Description

• The hiccup (or hiccough) is an onomatopoeic name stemming from the sound made by the abrupt glottic closure following involuntary contraction of the diaphragm and intercostal muscles.
• The medical term for hiccup is singultus, which stems from the Latin singult, originally used to describe the sharp intake of breath associated with prolonged sobbing.
• Usually a benign, yet recurrent nuisance
• Prolonged bouts of hiccups can be indicative of an underlying or serious condition.

Epidemiology

• Fetal hiccups are common in pregnancy, and are frequently felt in the third trimester.
• Hiccups are a physiologic movement in newborns, who may spend as much as 2.5% of their time hiccupping, which decreases in infancy.
• There is no seasonal, geographic, racial, or socioeconomic predilection.
• Persistent (>48 hours) and intractable (>1 month) hiccups more commonly occur in men and adults.

General Prevention

Avoid precipitating factors (e.g., eating rapidly, carbonated beverages, alcohol, tobacco).

Pathophysiology

• A hiccup reflex arc has been elucidated through the study of pathologic hiccups.
  • Afferent limb: receptors in the distal esophagus, stomach, and abdominal side of the diaphragm; signals travel through the phrenic nerve, vagus, and sympathetic (T6–T12) chain branches.
  • Central component: the middle and dorsolateral medulla; independent from the respiratory center, the hypothalamus, and the phrenic nerve nuclei
  • Efferent limb: phrenic nerve to the diaphragm; accessory nerves to the intercostal and scalene muscles, glottis structures, and the esophagus
• Hiccups are often unilateral, involving the left hemidiaphragm.

Etiology

• Environmental
  • Associated with a change in the ambient or internal temperature
  • Examples: cold showers, hot/cold beverages
• Central nervous system
  • Examples: neuromyelitis optica, migraine aura, brainstem lesion, hydrocephalus, VP shunt, meningitis, brain abscess
• Peripheral nervous system
  • Due to irritation or stimulation of phrenic or vagal nerves
  • GI: aerophagia, gastric insufflation, Gastroesophageal reflux disease (GERD), GI malignancies
  • Thoracic: asthma, goiter, pneumonia
  • CV: pericarditis, pericardial effusion, central catheter migration
• Toxic-metabolic
  • Examples: alcohol, tobacco, uremia, electrolyte imbalance, thrush
• Psychogenic
  • Examples: excitement, stress, conversion disorder, anorexia nervosa, secondary gain
• Medications
  • Examples: opioid, benzodiazepines, chemotherapy, anesthetic agents