hiccup

A hiccup or hiccough ( /ˈhɪkəp/ HIK-əp) is a myoclonus of the diaphragm that repeats several times per minute. In humans, the abrupt rush of air into the lungs causes the vocal cords to close, creating a "hic" sound.

In medicine it is known as synchronous diaphragmatic flutter (SDF), or singultus, from the Latin singult, "the act of catching one's breath while sobbing".^[1] The hiccup is an involuntary action involving a reflex arc.^[1]

A bout of hiccups, in general, resolves itself without intervention, although many home remedies are often used to attempt to shorten the duration.^[2] Medical treatment is occasionally necessary in cases of chronic hiccups.

Proximal cause of hiccups

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	Hiccup sound The sound of a human hiccup
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Phylogenetic hypothesis

Researchers at the Respiratory Research Group, University of Calgary, Canada, propose that the hiccup is an evolutionary remnant of earlier amphibian respiration; amphibians such as tadpoles gulp air and water across their gills via a rather simple motor reflex akin to mammalian hiccuping.^[3] In support of this idea, they observe that the motor pathways that enable hiccuping form early during fetal development, before the motor pathways that enable normal lung ventilation form. Thus, according to recapitulation theory the hiccup is evolutionarily antecedent to modern lung respiration. Additionally, they point out that hiccups and amphibian gulping are inhibited by elevated CO₂ and may be stopped by GABAB receptor agonists, illustrating a possible shared physiology and evolutionary heritage. These proposals may explain why premature infants spend 2.5% of their time hiccuping, possibly gulping like amphibians, as their lungs are not yet fully formed. Fetal intrauterine hiccups are of two types. The physiological type occurs prior to twenty-eight weeks after conception and tend to last five to ten minutes. These hiccups are part of fetal development and are associated with the myelination of the phrenic nerve, which primarily controls the thoracic diaphragm.

Intrauterine reflex

It has been proposed that fetal hiccupping ‘is a useful reflex to allow vigorous exercise of the respiratory inspiratory muscle without the inhalation of liquid. Immobilization of fetal muscle leads to disruption of development or atrophy, so that movement is required for normal development.’^[4] Fuller concludes: ‘hiccup should be reclassified as an essential intrauterine reflex that may recur, like other primitive reflexes, in adult life.’

Clearance of air from stomach

Hiccups are only found in mammals, and are most common in infants, becoming rarer as animals age. This may suggest that they evolved in order to allow air trapped in the stomach of suckling infants to escape, allowing more milk to be ingested.^[5]

Pre-phrenic nucleus irritation of medulla

Clinical case reports mention that lesions of the medulla that involve the area slightly ventral and lateral to nucleus and tractus solitarius result in hiccup. One (of several) explanations for this finding is that such a lesion “irritates” descending information from nucleus solitarius to the phrenic nucleus. The phrenic nucleus consists of a functionally related group of cell bodies in the ventral horn from C3-C5. Axons arising from the phrenic nucleus comprise the phrenic nerve, which innervates the diaphragm. The hiccups result from spasmodic lowering of the diaphragm that causes a short, sharp inspiratory cough. Brain stem lesions involving the area ventral and lateral to nucleus and tractus solitarius result in hiccup.^[6]

Signs and symptoms

• A single or a series of breathing diaphragm spasms, of variable spacing and duration.
• A brief (less than one half second), unexpected, shoulder, abdomen, throat, or full body tremor.
• Hiccups might be easily heard as a chirp, squeak, "hupp", or if controlled, a quick inhaling gasp, sigh, or sniff.
• The victim might complain of brief but distracting or painful, frequent or occasional interruptions in normal breath, with sudden momentary pain of the throat, chest, or abdomen.

Causes

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• Overeating^{[citation needed]}
• Rapid eating ^[5]
• Sudden temperature changes^{[citation needed]}
• Carbonated beverages, alcohol, dry breads, and some spicy foods.^[7]
• Laughing^[8]
• Certain drugs (opiates and benzodiazepines)^{[citation needed]}

• Tobacco use (nicotine)^{[citation needed]}

Causes of persistent hiccups

• Metabolic diseases^{[citation needed]}
• Diabetes^{[citation needed]}
• Kidney failure^{[citation needed]}
• Electrolyte imbalance^{[citation needed]}
• Deviated septum^{[citation needed]}

Infections

• Pneumonia^{[citation needed]}
• CLD^{[citation needed]}

CNS disorders

• Stroke^{[citation needed]}
• Multiple sclerosis^{[citation needed]}
• Tumors^{[citation needed]}
• Meningitis^{[citation needed]}
• Encephalitis^{[citation needed]}
• Traumatic brain injury^{[citation needed]}

Nerve damage/irritation

• Vagus and phrenic nerve involvement^{[citation needed]}
• Laryngitis^{[citation needed]}
• Cysts^{[citation needed]}
• Goiter^{[citation needed]}
• Gastroesophageal reflux^{[citation needed]}

