Validation and implementation of surgical simulators: a critical review of present, past, and future.

BACKGROUND: In the past 20 years the surgical simulator market has seen substantial growth. Simulators are useful for teaching surgical skills effectively and with minimal harm and discomfort to patients. Before a simulator can be integrated into an educational program, it is recommended that its validity be determined. This study aims to provide a critical review of the literature and the main experiences and efforts relating to the validation of simulators during the last two decades. METHODS: Subjective and objective validity studies between 1980 and 2008 were identified by searches in Pubmed, Cochrane, and Web of Science. RESULTS: Although several papers have described definitions of various subjective types of validity, the literature does not offer any general guidelines concerning methods, settings, and data interpretation. Objective validation studies on endourological simulators were mainly characterized by a large variety of methods and parameters used to assess validity and in the definition and identification of expert and novice levels of performance. CONCLUSION: Validity research is hampered by a paucity of widely accepted definitions and measurement methods of validity. It would be helpful to those considering the use of simulators in training programs if there were consensus on guidelines for validating surgical simulators and the development of training programs. Before undertaking a study to validate a simulator, researchers would be well advised to conduct a training needs analysis (TNA) to evaluate the existing need for training and to determine program requirements in a training program design (TPD), methods that are also used by designers of military simulation programs. Development and validation of training models should be based on a multidisciplinary approach involving specialists (teachers), residents (learners), educationalists (teaching the teachers), and industrial designers (providers of teaching facilities). In addition to technical skills, attention should be paid to contextual, interpersonal, and task-related factors.

Urinary sodium dodecyl sulfate electrophoresis with silver staining: a noninvasive diagnostic tool for obstructive uropathy in children.

PURPOSE: Obstructive uropathy such as ureteropelvic junction obstruction in the newborn is a major diagnostic and therapeutic dilemma. We investigated whether urinary sodium dodecyl sulfate electrophoresis with polyacrylamide gel electrophoresis with silver staining could be used to discriminate between children requiring and those not requiring pyeloplasty. MATERIALS AND METHODS: In a pilot study we analyzed the urine of 18 children (mean age 2.7 years) with grade III or IV hydronephrosis according to the Society for Fetal Urology classification. A total of 44 healthy children were studied as controls. Children with hydronephrosis were followed using ultrasound, (99m)technetium mercaptoacetyltriglycine diuretic renography and voiding cystourethrography. Urine was obtained by spontaneous voiding and studied by sodium dodecyl sulfate polyacrylamide gel electrophoresis with silver staining using Melzer's modification. After the study period test results were compared to outcomes, ie whether patients required surgery, and to normalization of previously abnormal protein excretion patterns. RESULTS: All but 1 of the healthy controls had a normal electrophoresis assessment. Of 9 patients followed for hydronephrosis 7 had an abnormal electrophoresis result preoperatively. One child had to be operated on twice because of relapse of ureteropelvic junction obstruction. Six children returned to a normal electrophoresis result postoperatively, including the child who was operated on twice. All children with an initially normal electrophoresis assessment displayed persistent normal values, except 1. Children shifting from a normal to an abnormal electrophoresis result underwent surgery after exclusion of urinary tract infection. CONCLUSIONS: Sodium dodecyl sulfate polyacrylamide gel electrophoresis with silver staining seems to be a good predictive test for clinically relevant ureteropelvic junction obstruction. Further studies are being performed to see whether the test can stand against the gold standard, (99m)technetium mercaptoacetyltriglycine diuretic renography.

Sexual functioning in patients with lower urinary tract dysfunction improves after percutaneous tibial nerve stimulation.

In this study, we evaluated the effect of lower urinary tract dysfunction and its neuromodulative therapy on sexual functioning. We studied 121 patients with an overactive bladder (OAB) (N = 83), chronic pelvic pain (N = 23) and nonobstructive retention (N = 15), which were treated with neuromodulation (i.e. percutaneous tibial nerve stimulation, PTNS). To obtain information on their sexual function, a self-administered standardized questionnaire was filled out before therapy as well as after 12 weeks of treatment. Before therapy, different aspects of sexual life were considered not normal in 25.3-45.6% of the cases. This improved significantly after treatment. Patients most likely to benefit were women, patients with an OAB and subjective responders. The aspects of sexual life which mostly improved were overall satisfaction, libido and the frequency of sexual activities. Sexual dysfunction is observed in a lot of patients with lower urinary tract disorders and may improve on successful therapy for the latter.

