Is the inner ear barotrauma DCI?

[LubaScuba]

I have a rather unusual question to ask. Is the inner ear barotrauma (window rupture) which happens during a dive, better to be considered as a special form of DCI and treated accordingly even if classical inner ear DCI is excluded? Could that be a bubble disorder as well... from compressed gas bubbles introduced to the scala space through the fistula and expanded on ascent damaging further the labyrinth structures? Histories indicate that could be the case. Any enlightening thoughts?

 

[jbd]

I have a rather unusual question to ask. Is the inner ear barotrauma (window rupture) which happens during a dive, better to be considered as a special form of DCI and treated accordingly even if classical inner ear DCI is excluded? Could that be a bubble disorder as well... from compressed gas bubbles introduced to the scala space through the fistula and expanded on ascent damaging further the labyrinth structures? Histories indicate that could be the case. Any enlightening thoughts?

If the expanding air in the middle ear was what caused the rupture of either of the windows then I would think it would just be a barotrauma. If a bubble formed in the inner ear and ruptured one or both windows into the middle ear then it would seem to be a form of DCI.

 

[Laurence Stein DDS]

I have a rather unusual question to ask. Is the inner ear barotrauma (window rupture) which happens during a dive, better to be considered as a special form of DCI and treated accordingly even if classical inner ear DCI is excluded? Could that be a bubble disorder as well... from compressed gas bubbles introduced to the scala space through the fistula and expanded on ascent damaging further the labyrinth structures? Histories indicate that could be the case. Any enlightening thoughts?

Hi LubaScuba,

I think JBD is on to something....sort of.

It is my understanding that DCI (decompression ILLNESS)is a heading under which pressure related problems are lumped. On the otherhand, DCS (decompression SICKNESS) is a specific type of DCI, also known as the "Bends". DCS is a diagnosis of a particular DCI type. DCI is a collection of many pressure related illnesses.

A ruptured oral or round window would occur if the air within the MIDDLE ear was not properly equalized. Without equilization, the thin membranes covering these openings in the bone are stretched until they break, allowing leakage of perilymph and potential damage to the hearing organ. Perhaps this could be catagorized as a type of DCI...allowing barotrauma to be one category of DCI.

Should one develop bubbles in the perilymph due to nitrogen coming out of solution (which I would tend to doubt), there probably wouldn't be enough volumetric change in those tiny bubbles to produce sufficient pressure to cause the windows to burst... as jbd has suggested. I would be surprised if you can rupture these membranes from the inside out due to just expanding gas bubbles coming out of solution during ascent.

The reason that I doubt that a sufficient volume of bubbles might form here is because any gas that is dissolved into the perilymph would very likely be of a lesser concentration than in the circulatory system due to the pressure gradients. Gas would have to diffuse into this avascular liquid and I would suspect (but don't know for sure) that it would take a rather long time to dissolve a significant amount of nitrogen in this liquid before it had enough potential volume if it turned into bubbles to cause a problem. Perhaps in a saturation dive situation this might be possible but I would suggest that "ear bends" would be the result and not a barotrauma. So you get DCS.

EAR BENDS! Yikes, you gotta be kidding! :11:

Assuming this doesn't really happen, then a ruptured oral or round window wouldn't be caused by expanding gas bubbles in perilymph and therefore would not be considered DCS but rather a DCI.

If I don't use another another double negative then I'm not gonna shoot myself!

Perhaps of the dive docs can make this a little more clear.

Think I'm gonna ring up one of the dive docs.


Laurence Stein, DDS

 

[CBulla]

Laurence,

You wrote a proof! And I followed it! You did well with geometry didn't you? Seriously, it made sense to me, I look forward to seeing what one of the other Doc's has to say as well. Thanks for the explaination

 

[LubaScuba]

Well, i agree that classical inner ear DCI is not really going to burst the window. I am not focused that much in classical inner ear DCI here as it has been nicely covered in literature. One thing that is pretty much left out is a possible bubble disorder after inner ear barotrauma at depth and eventual benefits of recompressing such cases in terms of saved hearing frequenzy spectrum.

Hi LubaScuba,

I think JBD is on to something....sort of.

It is my understanding that DCI (decompression ILLNESS)is a heading under which pressure related problems are lumped. On the otherhand, DCS (decompression SICKNESS) is a specific type of DCI, also known as the "Bends". DCS is a diagnosis of a particular DCI type. DCI is a collection of many pressure related illnesses.

