Bone Cyst Barotrauma

Bone cysts causing pain during ascent and or descent
Figure 9.6 Bone cysts causing pain during ascent and or descent. (a) An x-ray study showing a translucent cyst in the right ilium, next to the sacro-iliac joint. (b) A computed tomography scan showing two air cysts in the right ilium. (Courtesy of Dr B. L. Hart.)

Occasionally, pain may develop from an intraosseous bone cyst, probably with haemorrhage into the area, during descent or ascent, and may last for hours after the dive. The pelvic bones are most often involved, in the ileum and near the sacroiliac joints. An x-ray study, computed tomography or magnetic resonance imaging scan may demonstrate the lesions (Figure 9.6). This disorder has been confused clinically with decompression sickness, but it does not respond to recompression therapy and is sometimes aggravated by it.