Hiccup could be because of a referred gastrointestinal reflex elicited by abdominal inputs. The afferent pathway consists of the phrenic nerve, vagal nerve, cervical plexus, and sympathetic fibers of the lower thoracic segments and the efferent pathway consists of the motor part of the phrenic nerve, vagus nerve, and sympathetic fibers of the cervical and thoracic segments innervating the auxiliary respiratory musculature. The chapter discusses hiccup as a referred gastrointestinal (vagal) reflex, hiccup as myoclonus, and hiccup as a primitive motor pattern. The discussion on practical management includes folk remedies, noninvasive therapy, pharmacological therapy, and invasive therapy.