Erectile dysfunction in diabetic men: the neurological factor revisited

Measurement of electrochemical conductance of penile skin using Sudoscan®: A new tool to assess neurogenic impotence

OBJECTIVES

To investigate the value of electrochemical skin conductance (ESC) measurement at penile level using Sudoscan^® for the diagnosis of neurogenic impotence in diabetics.

METHODS

The following neurophysiological parameters were assessed in 25 male diabetics who complained of impotence and 25 age-matched normal male subjects without erectile dysfunction (age range: 29-70 years): ESC, sympathetic skin responses (SSR), warm detection thresholds (WDT), and cold detection thresholds (CDT) for the penis and the feet, vibration detection thresholds (VDT) for the penis, and sensory nerve conduction study of the dorsal nerve of the penis (DNP) with sensory nerve action potential (SNAP) recording.

RESULTS

Diabetic patients with impotence differed from controls with regard to most neurophysiological results at both penile and foot levels. Among penile innervation variables in the group of impotent diabetics, penile ESC was found to be the most frequently abnormal (80% of patients), followed by penile WDT, CDT, and DNP-SNAP amplitude (52% of patients), and then penile SSR amplitude and VDT (44% of patients). Various combinations of abnormalities were observed: penile ESC was the only abnormal test in 2 patients, while all tests were abnormal in 2 patients and remained normal in only one patient.

CONCLUSION

Erectile dysfunction is common in diabetic men, but the diagnosis of a neurogenic origin is challenging. This study showed that ESC measurement using Sudoscan^® is feasible and more sensitive than SSR recordings to show penile sympathetic innervation impairment. This new test should be further studied to better define its diagnostic accuracy and clinical correlates.

Sexual dysfunction in patients with peripheral nervous system lesions

Peripheral nervous system (PNS) disorders may cause sexual dysfunction (SD) in patients of both genders. These disorders include mainly polyneuropathies (particularly those affecting the autonomic nervous system (ANS)) and localized lesions affecting the innervation of genital organs. Impaired neural control may produce a malfunction of the genital response consisting of loss of genital sensitivity, erectile dysfunction, loss of vaginal lubrication, ejaculation disorder, and orgasmic disorder. In addition, there is often a loss of desire which actually has a complex pathogenesis, which goes beyond the mere loss of relevant nerve function. In patients who have no manifest health problems - particularly men with erectile dysfunction - one should always consider the possibility of an underlying polyneuropathy; in patients with SD after suspected denervation lesions of the innervation of genital organs within the lumbosacral spinal canal and in the pelvis, clinical neurophysiologic testing may clarify the PNS involvement. SD can alter self-esteem and lower patients' quality of life; opening up a discussion on sexual issues should be a part of the management of patients with PNS disorders. They may greatly benefit from counseling, education on coping strategies, and specific treatments.

Erectile dysfunction in patients with diabetes mellitus: its magnitude, predictors and their bio-psycho-social interaction: a study from a developing country

BACKGROUND

Persons suffering from diabetes mellitus (DM) are at higher risk of developing erectile dysfunction (ED). Several factors contribute to ED in patients of DM. Only few studies have attempted to explore physical, psychological and social factors in a single study. The aim of the index study was to measure the prevalence of ED in patients of DM and to determine the contributory role of various socio-demographic, physical, and psychological variables.

METHOD

One hundred and thirteen (N = 113) consenting consecutive male married diabetic patients were assessed on International Index of Erectile Function Questionnaire (IIEFQ-5), Dyadic Adjustment Scale (DAS) and Beck's Depression Inventory (BDI) to measure erectile performance, quality of marriage and depressive symptoms respectively. Pretested Bengali versions of these scales were used in the index study.

RESULTS

Prevalence of ED was 38.94%. ED group significantly differed from non-ED group in current age, family type, type of treatment for diabetes, presence of micro/macrovascular complications, history of current tobacco use, quality of marriage, and presence of depressive symptoms. In logistic regression analysis current age, body mass index (BMI) and presence of depressive symptoms had significant predictive role on occurrence of erectile dysfunction.

CONCLUSION

Prevalence of ED among diabetic patients is high compared to general population. Both physical and psychosocial factors predict the occurrence of ED in this group. So, both physicians and psychiatrists should remain aware about the multi-faceted causative role of ED in DM.

