The Effectiveness of Vibratory Stimulation in Anejaculatory Men with Spinal Cord Injury
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Paraplegia 31 (1993) 689-699 © 1993 International Medical Society of Paraplegia The effectiveness of vibratory stimulation in anejaculatory men with spinal cord injury. Review article H Beckerman MSc PT, 1 J Becher MD, 2 G J Lankhorst MD3 1 Research Associate, 2 Physician, Rehabilitation Medicine, 3 Professor of Rehabilitation Medicine, Department of Rehabilitation Medicine, Free University Hospital, PO Box 7057, 1007 MB Amsterdam, The Netherlands. Most spinal cord injury (SCI) men have fertility problems caused by anejacula tion and a decreased fertility of the ejaculate. There are several methods to induce ejaculation, such as vibratory stimulation and transrectal electrostimula tion. In order to investigate the current state of knowledge about the effective ness of vibratory stimulation and to prepare a controlled clinical trial we reviewed the available literature. Ten articles met our inclusion criteria. Articles were found by various strategies, such as computer searches and screening of relevant journals. We used a structured approach to evaluate these articles. In total 428 patients had been treated with vibration. Sixty percent (257) of the patients responded to treatment, ie produced ejaculate. Because of methodo logical shortcomings in most studies it remains unclear whether there is a relationship between injury type, such as level and completeness of the injury, and the response rate. Semen analyses showed a large intersubject variation. From the data available. it could be concluded that the semen volume is usually normal, whereas sperm motility and morphology of spermatozoa were in most cases far from normal. Side effects of vibratory stimulation were reported in 6% of the patients. Semen could be used for various (assisted) reproductive technologies, eg artificial insemination. in vitro fertilisation and microinsemination. Therefore, it is very important to know which stimulation method is most effective in treating anejaculatory SCI men. This review of the literature shows that the effectiveness of vibratory stimulation remains unclear. New, well designed clinical trials as well as basic research activities might clarify the effectiveness of vibratory stimulation and transrectal electrostimulation. Keywords: review; vibratory stimulation; spinal cord injury; ejaculation; fertility. Introduction although there is evidence that the semen In the Netherlands, each year 400 people quality of men without a history of infertility sustain a spinal cord injury (SCI) caused by has declined during the past 50 years.s accident. Beside other problems, most of Factors attributed to poor quality of the these mainly young men are confronted with ejaculate include, among other things, stasis fertility problems. One of the main causes of of prostatic fluid, testicular hyperthermia, infertility in these men concerns anejacula recurrent urinary tract infections and vari tion, which happens to nearly 85% of ous medications. such as antibiotics.6 them.1-3 In addition, the ejaculate has a In recent years, several methods have decreased fertility. Only 13 % of the SCI been used to induce ejaculation, such as men have a sperm concentration of more application of a vibrator to the penis, than 20 x 106 spermatozoa per millimetre transrectal electrostimulation, direct stimu ejaculate. Furthermore. sperm motility lies lation of the hypogastric nerve, direct as far below the desirable level of 60%. These piration of sperm from the vas deferens, and levels are still used as criteria for normality;1 other methods. Treatment of anejaculation 690 Beckerman et af Paraplegia 31 (1993) 689-699 and infertility is indicated if SCI men are (eg defining the study population, determin interested in determining their fertility ing the sample size and duration of the status or desire fathering a child. recruitment period) concerning the efficacy Ejaculation consists of two separate of both methods of transrectal electrostimu phases. (1) The emission phase includes lation we attempted to find answers to the sperm transport from the testicles to the following questions: seminal vesicle, exudation of seminal tluid How many spinal cord injured men can from the seminal vesicles and the prostate produce semen by vibrostimulation? and closure of the bladder neck (preventing These men possibly do not need or do not retrograde ejaculation). The sympathetic want to be treated with electrostimula innervation (T12-L2) is responsible for the tion, and should therefore not be enrolled contraction of these organs and emission. in the trial. (2) The ejaculation phase includes opening 2 What are the characteristics of responders of the external prostatic sphincter and