I have recently been involved in a case that might have turned out differently if a different approach to the diagnostic process had been used. Please note that this is just my opinion, based on what I know about this one case. I'm not a doctor and don't play one on TV. Take everything I say with a grain of salt.
I understand the value of FAD and the limitations of traditional provocative discography. I do believe that there is much room for improvement in this process and that evaluating cases like these will help us to avoid mistakes in the future.
The case in question started off with discectomy at L3-4, followed by SUCCESSFUL ADR at L3-4. Lumbar symptoms were largely resolved by the surgery, but as the months and years wore on, substantial lumbar symptoms returned, presumably from the moderately degenerated L5-S1 and possibly the less severely degenerated L4-5.
Functional Anaesthetic discography was performed as follows:
1. Inject local anesthesia into L4-5 and wait 30 minutes for the outcome.
2. After little of no effect @ 4-5, an injection into L5-S1 was done, generating dramatic pain relief.
Based on these results, L5-S1 was replaced and L4-5 was left untreated. This second disc replacement procedure did not improve things at all. Further testing with traditional discography confirmed L4-5 as a major pain generator. I really don't want to get into discussing the specifics of the case, as this person does not typically post on the Internet. I cannot be the one to share details. However, I believe that a discussion of the decision making process may make some readers better equipped to avoid similar problems. (It is with the client's approval that I post this level of detail.)
In my opinion, the FAD technique MIGHT have failed because the approach MAY be flawed. Keep in mind all the "I'm not a doctor" qualifiers and the fact that I'm simply presuming what might have happened.
I believe that if you have 2 pain generators (especially at adjacent discs) and one is clearly bigger than the other, it may be impossible to discern if the 2nd pain generator has been removed. It may be the case that, by itself, the 2nd pain generator would be disabling, but in the presence of an even bigger pain generator, the patient might not be able to identify pain relief when the 2nd generator is injected.
So, if L4-5 is really positive, but the patient can't tell in that first 30 minutes because the pain of L5-S1 completely overshadows the relief of pain at L4-5, then L4-5 looks negative. The injection at L5-S1 has the cumulative effect of the first injection plus the second injection, so it looks positive, regardless of the status of L4-5 (positive, negative or unequivocal).
IMHO, based on these results, the assumption that L4-5 is negative and L5-S1 is positive is not valid. (It's easy for me with 20-20 hindsight and knowing the results of further diagnostics.) It may be the case that L4-5 was as bad as L5-S1, but could not identified because the ongoing pain at L5-S1 was overwhelming. It may be the case that L4-5 was much less worse, but still bad enough to provide disabling pain.
I believe that all the decisions were made in good faith and that the same decision making process may produce positive results in a high percentage of cases. There is no point in second guessing what's been done... it's over. However, understanding what occurred may give others more tools that will improve their odds and reduce the risk of failed surgery being a failure of the diagnosis. (We have enough troubles.)
All the best,
Mark
PS... We discussed FAD here:
http://www.ispine.org/forum/ispine/1...procedure.html . I'll see if I can reach Descipher for comment.