Prognostic factors for successful percutaneous tibial nerve stimulation.

OBJECTIVE: In sacral as well as tibial nerve stimulation test stimulation is the main prognostic factor for success. In our study we tried to identify prognostic patient characteristics to improve patient selection for neuromodulation therapy. METHODS: PTNS was applied to 132 patients in 8 study centers (51 men, 81 women, mean age of 53 years (range: 21-82)). 83 patients were treated for overactive bladder, 16 for non-obstructive urinary retention and 33 for chronic pelvic pain. All patients had to fill out micturition or pain diaries, as well as quality of life questionnaires before and after treatment. Patient characteristics were evaluated for their prognostic value for successful outcome of neuromodulation therapy with use of logistic regression. RESULTS: Objective success was seen in 32.6% of patients, subjective success in 51.5%. Most evaluated clinical parameters proved not to be of prognostic value. A history of sexual and/or physical abuse was found in 12 of 103 interviewed patients, but did not alter PTNS treatment outcome. However, a low total score at baseline in the SF-36 questionnaire proved to be predictive for not obtaining objective (OR 0.444 [95% CI: 0.198-0.996], p = 0.04) or subjective success (OR 0.424 [CI: 0.203-0.887], p = 0.02). Especially patients with a low SF-36 Mental Component Summary were prone to fail neuromodulation therapy: OR 0.123 (95% CI: 0.273-0.552), p = 0.006 for objective success. These patients also scored worse on disease-specific quality of life questionnaires, although they had no different disease severity compared to patients with good mental health. CONCLUSION: Bad mental health as measured with the SF-36 Mental Component Summary does not depend on symptom severity and is a negative predictive factor for success of percutaneous tibial nerve stimulation. It therefore might be used as a tool for better patient selection in neuromodulation therapy.

Lower urinary tract symptoms after renal transplantation.

PURPOSE: We investigated the prevalence and nature of lower urinary tract symptoms after renal transplantation. In addition, we studied how these symptoms affect the quality of life and whether function of the lower urinary tract before transplantation was related to postoperative occurrence of lower urinary tract symptoms. MATERIALS AND METHODS: Data were gathered by a written questionnaire. The research group consisted of 63 patients who underwent renal transplantation in 1998 at the University Medical Center St Radboud Nijmegen. The control group consisted of 74 patients with nonurological complaints who visited an outpatient clinic at the same university. RESULTS: The most important finding was that patients who underwent renal transplantation needed to void more often than controls, both during the day and at night. After renal transplantation, almost 50% of the patients complained of frequency and 62% nocturia. Patients with a transplant had tended to perceive frequency and nocturia less as problems than those in the control group. CONCLUSIONS: No relation was found between the functioning of the lower urinary tract before transplantation, and occurrence of frequency and nocturia after. The amount of fluid intake at the interview was not related to the occurrence of frequency and nocturia. No abnormalities were found regarding bladder evacuation.

Posterior tibial nerve stimulation as neuromodulative treatment of lower urinary tract dysfunction.

PURPOSE: Recently, intermittent percutaneous posterior tibial nerve stimulation was introduced as a treatment modality filling the gap between conservative and surgical therapies in patients with certain types of lower urinary tract dysfunction. MATERIALS AND METHODS: In a prospective multicenter trial posterior tibial nerve stimulation was evaluated in 37 patients who presented with symptoms of bladder overactivity, that is the urgency and frequency syndrome and/or urge incontinence, and 12 with nonobstructive urinary retention. Results were recorded in voiding diaries and on quality of life questionnaires before and after treatment. Patients were classified as responders, including those in whom therapy was successful and chose to continue treatment after the initial 12 weeks, and nonresponders, those who chose to stop treatment. RESULTS: Overall, a positive response was seen in 60% of all patients. In patients with bladder overactivity a statistically significant decrease was observed in leakage episodes, number of pads used, voiding frequency and nocturia, and an equal increase in mean and smallest volume voided. Improvements were also seen in nonobstructive urinary retention, including number of catheterizations, total and mean volume catheterized, and total and mean volume voided. Disease specific quality of life and some domains of general quality of life improved, especially of bladder overactivity. Only mild side effects were observed. CONCLUSIONS: Posterior tibial nerve stimulation is a minimally invasive and successful treatment option for patients with certain types of lower urinary tract dysfunction.

