Hiccup


A hiccup is an involuntary contraction of the diaphragm that may repeat several times per minute. The hiccup is an involuntary action involving a reflex arc. 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. Medical treatment is occasionally necessary in cases of chronic hiccups.

Signs and symptoms

A hiccup consists of a single or a series of breathing diaphragm spasms, of variable spacing and duration, and a brief, unexpected, shoulder, abdomen, throat, or full body tremor. Hiccups may present as an audible chirp, squeak, "hupp", or if controlled, a quick inhaling gasp, sigh, or sniff. They may also present as brief but distracting or painful interruptions in normal breathing, with sudden momentary pain of the throat, chest, or abdomen.

Causes

Pathophysiological causes

Hiccups may be triggered by a number of common human conditions. In rare cases, they can be a sign of serious medical problems.

Pre-phrenic nucleus irritation of medulla

Clearance of air from stomach

One suggestion is 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.

Phylogenetic hypothesis

An international respiratory research group composed of members from Canada, France, and Japan 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, the hiccup is evolutionarily antecedent to modern lung respiration.
Additionally, this group points 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.

Treatment

Hiccups are normally waited out, as any fit of them will usually pass quickly. Folkloric 'cures' for hiccups are common and varied, but no effective standard for stopping hiccups has been documented. Hiccups are treated medically only in severe and persistent cases.
Numerous medical remedies exist but no particular treatment is known to be especially effective, generally because of a paucity of high-quality evidence. 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. 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.
Haloperidol, metoclopramide, and chlorpromazine 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.
A vagus nerve stimulator has been used 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."
Persistent digital rectal massage has also been proven effective in terminating intractable hiccups.

Folk remedies

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.
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. Other potential remedies suggested by NHS Choices include pulling your knees up to your chest and leaning forward, sipping ice-cold water and swallowing some granulated sugar.

Society and culture

The word hiccup itself was created through imitation. The alternative spelling of hiccough results from the incorrect assumption that it originates from the word cough.
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. In 2007, Florida teenager Jennifer Mee gained media fame for hiccuping around 50 times per minute for more than five weeks. Christopher Sands, a Briton, 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.
In Slavic, Baltic, German, Hungarian, Turkish, Romanian and Indian folklore it is said that hiccups occur when the person experiencing them is being talked about by someone not present.