Hiccups

Hiccups, medically known as singultus, refer to sudden, involuntary contractions of the diaphragm, a muscle involved in breathing that is located between the chest and the abdomen. These contractions result in abrupt inhalations of air that are usually followed by a characteristic “hic” sound created by the sudden closure of the vocal cords. 

A wide variety of factors can trigger hiccups. These triggers generally stimulate the peripheral ends of the hiccup reflex or act on its processing unit in the midbrain, resulting in the onset of hiccups. The cause of the hiccups impacts how long they last. 

Transient hiccups

Distention, or stretching, of the stomach is the most common trigger of transient hiccups. A large meal, carbonated beverages, sudden changes in body temperature, and significant alcohol consumption can cause stomach distention. An individual may also develop transient hiccups because they have swallowed air, which may occur while chewing gum or talking while eating. In some cases, smoking and intense emotional factors, such as excitement or stress, have been associated with sudden onset of hiccups. 

Persistent hiccups 

An individual may have persistent hiccups after undergoing general anesthesia during a surgical procedure. The administration of anesthesia typically requires the individual to extend their neck, which can stretch the phrenic nerves and trigger hiccups. Similarly, intubation, or the insertion of a tube into the individual’s airway to assist with breathing during anesthesia, may cause additional irritation that can stimulate hiccups. 

Chronic hiccups

Chronic hiccups, lasting longer than one month, can be caused by a variety of more persistent causes. Conditions that lead to the damage or irritation of the phrenic and vagus nerves are often associated with consequent hiccups. These conditions include pericarditis, or inflammation of the heart’s membrane (i.e., pericardium); laryngitis, or inflammation of the larynx in the throat; inflammation of the stomach from bacteria, like Helicobacter pylori; gastroesophageal reflux disease (GERD), which is characterized by acid reflux; and space-occupying lesions, like neck-cyst tumors, esophageal cancer, and enlarged thoracic lymph nodes. 

Metabolic disorders -- such as diabetes, electrolyte imbalances (e.g., hypocalcemia, hypokalemia, etc.), and kidney disease -- may also induce intractable hiccups.  Less frequently, long-term hiccups may be due to disorders of the central nervous system. These disorders impact the brain and spinal cord and include stroke, brain tumors, traumatic brain injury, and inflammation of the brain (e.g., meningitis, encephalitis).

When medications, like steroids, barbiturates, and tranquilizers, stimulate the reflex arc, they may also trigger long-lasting hiccups. Moreover, anything that touches or irritates the tympanic membrane (i.e., eardrum) can trigger the vagus nerve. 

Most episodes of transient hiccups do not need intervention because they will resolve on their own. However, if they persist and are bothersome, there are ways to stimulate certain neural pathways that may stop a case of hiccups. For example, studies have shown that irritating the nasopharynx (i.e., the anatomical area around the nose and pharynx) with a catheter, by pulling out the tongue, or by lifting the uvula (i.e., the teardrop-shaped tissue hanging at the end of the soft palate) with a spoon may resolve hiccups. Eating 1 teaspoon of dry granulated sugar could also be effective. Similarly, stimulating the vagus nerve by drinking a glass of water or applying a cold compress to the face may help. 

Interrupting the respiratory cycle is another approach that may stop transient hiccups. Holding one’s breath for several seconds or breathing into a paper bag are well-known ways to try to stop hiccups. A different method is the Valsalva maneuver, in which an individual strongly exhales while holding their mouth and nose closed. These maneuvers are generally effective for reducing the duration of transient hiccups, but they rarely resolve persistent or chronic hiccups.  

Hiccups refer to a sudden, involuntary contraction of the diaphragm that results in abrupt inhalations of air followed by a characteristic “hic” sound. Various causes have been identified, most of which include conditions that irritate or damage the phrenic and vagus nerves. Usually, hiccups last for a short period of time (i.e., transient hiccups) and are not concerning. Transient hiccups generally don't require further intervention, as they typically resolve on their own, but certain maneuvers may reduce their duration. Persistent hiccups, which continue for more than two days, and chronic hiccups, which last longer than one month, may need not only treatment to reduce the severity of the hiccups but also treatment of the underlying cause.