Bladder outlet obstruction triggers neural plasticity in sensory pathways and contributes to impaired sensitivity in erectile dysfunction

Lower urinary tract symptoms (LUTS) and erectile dysfunction (ED) are common problems in aging males worldwide. The objective of this work was to evaluate the effects of bladder neck nerve damage induced by partial bladder outlet obstruction (PBOO) on sensory innervation of the corpus cavernosum (CC) and CC smooth muscle (CCSM) using a rat model of PBOO induced by a partial ligation of the bladder neck. Retrograde labeling technique was used to label dorsal root ganglion (DRG) neurons that innervate the urinary bladder and CC. Contractility and relaxation of the CCSM was studied in vitro, and expression of nitric oxide synthase (NOS) was evaluated by Western blotting. Concentration of the sensory neuropeptides substance P (SP) and calcitonin gene-related peptide was measured by ELISA. Partial obstruction of the bladder neck caused a significant hypertrophy of the urinary bladders (2.5-fold increase at 2 wk). Analysis of L6-S2 DRG sections determined that sensory ganglia received input from both the urinary bladder and CC with 5-7% of all neurons double labeled from both organs. The contractile responses of CC muscle strips to KCl and phenylephrine were decreased after PBOO, followed by a reduced relaxation response to nitroprusside. A significant decrease in neuronal NOS expression, but not in endothelial NOS or protein kinase G (PKG-1), was detected in the CCSM of the obstructed animals. Additionally, PBOO caused some impairment to sensory nerves as evidenced by a fivefold downregulation of SP in the CC (P ≤ 0.001). Our results provide evidence that PBOO leads to the impairment of bladder neck afferent innervation followed by a decrease in CCSM relaxation, downregulation of nNOS expression, and reduced content of sensory neuropeptides in the CC smooth muscle. These results suggest that nerve damage in PBOO may contribute to LUTS-ED comorbidity and trigger secondary changes in the contraction/relaxation mechanisms of CCSM.

Association between metabolic syndrome and sexual dysfunction among men with clinically diagnosed diabetes

BACKGROUND

The worldwide epidemic of diabetes and obesity has resulted in a rapid upsurge in the prevalence of metabolic syndrome (MetS). MetS makes the individual liable to endothelial dysfunction which can initiate sexual dysfunction (SD). This study assessed the association between MetS and SD among clinically diagnosed diabetic subjects in Tema, Greater Accra Region of Ghana.

METHOD

Sexual functioning was assessed using Golombok Rust Inventory of Sexual Satisfaction in 300 consecutive diabetic men visiting the diabetic clinic of Tema General Hospital between November, 2010 and March, 2011. Anthropometric data including waist and hip circumference as well as blood pressure were measured. The levels of fasting blood glucose and serum lipid profile were assessed. All the men had a steady heterosexual relationship for at least 2 years before enrolment in the study.

RESULTS

The response rate was 91.3% out of the 300 subjects recruited for the study. Those with SD were significantly older and had diabetes for a longer period as compared to those without SD. The prevalence of MetS as defined by the various criteria was 78.8%, 43.4% and 51.8% for WHO, NCEP ATP III and IDF respectively. Central obesity (p = 0.0482) and raised blood pressure (p = 0.0309) are the significant MetS components when the studied population was stratified according to sexual functioning. Generally, SD as well as its sub-scales correlate positively with age, blood pressure, duration of diabetes and MetS score. Whereas TC and LDL-c correlated positively with non-communication, TG correlates positively with avoidance and infrequency.

CONCLUSION

SD and its sub-scales have a direct relationship with duration of diabetes, blood pressure and MetS score from this study. Central obesity and raised blood pressure seem to be the link between MetS and SD among this clinically diagnosed diabetic subjects.

Gene therapy as future treatment of erectile dysfunction

IMPORTANCE OF THE FIELD

Erectile dysfunction (ED) is a major men's health problem. Although the high success rate of treating ED by phosphodiesterase 5 (PDE5) inhibitors has been reported, there are a significant number of ED patients who do not respond to currently available treatment modalities.

