Simon Mitchell

Seb,

One of the points that David Doolette and I made in our paper was that inadequate decompression of the inner ear, combined with a probable susceptibility to adverse effects from formation of even very small bubbles, makes this organ vulnerable to DCS. Everyone seems to focus in on the isobaric counterdiffusion thing which is just another potential contributor. I guess we didn't make a good enough job of emphasising the former point. Anyway, inadequate decompression can occur with any breathing gas, including air. Isolated IEDCS certainly does occur in air diving, and there are several papers describing series of such cases. You could try:

Nachum et al. Inner ear decompression sickness in sport compressed-air diving.Laryngoscope. 2001 May;111(5):851-6.


Shupak A et al. Inner ear decompression sickness and inner ear barotrauma in recreational divers: a long-term follow-up. Laryngoscope. 2003 Dec;113(12):2141-7.


The latter paper also discusses the issue of distinguishing between IEDCS and IEB. I agree that this can be difficult, but there are usually a lot of clues available from a careful history and examination.

You could also try:

Klingmann C et al. Embolic inner ear decompression illness: correlation with a right-to-left shunt. Laryngoscope. 2003 Aug;113(8):1356-61.

This paper proposes a link between IEDCS and PFO. This is a very interesting finding and not at all incompatible with our theory of inadequate decompression of the inner ear. Indeed, I am drafting another paper (heavily dependent on David's modelling skills as usual) which addresses the "marriage" of our two hypotheses.

One of the problems you face in trying to understand this process, is that you are dabbling in an area that is at the limits of our current understanding.

Hope this helps.

Simon M