Ahiccup (scientific name singultus, from Latin for "sob, hiccup"; also spelled hiccough) is an involuntary contraction (myoclonic jerk) of the diaphragm that may repeat several times per minute. The hiccup is an involuntary action involving a reflex arc.[citation needed] Once triggered, the reflex causes a strong contraction of the diaphragm followed about a quarter of a second later by closure of the vocal cords, which results in the "hic" sound.
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 generally resolves itself without intervention, although many home remedies are often used to attempt to shorten the duration.[1] Medical treatment is occasionally necessary in cases of chronic hiccups.[2]
Hiccups affect people of all ages, even being observed in utero. They become less frequent with advancing age. Intractable hiccups, lasting more than a month, are more common in adults. While males and females are affected equally often, men are more likely to develop protracted and intractable hiccups.[3]
Histogram of period (in seconds) between each hiccup in a sequence of 50 samples in about 10 minutes. Mean: 11.40 s. Median: 10.715 s. Standard deviation: 2.88 s. Data set ranges from 6.28 s to 21.36 s.[original research]
A hiccup consists of a single or a series of breathing diaphragm spasms, of variable spacing and duration, and a brief (less than one half second), unexpected, shoulder, abdomen, throat, or full body tremor.
Hiccups may be triggered by a number of common human conditions. In rare cases, they can be a sign of serious medical problems such as myocardial infarction.[13]
Although no clear pathophysiological mechanism has been described, hiccups is known to have been the initial symptomofPlasmodium vivaxmalaria in at least one documented case.[16]
A leading hypothesis is that hiccups evolved to facilitate greater milk consumption in young mammals.[9] The coordination of breathing and swallowing during suckling is a complicated process. Some air inevitably enters the stomach, occupying space that could otherwise be optimally used for calorie-rich milk.
The hypothesis suggests that the presence of an air bubble in the stomach stimulates the sensory (afferent) limb of the reflex through receptors in the stomach, esophagus and along the underside of the diaphragm. This triggers the active part of the hiccup (efferent limb), sharply contracting the muscles of breathing and relaxing the muscles of the esophagus, then closing the vocal cords to prevent air from entering the lungs. This creates suction in the chest, pulling air from the stomach up into the esophagus. As the respiratory muscles relax the air is expelled through the mouth, effectively "burping" the animal.[citation needed]
There are a number of characteristics of hiccups that support this theory. The burping of a suckling infant may increase its capacity for milk by more than 15-25%, bringing a significant survival advantage. There is a strong tendency for infants to get hiccups, and although the reflex persists throughout life it decreases in frequency with age. The location of the sensory nerves that trigger the reflex suggests it is a response to a condition in the stomach. The component of the reflex that suppresses peristalsis in the esophagus while the airway is being actively blocked suggests the esophagus is involved. Additionally, hiccups are only described in mammals, the group of animals that share the trait of suckling their young.[citation needed]
An international respiratory research group composed of members from Canada, France, and Japan proposed that the hiccup is an evolutionary remnant of earlier amphibianrespiration.[17] 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, the hiccup is evolutionarily antecedent to modern lungrespiration.
Additionally, this group (C. Straus et al.) points out that hiccups and amphibian gulping are inhibited by elevated CO2 and may be stopped by GABABreceptoragonists, 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.[18]
The phylogenetic hypothesis may explain hiccups as an evolutionary remnant, held over from our amphibious ancestors.[19]
Episodes of hiccups usually last under 30 minutes. Prolonged attacks, while rare, can be serious. Root causes of prolonged hiccups episodes are difficult to diagnose.[failed verification] Such attacks can cause significant morbidity and even death.[3] An episode lasting more than a few minutes is termed a bout; a bout of over 48 hours is termed persistent or protracted. Hiccups lasting longer than a month are termed intractable. In many cases, only a single hemidiaphragm, usually the left one, is affected, although both may be involved.[3]
Hiccups are normally waited out, as any fit of them will usually pass quickly. Folk 'cures' for hiccups are common and varied. Hiccups are treated medically only in severe and persistent (termed "intractable") cases.[3]
Numerous medical remedies exist but no particular treatment is known to be especially effective, generally because of a lack of high-quality evidence.[20][21]
There are many superstitious and folk remedies for hiccups, including headstanding, drinking a glass of water upside-down, being frightened by someone, breathing into a bag, eating a large spoonful of peanut butter and placing sugar on or under the tongue.[24][25]
Acupressure, either through actual function or placebo effect, may cure hiccups in some people. For example, one technique is to relax the chest and shoulders and find the deepest points of the indentations directly below the protrusions of the collarbones. The index or middle fingers are inserted into the indents and pressed firmly for sixty seconds as long, deep breaths are taken.[26]
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.[27] Other potential remedies suggested by NHS Choices include pulling the knees up to the chest and leaning forward, sipping ice-cold water and swallowing some granulated sugar.[28]
A breathing exercise called Supra-supramaximal inspiration (SSMI) has been shown to stop persistent hiccups.[29] It combines the three principles of hypercapnia, diaphragm immobilization, and positive airway pressure. First, the subject must exhale completely, then take a deep breath. Then, they must hold their breath for ten seconds. After ten seconds, they must take another small breath without exhaling, then hold their breath for five seconds. Again, without exhaling, they must take another small breath and hold their breath for five seconds. Upon exhaling, the hiccups should be gone.