AREAS COVERED IN THIS REVIEW

To elucidate the current status of gene therapy applications for ED, gene therapy approaches for ED treatment are reviewed.

WHAT THE READER WILL GAIN

Gene therapy strategies that can enhance nitric oxide (NO) production or NO-mediated signaling pathways, growth factor-mediated nerve regeneration or K(+) channel activity in the smooth muscle could be promising approaches for the treatment of ED. Although the majority of gene therapy studies are still in the preclinical phase, the first clinical trial using non-viral gene transfer of Ca(2+)-activated, large-conductance K(+) channels into the corpus cavernosum of ED patients showed positive results.

TAKE HOME MESSAGE

Gene therapy represents an exciting future treatment option for ED, especially for people with severe ED unresponsive to current first-line therapies such as PDE5 inhibitors although the long-term safety of both viral and non-viral gene therapies should be established.

Assessment of erectile dysfunction in diabetic patients

Erectile dysfunction (ED) aetiology is multifactorial, including endocrine, neurological, vascular, systemic disease, local penile disorders, nutrition, psychogenic factors, and drug-related. This study was performed to compare the relevant comprehensive biochemical parameters as well as the clinical characteristics in diabetic ED and healthy control subjects and to assess the occurrence of penile neuropathy in diabetic patients and thus the relationship between ED and diabetes. A total of 56 patients accepted to undergo assessment for penile vasculature using intracavernosal injection and colour Doppler ultrasonography. Of the 56 diabetic patients, 38 patients were found with normal blood flow and thus they were considered as the diabetic-ED group, whereas, ED diabetic patients with an arteriogenic component were excluded. These patients with an age range between 17 and 58 years, complaining of ED, with duration of diabetic illness ranging from 2 to 15 years. The Control group comprised of 30 healthy subject aged between 19 and 55 years. Peripheral venous levels of testosterone, prolactin, follicle stimulating hormone (FSH), luteinizing hormone (LH), thyroid stimulating hormone (TSH), malondialdehyde and glycosylated haemoglobin (HbA(1)c) were obtained in all subjects. Valsalva manoeuvre and neurophysiological tests were also determined. Testosterone, prolactine, FSH, LH, and TSH hormones of the diabetic patients were not significantly different from those of the control group. Diabetic patients with ED have higher HbA(1)c and oxidative stress levels while the R-R ratio was significantly decreased. Bulbocavernosus reflex latency was significantly prolonged, whereas its amplitude, the conduction velocity and amplitude of dorsal nerve of penis were significantly reduced in the diabetic patients. We concluded that although ED is a multifactorial disorder, yet, the present study revealed that in ED patients without arteriogenic ED a neurogenic component is present. Furthermore, the complex effect of the Valsalva manoeuvre on cardiovascular function is the basis of its usefulness as a measure of autonomic function. Thus, it can be of value in the diagnosis of ED although these hypotheses require follow-up in a large study cohort.

Comparison of the International Index of Erectile Function erectile domain scores and nocturnal penile tumescence and rigidity measurements: does one predict the other?

OBJECTIVE

To describe the relationship between the International Index of Erectile Function (IIEF) erectile domain score, and nocturnal penile tumescence and rigidity values measured by RigiScan (Timm Medical Technologies, Eden Prairie, MN).

PATIENTS AND METHODS

In all, 73 men were evaluated with the IIEF and 2 nights of continuous penile monitoring with the RigiScan. Twenty-six men were evaluated before and after prostatectomy, for a total of 99 pairs of data points. We dichotomized the RigiScan results as 'adequate' (no erectile dysfunction, ED), or 'inadequate' (having ED), based on the 'best erectile event' over the 2 nights of monitoring. Two separate criteria for adequate erectile function were used, one of >70% rigidity for > or = 10 min, and the other >60% rigidity for > or = 10 min. The erectile domain score of the IIEF was calculated in the standard fashion.

RESULTS

Using both the 70% and the 60% rigidity criteria, there was a statistically significant association between the IIEF erectile domain scores and the RigiScan data (r = 0.27, P = 0.008 and r = 0.29, P = 0.003, respectively). However, the sensitivity of the IIEF to predict ED based on RigiScan results using the 70% rigidity criteria was 68.9%, and the specificity was 57.1%. When the IIEF was used as a continuous predictor of RigiScan results, the area under the receiver-operating characteristic (ROC) curve was 0.66. Using the 60% criteria, the sensitivity was 55.8% and the specificity was 73.2%; the area under the ROC curve was 0.72.