A ruptured oral or round window would occur if the air within the MIDDLE ear was not properly equalized. Without equilization, the thin membranes covering these openings in the bone are stretched until they break, allowing leakage of perilymph and potential damage to the hearing organ. Perhaps this could be catagorized as a type of DCI...allowing barotrauma to be one category of DCI.

Should one develop bubbles in the perilymph due to nitrogen coming out of solution (which I would tend to doubt), there probably wouldn't be enough volumetric change in those tiny bubbles to produce sufficient pressure to cause the windows to burst... as jbd has suggested. I would be surprised if you can rupture these membranes from the inside out due to just expanding gas bubbles coming out of solution during ascent.

The reason that I doubt that a sufficient volume of bubbles might form here is because any gas that is dissolved into the perilymph would very likely be of a lesser concentration than in the circulatory system due to the pressure gradients. Gas would have to diffuse into this avascular liquid and I would suspect (but don't know for sure) that it would take a rather long time to dissolve a significant amount of nitrogen in this liquid before it had enough potential volume if it turned into bubbles to cause a problem. Perhaps in a saturation dive situation this might be possible but I would suggest that "ear bends" would be the result and not a barotrauma. So you get DCS.

EAR BENDS! Yikes, you gotta be kidding! :11:

Assuming this doesn't really happen, then a ruptured oral or round window wouldn't be caused by expanding gas bubbles in perilymph and therefore would not be considered DCS but rather a DCI.

If I don't use another another double negative then I'm not gonna shoot myself!

Perhaps of the dive docs can make this a little more clear.

Think I'm gonna ring up one of the dive docs.


Laurence Stein, DDS

 

[gazzahawkes]

Hi all
I apologise if all parties cant make sense of this.


Ive seen patients with potential ear problems as described.
several even swore blind the Dr in question was wearing Pink Trousers.

Good to see you here Scuba luba.......

Love apache mafia

Ps Otoscope with inflatable thingy will be in ko lak as soon as weather improves and we can get of the rock cut off for a week now......

 

[Laurence Stein DDS]

Well, i agree that classical inner ear DCI is not really going to burst the window. I am not focused that much in classical inner ear DCI here as it has been nicely covered in literature. One thing that is pretty much left out is a possible bubble disorder after inner ear barotrauma at depth and eventual benefits of recompressing such cases in terms of saved hearing frequenzy spectrum.

LubaScuba, I'm back!

Perhaps I have misunderstood your question. Are you actually referring to the use of recompression following a barotrauma to the inner ear?

Speaking as a person who has experienced an oval window rupture with hearing loss, I can tell you that when it happens, it is very sudden and the tinnitus (ringing ears) is instant and persistent ever after. The damage (breaking the cilia in the organ of corti) occurs instantly at the time the window bursts. Once it happens, you're gonna have to compose yourself to deal with the vertigo. Then the very next thing you're going to do is start an ascent. I doubt that you will have much time to dissolve much gas into the perilymph.

While it may be possible to rupture the windows near the completion of a dive and the associated maximum absorbed gas, I would suspect that most of these injuries occur within the first few minutes of descent as the diver is trying ineffectively or unsuccessfully to equalize the ears. In this case the dive is over so quickly that little gas has had a chance to diffuse into the inner ear fluid.

Undergoing recompression will not heal the broken cilia...you've got just so many and once broken they don't grow back...recompression or not. What few, if any, bubbles remain are not going to cause additional damage that can be treated by hyperbaric treatment. I seriously doubt that hyperbaric treatment will do much to cure this type of barotrauma.

Upon re-re-reading you initial post, it seems you are asking whether air that is possibly introduced through the rupture INTO the perilymph could be removed by recompression...is that it? I don't have an answer for that. It could be that the bubble simply escapes the same way it was introduced.

I'm not sure if it wouldn't be too risky to re-pressurize an injured ear in a person who has already demonstrated that their ears didn't clear properly that day. You might put the person at risk for additional air to be forced into the inner ear during recompression.

One more consideration. I think the main source of inner ear damage is due to the sudden change in pressure as the window ruptures. The fluid suddenly moves and the impulse from that movement is transmitted to all structures surrounded by that fluid. Later, even if an air bubble is present, there is no longer a membrane to prevent free movement of anything within the inner ear so there is less transmitted impulse to those same structures.

I'm still working on getting one of the docs to respond.

