I first want to congratulate Dr Brock on his election and ascension to the presidency of the International Society for Sexual Medicine. AUANews has asked us to pen our positions on shock wave therapy for erectile dysfunction (ED) and other male sexual dysfunctions, and secondarily address the ethics of charging for shock wave therapy.

We debated this topic at the 22nd Annual Spring Meeting of the SMSNA (Sexual Medicine Society of North America) held in conjunction with the American Urological Association Meeting in New Orleans, May 2022. But that was not the beginning of this debate on shock wave therapy. In 2021, we were both authors on the SMSNA Position Statement on Restorative Therapies for Erectile Dysfunction. At that time, we both endorsed the recommendation that there was insufficient evidence to support stem cell therapies, platelet-rich plasma, and low-intensity shock wave therapy (LiSWT) in the routine management of ED.¹

I am pleased to see that Dr Brock’s review of the current literature has brought him around to supporting my argument: “as of today, it is unethical to charge for this therapy for all sexual dysfunctions. The 1 exception would be in patients with mild to moderate arteriogenic-induced erectile dysfunction…”

Why have we both modulated our positions on the role of LiSWT for the treatment of ED in clinical practice? Let’s briefly review the physics, putative tissue effects, reported outcomes, and society guidelines. A shock wave is a transient pressure disturbance that propagates rapidly (5 μs duration); it is faster than the speed of sound in the given medium in which it is traveling (in air, 770 mph). A shock wave is associated with a rapid rise from ambient pressure to its maximum pressure, followed by a negative phase of wave propagation. A megapascal (MPa) is the basic unit of pressure or tension measurement used to describe shock waves (1 MPa = 145 psi). Energy is propagated in the medium through which the wave travels in a series of compressions and relaxations. Shock wave lithotripsy for nephrolithiasis was the first medical application of this technology; shock wave lithotripsy generators used for kidney stones create peak wave pressures from 30 MPa to 110 MPa. Energies used in orthopedics (plantar fasciitis, lateral epicondylitis, calcific tendinitis) range from 18-35 MPa. Energies used in the cardiology, diabetic foot ulcers and ED are much lower (5-9 MPa) and referred to as LiSWT. Therapeutic shock waves are characterized by short rise time from ambient pressure to high pressure. Urologists intuitively appreciate how high-energy shock waves can fracture kidney stones; less intuitive is the concept that LiSWT produces lower-energy waves with the same physical forces of compression and relaxation to exert biologic effects on tissues. LiSWT has been reported to induce angiogenesis and stimulate neovascularization in animal penile tissues. A note of warning to both potential patients and practitioners: radial shock wave devices produce dispersive pressure waves of much lower energy and tissue penetration than LiSWT. Radial pressure wave devices are classified by the Food and Drug Administration (FDA) as class I and are equivalent to vibrators. LiSWT devices are class II devices and should be operated under medical supervision.

Studies have shown that LiSWT can improve erectile function assessed by the International Index of Erectile Function (IIEF) in prospective trials both single-armed and placebo-armed. The European Association of Urology and European Society of Sexual Medicine do address clinical applications for LiSWT and have included LiSWT in the management algorithm for vasculogenic ED.² European Association of Urology Guidelines conclude that LiSWT can ameliorate erection quality in patients with ED who are either nonresponders or inadequate responders to phosphodiesterase type 5 inhibitors and reduce the immediate need for more invasive treatments, like penile injections or penile prostheses. Similarly, the British Society for Sexual Medicine Guidelines on the Management of ED conclude LiSWT treatments are well tolerated and safe. LiSWT might be a preferred option for patients failing oral therapy but reluctant to advance to injection therapy.³