CONCLUSIONS

IIEF erectile domain scores and nocturnal penile tumescence and rigidity measurements are weakly associated, and the clinical utility of one test to predict the other is limited. However, because of the differences in the measured outcomes (perception of erectile function vs physiological capacity), a weak association does not disqualify either test's individual utility.

Long-term treatment with intracavernosal injections in diabetic men with erectile dysfunction

AIM

To assess the behavior of patients with diabetes mellitus (DM) and erectile dysfunction (ED) during 10 consecutive years of treatment with self-injection of vasoactive drugs.

METHODS

Thirty-eight diabetic men, including 12 with type I and 26 with type II diabetes, were followed up regularly for 10 years after they began self-injecting for severe ED. Real time rigidity assessment was used for the objective determination of the initial dosage and then doses were regulated in order to introduce an erection suitable for penetration and maintenance of erection for approximately 30 min. Patients were followed up every two months, and doses were increased only when the treatment response was not satisfactory.

RESULTS

The number of injections used per year by the patients was reduced each year (mean numbers: 50 in the first year and 22.5 in the 10th) and treatment shifted towards stronger therapeutic modalities (mixtures of vasoactive drugs instead of prostaglandin E1 alone). Type I diabetic men were standardized to a level of treatment as early as 5 years after the initiation of treatment. That level was finally reached by type II patients after another 4-5 years.

CONCLUSION

Treatment with self-injections of vasoactive drugs in diabetic men with severe ED is a safe and effective alternative in the long term. Diabetic men of both types show the same preferences in quality and quantity of treatment after 10 years. The key point for maintenance in treatment is the adjustment of the therapeutic method and dosage to optimal levels for satisfactory erections.

Endothelial and erectile dysfunction, diabetes mellitus, and the metabolic syndrome: common pathways and treatments?

The past decade has witnessed a dramatic increase in the prevalence of obesity. Comorbidities of obesity include type 2 diabetes mellitus, hypertension, and lipid abnormalities, all of which contribute to cardiovascular disease (CVD) and are associated with endothelial dysfunction. These abnormalities frequently cluster in individuals, and the term metabolic syndrome is now widely used to define this cluster. The syndrome is frequently (although not invariably) associated with insulin resistance and CVD. Diabetes is associated with CVD, which may be asymptomatic in some cases, particularly when associated with autonomic neuropathy. This has implications for guidelines on the evaluation of patients with erectile dysfunction (ED) and CVD. Treatment of ED in men with diabetes has been revolutionized by the introduction of phosphodiesterase 5 inhibitors. However, men with diabetes tend to respond less positively to these agents, at least as currently prescribed. This decreased responsiveness may be related to the severity of endothelial function in patients with diabetes. Additional therapeutic strategies may be needed to overcome this problem.

Linking erectile dysfunction and coronary artery disease

Coronary artery disease (CAD) and erectile dysfunction (ED) are both highly prevalent conditions that frequently coexist. Additionally, they share mutual vascular risk factors, suggesting that they are both manifestations of systemic vascular disease. The role of endothelial dysfunction in CAD is well established. Normal erectile function is primarily a vascular event that relies heavily on endothelially derived, nitric oxide-induced vasodilation. Accordingly, endothelial dysfunction appears to be a common pathological etiology and mechanism of disease progression between CAD and ED. The risk factors of diabetes mellitus, hypertension, hyperlipidemia, obesity and tobacco abuse contribute to endothelial dysfunction. This article reviews the role of vascular endothelium in health, the abnormalities resulting from vascular risk factors, and clinical trials evaluating the role of endothelial dysfunction in ED.

