INTRODUCTION

Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) is a widespread condition, which is observed in around 10.0% of men worldwide [1]. At the end of the 1990s, the National Institute of Health – National Institute of Diabetes and Digestive and Kidney Diseases (USA NIH-NIDDK) proposed a consensus definition for this condition and a uniform system of classification [2]. This classification was approved in clinical practice and in the scientific environment. It includes bacterial forms of prostatitis (acute and chronic), an abacterial form (chronic pelvic pain syndrome), and asymptomatic prostatitis.

CP/CPPS (category III NIH-NIDDK, 1999) is defined as pain or discomfort in the pelvic area associated with micturition disorders and/or sexual dysfunction, which lasted for over three out of the previous six months [2]. Adequate diagnostics include differential diagnostics with such diseases as urinary tract infections, cancer, abnormal development, or neurological diseases. Depending on the presence or absence of leukocytes in the prostate fluid, the condition is classified into inflammatory (category IIIa, NIH-NIDDK, 1999) and non-inflammatory types (category IIIb, NIH-NIDDK, 1999) [2].

Infectious agents can be detected in less than 10.0% of patients with prostatitis symptoms. An episode of acute bacterial prostatitis leads to the chronic form only in 10.0% of patients and to CP/CPPS in another 10.0% of patients [1]. CP/CPPS can manifest most symptoms of prostatitis in over 90.0% of men. Due to the heterogeneity and unclear pathophysiology of CP/CPPS, the development of effective treatment methods remains a complicated task. Despite numerous clinical studies, the universal approach to therapy is not proposed [3]. Thus, currently, there is a need for novel, efficient, and available methods of treating this condition.

One of the potentially interesting and promising methods in this area is focused shockwave therapy (fSWT). Shockwave therapy was implemented in clinical practice since 1970. It has been shown to be a well-tolerable and efficient treatment method in sportsmen with some orthopedic pathology (pseudarthrosis and various tendinopathies) [4][5]. Later, the method was used in urology to treat vasogenic erectile dysfunction and Peyronie’s disease [6][7]. In 2018, a major systemic Cochrane review was published on the efficiency of SWT in the treatment of CP/CPPS [8]. At the same time, the authors noted that it was impossible to evaluate the quality of life of patients.

The study aimed to evaluate the efficacy of the method and the quality of life of patients after treatment of CP/CPPS with fSWT.

MATERIALS AND METHODS

Study design. A prospective cohort study included patients with diagnosed CP/CPPS. Before the study, all patients signed an informed consent form for participation in the study. The study included a detailed study of medical history, prostate transrectal ultrasound (TRUS), PSA in the blood (for men older than 40 years old), a cultural study of prostate fluid (to exclude the inflammatory component), uroflowmetry (to exclude infravesical obstruction), and a digital rectal examination in a chair to find trigger points in the pelvic floor muscles and in the projection of the prostate bed (Fig. 1). The diagnosis was verified based on the patient's questioning and the presence or absence of pain in the prostate area during palpation (the pain as disturbing). The study exclusion criteria included contraindications to the fSWT method, signs of active inflammation in prostate fluid, and prostate volume >40 cm³ with signs of infravesical obstruction (peak rate <12 ml/s by the results of uroflowmetry). In addition, patients with elevated levels of PSA (>4 ng/ml) underwent pelvic area MRI. Patients with a prostate nodule > Pi-RADS 2 were excluded from the study.

Endpoints. The primary study endpoint was the evaluation of a decrease in the score for each domain of the validated NIH-CPSI questionnaire (National Institute of Health – Chronic Prostatitis Symptom Index) validated in Russia. The secondary study endpoint was a decrease in the manifestation of accumulation symptoms according to the IPSS (International Prostate Symptom Score) and a change in the quality of life (QoL).

Treatment protocol. Men visited the clinics three times per week for 4 weeks (12 sessions). Each patient underwent a session of fSWT using BTL-6000 fSWT («BTL Medical Technologies», Reading, Berkshire, UK) by the protocol “Chronic pelvic pain”. The patients received 3500 impulses at 8 Hz frequency via an applicator applied to the area in the prostate projection. The position of the applicator was changed every 300–500 impulses. A month after the last session, the patients filled in validated questionnaires.

Statistical analysis. The data showed normal distribution by Shapiro-Wilk’s test. All quantitative data were described as mean ± standard deviation. The dynamic of the treatment results was evaluated using the Wilcoxon paired test. Treatment results at various dates were compared with the Friedman test. Multiple comparisons were evaluated using the Benjamini-Hochberg adjustment. Qualitative data were described with absolute values (n) and percent (%). They were analyzed with the Pearson chi-square test. Fisher’s test was used when the number of expected values in a cross-table cell was < 5. The differences were significant at p < 0.05. All calculations were made in R ver.4.1.3 («The R Foundation for Statistical Computing», Vienna, Austria).

