Introduction

Erectile dysfunction (ED) is the inability to maintain an erection sufficient for satisfactory sexual function (1). The prevalence in males over forty years of age has been reported to be 52% in United States and 69.2% in Turkey (2). A prevalence of nearly 322 million people in 2025 is predicted (3). Penile erection occurs due to a complex interaction of psychological, neural, vascular and endocrine factors. ED is related to these multifactorial problems and its prevalence increases with age. Factors associated with vascular disorders play an important role in ED etiology. These causes are divided into three categories as arteriogenic ED, venogenic ED and mixed vasculogenic. Among vasculogenic ED causes, arteriogenic factors play an important role (1,4).

Even though phosphodiesterase type 5 inhibitors (PDE5i) are actively used as the primary option in ED treatment, the demanded response is not achieved in 40-50% of patients. Although application of vasoactive agents and penile prosthesis implantation are recommended as secondary and tertiary treatment options in irresponsive patients, patients are generally not interested in these treatments (5). Thus, treatment methods which may be tolerated easily by non-invasive patients are required.

There are studies showing that low-intensity linear shockwave treatment (LI-ESWT) is effective and successful in patients with ED due to vascular disorders, especially in those with arteriogenic ED (6,7,8). It is claimed that LI-ESWT causes neovascularization by stimulating angiogenesis and increases endothelial cell proliferation (7,9).

The aim of this study was to evaluate the efficacy of LI-ESWT in patients with severe arteriogenic ED by comparing LI-ESWT combined with the daily use of PDE5i (tadalafil 5 mg) with the daily use of PDE5i.

Materials and Methods

Patients presenting with the complaint of ED between October 2014 and December 2015 were evaluated.

A careful and detailed anamnesis was taken to eliminate psychogenic and neurological factors. Genital examination and neurological examination, including perianal sensation, anal sphincter tonus and bulbocavernosus reflex, were made. International Erectile Function Index Questionnaire - Erectile Function Domain Scores (IIEF-EF) were calculated and ED degree was determined. The patients were also evaluated with Erection Hardness Score (EHS) and sexual encounter profile (SEP) 2 and 3 before the treatment. IIEF-EF score, EHS evaluation and SEP2 and SEP3 questions are present in Table 1.

Hormone tests and other laboratory tests, including follicle-stimulating hormone, luteinizing hormone, testosterone, prolactin, and blood glucose tests, urinalysis, kidney and liver function tests, lipid profile and complete blood count of the patients were evaluated.

Penile Doppler ultrasonography (PDU) was performed in all patients with suspected vasculogenic ED.

Before the PDU, 60 mg papaverine HCl was intracavernosally injected using a 26-gauge 2 mL injector from the proximal 1/3 part of the penis. Then, at the 5th, 10th, 15th and 20th minutes, arterial and venous penis flows were evaluated. Acuson S2000, 9 MHz linear probe (Siemens Medical, Erlangen, Germany) was used for measurements. In patients with a peak systolic blood flow velocity below 30 cm/second, arterial insufficiency (arteriogenic ED), in patients with end-diastolic flow velocity, venous insufficiency (venogenic ED) and in patients with both of these problems, the diagnosis of mixed ED was established.

A total of 23 patients in severe ED group with an IIEF-EF score of 10 and below and having arteriogenic ED based on PDU result were included in the study. These patients were separated into two groups: LI-ESWT + tadalafil 5 mg treatment (n=10) group and tadalafil 5 mg only (n=13) group. LI-ESWT (RENOVA, Direx Medical Systems, Israel) was applied once a week for four weeks in four different anatomic areas: the right and left corpus cavernosum and the right and left penile crura. The treatment was performed as follows: 5000 waves of 0.09 mJ/mm2, 300 intensity waves/min (5 Hz), 40 mm deep, in four areas (cavernosum right, left waves on each side 900, and left and right crus waves 1600 on each side); each session lasting 20 min with a one-week interval between each session (7,8). 5 mg tadalafil treatment was orally started once a day in both groups and the treatment was continued for three months. In the first and third months after treatment, the patients were re-evaluated with IIEF-EF score, EHS, SEP 2 and 3.

All procedures performed in this study involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. The study was approved by the Necmettin Erbakan University Local Ethics Committee (approval number: 2017-822). Consent according to Helsinki Declaration was taken from the patients.

Inclusion Criteria

Patients over 20 years of age who were followed up for at least three months and had ED lasting more than three months, had a IIEF-EF score of ≤10, penile arterial deficiency based on PDU, EHS ≤2, no neurological, hematological, oncological or psychiatric disorder or penile anatomic anomaly and not using antiandrogen and not receiving radiotherapy were included in the study. All individuals who participated in the study were informed about the study and their written consents were obtained.

Statistical Analysis

LI-ESWT + tadalafil and tadalafil only groups were statistically compared. The chi-square (χ2) test was used for analysis of the relationship between categorical variables. For comparisons between two groups, Student’s t test and Mann-Whitney U test were used as appropriate. Two-Way ANOVA was used to assess the changes in pre-treatment and post-treatment variables. A p value of less than 0.05 was considered statistically significant. Statistical evaluation of data was made using SPSS 15 for Windows.