Sildenafil in the treatment of erectile dysfunction in men with diabetes: demand, efficacy and patient satisfaction

The objective of this study is to describe the eligibility, consumption, efficacy and patient satisfaction when treating men with diabetes with Sildenafil. The study is a prospective, self-reported, flexible-dose study. In total, 45 patients with diabetes (type 1 or 2), complaining of erectile dysfunction, were treated with Sildenafil over a 12-week period. Efficacy was assessed using a patientlog, a general satisfaction questionnaire and the International Index of Erectile Function (IIEF). Of 326 men, 192 reported erectile dysfunction, 79 did not fulfil the criteria for Sildenafil treatment and 49 declined to participate. In the group of 33 (age 45-75 y, mean+/-s.d.: 58.1+/-7.2) completing the study, erectile function was significantly improved (P < 0.0001). A total of 12 patients (36.4%) experienced no treatment effect at all. Eligibility and desire for treatment was low. Sildenafil is far from being a 'cure all' in the treatment of ED in diabetes.

Efficacy of sildenafil citrate in treatment of erectile dysfunction: effect of type 2 diabetes

PURPOSE

To assess efficacy of sildenafil citrate in treatment of erectile dysfunction: effect of type 2 diabetes.

MATERIALS AND METHODS

A total of 466 male patients with erectile dysfunction (ED) were enrolled in this study. Of them 382 were diabetic and 84 were non-diabetic. Patients were screened for ED using the erectile function domain of the International Index for Erectile Function (IIEF). Patients underwent routine laboratory investigations, in addition to total testosterone and prolactin assessment. To assess the effect of diabetes on efficacy of sildenafil, we compared the pre and post sildenafil responses to erectile function domain, Q3, Q4. Overall satisfaction and global efficacy question (GEQ) were also assessed.

RESULTS

Mean age +/- S.D. was 53 +/- 8.4 and 49.7 +/- 10.6 years for patients with and without diabetes respectively. There were significant associations between increased severity of ED and longer duration, poor metabolic control and presence of more than one diabetes-related complication (p < 0.05 for each). Differences were significant between pre and post sildenafil administration regarding erectile function domain, Q3, Q4 (p < 0.05 for each). In the non-diabetic patients the GEQ and the overall satisfaction were significantly higher than in diabetics (p < 0.05 for each). Global efficacy question was significantly low in patients with fair and poor metabolic control, longer duration of diabetes, and patients with diabetic complications (p < 0.05 for each).

CONCLUSIONS

Sildenafil is an effective treatment for diabetic patients with ED. Although the efficacy of sildenafil was negatively affected by factors as poor control and longer duration of diabetes and presence of more than one diabetes-related complication, however, the global efficacy and the overall patients' satisfaction were high.

IMPROVEMENT IN ERECTILE DYSFUNCTION AFTER NEUROTROPHIC FACTOR GENE THERAPY IN DIABETIC RATS

PURPOSE

Erectile dysfunction (ED) is a common but difficult to treat complication of diabetes mellitus (DM). We have previously reported herpes simplex virus (HSV) vector mediated delivery of nerve growth factor into the bladder to treat diabetic cystopathy and neurotrophin-3 (NT3) gene transfer for pyridoxine treatment. Nerve growth factor and NT3 are neurotrophic factors that may protect nerves from mechanical and metabolic damage. We investigated the effects of HSV mediated delivery of NT3 for the treatment of diabetic ED.

MATERIALS AND METHODS

Male Sprague-Dawley rats weighing 300 to 400 gm were injected with 65 mg/kg streptozotocin to induce DM. After 4 weeks 20 microl containing 5 x 10 pfu replication defective HSV vector expressing lacZ (6 rats) or NT3 (6) were injected directly into the cavernous nerve sheath with a 30 gauge needle. Four weeks later the animals underwent measurement of intracavernous pressure under electrical stimulation (20 Hz, 0.5 millisecond and 10 V) of the cavernous nerve. Staining for lacZ and neuronal nitric oxide synthase in the major pelvic ganglia was also performed.

RESULTS

beta-Galactosidase staining revealed lacZ positive neurons in the major pelvic ganglia. Maximal intracavernous pressure induced by electrical stimulation showed statistically significant mean values +/- SEM of 15.1 +/- 2.1 and 43.8 +/- 11.1 cm H2O in the lacZ and NT3 vector injected groups, respectively (p = 0.03). The mean number of neuronal nitric oxide synthase positive neurons per section in the NT3 group was significantly higher than that in the lacZ control group at 3.33 +/- 0.23 and 0.64 +/- 0.14 neurons per high power field, respectively (p < 0.001).