Low-dose oxybutynin for the treatment of urge incontinence: good efficacy and few side effects.

OBJECTIVE: Oxybutynin is an efficacious pharmacotherapeutic agent for the treatment of urge incontinence. However, many patients discontinue therapy because of the considerable side effects. This study aims at assessing the efficacy of a low-dose oxybutynin (2.5 mg three times daily) in relation to the concomitant profile of side effects. METHODS: Unselected primary care practice patients with involuntary urine loss were eligible for this study. A specially designed questionnaire was used to establish the diagnosis of symptomatic urge incontinence. All patients started with an oral dose of oxybutynin of 2.5 mg three times daily, and the responses with regard to efficacy and side effects were assessed after 2 and 6 weeks. Efficacy was evaluated using subjective patients' impression as well as data extracted from their voiding diaries. Adverse events possibly related to the use of oxybutynin were specifically asked for. Patients who experienced little or no symptomatic relief and who experienced no side effects were given a higher dose (5 mg three times daily). RESULTS: General practitioners recruited 416 patients with symptomatic urge incontinence. Increasing the dose to 5 mg three times was preferred by 115 patients (28%). After 6 weeks 393 patients reported a partial or complete symptomatic cure (positive responder rate 95%). The average number of micturitions per 24 h decreased from 9.9+/-(SD)3.7 to 6.0+/-2.5 (p<0.001), and the average number of episodes of urine loss per 24 h decreased from 6.0+/-3.6 to 1.7+/-1.8 (p<0.001). A total of 123 patients (30%) reported side effects attributable to the use of oxybutynin; 42 patients (10%) had to stop the medication because of the severity of these side effects. CONCLUSION: Successful pharmacological treatment of symptomatic urge incontinence can be given in a primary care setting using oxybutynin. Starting with a low dose of 2.5 three times daily, a subjective and objective efficacy can be achieved with fewer side effects than reported in the literature.

Comparison of different computer models of the neural control system of the lower urinary tract.

This paper presents a series of five models that were formulated for describing the neural control of the lower urinary tract in humans. A parsimonious formulation of the effect of the sympathetic system, the pre-optic area, and urethral afferents on the simulated behavior are included. In spite of the relative simplicity of the five models studied, behavior that resembles normal lower urinary tract behavior as seen during an urodynamic investigation could be simulated. The models were tested by studying their response to disturbances of the afferent signal from the bladder. It was found that the inhibiting reflex that results from including the sympathetic system or the pre-optic area (PrOA) only counteracts the disturbance in the storage phase. Once micturition has started, these inhibiting reflexes are suppressed. A detrusor contraction that does not result in complete micturition similar to an unstable detrusor contraction could be simulated in a model including urethral afferents. Owing to the number of uncertainties in these models, so far no unambiguous explanation of normal and pathological lower urinary tract behavior can be given. However, these models can be used as an additional tool in studies of the mechanisms of the involved neural control.

Sacral root neuromodulation in the treatment of refractory urinary urge incontinence: a prospective randomized clinical trial.

OBJECTIVES: To compare the effectiveness of sacral root neuromodulation with that of conservative management in ameliorating symptoms of refractory urinary urge incontinence and enhancing quality of life, to assess the objective response to neuromodulation as revealed by urodynamic testing, and to delineate the long-term outcomes of neuromodulation. METHODS: Forty-four patients with refractory urge incontinence were randomized to undergo neuromodulation with an implantable impulse generator (n = 21) or to continue their prior conservative management (n = 23). At 6 months the control group was eligible for crossover to implant. Patient evaluation included voiding diaries, quality of life questionnaires, urodynamic testing, and documentation of adverse events. Long-term follow-up evaluations were conducted at 6-month intervals up to 36 months. RESULTS: At 6 months mean leakage episodes, leakage severity and pad usage in the implant group were significantly lower by 88% (p < 0.0005), 24% (p = 0.047) and 90% (p < 0.0005), respectively, than the corresponding control group mean values. Improvements in leakage episodes and pad usage of >/=90% were attained by 75 and 85% of the implant group, respectively, but none of the control group. One third of implant patients, but none of the control patients, achieved >/=50% improvement in leakage severity. Over half of the implant patients (56%) were completely dry compared with 1 control patient (4%). Implant patients, but not control patients, exhibited significant improvement with respect to two quality of life measures. Neuromodulation resulted in increases of 220% (p < 0.0005) and 39% (p = 0.013), respectively, in urodynamically assessed bladder volume at first contraction and maximum fill. At 36 months the actuarial rate of treatment failure was 32.4% (95% CI, 17.0-56.0%). Adverse events most frequently involved pain at the implant site, and the incidence of serious complications was low. CONCLUSIONS: Neuromodulation is markedly more effective than conservative management in alleviating symptoms of refractory urge incontinence. Quality of life and urodynamic function are also improved by neuromodulation. The effects of neuromodulation are long-lasting, and associated morbidity is low.

