Interventional Therapy: Trialing for Intrathecal Therapy
Sometimes it is easier to go with the flow and not challenge paradigms. It is usually less controversial then to take the road less traveled by. As Robert Frost suggested, taking a different path and challenging old beliefs can make all the difference. It is a difference which we clinicians wish to make. In the March 2007 issue of this journal (Vol 7: Issue 2), I challenged the need to conduct intrathecal trials before implanting an intrathecal delivery system. That article inspired Drs. Doleys and Krauss to provide their own perspective on the subject and I couldnt be more delighted. He and Dr Krauss have offered an expanded perspective which I believe makes the discussion richer. I think you will all agree. It would be wonderful if this department in this journal could receive more thoughtful critiques like this one.
Lynn Webster, MD, FACPM, FASAM
In his article on the necessity of performing preimplant intrathecal (IT) trials published in Practical Pain Management, March 2007, Dr. Lynn Webster1 outlines a number of very prominent concerns. Not the least of which is the potential risk that accompanies a preimplant trial or, for that matter, any procedure involving manipulation, modification, or alteration of central nervous system structures. He appropriately questions the probability that the preimplant trial predicts long term success in the chronic pain patient, as well as the ability of a preimplant trial, particularly of a few days duration, to provide adequate time to rule out placebo effects, tolerance versus opioid induced hyperalgesia, and specific effects of any one or combination of multiple agents available for spinal infusion. Dr. Webster concludes that the requirement of a preimplant trial is contradicted by the lack of predicability, lack of ability to simulate infusion rate and volume, lack of sufficient time to monitor patients response, lack of compatibility with emerging drugs and drug combinations, and the possibility that implanting the entire system poses less danger for infection than a temporary catheter.
Although we concur with Dr. Websters concerns, they may not be so persuasive as they first appear. Concerning his comments about the paucity of data regarding IT trials, it is important to distinguish between the lack of evidence about a given procedure versus the absence of studies. Within the arena of evidence-based medicine, randomized, controlled studies are held in high esteem as being evidentiary. Applying this criteria, muchif not mostof the therapeutic procedures carried out in the treatment of chronic pain lacks sufficient scientific evidence. One needs only to examine Cochran reviews to be reminded of this. Rather, the apparent lack of evidence is an indictment against those of us who engage in clinical based researchas well as the pharmaceutical and technological industries which profit from these proceduresfor not organizing, funding and conducting relevant studies. Unfortunately, as often as not, guidelines and recommendations are a product of individual clinicians blatant assertions as to their own experience rather than systematic study. The exception may be Anderson and Burchiels study2 which failed to reveal any differences between the use of intrathecal bolus injections compared to continuous epidural trials, at least within the context of their particular outcome measures and definition of success. Nonetheless, in a recent survey involving 205 implanters with an average of nearly 13 years of experience, 70% reported using continuous intrathecal or epidural trials for cancer pain patients and 80% for noncancer pain patients.3 None felt that the trialing should be abandoned. Perhaps it is more appropriate to note the sheer lack of studies which have attempted to compare one trialing approach to another, then to imply that trialing has not been studied. Indeed, the number of factors involved in considering different trialing approaches is somewhat finite4 and should make this a reasonable area of study.
Please refer to the June 2007 issue for the complete text. In the event you need to order a back issue, please click here.