The Collaborative International Dictionary of English v.0.48:

Caisson disease \Cais"son dis*ease"\ (Med.)
   A disease frequently induced by remaining for some time in an
   atmosphere of high pressure, as in caissons, diving bells,
   etc. It is characterized by neuralgic pains and paralytic
   symptoms. It is caused by the release of bubbles of gas,
   usually nitrogen, from bodily fluids into the blood and
   tissues, when a person, having been in an environment with
   high air pressure, moves to a lower pressure environment too
   rapidly for the excess dissolved gases to be released through
   normal breathing. It may be fatal, but can be reversed or
   alleviated by returning the affected person to a high air
   pressure, and then gradually decreasing the pressure to allow
   the gases to be released from the body fluids. It is a danger
   well known to divers. It is also called the bends and
   decompression sickness. It can be prevented in divers by a
   slow return to normal pressure, or by using a breathing
   mixture of oxygen combined with a gas having low solubility
   in water, such as helium.
   [Webster 1913 Suppl. +PJC]

WordNet (r) 3.0 (2006):

decompression sickness
    n 1: pain resulting from rapid change in pressure [syn:
         decompression sickness, aeroembolism, air embolism,
         gas embolism, caisson disease, bends]