Regards,

Laurence Stein, DDS

 

[Nomaster]

LubaScuba, I'm back! . . .
Speaking as a person who has experienced an oval window rupture with hearing loss, I can tell you that when it happens, it is very sudden and the tinnitus (ringing ears) is instant and persistent ever after. The damage (breaking the cilia in the organ of corti) occurs instantly at the time the window bursts. . .
Undergoing recompression will not heal the broken cilia...you've got just so many and once broken they don't grow back...recompression or not. . .

Regards,

Laurence Stein, DDS

You may have just given me a clue to the origin of my tinnitus.
How do you pronounce it? I understand that in some parts of the US it's pronounced tin-eye-tis and in others tin-ni-tus.

Tom

 

[Saturation]

Dr. Stein is correct. Let me summarize his posts.

DCI is the broad term for all pressure related diseases, of which DCS, the bends, is one. Various forms of barotrauma are other forms of DCI.

Rupture of the round window or perilymph fistula, PLF, is a barotrauma event due to equalization pressures too great for the round window to bear. It is not treated with recompression, it could worsen the issue and lead to deafness. Free gas, almost certainly from the breathing mixture, can enter the middle ear space during equalization and disrupt the middle ear, but not usually inside the labyrinth.

Inner ear DCS, IECDS, is due to gas bubbles inside labyrinth, manifesting very commonly as vertigo. Its is treated with recompression.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2396811&dopt=Abstract

The diagnosis is made clinically but it is important since one disease is recompressed, the other is not.

PLF can have wide ranges of symptoms depending on what the free gas does inside the middle ear: the most common is tinnitus & deafness early on, to vertigo. It occurs commonly during equalization and descent, and thus divers may have symptoms early in the dive. If it occurs on ascent, say due to a reverse block, its more difficult to diagnose against IEDCS if vertigo is a presenting symptom. PLF symptoms ease once surfacing.

Usually IEDCS is mostly vertigo in presentation and associated with stop decompression dives and moreso, with trimix. Very rarely does hearing loss and deafness accompany it until later, when the inner ear is damaged by DCS. IEDCS symptoms worsen once surfacing, as more bubbles form in the inner ear.

 

[LubaScuba]

Well you are right, recompressing could worsen it...because of equalization. Myringotomy is rather problematic as it implies the meningitis risk in these cases having a "nice" way to subarachnoidal space. How about slow descent rates (ie 2ft/min) together with passive equalizing, upright position during treatment, ear defenders during noisy vents, BIBS mask removal before resistance on exhaling starts...?
How can you explain marked improvement (almost full resolution) in hearing, tinnitus and vertigo during first O2 period at 60ft (USN table VI) in patient who had done forceful Valsalva at bottom, had sudden onset of tinnitus, severe sensoneural hearing loss and nasty vertigo?
"Post hoc ergo propter hoc" bias? It is true that PLF's improve spontaneously to a point but as far as i know not within couple of hours and not to such extent. What about all the successful HBO treatments of sudden hearing loss performed in Germany?

Dr. Stein is correct. Let me summarize his posts.

DCI is the broad term for all pressure related diseases, of which DCS, the bends, is one. Various forms of barotrauma are other forms of DCI.

Rupture of the round window or perilymph fistula, PLF, is a barotrauma event due to equalization pressures too great for the round window to bear. It is not treated with recompression, it could worsen the issue and lead to deafness. Free gas, almost certainly from the breathing mixture, can enter the middle ear space during equalization and disrupt the middle ear, but not usually inside the labyrinth.

Inner ear DCS, IECDS, is due to gas bubbles inside labyrinth, manifesting very commonly as vertigo. Its is treated with recompression.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2396811&dopt=Abstract

The diagnosis is made clinically but it is important since one disease is recompressed, the other is not.

PLF can have wide ranges of symptoms depending on what the free gas does inside the middle ear: the most common is tinnitus & deafness early on, to vertigo. It occurs commonly during equalization and descent, and thus divers may have symptoms early in the dive. If it occurs on ascent, say due to a reverse block, its more difficult to diagnose against IEDCS if vertigo is a presenting symptom. PLF symptoms ease once surfacing.

Usually IEDCS is mostly vertigo in presentation and associated with stop decompression dives and moreso, with trimix. Very rarely does hearing loss and deafness accompany it until later, when the inner ear is damaged by DCS. IEDCS symptoms worsen once surfacing, as more bubbles form in the inner ear.