Neuromodulation by implant for treating lower urinary tract symptoms and dysfunction.

OBJECTIVE: Patients with irritative micturition complaints, pelvic pain, involuntary urine loss or urinary retention are sometimes difficult to treat. The advent of direct sacral nerve stimulation offers a therapeutic alternative if conservative measures fail and surgery is considered. This paper reviews therapeutic neuromodulation by implant for treating lower urinary tract symptoms and dysfunction. METHODS: The international literature is reviewed on topics such as the physiological basis of neuromodulation, techniques of acute testing and chronic implantation, and clinical results. Future developments and ways for possible improvement are discussed. RESULTS: The mode of action of neuromodulation is probably through restoring the correct balance between excitatory and inhibitory impulses from and to the pelvic organs at a sacral and supra-sacral level. Depending on the predefined success criteria, average success rates of definitive implants vary from 50 to 70%. From the data it seems that patients with urge incontinence and urinary retention are the best candidates for neuromodulation. In the literature the lack of standardisation of selection criteria, stimulation parameters and definitions of success is striking. CONCLUSIONS: Neuromodulation by implant is a useful therapeutic alternative. It should at least be considered in patients with therapy-resistant urge incontinence and urinary retention before proceeding to surgery. Issues such as underlying physiology, methodological standardisation, technical improvements, and patient selection must be addressed in future research.

A computer model for describing the effect of urethral afferents on simulated lower urinary tract function.

A computer model of mechanical properties of the bladder, the urethra and the rhabdosphincter, as well as their neural control is presented in this paper. The model has a rather simple design and processes sensory information from both the bladder wall tension and urethral stretch. It is assumed that afferent signals from the urethra are involved in a sacral excitatory reflex and a supraspinal inhibitory reflex. Pressure and flow signals that resemble experimentally measured normal human behaviour could be simulated with this model. From these simulations the relation between the neural control mechanisms used in the model and the neural control mechanism in vivo cannot be judged entirely because similar behaviour could be simulated with models that are bas ed on different neural control mechanisms. Also behaviour that resembles detrusor overactivity was simulated with our model after an externally induced rise in detrusor pressure was added. Detrusor overactivity, sometimes in combination with urethral relaxation, can occur during a urodynamic investigation. A possible explanation for this detrusor overactivity might be that the micturition reflex is triggered by unknown disturbances and is inhibited immediately after by the same mechanism that normally ceases voiding. The described model provides such a mechanism. Based on these simulations, therefore, it is concluded that urethral afferent signals might be important in lower urinary tract control.

[Infertility caused by ejaculation disturbances and anorgasmy]. / Infertiliteit bij ejaculatiestoornissen en anorgasmie.

Recent progress in andrology, reproduction biology and medical sexuology have led to a substantial increase of the proportions of pregnancy achieved by males with ejaculation disorders or anorgasmy. Impairment in libido and excitement usually has a psychic cause, apart from rare endocrinological abnormalities such as hyperprolactinaemia and androgen depletion. Another possible cause is chronic use of certain drugs. Causes of erection disorders can be classified on the basis of psychogenous, vascular and neurogenous factors. Ejaculation disorders are caused by embryonal anomalies, neurological disorders and use of certain (psychoactive) pharmaceutical agents. Collecting sperm proves to be virtually always possible. According to current views, the treatment of infertility in ejaculation disorders or anorgasmy should be if possible, elimination of the primary cause or else: in-vitro fertilisation (IVF)/intracytoplasmatic sperm injection (ICSI) with semen obtained after processing a retrograde ejaculate or by means of vibro-ejaculation or electro-ejaculation.

