The involuntary contraction of the diaphragm muscle, medically known as singultus, is a common experience that typically lasts only a few minutes. This sudden reflex starts with a strong, involuntary spasm of the diaphragm, the large muscle separating the chest and abdomen. The diaphragm’s abrupt movement causes a quick intake of breath, which is immediately halted by the sudden closure of the glottis, the opening between the vocal cords. The rapid closure of the glottis produces the characteristic “hic” sound.
The Anatomy of a Hiccup
The physiological mechanism of a hiccup involves a complex reflex arc that begins with irritation along specific nerve pathways. The afferent, or sensory, side of this arc is composed primarily of the vagus nerve, the phrenic nerve, and sympathetic nerves that innervate the abdominal and thoracic organs. The signal travels to a central hiccup center, believed to be located in the brainstem, likely involving the medulla oblongata.
From the brainstem, the efferent, or motor, signal travels back down through the phrenic nerve to the diaphragm. This causes the diaphragm and, to a lesser extent, the intercostal muscles, to contract sharply and erratically. Almost simultaneously, the recurrent laryngeal nerve, a branch of the vagus nerve, signals the vocal cords to snap shut. This coordinated action generates the distinct sound and sensation of a hiccup, an event that occurs without conscious control.
The Longest Documented Case
The longest recorded case of continuous hiccups belongs to Charles Osborne, a farmer from Anthon, Iowa, whose ordeal lasted 68 years. His hiccups began on June 13, 1922, and continued almost nonstop until February 1990, a year before his death at age 97. Osborne’s hiccup spree was recognized by Guinness World Records, making him a unique case in medical history.
The onset of his condition occurred while he was working on a farm, hanging a 350-pound hog for butchering. He recalled falling down and starting to hiccup immediately after the incident. A doctor theorized that the fall damaged a small blood vessel in the brainstem, disrupting the area that controls the hiccup reflex. Over the nearly seven decades, Osborne was estimated to have hiccupped approximately 430 million times.
Acute Versus Intractable Hiccups and Underlying Causes
Hiccups are classified medically based on their duration, which distinguishes a common annoyance from a serious medical symptom. Episodes lasting less than 48 hours are considered acute, or transient, and are typically triggered by temporary issues such as drinking carbonated beverages, eating too quickly, or experiencing high excitement. Hiccups that persist for more than two days are classified as persistent, while those that continue for over a month are termed intractable singultus.
Intractable hiccups are rare, affecting an estimated one in 100,000 people, and often indicate an underlying health problem affecting the reflex arc. Irritation along the phrenic or vagus nerves is a frequent cause, which can stem from gastrointestinal issues like gastroesophageal reflux disease (GERD) or a hiatal hernia. Other peripheral causes include pneumonia, tumors in the neck or chest, and even a heart attack, as these conditions can irritate the diaphragm or the nerves supplying it.
Central nervous system disorders can also trigger intractable hiccups by interfering with the brainstem’s hiccup center. Conditions such as strokes, multiple sclerosis, or brain tumors can disrupt the signaling pathway that regulates the reflex. Since chronic hiccups interfere with a patient’s ability to eat, sleep, and breathe, they warrant a thorough medical evaluation to identify and treat the root pathology.