What causes hiccups?

Causes of Hiccups

Hiccups are caused by a complex reflex arc involving peripheral phrenic, vagal and sympathetic pathways with central midbrain modulation, and can be triggered by various physical, chemical, inflammatory or neoplastic factors affecting this pathway. 1

Pathophysiology

• Hiccups result from sudden erratic contractions of the diaphragmatic and intercostal muscles followed immediately by laryngeal closure, producing the characteristic "hic" sound 1
• The hiccup reflex arc involves:
  • Afferent limb: vagus nerve, phrenic nerve, and sympathetic chain (T6-T12)
  • Central processor: located in the midbrain
  • Efferent limb: primarily the phrenic nerve to the diaphragm 1, 2

Common Causes of Hiccups

Gastrointestinal Causes

• Gastroesophageal reflux disease (GERD) - the most common cause of persistent hiccups 3
• Gastric distention from overeating or carbonated beverages 2
• Gastritis or peptic ulcer disease 2
• Abdominal surgery 2

Central Nervous System Causes

• Stroke affecting the brainstem 1
• Space-occupying lesions (tumors) 1
• Brain injury 1

Thoracic Causes

• Myocardial infarction 2
• Pericarditis 1
• Thoracic surgery 1

Metabolic/Systemic Causes

• Alcohol consumption 2
• Renal failure 2
• Electrolyte imbalances 1

Medication-Induced Causes

• Anti-Parkinson medications 1
• Anesthetic agents 1
• Steroids 1
• Chemotherapeutic agents 1

Other Causes

• Psychogenic factors 4
• Foreign body irritation of the tympanic membrane or ear canal 1
• Herpes zoster infection affecting the phrenic nerve 1

Classification by Duration

• Acute hiccups: Episodes lasting less than 48 hours, usually self-limiting 1
• Persistent hiccups: Episodes lasting more than 48 hours but less than 2 months 1
• Intractable hiccups: Episodes lasting more than 2 months 1

Clinical Significance

• Short hiccup bouts are usually benign and resolve spontaneously 2
• Prolonged hiccups can lead to:
  • Sleep deprivation
  • Weight loss
  • Depression
  • Decreased quality of life 2

Diagnostic Approach for Persistent Hiccups

• Detailed medical history and physical examination to identify potential triggers 2
• For persistent cases, consider:
  • Upper gastrointestinal investigations (endoscopy, pH monitoring, manometry) 2
  • Abdominal ultrasound 2
  • Chest or brain CT scan when indicated 2
  • Laboratory tests to rule out metabolic causes 1

Treatment Considerations

• For short-term hiccups, simple physical maneuvers that stimulate the uvula/pharynx or disrupt diaphragmatic rhythm are often effective 4
• For persistent or intractable hiccups:
  • First-line therapy should include proton pump inhibitors (PPIs) due to the high prevalence of GERD as an underlying cause 3
  • Pharmacological options include chlorpromazine, metoclopramide, baclofen, and gabapentin 1, 4, 2
  • Non-pharmacological approaches such as nerve blockade, phrenic nerve stimulation, acupuncture, and breathing techniques may be beneficial in refractory cases 1

Understanding the underlying cause of hiccups is crucial for effective management, particularly in cases that persist beyond the typical self-limited episode.