To the Editor:—
As one of the inventors of the pulsed radiofrequency technique for pain therapy, I disagree with the Editorial View of the history of this technique. The authors state that the history was based on a “personal written communication” from William Rittman, M.S. (Principal, RF Medical Devices, Middleton, MA). The editorial stated that there was a chance meeting at a 1995 scientific conference in Austria between Mr. Rittman and Menno Sluijter, M.D., Ph.D. (Professor Emeritus, Department of Anesthesia, Maastricht University, Maastricht, Netherlands), and a Soviet-bloc scientist, and
this scientist challenged the conventional belief that pain relief after radiofrequency treatment was a result of tissue destruction, suggesting that pain relief could result from the strong magnetic fields induced by voltage fluctuations in the area of treatment. Mr. Rittman returned to the bench and quickly devised a means of creating the same high-voltage fluctuations without any heating at the tip of the needle by using pulses of electrical current rather that continuous current. Dr. Sluijter immediately introduced the technique into clinical practice …
In my opinion, Mr. Rittman's view of the history of pulsed radiofrequency, as described in the editorial, is factually incorrect and misleading, and ignores the roles that Dr. Sluijter and I played in it. I give my view of the history here.
I was the scientific director of all radiofrequency generators and radiofrequency electrodes built at Radionics since 1970, including the first pulsed radiofrequency unit in 1995. I was also the overall director of Radionics. Mr. Rittman reported to me, and I was aware of all research he was doing. I was the main contact at Radionics with Dr. Sluijter, with whom I had worked closely since 1977. Therefore, I know the history well.
After the meeting with the Soviet-bloc scientist, Dr. Sluijter and Mr. Rittman were intrigued by his magnetic field idea and discussed it with me. I made quantitative estimates that magnetic field effects are negligible for our parameter range and that only the electrical field could possibly produce biologic effects to reduce pain, outside of the known radiofrequency heating effects. To test the magnetic field hypothesis, Mr. Rittman suggested disconnecting the reference electrode to isolate the magnetic effect and eliminate electric effects. I again argued that pain relief effects when the reference electrode was disconnected could only arise from either a transient electric field pulse when the radiofrequency is turned on or from capacitively induced radiofrequency electric fields. Dr. Sluijter tried this suggestion on a few patients, and some of them experienced pain relief. However, the percentage of success was not high enough to be convincing.
Dr. Sluijter then called me and suggested making a stream of pulses that might work better than a transient electric field pulse that I had postulated earlier. I liked his idea. Intense discussions followed among Sluijter, Rittman, and myself on an appropriate pulsed radiofrequency waveform that would be practically adaptable to the existing Radionics RFG −3C RF Lesion Generator. Careful attention had to be given to what was possible and safe related to the existing generator's circuits, software, and signal outputs. This led to the specification for the first pulsed radiofrequency generator. The actual design and bench work to build the first pulsed radiofrequency unit in 1995 was not done by Mr. Rittman at all. It was done by two other Radionics engineers: Raymond Fredricks and Jack Thomasian. The unit was sent to Dr. Sluijter, and he did a small patient series with the unit in early 1996. The results were encouraging. At that time, I performed more detailed calculations to prove that the magnetic field near our electrode at our radiofrequency voltages and frequencies is about 1 gauss, approximately equal to the earth's magnetic field. Therefore, the magnetic field is irrelevant. I also calculated that the electric fields and currents are very large, in biologic terms, and are the likely agents to produce the clinical effect observed.
Sluijter, Cosman, Rittman, and van Kleef published the world's first article on pulsed radiofrequency, which included the above work, in The Pain Clinic in 1998. A U.S. patent on pulsed radiofrequency for pain therapy was first applied for in June 1996 with the proper inventors: Sluijter, Rittman, and Cosman. Four U.S. patents were eventually issued stemming from that initial patent application.
The discovery of the pulsed radiofrequency technique for pain therapy involved many events, exchanges of ideas among the inventors, and well-thought-out implementations. It was certainly not a quick, solo performance by Mr. Rittman as the editorial portrays.
Professor of Physics, Emeritus, Massachusetts Institute of Technology, Cambridge, Massachusetts. firstname.lastname@example.org