Variability in responses to Cryolipolysis

It is reported that 100% of cryolipolysis subjects had good outcomes following treatment with the Zeltiq device in its first major study.  Further reports by serious and dependable physicians have reported similar results in all their treated patients. So why am I unable to achieve striking outcomes in all my patients on the West Coast of the USA?  Not to say that I am unhappy with the overall results, for I still believe that this is currently the best device for non-invasive localized fat reduction. But as often happens, a mature look at long term outcomes can be quite revealing.

I estimate that about 70% of my patients have good results, which means that 3 out of 10 patients are unimpressed.  I am surrounded by dermatology residents and fellows who call it as they see it, and they give me that quizzical look when I recount the original study outcomes, wherein every patient could see obvious improvement.  We are careful to take standard digital images and we compare them diligently. True, we don’t employ the three dimensional Vector system, and neither do I perform ultrasound or MRIs on patients, but frankly if they can’t feel or see the difference, what’s the point? It’s not enough for us to be satisfied that 100% of patients have measureable improvement by U/S or MRI.  Innovativel devices can be killed by hype.

So why are some investigators seeing results in all their patients, and others not. This was one of the issues discussed informally by Christine Dierickx, Henry Chan, Rox Anderson, Arielle Kauvar, and Chris Zachary in Paris recently at Les Journées Parisiennes du Laser 2010 conference, a premier meeting of French laser specialists. Henry Chan has also experienced some patients with little improvement in Hong Kong. Arielle Kauvar has noticed improvement in all her patients. We need to determine from Zeltiq users worldwide whether there are outcome differentials, and if so whether these are related to age and gender, or anatomic, geographic, ethnic, technique or other differences between our patient populations.  These might then provide clues as to the cause of this disparity in outcomes.

While musing over lunch, no doubt thinking ‘we are what we eat’, Rox Anderson suggested that the Californian diet was probably lower in saturated and trans fats, and that their fat might ‘freeze’ differently, whereas the East Coasters who enjoy more Philly cheese steak sandwiches might have longer fatty acid chain adipose tissue, with a more responsive outcome.  While humorous, this thought has merit, and would be easy to study, even retrospectively.

Also discussed was the question of painful responses. Two patients with prolonged and severe pain post-Zeltiq were previously reported in this Blog. At the time they seemed to be absolute outliers.  However, it is clear that there have been a very small number of similar but less extreme painful responses, lasting several weeks. The cause of this painful response is not understood, but could be related to the acute panniculitis itself, or possibly a vascular event, an acute neuritis, or some other noxious stimulus to the fat, the underlying fascia, or possibly the underlying muscle.  Rox reminded us that the glomus cell is involved in the control of vascular shunting in a cold environment, and that these shunts can be associated with significant pain. Given that the Zeltiq suction device effectively shuts off the vascular supply to the affected skin and subcutaneous tissue for 60 minutes, one could predict hypoxic tissue responses, despite the protective nature of the cooling.

The normal sequelae of numbness, a modest burning sensation, and other paresthesias are commonplace for several weeks or months.  All patients should be informed about these. Further, these side effects might be used therapeutically in order to control chronic cutaneous pain syndromes, such as post herpetic neuralgia.

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