RESULTS

The study included 48 men. The mean age of patients was 40 ± 9.0 years old. The size of the prostate was 27.6 ± 5.6 cm³ according to the TRUS results. The authors studied various domains of the questionnaire and obtained the following results in the pretreatment stage: 10.0 ± 4.7 score in domain I “Pain”, 5.88 ± 2.40 score in domain II “Micturition”, 4.42 ± 0.90 score in domain III “Influence of symptoms” and 4.04 ± 1.27 sore in domain IV “Quality of life”. The mean IPSS score before treatment was 17.2 ± 4.8 score; the quality of life was 4.48 ± 0.99 score.

After the first three sessions of the therapy, the control questionnaire survey revealed a significant decrease in NIH-CPSI score in the domain I “Pain”, which was observed to the third week (Fig. 2). At the same time, there was no significant decrease in the score in domain II “Micturition”. By the end of the study, in domains III and IV, the score was distributed as 4.67 ± 0.93 and 2.33 ± 1.06, respectively. It should be noted that the total mean IPSS score during the period of observation did not decrease significantly. By the end of the follow-up, it was 17.8 ± 4.8 score (p = 0.074). The QoL index changed from 4.48 ± 0.99 to 2.62 ± 0.91 (p < 0.001).

The dynamic of the changes in the NIH-CPSI parameters in each domain is presented in the table. The authors received statistically significant differences in domains I, II, and IV. IPSS score and domain II did not show significant changes.

DISCUSSION

Symptoms of CP/CPPS can result from physical dysfunction, for example, pelvic muscles spasm and muscular hypersensitivity [9][10]. The methods of treatment that target the relaxation and improvement of pelvic muscles coordination (biological feedback, retraining of pelvic floor muscle control, myofascial release of the painful trigger points) can play a certain role in the weakening of symptoms in patients with CP/CPPS [11][12]. In the context of the treatment of myofascial pain syndrome, fSWT is grounded pathophysiologically. The results of a decrease in the pain domain can indirectly confirm this hypothesis.

Although the authors did not obtain a significant improvement in micturition symptoms, according to previous studies, the correlation tests between the NIH-CPSI symptoms domains showed that pain had a more significant effect on QoL than micturition symptoms [13]. Therefore, the treatment of pain syndrome is a priority aspect of therapy to improve QoL. Additionally, to improve the efficiency of treatment, a combination of SWT and other effective methods (peripheral magnetic neuromodulation) cannot be excluded [14].

The waves for fSWT can be generated by electrohydraulic, electromagnetic, and piezoelectric mechanisms depending on the apparatus used [15]. In all three methods of generation, the wave is formed in the fluid inside an applicator. Further, this wave is focused by a lens and transmitted to the tissue. In turn, waves for radial SWT are generated by the acceleration of compressed air via a tube, which is directed to the applicator and contacts the skin. Because of these differences in the generation, there are physical differences between the waves produced by each method. First, radial shock waves have a more superficial effect because maximal energy is achieved on the skin in comparison with focused shock waves that achieve maximal energy in the point of focus located deeper in the body tissues [16]. Second, it has been shown that pressure waves generated by the radial SWT cannot be called shock waves from the fundamental point of view because they do not possess typical physical properties of shock waves, such as short rising time, high peak pressure, and non-linearity [17].

However, often, the term “shock wave therapy” is used not correctly. Besides, not all available devices really generate focused shock waves. Such terms as “radial waves”, “acoustic waves”, “sound waves”, or “radial impulse therapy” are synonyms for many people; sometimes, they are used as synonyms for shock waves, although based on physical nature, these are different technologies [18]. This can provide quite controversial results from previous studies.

In addition, the search for the optimal treatment protocol is the priority task currently. Zhang et al. (2018) reported on the effectiveness of treatment by the protocol 10 Hz 1 time/week for 8 weeks [19]. At the same time, Zeng et al. (2012) proposed the following protocol: 2000 impulses at 2 Hz 5 times/week for 2 weeks [20]. In the present study, the authors chose the main protocol based on clinical experience.

Limitations. However, the study has some limitations. It is the absence of blinding and the control group, which cannot exclude a placebo effect.

CONCLUSION

The study showed the effectiveness of focused shock wave therapy as an independent method of treatment for CP/CPPS. Further well-planned multicenter studies are needed to establish the optimal protocol and duration of therapy.