There have been a number of interesting posts this week about a new device that has recently been introduced to the US market and I thought it might be an interesting subject for a brief synopsis. I have used this device on a number of patients for a number of indications over the past six or seven months and the results are quite promising. The name of the device is Iovera and while the concept is not new, the delivery mechanism is quite unique and efficient. Iovera is different from past, similar treatments because although cold has been used for many years to treat several clinical conditions, the ability to precisely regulate the temperature and area treated have been problems which this device manages quite well.
Basically, the device delivers a stream of liquid nitrous oxide (which is very cold, about -56ºC) through a closed mechanism to the tips of the probe used. In other words, nothing is actually injected into the patient - the liquid nitrous oxide simply flows through the device and the tip(s) becomes very cold thus causing the natural bodily fluids around it to freeze and essentially creating a tic-tac-sized ice ball near the target nerve. What actually happens to the nerve is akin to what is known as a Sunderland II axonotmesis. Say that three times fast. In layman’s terms, there is some degeneration of the (axons of the) neurons downstream from the treatment site, but the overall structure (i.e. scaffold) of the nerve remains the same. This type of “insult” allows the neurons to eventually re-grow in their typical configuration, back down through the treatment site over a period of a few weeks or months, thus ultimately restoring nerve function. One thing to point out here is that the nerve is theoretically not “destroyed” as some have suggested. Therefore, the term cryoablation is not really appropriate in my opinion because to ablate something as I have mentioned elsewhere (https://www.facebook.com/Peled-Migraine-Surgery-326501717396487/?fref=nf) means to excise or destroy. I prefer to use the term cryo-neuromodulation because it is more precise what you are actually doing which is modulating the actions of the nerve on a temporary basis. These phenomena and concepts pose some really interesting questions about the role of such a device in any number of clinical scenarios, but since we’re particularly focused on chronic headaches such as ON…..here goes.
The fact that the nerve is not completely “destroyed” may be bad or good depending on your perspective. In the case of painful conditions like ON or TN, one might argue that since the nerve will work again, this is a temporary fix. In fact, at this point, Iovera is being used as a management tool. Even if the results last 2-3 months at a time, you will still need to come in several times per year for treatment. However, I personally believe that combined with other treatment modalities, there is real promise for this device. As a lot of you know, many patients have a hard time for several months following surgical decompression or transection because the nerves are inflamed secondary to surgical manipulation and the baseline injury/pathology. Now just imagine if one were able to modulate those nerves by essentially shutting them down for three months by precisely targeting them intra-operatively. It’s tempting to think of how potentially comfortable (albeit numb) a patient might feel in those first 90 days while at the same time taking comfort in knowing that the numbness should eventually fade away. Even though decompressing a nerve improves the nerve physiologically following recovery, it is also tempting to think about the possibility that the cold stimulus may actually improve or simply speed up the regeneration and recovery process as another inducement to do so. Moreover, there is the really tempting idea of also using the Iovera device on the nerve(s) to the surgical incision itself or the surgically dissected areas to minimize the typical post-operative pain. In fact, a very early study in total knee replacement patients suggested that post-operative opioid requirements were decreased in patients treated this way. Finally, if a nerve or patient are not candidates for surgical intervention, this device could represent a big arrow in the quiver of non-surgical treatment options. My short post just scratches the surface of the many questions and possibilities raised by this device. While the available data and the overall experience with cryo-neuromodulation using Iovera is limited at this point, I do believe it device has a substantive role in treating ON, perhaps TN and potentially many other disorders….time will tell.