CONCLUSIONS

We report that gene therapy for the treatment of diabetic ED is feasible with HSV vectors. NT3 gene therapy may be applicable for the treatment of ED induced by DM.

[Efficacy and safety of sildenafil in patients with erectile dysfunction and hypertension. Prognostic factors]

BACKGROUND

Our purpose was to assess the efficacy and safety of sildenafil as a treatment for erectile dysfunction in hypertensive patients, and to investigate those factors associated with a treatment failure.

PATIENTS AND METHOD

Open, prospective study including 114 patients suffering from erectile dysfunction plus arterial hypertension who were evaluated by anamnesis, physical examination, blood tests including glycemia and lipidic and hormonal profiles, penile colour Doppler ultrasonography after intracavernosal prostaglandin E1 (PGE1) injection, and the Sexual Health Inventory for Men (SHIM). Efficacy of sildenafil was assessed by administering again the SHIM and by means of a global assessment questionnaire. Side effects were also recorded. Factors influencing treatment outcome were evaluated by univariate and multivariate statistical analysis.

RESULTS

Overall, sildenafil was effective in 59.2% of 103 eligible patients. Efficacy in patients with psychogenic erectile dysfunction was 75%, whereas in those with an organic etiology, the efficacy was 50.7%. Age, diabetes mellitus, nocturnal penile tumescence, response to intracavernosal PGE1 injection and erectile dysfunction severity (defined by the SHIM basal score) significantly influenced treatment response (p < 0.05) after an univariate analysis. The multivariate analysis, however, selected only diabetes mellitus and severity of erectile dysfunction as the prognostic factors. No severe side effects were noticed.

CONCLUSIONS

Sildenafil is a rather effective and well-tolerated treatment for erectile dysfunction in hypertensive patients. Baseline severity of erectile dysfunction and diabetes mellitus represent the prognostic factors most significantly associated with treatment outcome.

Multicentral clinical evaluation of the aetiology of erectile dysfunction: a survey report

Patients with erectile dysfunction, who admitted to 4 different urological centres in Turkey were evaluated in terms of aetiological factors to establish the aetiology of erectile dysfunction in our population and compare it with the data derived from Western communities. After the history, physical examination, psychological evaluation and laboratory testing, a clinical diagnosis was established as primarily psychogenic, organic, or mixed aetiology. Mean patient age was 43.5 years (range 17 to 69), and 9 of the patients were unmarried. Of the patients 53 had vascular risk factors, and 10 reported a history of alcohol abuse. Eleven patients were using drugs that might interfere with the disorder. In this multicentral study of 115 impotent men, an organic cause was found in 43%, psychogenic in 47%, and mixed in 19%. Mean age of the overall patients was 43.48. When the ages of the patients with organic erectile dysfunction and those with psychogenic erectile dysfunction were compared, it was clearly seen that those with organic erectile dysfunction were much older (52.73 versus 33.02).

Evaluation and treatment of erectile dysfunction in men with diabetes mellitus

Diabetic men have a more than 3-fold increased prevalence of erectile dysfunction (ED) compared with nondiabetic men. Erectile function is primarily a vascular phenomenon, triggered by neurologic controls and facilitated by appropriate hormonal and psychological components. Recent advances in the understanding of the physiology of penile vasculature and its role in male sexual performance have influenced the clinical approach to ED. The pathophysiological alterations leading to impotence in diabetic men include vasculogenic, neurogenic, and hormonal etiologies. A clinical work-up, including a thorough history and physical examination, is an important aspect of ED management. Biochemical evaluations to rule out secondary causes like hypogonadism and thyroid abnormalities are suggested. Oral medications acting through phosphodiesterase inhibition in penile vasculature have revolutionized treatment of impotence in diabetic men. Because of a high success rate in treating ED of various etiologies, these agents are the treatment of choice for most patients. Safety and efficacy of vacuum-constriction devices, intraurethral suppositories, intracavernosal injections, and other therapies are discussed. A clinical algorithm for the evaluation and management of ED is provided for use in the primary care setting.