Drinking through a straw with the ears plugged is a folk remedy that can be successful.[30] In 2021 a scientific tool with a similar basis was tested on 249 hiccups subjects; the results were published in the Journal of the American Medical Association (JAMA).[31][30] This device is named FISST (Forced Inspiratory Suction and Swallow Tool) and branded as "HiccAway". This study supports the use of FISST as an option to stop transient hiccups, with more than 90% of participants reporting better results than home remedies. HiccAway stops hiccups by forceful suction that is being generated by diaphragm contraction (phrenic nerve activity), followed by swallowing the water, which requires epiglottis closure.[32]
The word hiccup itself was created through imitation. The alternative spelling of hiccough results from the association with the word cough.[33]
American Charles Osborne (1894–1991) had hiccups for 68 years, from 1922 to 1990,[34] and was entered in the Guinness World Records as the man with the longest attack of hiccups, an estimated 430 million hiccups.[35]
In 2007, Florida teenager Jennifer Mee gained media fame for hiccuping around 50 times per minute for more than five weeks.[36][37]
British singer Christopher Sands hiccupped an estimated 10 million times in a 27-month period from February 2007 to May 2009. His condition, which meant that he could hardly eat or sleep, was eventually discovered to be caused by a tumor on his brain stem pushing on nerves causing him to hiccup every two seconds, 12 hours a day. His hiccups stopped in 2009 following surgery.[38]
^ abcdWilkes, Garry. "Hiccups". eMedicine. WebMD. Archived from the original on 29 October 2008. Retrieved 29 June 2023.{{cite web}}: CS1 maint: bot: original URL status unknown (link)
^"Hiccups Happen!"(PDF). University of Maryland Hospital for Children. Archived from the original(PDF) on 10 January 2012. Retrieved 2 April 2012.
^Lauterbach, E. C. (1999). "Hiccup and apparent myoclonus after hydrocodone: review of the opiate-related hiccup and myoclonus literature". Clinical Neuropharmacology. 22 (2): 87–92. doi:10.1097/00002826-199903000-00004. PMID10202603.
^Witoonpanich R, Pirommai B, Tunlayadechanont S (2004). "Hiccups and multiple sclerosis". Journal of the Medical Association of Thailand (Chotmaihet Thangphaet). 87 (10): 1168–71. PMID15560692.
^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. PMID12539245. S2CID14200209.
^Porter, Robert S., ed. (2011). "Hiccups". The Merck Manual Online. Merck Sharp & Dohme. Archived from the original on 14 October 2013. Retrieved 7 October 2011.
^Engleman EG, Lankton J, Lankton B (December 1971). "Granulated sugar as treatment for hiccups in conscious patients". The New England Journal of Medicine. 285 (26): 1489. doi:10.1056/nejm197112232852622. PMID5122907.
^Morris, Luc G.; Marti, Jennifer L.; Ziff, David J. (1 January 2005). "Errata". Journal of Emergency Medicine. 28 (1): 117–118. doi:10.1016/j.jemermed.2004.11.013 – via www.jem-journal.com.
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. 117 (1): 26–31. INIST19986878. Hiccup related to reflex in fish and amphibians.