A hiccup (hiccough) is a brief burst of inspiratory activity involving the diaphragm and the inspiratory intercostal muscles with reciprocal inhibition of expiratory intercostal muscles. The sound ("hic") and discomfort result from glottic closure immediately after the onset of diaphragmatic contraction, i.e., the latter is insufficient or asynchronous. Hiccups may be characterized as a physiological form of myoclonus (or singultus).
Most episodes of hiccups are self-limited, but prolonged or intractable hiccuping (hocquet diabolique) should prompt a search for a structural or functional cause, either gastroenterological or neurological. Hiccuping is seldom the only abnormality if the cause is neurological since it usually reflects pathology within the medulla or affecting the afferent and efferent nerves of the respiratory muscles. Medullary causes include:
Infarction (posterior inferior cerebellar artery territory; lateral medullary syndrome, especially middle level and dorsolateral lesion locations)
Tumor Abscess Tuberculoma Syrinx Hematoma Demyelination
CNS infection, e.g., viral encephalitis
Treatment should be aimed at the underlying cause. If none is identified, physical measures to stop the hiccups, such as rebreathing, may then be tried. Of the many various pharmacotherapies tried, the best are probably baclofen and chlorpromazine.
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