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Why hiccups are still a medical mystery

Child with hiccups
Written by Paul Taylor

QUESTION: My young son often gets the hiccups. That’s got me wondering why do people hiccup, and is there a proven way to make them stop?

ANSWER: Hiccups may be extremely common, but that doesn’t mean doctors have figured out what actually causes them.

Hiccups are one of the unsolved mysteries of the human body.  Maybe that’s not totally surprising. After all, they don’t usually indicate that something is seriously wrong and they normally stop on their own – often within a few minutes.

So, it’s not seen as a pressing problem that needs a lot of deep analysis and medical investigation, says Dr. Donald Redelmeier, a staff physician at Sunnybrook Health Sciences Centre and a professor of medicine at the University of Toronto.

What can be said with some certainty is that a hiccup involves two very distinct actions:

  • The diaphragm, the main muscle the powers the lungs, goes into spasm or contraction.
  • The epiglottis, a flap of tissue behind the tongue, slams shut over the top of the windpipe leading to the lungs.  This is known as “glottic closure” and the sudden reflexive motion produces the typical “hic” sound.

But there is no consensus about whether this sequence begins in the chest or the throat, says Dr. Redelmeier. In other words, does the spasm in the diaphragm trigger the epiglottis to shut, or vise versa?

Dr. Redelmeier, for one, thinks it starts in the throat. And he says hiccups illustrate a “much larger story” about the complex reflexes that help keep us alive.

He points out that the mouth is used to take in solids, liquids and air – and they must end up in the right place. If food or liquid goes down the wrong way and enters the lungs, it can lead to a potentially deadly infection known as aspirational pneumonia.

To prevent this from happening, a reflex triggers the epiglottis to cover the opening to the lungs when you swallow, thereby funneling food or drink down the esophagus into the stomach.

“It’s kind of amazing that we can breathe air into our lungs and drink into our stomachs and keep those two paths separate. ” says Dr. Redelmeier. “Most people just take this for granted.”

He speculates that this reflex could be hyperactive in young people and that extra responsiveness might explain why hiccups are fairly common in babies and young children.

As we age, the muscles that cause the epiglottis to spring into action might become less twitchy. As a result, older adults seem to have fewer bouts of hiccups than the young.

However, in people with certain neurological conditions – such as Parkinson’s disease, amyotrophic lateral sclerosis (ALS) and stroke – this reflex can cease to function properly.

“They are not suffering from hiccups anymore,” says Dr. Redelmeier.  “On the contrary, they have got a much more serious problem of liquids and solids ending up in their lungs.” For this group of patients, aspirational pneumonia is a common cause of death.

So, it’s important to keep the annoying hiccup in perspective.  It basically seems to be a protective response – although the timing is a bit off.  The epiglottis seals the windpipe “at the wrong moment, when it doesn’t really need to,” says Dr. Redelmeier.

In very rare cases, tumours, nerve damage or other medical ailments can cause persistent hiccups – lasting hours, days or even longer – and the patient needs to see a doctor.

According to Guinness World Records, an Iowa farmer, Charles Osborne, had a case of continuous hiccups lasting for 68 years, from 1922 to 1990.  They apparently started when he was attempting to weigh a hog before slaughter and the animal accidently fell on top of him.

The unfortunate farmer had several unsuccessful operations to correct the problem. The hiccups finally stopped on their own, but he died a year later from an unrelated cause – complications from ulcers.

Of course, the Iowa famer represents an extreme case and most of the time hiccups are fleeting.

On the Internet, you’ll find much speculation about the things that might trigger a routine bout of hiccups, ranging from an overly full stomach to excessive alcohol consumption. You’ll also come across scores of home remedies, including holding your breath, swallowing granulated sugar and pulling hard on your tongue. Yet it’s difficult to prove any of these approaches will work because most hiccups start and stop automatically – for no apparent reason.

“There are lots of competing theories about how to halt them, but they’re based on opinion,” says Dr. Redelmeier. “You are not going to find any vigorous randomized controlled trials out there for hiccups.”

This dearth of studies is unlikely to change. So, the biological nuances behind hiccups will probably remain a mystery for the some time to come.

 

About the author

Paul Taylor

Paul Taylor, Sunnybrook’s Patient Navigation Advisor, provides advice and answers questions from patients and their families, relying heavily on medical and health experts. Email your questions to AskPaul@sunnybrook.ca
and follow me on Twitter @epaultaylor