ESSM Newsletter # 39

15 ESSM Today After the age of 40, a third of males has prob- lems in achieving an erection. While psychologi- cal factors play a major role in erectile disorders in young people, in adulthood and old age or- ganic problems have a greater responsibility in this disease (1). In healthy males, an erection is a complex event that causes changes in the muscles, nerves, and blood vessels of the penis. Instead, an erectile dysfunction (ED) occurs when the blood does not arrive or remain sufficiently in the penis thereby preventing to maintain a good erection (2). The ED can be attributed to causes that can be largely distinghuised in psychological, neuro- genic, endocrine, iatrogenic and vasculogenic. Research has documented several risk factors for ED, such as: age, cigarette smoking, alcohol and drug abuse, medications (antihypertensives, antidepressants, major tranquilizers, hormones, etc.), diabetes, obesity and dyslipidaemia, arterial hypertension, cardiovascular diseases, athero- sclerosis, endocrinopathies, chronic systemic diseases (chronic renal failure, hepatopathies), central and peripheral neurological diseases, pelvic surgery (radical surgery for prostate, blad- der, large intestine neoplasia) (3). In particular, the vasculogenic ED is certainly the most frequent risk factor with a high prevalence (40%) in men with high cardiovascular risk as described in the Massachusetts Male Aging Study published in 1994 (4). The first line of treatment for ED is the use of oral agents, such as 5 phosphodiesterase inhibitors to which, however, are linked some marked con- traindications, such as the concomitant use of nitroderivatives. Although useful, the oral therapy is not able to act on the primus movens of the pathology but it has positive effects exclusively on the symptomatology (5). The mechanism of function of low intensity shockwaves (Li-ESWT) has been able to act on the causal mechanism underlying ED. The mechanism by which they act is still not perfectly LI-ESWT in Andrology: A new intriguing opportunity to care for patients by Paolo Verze and Georgios Hatzichristodoulou clear, but the most recent hypotheses state that LI-ESWT stimulate neoangiogenesis, recruit stem cells and help nerve regeneration by activating Schwann cells. The shockwave is made of a longitudinal acous- tic wave consisting of a short pulse of about 5 microseconds duration which has the charac- teristic of instantly reaching a positive pressure peak with a subsequent longer period of negative pressure (6) (Figure 1). This mechanism acts in two ways: it provokes a direct mechanical dam- age created by the wave itself and it creates a mechanism of swelling and subsequent collapse of bubbles inside blood vessels (7). The capil- laries, i.e. smaller diameter vessels, are firstly involved, and then the larger vessels. Due to the formation and subsequent breakage of these micro-bubbles, a damage to the endothelium with associated vascular shear stress is provoked inside the capillaries. These “micro-traumas” trigger a recall of both progenitor cells and growth factors that elicit neo-angiogenesis (8) with the formation of new blood vessels forma- tion (Figure 2). It has been shown that in the rat hindlimb, shockwave provoked an upregulation of stro- mal cell-derived factor 1 (SDF-1) (9). SDF-1 is a ligand for CXCR-4, which is strongly expressed on endothelial progenitor cells (EPCs), and plays a crucial role in cell homing and function (10). In the rat ischaemic hindlimb model, combining shockwave therapy with perfusion of exogenous EPCs revealed additive effects in augmenting perfusion, showing that shockwaves increase neo-vascularization. Furthermore, shockwave therapy stimulate neuronal nitric oxide synthase (nNOS) enzymatic activity and NO production in neuronal cells in a dose-dependent fashion (11). Several studies (Hausner et al. (12); Schuh et al. (13)) report positive effects of shockwave therapy on nerve regeneration, by supporting Schwann cell proliferation. Different technological devices for treating the vasculogenic ED have been developed and classified, generally, into Focussed and Linear Li-ESWT. The Focussed Li-ESWT has the charac- Georgios Hatzichristodoulou Associate Professor of Urology Department of Urology and Pediatric Urology, Julius-Maximilians- University of Würzburg Würzburg, Germany hatzichris_g@ukw.de Paolo Verze Assistant Professor of Urology Department of Neurosciences, Reproductive sciences and Odontostomatology, University of Naples Federico II, Naples, Italy pverze@gmail.com Figure1. Example of the schematic depiction of a shockwave as used in the treatment of ED. The figure illustrates a shockwave, i.e. a longitudinal acoustic wave made of a short pulse of about 5 µs duration, composed of an instantaneous jump to a positive acoustic peak pressure (‘shock’) followed by a longer-lasting period of negative pressure.