con and nonresponders? The nonresponders traction of the smooth muscles of the can possibly be treated with electrostimu urethra and the skeletal muscles of the !ation and would be optimal candidates pelvis (ischiocavernosus and bulbocaver for the trial. nosus), to propel the seminal tluid through 3 What is the quality of semen produced by the urethra. The ejaculation phase is con vibrostimulation? This could be com trolled by parasympathetic and somatic pared with the quality of semen produced nerves S2-S4.7 Depending on the level and by electrostimulation (eg the method of completeness of the spinal cord injury this Brindley or of Seager). process is more or less impaired. By applying a vibrator to the shaft of the In order to investigate the current state of penis some spinal injured men are able to knowledge about the effectiveness of vibrat ejaculate. Vibratory stimulation causes a ory stimulation we reviewed the available retlex ejaculation starting with transmission literature on this topic. of afferent nerve stimuli via the pudendal nerve from the penile shaft to nuclei in the spinal cord. Vibratory stimulation is a sim Method ple, safe, noninvasive and painless method of treatment. Furthermore, vibratory stimu Literature search lation offers the distinct advantage of being Articles were eligible if they met the follow adaptable for home use, without the inter ing inclusion criteria: vention of a physician. Thus most treatment 1 Intervention: the study had to deal with programmes start with vibration.8-13 vibratory stimulation. If SCI patients fail to respond to vibra 2 Study design: controlled and uncontrolled tion, treatment has usually been continued clinical trials (eg planned experiments) with transrectal electrostimulation.�·II.13-1:i were selected. In addition, There are two well described methods, unplanned observational studies were in namely transrectal electrostimulation as cluded as well as individual case reports. described by Brindley, 16 and the method 3 Study population: only studies comprising developed by Seager.2 The mechan men with a spinal cord injury were in ism of both of these methods is different. cluded. Brindley stimulates the pudendal nerve, 4 Language: trials published in any lan whereas Seager stimulates the pelvic guage were eligible. muscles. At present the efficacy of each of these methods has not been studied in Articles were found by various strategies. randomized clinical trials. In general, the A computer search was carried out (MED treatment of infertility of SCI men is still a LINE for the period 1980-1992) using the matter of trial and error, mainly based on key words "spinal cord injury', "infertility' clinical experie!!ce. and 'vibration', "vibratory stimulation' or In preparing a randomized clinical trial "vibrostimulation'. In addition, a number of Paraplegia 31 (1993) 6R9-699 Vibratory stimulation in anejaculatory SCI men 691 relevant journals were screened and refer . a danger of reporting only the positive ences in articles were exammed. Fmally, results. Uncontrolled trials and unplanned some articles were found by checking the observational studies especially have the proceedings of conferences. potential to provide a very distorted view of the efficacy of a therapy. The sample size of the study (criterion C) Assessment of the literature gives some idea about the relevance and the To obtain valid answers to our research generalisation of the study results. Large questions we decided to use a structured sample sizes allow subgroup analyses, and approach to evaluate th e I·Iterature. 17-19 possibly give better insight into patients who Table I lists the criteria we used to assess the do or do not respond. quality of the articles selected. Inclusion of . The main outcome parameters (criterion all available studies in a review, not takmg D) are the number of responders (with into account the validity of the study, can ante grade or retrograde ejaculation) and introduce a substantial amount of informa nonresponders, semen volume, sperm tion bias. The first criterion (A) concerns count, sperm motility, and morphology. the description of the treatment. Different Characteristics of responders and, more treatment techniques, number of treatments importantly, nonresponders give us an id a and treatment frequency could result in . � about the study population to be Illcluded III different outcomes. Therefore, a detailed our randomised clinical trial (criterion E). description is necessary. The presence of Using this information, sample size calcul inclusion and exclusion criteria in the art � tions and prevalence figures of SCI men III icles (criterion B) was checked to assess he � the Netherlands, the duration of the recruit consistencv of the investigator in choosmg ment period and related to this the d ration admission