Results

The mean age of the patients in LI-ESWT + tadalafil and tadalafil groups was 52.7 (44-64) years and 54.2 (38-67) years, respectively (p=0.32).

No statistically significant differences were detected in the details of patient characteristics in two groups. Details of patient characteristics in the groups are shown in Table 2.

In LI-ESWT + tadalafil 5 mg and tadalafil 5 mg only groups, the median IEEF-EF scores were as follows: before treatment: 7.1 (5-10), 7.6 (6-10) (p=0.26), 1 month after treatment: 10.6 (7-14), 9.35 (6-13) (p=0.1), and 3 months after treatment: 11.1 (7-14), 10.8 (7-13) (p=0.21), respectively. No statistically significant difference was detected in IIEF-EF scores measured before treatment and 1 and 3 months after treatment. At the end of the third month, the mean IIEF-EF score increased 4 points in LI-ESWT + tadalafil 5 mg group and 3.2 points in tadalafil 5 mg only group (p=0.33). In both evaluations made in 1 and 3 months after treatment, there were two (20%) patients with an EHS score of >2 in LI-ESWT + tadalafil 5 mg group and three patients in tadalafil 5 mg only group. No statistically significant difference was detected in EHS score in 1 and 3 months after treatment between the groups (p=0.16 and p=0.16, respectively). No statistically significant difference was detected in the rate of patients reporting positive responses to SEP2 and SEP3 in 1 and 3 months after treatment between the groups (p=0.25 and p=0.25, respectively). Pre- and after-treatment IIEF-EF scores and EHSs, and the rate of patients who reported positive responses to SEP2 and SEP3 are given in Table 3. None of the patients reported a significant side effect or discomfort due to LI-ESWT treatment.

Discussion

ED treatment options have quite increased in time. PDE5i, intracavernosal injections and penile prostheses are used for treatment in general. Though these treatments are effective and safe, they are “optional” therapies. Although these treatments aim to improve sexual function and erection quality, their improving effects on erection mechanism are generally not permanent or natural. Search for a better treatment for spontaneously re-providing sexual activity in males is the next step in ED management. No significant progress has been achieved although researches on stem cell treatment or gene therapy are being continued (10).

Organic and psychological factors are the main underlying causes in ED etiology. Organic factors play a significant role in the etiology and vasculogenic factors primarily cause ED. Thus, diseases causing vascular pathologies are the main risk factors for vasculogenic ED and, ED risk increases nearly 1.5-4 times in the presence of these risk factors (11,12). Vasculogenic ED occurs with the relaxation problem in endothelium-dependent or endothelium-independent smooth muscle cells and atherosclerotic obstruction in cavernous arteries. As atherosclerosis affects the whole vascular system in the body, the earliest symptom is expected to occur in the artery with the smallest lumen diameter. Atherosclerosis-related symptoms in penile artery are observed in early period since the lumen of penile artery is also narrow (13,14).

Insufficient penile artery flow is responsible for 55% of EDs and severe penile arterial flow inadequacy in 90% of patients in whom a response to treatment cannot be achieved with PDE5i (15).

LI-ESWT has been used as a new therapy for ED in the last 10 years. Clinical studies and reports on this subject have increased especially in recent years. This means that LI-ESWT has gradually gained acceptance both by doctors and the patients (16).

Pelayo-Nieto et al. (8) applied LI-ESWT with 5000 shockwaves to 15 patients with mild-moderate ED once a week for four weeks and detected an increase of 5.46 (14.23-19.69) points in IIEF scores (p<0.013) and 33% recovery in patients with a EHS below 2 (p<0.01) in the evaluation they made at the end of the first month of treatment.

Vardi et al. (17) applied a total of six sessions of LI-ESWT (twice in three weeks) for nine weeks after administration of PDE5i treatment for a month in a sham-controlled study they made. According to the evaluation made one month after treatment, there was an increase of 6.7 points in IIEF score in the treatment group and 3 points in sham group (p=0.0322). Therate of patients with an EHS of 3 and above increased to 77.5% and the penile blood flow increase was also found to be significant in the treatment group. In the evaluation made in the third month, it was reported that IIEF score increased another two points.

Bechara et al. (7) applied LI-ESWT (four weeks, 5000 shockwaves once a week) in 20 patients irresponsive to PDE5i treatment. They reported a rate of response to treatment of 60% and an increase of 5.8 points in IIEF-5 score. The rate of patients reporting positive responses to SEP2 and SEP3 also increased at a statistically significant level. It was reported that only 20% of patients in this study (n=4) were in severe ED group and 3 out of 8 patients not responding to treatment (37.5%) were in severe ED group.

Chung and Cartmill (18) reported that IIEF score increased ≥5 points in 60% of patients in the evaluation made six weeks later on 30 patients who received LI-ESWT (3000 shockwaves, 6 weeks, once in two weeks).

