Why do hiccups occur? An expert guide to the anatomy of a hiccup

The average person experiences a bout of hiccups anywhere from a few times a month to several times a year. While typically harmless, these involuntary spasms can be a frustrating and mysterious annoyance. Understanding the physiology behind why do hiccups occur can shed light on this common human reflex.

Quick Summary

Hiccups are a reflex caused by an involuntary spasm of the diaphragm, followed by a rapid closing of the vocal cords that creates the characteristic 'hic' sound. This reflex is often triggered by irritation to the nerves connecting the diaphragm and the brain, which can be caused by various lifestyle factors and, in rare cases, underlying medical conditions.

Key Points

• Diaphragm Spasm: Hiccups are caused by an involuntary, sudden contraction of the diaphragm muscle, which is essential for breathing.

• Vocal Cord Closure: The characteristic "hic" sound is produced by the rapid closing of the vocal cords immediately after the diaphragm spasm.

• Lifestyle Triggers: Common causes of short-term hiccups include eating too fast, drinking carbonated beverages or alcohol, and experiencing strong emotions.

• Persistent Issues: Hiccups lasting more than 48 hours can be a symptom of a serious underlying medical condition, requiring a doctor's evaluation.

• Nerve Irritation: The reflex is controlled by a nervous system pathway, and irritation to the vagus or phrenic nerves is often the root cause of the spasms.

• Home Remedies: Many temporary hiccups can be stopped by simple maneuvers like holding your breath or sipping cold water, which help to interrupt the reflex.

The Anatomy of a Hiccup: The Diaphragm and Vocal Cords

At its core, a hiccup is a two-part physiological event. It begins with an involuntary, spasmodic contraction of the diaphragm, a large muscle at the base of the lungs that is essential for breathing. This sudden movement causes a rapid intake of air. The second part of the event is the abrupt closure of the glottis—the space between your vocal cords—which produces the signature "hic" sound. While the specific functional purpose of hiccups remains a subject of scientific debate, the reflex arc that controls it is well understood.

The hiccup reflex arc involves several key components of the nervous system. The afferent pathway consists of the vagus, phrenic, and sympathetic nerves, which transmit sensory information. This information is processed by the central hiccup center in the brainstem. Finally, the efferent pathway sends signals back to the diaphragm and respiratory muscles, causing the contraction and resulting hiccup. Irritation or disruption along any part of this pathway can trigger a bout of hiccups.

Common Triggers for Short-Term Hiccups

For most people, hiccups are a temporary nuisance caused by simple, everyday factors. These acute hiccups typically last only a few minutes and resolve on their own. Some of the most common triggers include:

• Eating or drinking too quickly: This can cause you to swallow excess air, which distends the stomach and irritates the diaphragm.
• Carbonated beverages and alcohol: Both can lead to bloating of the stomach, putting pressure on the diaphragm and triggering spasms.
• Emotional stress or excitement: Strong emotions can disrupt the normal rhythm of breathing, leading to diaphragmatic spasms.
• Sudden temperature changes: Ingesting hot or very cold foods and drinks can irritate the nerves that control the diaphragm.
• Spicy food: Certain spicy foods can irritate the phrenic nerve, which is located near the esophagus.

These triggers are generally harmless and easy to avoid once identified. By being mindful of these habits, you can often prevent or reduce the frequency of short-lived hiccups.

When Hiccups Become Persistent or Intractable

While most cases are benign, hiccups can occasionally become persistent (lasting more than 48 hours) or, more rarely, intractable (lasting longer than a month). In these cases, hiccups may signal a more serious, underlying medical issue. It is crucial to see a doctor if your hiccups persist, as they can interfere with daily life, including sleeping and eating.

Persistent and intractable hiccups can result from a wide array of conditions, such as:

• Gastrointestinal disorders: Conditions like Gastroesophageal Reflux Disease (GERD), inflammatory bowel disease, or esophageal tumors can irritate the diaphragm-controlling nerves.
• Central Nervous System disorders: Problems with the brain or spinal cord, such as stroke, brain tumors, multiple sclerosis, or meningitis, can disrupt the hiccup reflex arc.
• Metabolic disorders: Conditions like diabetes, kidney disease, or an electrolyte imbalance can be a factor.
• Nerve irritation: Damage or irritation to the vagus or phrenic nerves from conditions like a tumor, a hair touching the eardrum, or a sore throat can cause long-term hiccups.
• Certain medications: Some drugs, including steroids, sedatives, and chemotherapy agents, can be associated with persistent hiccups.

