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The 2010 Supplement to the Journal of Athletic Training has a vast number of abstracts contained within. Today I want to discuss the abstract entitled The Effects of Ultrasound Transducer Velocity on Intramuscular Tissue Temperature Across a Treatment Site.

Ultrasound is a commonly used, yet maligned modality. As a result, it is important to have studies that speak to it’s efficacy (or lack thereof for that matter) as a treatment and also help to determine parameters for use.

This study aimed to determine if transducer velocity (how quickly the soundhead is moved over the surface) affected intramuscular tissue temperature. Now the authors stated that the general recommendation for soundhead velocity is 4 cm/s and the recommended treatment area is twice the size of the soundhead. Whether the velocity recommendation or whether there was uniform heating within the treatment area were points of interest for this study.

The researchers had 12 subjects and performed continuous ultrasound treatment for 10 minutes at 1 MHz frequency and 1.5 w/cm2 intensity. Intermuscular temperature changes were assessed via sensor probes at 2.5 cm below skin surface. The researchers used velocities of 2 cm/s, 4 cm/s, and 6 cm/s and compared the results.

The study concluded that sound head velocity had no effect on temperature rise during treatment. The other finding in this study was that tissue heating was not uniform across the treatment area. The further away from the center of the treatment area, the less the increase in tissue heating.

Here is an alternate, yet very similar study from 2006 that yielded very similar results. The parameters of this study were very similar. The treatment area was twice the size of the soundhead. This study measured transducer velocities of 2-3 cm/s, 4-5 cm/s, and 7-8 cm/s. Muscle temperature for this study was measured at 3 cm below one-half of the skinfold thickness. Overall, this study showed very similar tissue temperatures between the three tested treatment velocities.

Overall, the one abstract reveals some compelling evidence regarding ultrasound as a treatment. Both studies when looked at together are even more convincing.

So here are some conclusions that we can come to about ultrasound as a treatment based upon both of these studies:

  • There were no significant changes in intermuscular temperature from transducer velocities of 2 cm/s to 8 cm/s.
  • The further away from the center of the treatment area, the less the intermuscular temperature increase
  • Continuous ultrasound at 1.5 cm/2 x 10 minutes in two separate studies produced tissue temperature increases of 4 to 5 degrees celsius
  • Intermuscular tissue temperature was shown to increase during treatment from 2.5cm to approximately 3cm below the skin.

So at the end of the day:

  • Transducer head velocity plays little role in the elevation of intermuscular tissue temperature
  • Treatment parameters of 1.5 cm/2 x 10 minutes of continuous ultrasound seem to be good starting points to deliver muscular tissue temperature increase
  • Using the above treatment parameters, you can expect approximately 4-5 degrees Celsius of temperature increase
  • The larger your treatment area is, the less the tissue temperature increase at the outer rims of the treatment area.

So as we try to become more evidence-based in our approach, these findings can help us to make more appropriate choices in the use of ultrasound as a treatment modality.

What are your thoughts? Did you find any other conclusions from these studies?

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A study was published in a 2006 issue of the Journal of Athletic Training that I found interesting back then and wanted to revisit again now. The study, entitled Cortisol Concentrations in Human Skeletal Muscle Tissue After Phonophoresis with 10% Hydrocortisone Gel, was of interest to me because I have performed many a phono treatment over my career and wanted to see “if this stuff really worked”. (Kind of backwards isn’t it but continual learning, that’s the point of all this right.)

Phonophoresis is a treatment that is commonly prescribed by physicians to treat musculoskeletal injuries and the goal of this study was to help determine if the technique really was able to deliver the hydrocortisone to the skeletal muscle tissue that was being targeted with the treatment.

The samples consisted of 6 individuals in the sham group and 6 in the phonophoresis group. Each leg of each subject was utilized for this study. One leg was chosen for treatment and the other was chosen as the control for each subject.

The study involved 12 indivduals who were split into the treatment and sham group. Treatments utilized 10% hyrdrocorisone for the medication and the region being treated was the vastus lateralis. The treatment protocol utilized ultrasound delivered at 1.0 MHz x 1.0 W/cm2 and at 7 minutes utilizing a continuous treatment setting.