Central modulation of the NO/cGMP pathway affects the MPOA-induced intracavernous pressure response

Alterations in the nitric oxide (NO)/cGMP levels in hypothalamic nuclei, including the medial preoptic area (MPOA), regulate critical aspects of sexual behavior and penile reflexes. However, the effects of altered central nervous system (CNS) NO/cGMP levels at the end organ level, that is, on the magnitude/quality of the erection so achieved [intracavernous pressure (ICP) response], has yet to be evaluated. The goal of this report was to evaluate the effects of intrathecal administration of modulators of NO and cGMP levels on ICP responses to stimulation of the MPOA and cavernous nerve in rats in vivo. In all cases, intrathecal administration of compounds that increase and decrease cGMP and NO levels, respectively, was associated with corresponding increases and decreases in the MPOA-stimulated ICP response. Specifically, sodium nitroprusside (SNP), 8-bromo-cGMP, and sildenafil increased the MPOA-stimulated ICP response, whereas N(omega)-nitro-L-arginine methyl ester reduced it. None of the intrathecal treatments had detectable effects on blood pressure or the cavernous nerve-stimulated ICP response, although intravenous sildenafil increased the latter. These data clearly indicate that intrathecal drug administration affects central and not peripheral neural mechanisms and, moreover, documents that CNS NO/cGMP levels can affect erectile capacity per se (i.e., ICP) in the rat model.

Relaxation induced by omeprazole does not change in diabetic rabbit corpus cavernosum

OBJECTIVE

To investigate the changes in relaxation responses to omeprazole in corpus cavernosal strips from rabbits with diabetes induced by alloxan.

MATERIALS AND METHODS

Diabetes was induced in 10 New Zealand white rabbits. After 8 weeks, the reactivity to electrical-field stimulation, carbachol and omeprazole of corporal strips from the penises of the diabetic animals and from 10 untreated controls was assessed in organ chambers.

RESULTS

In the diabetic group, the relaxation responses of corpus cavernosal strips to omeprazole were comparable with those of the control group, whereas the relaxation responses to electrical field stimulation and carbachol were impaired.

CONCLUSION

The relaxant effect of omeprazole in corpus cavernosum was not affected by diabetes, in which neurogenic and endothelium-mediated relaxations were impaired.

Relationship between penile thermal sensory threshold measurement and electrophysiologic tests to assess neurogenic impotence

OBJECTIVES

Erectile function is usually assessed by neurophysiologic tests such as the bulbocavernosus reflex or pudendal nerve somatosensory evoked potentials. These tests investigate only large nerve fibers, although erection depends on autonomic nerve fibers, which are of small diameter. Warm and cold sensory fibers have similar calibers as the autonomic nerve fibers, and their integrity can be reliably evaluated by the measurement of thermal sensory thresholds. We studied penile thermal sensory testing in parallel with standard electrophysiologic tests to assess their sensitivity in the diagnosis of penile neuropathy.

METHODS

Twenty-five normal male subjects without erectile dysfunction or evidence of diffuse neuropathy (group 1) and 35 diabetic patients who complained of impotence (group 2) were studied. Erectile function was quantitated using the erectile dysfunction symptom score. Warm, cold, and vibratory sensory thresholds were assessed on the dorsal aspect of the penis. In addition, penile sympathetic skin responses and pudendal nerve somatosensory evoked potentials were recorded.

RESULTS

We found a significant difference between the two groups in the erectile dysfunction symptom score (P <0.0001), cold threshold (P = 0.0007), and warm threshold (P = 0.0025), but not for the other parameters. The erectile dysfunction symptom score correlated with the penile warm and cold thresholds (P = 0.0006 and 0.002, respectively).

CONCLUSIONS

Thermal thresholds assess small nerve fiber damage, which can indirectly reflect autonomic disturbances, particularly in the context of a diffuse neuropathy such as diabetic polyneuropathy. Penile thermal sensory testing correlated strongly with the clinical evaluation of erectile function and is a new and promising tool for the diagnosis of neurogenic impotence.