In their placebo-controlled study, Olsen et al. (19) evaluated patients 5, 12 and 24 weeks after LI-ESWT (3000 shockwaves, 5 weeks) treatment lasting five weeks. Patients who had an EHS below 2 before the treatment were included in both groups. While the rate of patients with an EHS between 3 and 4 was 57% in the fifth week in LI-SWT group, it was measured as 54% in placebo group. These rates decreased in the 24th week to 19% and 23%, respectively. No significant difference was detected in IIEF scores between the two groups.

Srini et al. (20) applied LI-ESWT to patients responding to PDE5i and reported that 78% and 71% of patientshad a EHS between 3 and 4 in the first and fifth months, respectively.

Reisman et al. (21) reported that there was an increase of 8.5 points in IIEF-5 score in severe ED patients after LI-ESWT. It was reported that the rate of patients reporting positive responses to SEP3 increased from 25% to 60% in the first month.

Yee et al. (22) reported that there was no significant difference in IIEF and EHS scores between treatment and sham groups 13 weeks after LI-ESWT.

Although there been studies reporting that LI-ESWT provided a benefit in ED treatment, there are differences between the results. The reason for this may be the application of this treatment without separating ED patients into specific groups and application of different shockwaves for different durations with different protocols during the treatment. Moreover, in different studies, whether or not PDE5i was used before and during treatment may also have resulted in differences (7,17,18,19,20,21,22). Therefore, we tried to specify ED patients in our study and patients in severe ED group found to have arterial insufficiency based on penile Doppler ultrasonography results were included in the study group. We evaluated whether LI-ESWT treatment created a difference or not by giving PDE5i to both groups during the treatment. No significant LI-ESWT treatment-related side effect was observed in any of the previous studies, and in our study.

In a meta-analysis made quite recently, it was reported that IIEF of the patients in mild ED group increased significantly (p<0.0001) but a significant increase was not observed in IIEF in severe and moderate ED patients (p=0.30 and p=0.49, respectively). Additionally, in this study, it was reported that increased number of shockwaves and treatment periods less than 6 weeks cause a better therapeutic efficiency (23).

We applied 5000 shockwaves once a week for four weeks in our study. There was no difference between the two groups in diseases which could create vascular pathology. However, although we additionally gave tadalafil 5 mg/day to our LI-ESWT patient group, no significant difference was detected in IIEF score between them and the group given tadalafil 5 mg/day only. While IIEF-EF score increased 4 points in LI-ESWT + tadalafil group at the end of the third month, it increased 3.2 points in tadalafil group.

We assume that the main reason behind the significant difference found between the two groups after the treatment is the inclusion of severe arteriogenic ED patients in the study. Similarly, Bechara et al. (7) reported that 3 out of 4 patients in severe ED group were irresponsive to LI-ESWT. In addition, the form of LI-ESWT protocol and treatment duration are controversial in many studies (8,17,18,19). However it has been reported that treatment lasting longer than six weeks did not have a positive effect on the results (23). There is no study comparing the treatments lasting 4, 5 and 6 weeks. Thus, we have not found a difference between treatment responses since the LI-ESWT protocol we applied for four weeks was not satisfactory. A satisfactory recovery may not have occurred in the results since the rate of the presence of the diseases which could result in vascular pathologies was high in both groups.

These results showed that LI-ESWT + tadalafil treatment does not have any effect in patients with severe ED penile arterial insufficiency compared to tadalafil treatment only. Therefore, we assume that penile prosthesis treatment would be more appropriate in patients with severe ED, penile arterial insufficiency and in those not benefiting from medical treatment. LI-ESWT treatment is not reimbursed by the Ministry of Health of Turkiye and the cost of four-week treatment is nearly 4000 Turkish Liras (1072$) per patient. Its high cost makes the applicability of this treatment more difficult.

Study Limitations

Low number of patients, presence of diseases which may cause vascular pathologies in our patients (i.e. diabetes mellitus, hypertension and coronary heart disease) and the cost of the treatment can be counted among our limitations for applying the treatment only four weeks and for not increasing the number of LI-ESWT sessions.

Conclusion

LI-ESWT can be applied without any significant side effects and has positive effect on the results. However, it provides no advantage in patients with severe ED or penile arterial insufficiency. Studies separating larger number of participants into more specific ED groups are required to evaluate the treatment efficacy better.

Ethics

Ethics Committee Approval: The study was approved by the Necmettin Erbakan University Local Ethics Committee (approval number: 2017-822).

Informed Consent: Consent form was filled out by all participants.

Peer-review: External and internal peer-reviewed.

Authorship Contributions

Surgical and Medical Practices: M.G.S., C.K., Concept: M.G.S., C.K., Design: M.G.S., C.K., Data Collection or Processing: M.G.S., C.K., Analysis or Interpretation: M.G.S., C.K., Literature Search: M.G.S., C.K., Writing: M.G.S., C.K.

Conflict of Interest: No conflict of interest was declared by the authors.

Financial Disclosure: The authors declared that this study received no financial support.