After some prep work was done following the single treatment, a needle biopsy was performed in which a sample was extracted from the vastus lateralis muscle. The muscle biopsy was then examined for cortisol concentrations.

Now, the authors acknowledge that phonophoresis has been effective in the driving low-molecular-weight compounds through the dermal layer.  After that however, it is uncertain if the medication is able to make it to the targeted tissues. Hence, this study.

The results as reported by the authors showed no significant difference in cortisol concentration between the control limb and the treatment limb, in either the sham or phonophoresis samples. No significant differences were noted between the sham and phonophoresis groups. So the final conclusion resulting from this study was that 10% hydrocortisone based phonophoresis treatment (delivered at the said parameters) did not raise the concentration of cortisol in human skeletal muscle tissue following treatment.

As we try to base our treatment decisions upon sound evidence, I thought that this study would help give us some additional insight into this common treatment.

Here are some of my observations as well as some additional commentary and discussion added by the authors:

  1. First off, the subjects were better men and women than me. Offering to have some muscle extracted for the sake of science is quite admirable. As you read the study, you’ll think the same thing.
  2. The authors admit that the sample size is small and I would agree. I would have loved to see a much larger sample but going back to the first point, getting many more to commit to what these subjects did may have been a minor miracle in and of itself.
  3. Probably one of the more interesting points the authors brought up centered around treatment length and intensity. At first blush, my thought was that the intensity was probably too low and the treatment length could have been longer. (Treatment lengths for ultrasound will generally vary from 5-20 minutes). The authors did report however that studies with swine showed an increase in cortisol levels with prolonged treatment (17+ minutes) and with lower intensities. I found this very interesting. Treatments at .1 and .3 W/cm2 were more effective in the swine. I may have surmised that higher intensity coupled with longer treatment times would be more effective but previous studies indicate otherwise. How this translates to human studies remains to be seen but the authors do note that utilizing multiple treatment settings for the delivery of phonophoresis should be further investigated. I agree.
  4. Another point the authors brought up was regarding injured vs. uninjured tissue. All of the subjects in this study were of apparent good health. The authors noted that healthy tissue may be more resistant to pharmaceutical delivery. Some studies have also shown injured cells to be more amenable to pharmaceutical delivery. This is a very valid point and very well could have some merit.
  5. Another point the authors discuss revolves around thermal vs. non-thermal delivery. The authors site a reference that notes that non-thermal delivery played a significant role in transdermal drug delivery. This is a valid consideration as well. Does the thermal aspect of the treatment alter or hinder the delivery of the medication versus the mechanical delivery settings? Is a pulsed setting more appropriate in this type of treatment?
  6. The authors also discuss the delivery of the medication indirectly through the blood (once the drug is delivered subdermally, the medication is delivered to the muscle through its blood supply) as opposed to directly through delivery of the medication to the  muscle tissue itself. They discuss this possibility as unlikely but do address it for discussion purposes.

Overall, the study was very interesting and I commend the authors for venturing into this study. It is important to have research validate our methodology. There are a lot of variables that this study was unable to account for but I do think that we did discover some important findings as a result.

So what are some takeaways.
Well aside from the point regarding injured vs. non-injured tissue, the study stongly shows that trying to deliver phonophoresis using 10% hydrocortisone cream to deep muscle tissue at the settings demonstrated is largely ineffective. One would argue that using similar parameters as illustrated and expecting different results is not good practice.

Secondly, the medication is not cheap. I wouldn’t necessarily consider “wasting” this medication utilizing application settings that are ineffective as good practice either.

Does this study particular study discount the use of phonophoresis? At this point, I’d say no but it definitely helps us to start thinking more about what we are trying to accomplish with this treatment and what methods we may go about  in order to accomplish our goals. We really need to consider the area we are treating and the parameters that we are using. What are our goals for the treatment as well? This study should help us to be more specific with our treatment goals.