It is important to remember that these are rare occurrences, and a medical evaluation is needed to determine the exact cause.

A Comparison of Hiccup Types

To better understand the differences between common and persistent hiccups, consider the following comparison:

Feature	Acute (Transient) Hiccups	Persistent/Intractable Hiccups
Duration	Lasts less than 48 hours, often just a few minutes.	Lasts longer than 48 hours (persistent) or over 1 month (intractable).
Common Causes	Eating/drinking too fast, carbonated drinks, spicy food, emotional stress, sudden temp changes.	Underlying medical conditions, nerve damage, side effects of medication, surgery.
Underlying Mechanism	Temporary irritation to the diaphragm or hiccup reflex nerves.	More complex, systemic issues affecting the nervous system or other body systems.
Intervention	Self-resolving, often helped by simple home remedies like holding breath or drinking water.	Requires medical evaluation and treatment for the underlying cause.
Associated Health Risk	Usually benign and harmless.	Can be a sign of serious pathology and lead to complications like weight loss or exhaustion.

How to Manage and Stop Hiccups

For short-term hiccups, several folk remedies and simple maneuvers have been anecdotally proven to help interrupt the hiccup reflex.

1. Hold your breath: This increases the carbon dioxide in your blood, which may help relax the diaphragm.
2. Breathe into a paper bag: Also increases the amount of carbon dioxide you inhale.
3. Drink ice-cold water: The cold sensation can stimulate the vagus nerve.
4. Try the Valsalva maneuver: Pinch your nose and close your mouth while trying to exhale. This increases pressure in your chest.
5. Swallow a teaspoon of dry sugar: The texture and action of swallowing can distract the hiccup reflex.
6. Gargle ice water: The act of gargling can stimulate the nerves in the throat and interrupt the reflex.
7. Pull gently on your tongue: This stimulates nerves in the back of the throat and may stop the hiccups.

If hiccups become persistent or interfere with your life, it is crucial to consult a healthcare professional, as these home remedies are unlikely to resolve the issue. Medical treatment for chronic hiccups focuses on addressing the root cause.

Hiccups in Infants

Interestingly, hiccups are very common in infants, especially after feeding. While the exact reason is not fully understood, it is believed to be due to an infant's stomach expanding and irritating the diaphragm as they swallow milk or air. For most babies, these hiccups are a sign of healthy development. However, frequent hiccups in conjunction with other symptoms like frequent spitting up or arching the back could be a sign of GERD, and it's best to consult a pediatrician.

Conclusion

In most cases, a bout of hiccups is a temporary and benign phenomenon caused by irritation to the diaphragm, often from simple actions like eating too quickly or consuming carbonated drinks. The reflex arc involving the diaphragm and vocal cords is responsible for the characteristic "hic" sound. While simple home remedies can often stop a short bout, persistent or intractable hiccups should prompt a visit to a doctor to investigate potential underlying causes. Understanding the basic mechanics behind why do hiccups occur helps demystify this common bodily reflex.

For more in-depth information on the complexities of the diaphragm and its function, you can read more at the Cleveland Clinic website.

Frequently Asked Questions

What is the primary cause of hiccups?

The primary cause of hiccups is a sudden, involuntary contraction of the diaphragm muscle, which separates the chest from the abdomen.

Why does the 'hic' sound happen?

The "hic" sound occurs because the diaphragm's involuntary spasm causes a sudden intake of air, which is then stopped by the rapid closing of the vocal cords.

Are there medical conditions that cause persistent hiccups?

Yes, persistent hiccups lasting more than 48 hours can be a symptom of various medical conditions, including GERD, stroke, meningitis, or tumors affecting the nervous system.

Do babies get hiccups?

Yes, hiccups are common and normal in babies, often occurring after feeding due to the stomach expanding and irritating the diaphragm.

When should I see a doctor for hiccups?

You should see a doctor if your hiccups last longer than 48 hours, or if they are severe enough to interfere with your ability to eat, sleep, or breathe normally.

Why do hiccups occur more often when eating or drinking fast?

Eating or drinking too quickly can cause you to swallow excess air. This causes stomach distension, which can put pressure on and irritate the diaphragm.

Do home remedies like holding your breath actually work?

Many home remedies, like holding your breath or sipping cold water, work by disrupting the normal breathing pattern or stimulating nerves, which can help interrupt the hiccup reflex.

Can stress cause hiccups?

Yes, strong emotional states, such as stress, excitement, or anxiety, can lead to disruptions in breathing patterns and trigger hiccups.