Hiccup: mystery, nature and treatment.

Hiccup is the sudden onset of erratic diaphragmatic and intercostal muscle contraction and immediately followed by laryngeal closure. The abrupt air rush into lungs elicits a "hic" sound. Hiccup is usually a self-limited disorder; however, when it is prolonged beyond 48 hours, it is considered persistent whereas episodes longer than 2 months are called intractable. A reflex arc involving peripheral phrenic, vagal and sympathetic pathways and central midbrain modulation is likely responsible for hiccup. Accordingly, any irritant in terms of physical/chemical factors, inflammation, neoplasia invading the arc leads to hiccups. The central causes of hiccup include stroke, space occupying lesions and injury etc, whereas peripheral causes include lesions along the arc such as tumors, myocardial ischemia, herpes infection, gastroesophageal reflux disease and applied instrumentations on human body etc. Besides, various drugs (eg, anti-parkinsonism drugs, anesthetic agents, steroids and chemotherapies etc) are the possible etiology. An effective treatment of persistent hiccup may be established upon the correct diagnosis of lesion responsible for the serious event. The pharmacotherapy of hiccup includes chlorpromazine, gabapentin, baclofen, serotonergic agonists, prokinetics and lidocaine. Non-pharmacological approaches such as nerve blockade, pacing, acupuncture and measures to hold breathing are also successful. Finally, alternative medicines and remedies are convenient to treat hiccups with uncertain effect. In conclusions, hiccup is likely to result from lesions involving the hiccup reflex arc. The lesion may need to be localized correctly for ablative treatment in patients with intractable hiccup. Apart from lesion ablation, drugs acting on reflex arc may be effective, while some other conventional measures may also be tried.