Comparison of biothesiometry and neuro-urophysiological investigations for the clinical evaluation of patients with erectile dysfunction.

In the literature the determination of the vibration sensitivity threshold of the penile glans by means of biothesiometry has been introduced as a cost-effective office test for the evaluation of penile neuropathy in impotent men. At our facility we have gained extensive experience with neuro-urophysiological tests for the evaluation of penile innervation. These neuro-urophysiological tests have the disadvantage of complexity, invasiveness and time consumption. In our study both methods were compared in 31 impotent patients. The results showed that penile glans biothesiometry yields consistent results when measurements are repeated during 1 session. However, no relationship was found between the outcome of penile glans biothesiometry and neuro-urophysiological tests of the dorsal penile nerve, which is probably due to the fact that vibration is not an adequate stimulus to the skin of the penile glans that contains free nerve endings (that is pain receptors) only, and hardly any vibration receptors. We conclude that biothesiometric investigation of penile glans innervation is unsuited for the evaluation of penile innervation and cannot replace neuro-urophysiological tests.

Use of sacral reflex latency measurements in the evaluation of neural function of spinal cord injury patients: a comparison of neuro-urophysiological testing and urodynamic investigations.

Complete suprasacral spinal cord injury is followed by great changes in the neural control and function of the lower urinary tract. In the literature there is some controversy about the relationship between detrusor function and results of neurophysiological tests of sacral root conduction after the spinal shock phase. Therefore, we studied this relationship in a group of 73 patients with clinical as well as neurophysiological documented complete suprasacral spinal cord injury, and compared sacral reflex latency measurements (bulbocavernosus and urethro-anal reflexes) with detrusor function, documented by urodynamic investigation. A high incidence of sacral reflex latency abnormalities was found. Comparison of sacral reflex latencies with detrusor reflex activity showed a statistical significant correlation. No such relationship could be found between urodynamic characteristics of the detrusor in patients with detrusor hyperreflexia and sacral reflex latency measurements. We conclude that sacral reflex latency measurements can give an indication about the existence of reflex detrusor activity. On the other hand, these neurophysiological measurements do not provide a reliable indication of the detrusor function after complete spinal cord injury.

Erectile dysfunction in diabetic men: the neurological factor revisited.

In the literature the importance of the neurological factor in the etiology of erectile dysfunction in patients with diabetes mellitus is subject to debate. We report on the findings of neurophysiological investigations in 27 impotent and 30 potent diabetic patients, as well as 102 impotent nondiabetic patients. Additionally, hormonal and vascular evaluations were done. The neurophysiological evaluations consisted of assessment of somatic as well as autonomic sensory nerves, by measuring the latencies of somatosensory evoked potentials of the posterior tibial and pudendal nerves, and of the bulbocavernosus and urethro-anal reflexes. The results show a higher incidence of more severe peripheral and autonomic sensory neuropathy in impotent diabetic men. Also, a preponderance of abnormal intracavernous pharmacological tests, suggesting vasculogenic impotence, was found in impotent diabetic patients. No important endocrinological differences were found among the 3 groups under investigation. Significant differences occurred for plasma glucose and glycosylated hemoglobin. We conclude that diabetic urogenital sensory neuropathy has a crucial role in the etiology of diabetic impotence. Angiopathy seems to be of secondary importance. The results show that poor diabetes regulation is associated with diabetic impotence.

Penile pharmacological duplex ultrasonography: a dose-effect study comparing papaverine, papaverine/phentolamine and prostaglandin E1.

Alternations of penile blood flow are believed to be the most frequent organic cause of erectile dysfunction. Penile duplex ultrasonography following intracavernous injection of a vasoactive agent is an accepted method for diagnosis of penile vascular dysfunction. To determine the diagnostic efficacy of commonly used vasoactive drugs we studied the hemodynamic effects of different dosages of papaverine, the combination of papaverine and phentolamine, and prostaglandin E1 in men with erectile dysfunction and men with normal erectile potency using color duplex ultrasonography. We concluded that 12.5 mg. papaverine and 10 micrograms. prostaglandin E1 are the drugs of choice to be used in conjunction with penile duplex ultrasonography because of optimal effects on cavernous arterial dilatation and low risk of prolonged erection. However, low dose papaverine or prostaglandin E1 has a limited value in evaluating veno-occlusive function.

