A hiccup (// HIK-əp; also spelled hiccough) is an involuntary contraction (myoclonic jerk) of the diaphragm that may repeat several times per minute. In medicine it is known as synchronous diaphragmatic flutter (SDF), or singultus, Latin for the act of catching one's breath while sobbing. The hiccup is an involuntary action involving a reflex arc. Once triggered, the reflex causes a strong contraction of the diaphragm followed about 0.25 seconds later by closure of the vocal cords, which results in the classic "hic" sound. At the same time, the normal peristalsis of the esophagus is suppressed.
Hiccups may occur individually, or they may occur in bouts. The rhythm of the hiccup, or the time between hiccups, tends to be relatively constant.
A bout of hiccups, in general, resolves itself without intervention, although many home remedies are often used to attempt to shorten the duration. Medical treatment is occasionally necessary in cases of chronic hiccups.
- 1 Why hiccups evolved
- 2 Signs and symptoms
- 3 Causes
- 4 Pathologic causes for hiccups
- 5 Treatment
- 6 Society and culture
- 7 See also
- 8 References
- 9 Further reading
- 10 External links
Why hiccups evolved
The sound of a human hiccup
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It has been proposed 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. 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.
The phylogeny hypothesis explains how the hiccup reflex might have evolved, and if there is not an explanation it may explain hiccups as an evolutionary remnant, held-over from our amphibious ancestors. This hypothesis has been questioned because of the existence of the afferent loop of the reflex, the fact that it does not explain the reason for glottic closure, and because the very short contraction of the hiccup is unlikely to have a significant strengthening effect on the slow-twitch muscles of respiration.
Clearance of air from stomach
A more recent explanation by Howes in 2012 suggests that hiccups may have evolved along with other reflexes developed in mammals that allow them to coordinate suckling milk and breathing. Hiccups are only found in mammals, and are most common in infants, becoming rarer as mammals age. This may suggest that they evolved to allow air trapped in the stomach of suckling infants to escape, allowing more milk to be ingested. The hypothesis suggests that the air bubble in the stomach stimulates the sensory limb of the reflex at receptors in the stomach, esophagus and along the diaphragm. This triggers the hiccup, which creates suction in the chest, pulling air from the stomach up and out through the mouth, effectively burping the animal. This theory is supported by the strong tendency for infants to get hiccups, the component of the reflex that suppresses peristalsis in the esophagus, and the existence of hiccups only in milk-drinking mammals.
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 breathing, with sudden momentary pain of the throat, chest, or abdomen.
- Rapid eating 
- Intense emotions such as fear, anxiety, excitement, joy or euphoria
- Carbonated beverages, alcohol, dry breads, and some spicy foods.
Pathologic causes for hiccups
Hiccups may be triggered by a number of common human conditions. Rarely, they can be a sign of serious medical problems.
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 cause hiccups. 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.
- Metabolic diseases
- Diabetes
- Kidney failure
- Electrolyte imbalance
- Deviated septum
- Stroke 
- Multiple sclerosis
- Tumors
- Meningitis 
- Encephalitis
- Traumatic brain injury
- Vagus and phrenic nerve involvement
- Laryngitis
- Cysts
- Goiter
- Gastroesophageal reflux
Numerous medical remedies exist but no particular treatment is known to be especially effective. 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. 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 vagus nerve stimulation techniques mentioned previously.
An anecdotal medical approach is to install lidocaine liniment 3% or gel 2% into the ear canal. 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.
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. 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. The carbonation promotes quicker absorption. Carbonated beverages, including beer, by themselves may provoke hiccups in some people.
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.
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."
Society and culture
There are many superstitious and folk remedies for hiccups, including Headstanding, drinking a glass of water upside-down, being frightened by someone, breathing in a plastic bag and (most successfully) eating a large spoonful of peanut butter.
American Charles Osborne had hiccups for 68 years, from 1922 to February 1990, and was entered in the Guinness World Records as the man with the longest attack of hiccups an estimated 430 million hiccups later. 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". She was found guilty of first degree murder in September 2013 and sentenced to life in prison without parole. Briton Christopher Sands had hiccupped an estimated 10 million times in a 27-month period from February 2007 to May 2009 which were eventually discovered to be due to a tumor on his brain stem that had been pushing on nerves, causing him to hiccup every two seconds, 12 hours a day, an affliction that meant that he could hardly eat or sleep and finally stopped in 2009 following brain surgery.