I think that the authors clearly point to the fact that more research needs to be done and I agree. The trick is to take what we learned through this study and apply it to our daily practice.

What are your thoughts? Do you have any additional observations? Do you know of additional studies that refute or validate these findings. Feel free to share your comments.

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I came across an interesting study yesterday comparing the use of ultrasound vs. low level laser therapy in treating Carpal Tunnel Syndrome.  The study was published in 2004 and conducted by Amir H. Bakhtiary and Ali Rashidy-Pour, Rehabilitation Faculty in the Physiology Department at Semnan Medical Sciences University, Iran. The study, entitled Ultrasound and laser therapy in the treatment of carpal tunnel syndrome, was published in the Australian Journal of Physiotherapy.

5770147_aad5619c5f1It is important for continued research such as this to be done. Low level laser therapy and other forms of light therapy have burst onto the scene over the last several years, particularly in the United States and so continued study as to their efficacy is important. Furthermore, carpal tunnel syndrome can be a debilitating condition and further studies to help provide quality treatment for those with CTS is important.

This study is of particular interest to me because as an athletic trainer in the industrial setting, this is a condition I see plenty of. Secondly, this is of interest because I have extensively used both treatments in the past to treat carpal tunnel syndrome and I was interested to see the results. This particular study concluded:  “Our clinical trials showed that ultrasound treatment is more effective than low level laser treatment in patients with mild to moderate carpal tunnel syndrome.”

The study had a sample group of 50 patients and a total of 90 wrists were treated. Each wrist was treated exclusively with either ultrasound or laser treatment. Patients were treated daily over a three week period for a total of 15 treatments.

The part that I found most interesting however involved the treatment parameters and this is probably where I have the most questions with the study. Ultrasound was delivered at a dosage of 1.0 W/cm2 for a total of 15 minutes per treament. The low lever laser treatment on the other hand was delivered at a total of 9 Joules over 5 points along the median nerve. This dosage equates, according to the study, to 1.8 Joules per treatment point.

According to the study, the results overwhelmingly favored ultrasound as a superior treatment based upon pre and post-treatment measurements.

As someone who has treated CTS for over the last 15 years utilizing each of these modalities, I observed the following in regards to this study:

  • Ultrasound was delivered at an intensity of 1.0 W/cm2. This seems to be reasonable. I may tend to use a slightly higher intensity personally (1.25 W/cm2) but this is dependent upon several factors and for the sake of the study, this seems fair.
  • Ultrasound was delivered at a treatment time of 15 minutes per treatment. This treatment time seems to be on the excessive side. (Now, on the flip side – if this did have positive results, maybe we need to reexamine our treatment times regarding ultrasound – but that is for another discussion.) Typical treatment times for the administration of ultrasound is generally 5-10 minutes, wouldn’t you agree? So, using ultrasound for 15 minutes per treatment seems to be in excess of what would be considered normal.
  • According to the study, laser was delivered at 1.8 Joules x 5 treatment sites for a total of 9 Joules. While the treatment dosage of ultrasound may be excessive, the treatment dosage for the laser treatment seems to be extremely low. The laser that we use at our facility utilizes three infrared diodes that each deliver 1 Joule of energy per treatment cycle. So for every 33 second cycle that we administer treatment, 3 Joules of energy are delivered per site. We typically will treat each site with 3 treatments and then treat a total of 3-5 sites at the wrist and hand. (Treatment is based upon manufacturer’s recommendations). So each site will receive 9 Joules of energy and this would again be repeated at 3-5 sites. This is a significant contrast to the treatment dosages used in the study.

Studies in this vain are important and I applaud those who conducted this study. Having said that, I am not sure that you can make the conclusion that ultrasound is a more effective treatment in mild to moderate CTS cases based upon the above observations. I do find the results, particularly with the ultrasound, interesting and definitely worth more investigation. I am just not completely sure, based upon what I read in the study, that the treatment dosages were “equitable”.

Am I incorrect in my observations? What are your thoughts? I am interested to hear what you think.

Photo Credit,  mrebert

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