Motor evoked potentials from the bladder on magnetic stimulation of the cauda equina: a new technique for investigation of autonomic bladder innervation.

Although neurophysiological techniques have become widely accepted in the diagnostic evaluation of urogenital tract dysfunction, arguments have been forwarded to question their validity. Current techniques merely deal with somatosensory nerves, whereas micturition and sexual functions depend on autonomic motor nerve function as well. This study presents a new technique of motor evoked potentials obtained after magnetic stimulation of the cauda equina. Bladder and pelvic floor motor evoked potentials could be measured with concentric needle electrodes. Mean latency was 35.6 msec. for bladder motor evoked potentials and 10.6 msec. for pelvic floor motor evoked potentials. The technique was easy to perform, and provided consistent and objective data. No harmful side effects were noted.

Assessment of penile blood flow by duplex ultrasonography in 44 men with normal erectile potency in different phases of erection.

Duplex ultrasonography is important in the diagnosis of vasculogenic erectile dysfunction. We measured the ultrasonographic parameters of cavernous blood flow in different phases of penile erection. We examined 44 volunteers with normal erectile potency. Doppler spectra of the cavernous artery were obtained in a time-dependent manner after intracavernous administration of papaverine. Following intracavernous pharmacological stimulation, the Doppler spectrum alters according to a specific pattern indicating the different hemodynamic phases of erection. Peak flow velocity and acceleration time, measured in the early post-injection phase, may be used to grade arterial inflow. The difference between resistance index in the pre-injection and late post-injection phases may be used to estimate veno-occlusive function. References values are defined.

Penile sensory disorders in erectile dysfunction: results of a comprehensive neuro-urophysiological diagnostic evaluation in 123 patients.

A total of 123 patients with complaints of erectile dysfunction and no clinically overt neurological disease underwent a comprehensive neuro-urophysiological diagnostic evaluation. The results were compared with those obtained in 50 healthy volunteers. Data gathered consisted of somatosensory evoked potentials from the posterior tibial nerve (tibial evoked potential) and from the dorsal penile nerve (pudendal evoked potential). Also, 2 sacral reflex latencies were measured (bulbocavernosus reflex and urethro-anal reflex). A total of 58 patients (47%) had at least 1 abnormal neuro-urophysiological measurement. Neuro-urophysiological abnormalities were found more frequently in older patients. The tibial evoked potential was abnormal in 30 patients (24%), pudendal evoked potential in 21 (17%), bulbocavernosus reflex in 26 (21%) and urethro-anal reflex in 32 (26%). It was concluded that somatosensory disturbances constitute an important part of neuro-urophysiological abnormalities. Our results suggest a relationship between erectile dysfunction and subclinical, age-related (penile) sensory disorders. Our study corroborates the importance of penile sensibility for erectile (patho)physiology as suggested by others and supports the concept of sensory deficit impotence as an important cause of erectile dysfunction.

Evidence for early lower urinary tract dysfunction in clinically silent multiple sclerosis.

The occurrence of micturition complaints as late sequelae of multiple sclerosis is well studied and documented. However, no reports exist on urologically asymptomatic patients with a relatively short disease duration. In a prospective study of 40 patients with definite multiple sclerosis (mean disease duration 5 years), urodynamic investigations (cystometry and pressure-flow study) were combined with neuro-urophysiological measurements (cortical evoked potentials and sacral reflex latencies). Patients with (13) and without (27) micturition complaints were investigated. Neurourodynamic abnormalities were seen in 35 of 40 patients (88%). The lower urinary tract proved to be afflicted by multiple sclerosis at an early stage of the disease. Early neurourodynamic investigations had clinical implications. All of the complaining and half of the noncomplaining patients showed urodynamic abnormalities upon which the need for further followup and eventual therapeutic intervention was based. We conclude that neurourodynamic testing of a urinary functional system can be worthwhile as part of the initial diagnostic evaluation in patients with proved multiple sclerosis.