The cause depends on who you ask. The ancient Greeks thought hiccups were violent emotions erupting from body. Today, evidence points to spasms in the diaphragm, the large muscle between the chest and abdomen that aids airflow during breathing (the medical term for hiccups is synchronous diaphragmatic flutter). A spasm of the diaphragm can be brought on by any number of things that might irritate the nerves that control the movement of the muscle. A full stomach, heavy boozing, rapid shifts in temperature either inside or outside of the stomach, and certain emotions like shock or excitement are all common culprits.
No matter the cause*, the result is the same. The diaphragm spasms and causes us to take a quick breath. The sudden rush of air causes the epiglottis (the flap that protects the space between the vocal cords) to shut and interrupt the breath, which makes the familiar "hic" sound.
What Cures Them?
A good cure also depends on the person you ask. Almost all cures are based on one of two principles. One type works its magic by overwhelming the vagus nerve with another sensation. The vagus nerve is a cranial nerve that innervates the stomach and conveys sensory information about the body's organs to the brain. When distracted by overwhelming information of another sort, it basically tells the brain that something more important has come up and the hiccuping should probably be stopped (vagus nerve stimulation is also used to control seizures in epileptics and treat drug-resistant cases of clinical depression). The other method for curing hiccups is to interfere with breathing, increasing the amount of carbon dioxide in the blood, and causing the body to focus on getting rid of the of the CO2 and not making hiccups.
Swallowing a spoonful of sugar is probably the most commonly prescribed hiccup cure and falls in the first category. A teaspoon of sugar is usually enough to stimulate the vagus nerve and make the body forget all about the hiccups. Even ardent supporters of the sugar cure disagree if the sugar should be taken dry or washed down with water, though.
If this home remedy doesn't work, and your hiccups are both severe and persistent, you may need to bring out the big guns. For chronic cases like this, doctors sometimes use a cocktail of Reglan (a gastrointestinal stimulant) and Thorazine (an anti-psychotics with sedative properties) to quiet things down. In some cases that resist these drugs, Kemstro, an anti-spasmodic, is also used. Other doctors have used vagus nerve stimulators implanted in the upper chest of patients. The pacemaker-like devices send rhythmic bursts of electricity through the vagus nerve to the brain to keep the hiccup cycle in check.
Sugar has always worked on our web editor Jason's hiccups. I prefer to hold my breath until they go away. What method do you use?
* While the causes mentioned above are pretty common, there have been specific cases of hiccups attributed to skull fractures, tuberculosis and constipation (a winning combination if there ever was one).