In Slavic, Baltic and Hungarian folklore, it is said that hiccups occur when the person experiencing them is being talked about by someone not present. It is not clear how and why but hiccups in Indian, Nepalese and Arabic folklore are similarly said to occur when the person experiencing them is being thought of by somebody close.
- Wilkes, Garry (2 August 2007). "Hiccups". eMedicine. Medscape. Retrieved 22 April 2009.
- "Hiccups". Home Remedies. Retrieved 5 November 2011.
- Straus, C.; Vasilakos, K; Wilson, RJ; Oshima, T; Zelter, M; Derenne, JP; Similowski, T; Whitelaw, WA (February 2003). "A phylogenetic hypothesis for the origin of hiccough". BioEssays 25 (2): 182–188. doi:10.1002/bies.10224. PMID 12539245.
- Howes, D. (2012). "Hiccups: A new explanation for the mysterious reflex". BioEssays: n/a. doi:10.1002/bies.201100194.
- "Hiccups Happen!". University of Maryland Hospital for Children. Retrieved 2 April 2012.
- Milano, Meadow. "Causes of Hiccups". Archived from the original on 2010-11-25. Retrieved 2 April 2012.
- NUCLEUS & TRACTUS SOLITARIUS (VISCEROSENSORY). neuroanatomy.wisc.edu
- "Hiccups: Causes". MayoClinic.com. 2011-06-03. Retrieved 2013-07-10.
- Witoonpanich, R; Pirommai, B; Tunlayadechanont, S (2004). "Hiccups and multiple sclerosis". Journal of the Medical Association of Thailand = Chotmaihet thangphaet 87 (10): 1168–71. PMID 15560692.
- "Gastroesophageal Reflux Disease". A.D.A.M Medical Encyclopedia. PubMed Health. Retrieved 28 January 2013.
- Porter, Robert S., ed. (2011). "Hiccups". The Merck Manual Online. Merck Sharp & Dohme.
- Thomas, R. H; Thomas, N. J P (2006). "Miracle hiccough cure gets the attention it deserves". BMJ 333 (7580): 1222. doi:10.1136/bmj.39051.721632.3A.
- Engleman EG, Lankton J, Lankton B (December 1971). "Granulated sugar as treatment for hiccups in conscious patients". N. Engl. J. Med. 285 (26): 1489. doi:10.1056/NEJM197112232852622. PMID 5122907.
- Boswell, Wendy (25 March 2007). "MacGyver Tip: Cure hiccups with sugar". The People's Pharmacy (Lifehacker). Retrieved 30 November 2009.
- "Teen's hiccups stop after five weeks". ABC News Online. 2 March 2007. Archived from the original on 2007-03-04.
- Iwasaki, N; et al. (May 2007). "Hiccup treated by administration of intranasal vinegar". No to Hattatsu 39 (3): 202–5. PMID 17515134.
- Schaffer, Amanda (10 January 2006). "A Horrific Case of Hiccups, a Novel Treatment". New York Times. Retrieved 24 April 2008.
- Lockhart, R. D. (1974). Anatomy of the human body (2nd ed.). Lippincott. pp. 202–5.
- In pictures | Guinness medical record breakers | Longest attack of hiccups. BBC News. Retrieved on 2 June 2013.
- "Survivor of 68-Year Hiccup Spell Dies" (Sunrise Edition: 2.B. ed.). Omaha World-Herald. 5 May 1991.
- "Florida girl hiccuping again after returning to school". msnbc.msn.com. 16 March 2007.
- ""Hiccup Girl" Jennifer Mee May Use Tourette's Defense, Says Lawyer". CBS News. 27 October 2010.
- Symons, Jane (8 May 2008). "So does holding your breath REALLY banish hiccups?". London: The Sun.
- Provine, Robert R. Curious Behavior: Yawning, Laughing, Hiccupping, and Beyond (Harvard University Press; 2012) 246 pages; examines the evolutionary context for humans
- Shubin, Neil (February 2008). "Fish Out of Water". Natural History: 26–31. – hiccup related to reflex in fish and amphibians.
|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.
- WebMD: Hiccups