This issue has come up once, and only once, in  Question 15 from the first paper of 2001.

A hiccup, or singultus, or synchronous diaphragmatic flutter, is a myoclonic spasm of the diaphragm, which is stimulated by the phrehnic nerve. The signal to hiccup is sent from the nucleus tractus solitarius.

This signal can be stimulated by a number of pathological conditions. A brief review lays these bare:

  • Foreign body in the external auditory canal
  • Medullary lesions (especially PICA artery)
  • Medullary demyelination
  • Spinal syrinx
  • Encephalitis
  • Meningitis
  • Gastro-esophageal reflux
  • Gastric distension
  • Pancreatitis
  • Thoracic aortic aneurysm
  • Mediastinal tumours
  • Pleural and pericardial effusion
  • Uremia
  • Hypocalcemia
  • Hyponatremia
  • Methyldopa

Management options:

  • Increase the PaCO2
  • Vigorously stimulate the posterior pharynx
  • Phrenic nerve block
  • Valsalva manoeuvre
  • Apparently, chlorpromazine remains the most consistently effective agent.
  • Metaclopromide may also be useful.
  • If completely stuck, one might make an attempt at sexual intercourse.

The review article remarks that "The more than 100 forms of physical or pharmacological treatment for intractable hiccups include prayers to St Jude, the patron saint of lost causes". As reliable remedies, the author recommends to raise the PaCO2 and to vigorously stimulate the posterior pharynx. Apparently, chlorpromazine remains the most consistently effective agent.

References

Kolodzik, Paul W., and Mark A. Filers. "Hiccups (singultus): review and approach to management." Annals of emergency medicine 20.5 (1991): 565-573.

Howard, Robin S. "Persistent hiccups." BMJ: British Medical Journal 305.6864 (1992): 1237.

Peleg, Roni, and Aya Peleg. "Case report: sexual intercourse as potential treatment for intractable hiccups." Canadian Family Physician 46 (2000): 1631.