In 2017, the FDA approved an LiSWT machine in the management of diabetic foot ulcers. At this time, LiSWT is not FDA approved for ED. If a urologist wants to incorporate LiSWT into clinical practice of ED, there are several technical options which must be considered in the delivery of care. The various technical considerations are: which LiSWT generator (electrohydraulic, electromagnetic, piezoelectric); what types of shocks to deliver (focused, linear, semifocused, unfocused); what treatment parameters (energy flux density, number of shocks per session, number of sessions per week, total number of pulses delivered); and, lastly, which target sites (pendulous shaft vs pendulous shaft and crural bodies). Energy flux density (EFD) refers to the energy delivered per shock wave pulse (mJ/mm²). Dr Harmut Porst has published a review of 6 LiSWT commercial generators using different sources of energy.⁴ The paper serves as a primer for currently marketed SWT devices. The treatment protocols reviewed for vascular ED included EFDs ranging from 0.09 to 0.55 mJ/mm². A recent meta-analysis of 16 randomized, controlled trials of LiSWT found that when EFD of 0.09 mJ/mm² was applied the IIEF improvement was better than when EFD was between 0.1 and 0.2 mJ/mm², and that 1,500 or 2,000 pulses per treatment were similarly better for IIEF improvements than 600 or 3,000 pulses. Improvements after 6 months were better than at 1 or 3 months posttreatment. Only 1 of the 16 trials followed patients to 12 months. So, as Dr Brock points out, we do not have long-term efficacy data or know the impact of maintenance therapy.

Each of the guidelines cited provide consensus that LiSWT applied to the penis appears to be safe and well tolerated, with penile pain and bruising the most common complications. European and British Guidelines both advise that LiSWT appears to have some efficacy in men with mild-moderate vascular ED and may help nonresponders to phosphodiesterase type 5 inhibitor drugs. Any evidence that LiSWT may reduce penile pain in Peyronie’s disease is confounded by the natural history of Peyronie’s disease, which is associated with spontaneously ameliorating penile pain over 6-12 months. LiSWT efficacy on plaque size is confounded by lack of refinements on how to measure plaque length, width, and thickness. None of the guidelines cited has recommended LiSWT in the management of Prostatitis Category IIIb (NIH), which is genitourinary pain with or without voiding symptoms unaccompanied by bacteria. Nor have there been sufficient studies to suggest treatment protocols.

Dr Brock has cited 4 core beliefs as the foundation of medical ethics. I heartily agree with each, but my recollection of the classics calls for a different order, beginning with the admonition attributed to Hippocrates: “Primum non nocere.” First, do no harm. Second would be “doing good.” Third would be “giving the patient a voice in the choice of his care.” The final would be “ensuring fairness.” The clinical data on LiSWT for ED clearly support that it does no harm. Clinicians who apply the therapy are indeed attempting to do good, with a basis for that belief in the literature. Admittedly, LiSWT has not lived up to the promise of restoring normal erectile function, but neither do any of our homeopathic recommendations (lose weight, medically manage lipids/blood pressure/glucose, exercise). That does not stop us from attempts to do good by recommending lifestyle modification in the initial management of ED. Ensuring fairness in medical practice, I assume, means charging a fair price. That’s a debate a U.S. physician could never win against a Canadian. One system ascribes to a fee-for-service model of health care and the other has opted for universal care. In the latter, there is greater financial fairness/equity, but government predominates in choice of options compared to the patient or the physician.

For any patients considering LiSWT for vascular ED management, I would advocate they ask their provider these questions:

• What does the procedure involve (how many treatments, how frequently) and what does it cost?
• What are the benefits and what are my chances of benefitting?
• Could the procedure make me worse?
• What are the alternatives?
• What are the risks?
• What will happen if I don’t have the procedure?

The companion article, “Shock Wave Therapy: Is It Ethical to Offer and Charge for Erectile and Other Sexual Dysfunctions?” was published in the February 2023 issue of AUANews (Volume 28, Issue 2). This companion article can be accessed via the link: https://auanews.net/issues/articles/2023/february-2023/shock-wave-therapy-is-it-ethical-to-offer-and-charge-for-erectile-and-other-sexual-dysfunctions.