Treatment

Numerous medical remedies exist but no particular treatment is known to be especially effective.^[9] Many drugs have been used, such as baclofen, chlorpromazine, metoclopramide, gabapentin, and various proton-pump inhibitors. Hiccups that are secondary to some other cause like gastroesophageal reflux disease or esophageal webs are dealt with by treating the underlying disorder. Home treatment like drinking water is effective. A simple treatment involves increasing the partial pressure of CO₂ and inhibiting diaphragm activity by holding one’s breath or rebreathing into a paper bag. Vagus nerve stimulation can improve hiccups, done at home by irritating the pharynx through swallowing dry bread or crushed ice, or by applying traction to the tongue, or by stimulating the gag reflex. The phrenic nerve can be blocked temporarily with injection of 0.5% procaine, or permanently with bilateral phrenicotomy or other forms of surgical destruction. Even this rather drastic treatment does not cure some cases, however.

In Plato's Symposium, Aristophanes has a case of the hiccups and is advised by Eryximachus, a physician, to cure them by holding his breath, or, failing that, by gargling or provoking sneezing. This ancient recommendation can be compared with the vagal nerve stimulation techniques mentioned previously.

It has been noted, however, that the process of holding one's breath serves only to quiet the sound.^{[weasel words]} When the breath is held in such a way that the chest cavity and lips are used to create a prison for the sound, hiccups can go unnoticed, but it must be noted that hiccups will run their full course when this method is acknowledged.^{[weasel words]} Many have noted, however, that this is the only true course of action.^{[weasel words]}

An anecdotal medical approach is to install lidocaine liniment 3% or gel 2% in the external ear. Somehow this creates a vagus nerve-triggering reflex through its extensions to the external ear and tympanus (ear drum). The effect can be immediate, and also have lasting effect after the lidocaine effect expires after about two hours.^[10]

A solution involving sugar placed on or under the tongue was cited in the December 23, 1971 issue of the New England Journal of Medicine.^[11]

Hiccups are treated medically only in severe and persistent (termed "intractable") cases, such as in the case of Jennifer Mee, a 19-year-old woman who, in 2007, hiccuped continuously for five weeks.^[12] Haloperidol (Haldol, an anti-psychotic and sedative), metoclopramide (Reglan, a gastrointestinal stimulant), and chlorpromazine (Thorazine, an anti-psychotic with strong sedative effects) are used in cases of intractable hiccups. Effective treatment with sedatives often requires a dose that renders the person either unconscious or highly lethargic. Hence, medicating with sedatives is only appropriate short-term, as the affected individual cannot continue with normal life activities while under their effect.

Persistent and intractable hiccups due to electrolyte imbalance (hypokalemia, hyponatremia) may benefit from drinking a carbonated beverage containing salt to normalize the potassium-sodium balance in the nervous system.^{[citation needed]} The carbonation promotes quicker absorption. Carbonated beverages, including beer, by themselves may provoke hiccups in some people.^{[citation needed]}

The administration of intranasal vinegar was found to ease the chronic and severe hiccups of a three-year old Japanese girl. Vinegar may stimulate the dorsal wall of the nasopharynx, where the pharyngeal branch of the glossopharyngeal nerve (the afferent of the hiccup reflex arc) is located.^[13]

Dr. Bryan R. Payne, a neurosurgeon at the Louisiana State University Health Sciences Center in New Orleans, has had some success with an experimental procedure in which a vagus nerve stimulator is implanted in the upper chest of patients with an intractable case of hiccups. "It sends rhythmic bursts of electricity to the brain by way of the vagus nerve, which passes through the neck. The Food and Drug Administration approved the vagus nerve stimulator in 1997 as a way to control seizures in some patients with epilepsy."^[14]

Society and culture

American Charles Osborne had hiccups for 68 years, from 1922 to 1990, and was entered in the Guinness World Records as the man with the longest attack of hiccups.^[15] In 2007, Florida teenager Jennifer Mee gained media fame for hiccuping around 50 times per minute for more than five weeks; she was given the nickname "Hiccup Girl".^[16][17] Briton Christopher Sands had hiccups for a period of almost three years which were eventually discovered to be due to a tumor located on the part of the brain that controls vascular activity. ^[18]

In Slavic and Baltic folklore, it is said that hiccups occur when the person experiencing them is being talked about by someone not present. Hiccups in Indian folklore are similarly said to occur when the person experiencing them is being thought of by somebody close.^{[citation needed]}

See also

• Getting the wind knocked out of you
• Sneeze
• Cough
• Mr. Hiccup

References

Further reading

External links

Look up hiccup in Wiktionary, the free dictionary.

• BBC News: Why we hiccup
• WIRED: The Best Cure for Hiccups: Remind Your Brain You’re Not a Fish
• Cymet TC (June 2002). "Retrospective analysis of hiccups in patients at a community hospital from 1995-2000". J Natl Med Assoc 94 (6): 480–3. PMC 2594386. PMID 12078929. //www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2594386.