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EBMG

Hiccup

Hiccup is a myoclonus of the diaphragm in which the diaphragmatic muscle is suddenly contracted. Simultaneously, the intercostals muscles are contracted and the larynx is closed which generates the hiccup sound.
The exact cause or bodily purpose of hiccup is not known.
Physiological hiccup resolves spontaneously, prolonged hiccup may require drug treatment.

Hiccup is generated by a reflex arc involving the phrenic nerve, the vagus nerve and the sympathetic nervous system as the afferent nerves, diencephalon as the central regulator, and the phrenic nerve as the primary efferent branch. Any factor stimulating these nerves and thus the reflex arc at any point may cause hiccup.
Physiological hiccup is usually of short duration (less than 48 hours). It is associated with sudden distension and/or irritation of the stomach that may be caused by, e.g., overeating, consumption of carbonated drinks or changes in the temperature of foods or drinks.
Prolonged hiccup lasts for more than 48 hours, and intractable hiccup lasts for more than 2 months. The possible causes are numerous.

Causes of central origin
- Brain stem diseases
  - Bleeding, infarction, tumour, trauma, multiple sclerosis
Peripheral causes
- Mediastinal conditions or diseases
  - Lymphadenopathy
  - Myocardial infarction
- Diseases of the upper abdomen
  - Hiatus hernia, gastric carcinoma, subphrenic abscess, ileus, postoperative condition
Toxic and metabolic causes
- Alcohol, uraemia, electrolyte disturbances
- Drugs: glucocorticoids, antiparkinsonian drugs, psychotropic drugs, anaesthetic agents, cytotoxic drugs
Other causes
- Psychiatric causes, ”essential hiccup” with no discernible cause

The investigations are directed to exclude the above-mentioned disorders, taking into account the patient's other possible symptoms and signs.
In addition to the clinical examination, the basic investigations include chest x-ray, blood tests as well as other tests determined by the clinical suspicion of the possible cause of the hiccup.

Any underlying condition that may affect the occurrence of the hiccup is treated. Alcohol intake as a risk factor is taken into account.
Physiological hiccup
- A spoonful of fine dry sugar
- Breathing into a paper bag
- Drinking from the opposite brim of a glass
- Gargling with ice water
Drug treatment trial in prolonged hiccup
- First-line treatment
  - Gabapentin 1 200 mg/day orally divided into 3 doses
  - Baclofen 30-60 mg/day divided into 3 doses
- Secondarily
  - Droperidol 1.25-2.5 mg intravenously
  - Valproate 1 g/day orally divided into 2 doses
  - Metoclopramide 40 mg/day per rectum
Phrenectomy is very rarely indicated.

Chang FY, Lu CL. Hiccup: mystery, nature and treatment. J Neurogastroenterol Motil 2012;18(2):123-30. [PubMed]
Steger M, Schneemann M, Fox M. Systemic review: the pathogenesis and pharmacological treatment of hiccups. Aliment Pharmacol Ther 2015;42(9):1037-50. [PubMed]