Effects of vitamin E and sodium selenate on neurogenic and endothelial relaxation of corpus cavernosum in the diabetic mouse

We studied the effect of vitamin E and sodium selenate treatment on the neurogenic and endothelium-dependent relaxation of isolated corpus cavernosum obtained from streptozotocin-induced diabetic mice. Relaxant responses of corpus cavernosum precontracted by phenylephrine to electrical field stimulation and to acetylcholine were significantly decreased in diabetic mice. There was no significant difference between diabetic and non-diabetic groups for the relaxant response of corpus cavernosum to sodium nitroprusside and papaverine. Treatment with sodium selenate, but not vitamin E, partially prevented the impairment of the neurogenic relaxation, whereas both had a significant, partial restorative action on endothelial dysfunction in corpus cavernosum obtained from diabetic groups. Neither agent exhibited a significant action on the relaxant responses of corpus cavernosum obtained from non-diabetic mice. A decrease in the sensitivity of the neurogenic impairment to antioxidant action may develop more rapidly than that of endothelial dysfunction in streptozotocin-induced diabetic mice.

Does diabetes mellitus affect the progress of tolerance to isosorbide dinitrate (ISDN) in corporal tissue?

For erection to take place, the penile arteries and sinusoids have to dilate, thereby increasing the blood flow into the penis. There is increasing evidence that release of l-arginine derived nitric oxide (NO) from nonadrenergic-noncholinergic (NANC) nerves and from the sinusoidal endothelium is a major event in penile smooth muscle relaxation and promotes the endogenous formation of cyclic guanosine monophosphate (cGMP). Nitrovasodilators can be attributed to the activation of soluble guanylate cyclase, resulting in an increase in intracellular level of cyclic guanosine monophosphate, but prolonged exposure to high levels of nitroglycerine and other organic nitroesters induces tolerance against the cardiovascular effect. In this study, the aim was to determine the effect of diabetes on the corporal smooth muscle relaxant effect of ISDN and the effect of diabetes on the process of tolerance to the drug. For this purpose, alloxan-induced diabetic rabbits were used to form diabetes group. The responses of the corpus cavernous strips obtained from control and alloxan-induced diabetic rabbit were studied in organ chamber. In conclusion, prolonged in vitro exposure of corpus cavernosum strips obtained from control and diabetic groups to high concentrations of ISDN caused significant desensitization to the relaxant effect the drug. So, prolonged exposure of corporal tissue to the agents like nitroglycerine, used for treatment of impotence, may render ineffective the therapy in diabetic erectile impotence. However, intolerance to nitric oxide provides a rationale for the concept of using nitro oxide agents (like SNP) in the treatment of diabetic erectile dysfunction.

Diabetes, hypertension and erectile dysfunction

Diabetes mellitus (DM) and hypertension are independent risk factors for erectile dysfunction (ED), macrovascular disease and microangiopathy. ED is very common among diabetic patients. Men with DM have ED at an earlier age and with a significantly higher prevalence (as high as 75%). The prevalence of DM also tends to be higher in patients with Peyronie's disease. DM impairs neurogenic and endothelium-mediated relaxation of penile smooth muscle. It is impossible to separate DM from hypertension and from the other vascular risk factors. Good glycaemic and hypertension control in diabetics is very important since these factors increase the risk of both microvascular and macrovascular complications, possibly including ED.

Effect of insulin therapy for diabetic cystopathy--urodynamic and histological findings in a rabbit model

OBJECTIVE

To investigate the efficacy of insulin therapy in preventing cystopathic changes in diabetes using a rabbit model.

MATERIALS AND METHODS

Twenty-four New Zealand white rabbits were studied in three groups: eight in group 1 as control, eight in group 2 with diabetes by administration intravenously alloxan hydrochloride and eight in group 3 administered insulin therapy after induction of diabetes. Urodynamic investigations were carried out in three groups at the end of 8 weeks. Tissue sections prepared from all groups were studied histologically.

RESULTS

Bladder capacity and compliance increased in diabetic non-treated group. There was no significant difference between the control group and the diabetic group treated with insulin. The neuropathic changes were observed in the diabetic group, whereas the findings of the histological study were similar in the control and in the insulin treatment group.

CONCLUSIONS

This animal model indicates that insulin therapy can prevent or delay urodynamic and histopathological changes in diabetes mellitus. These results must be supported by in vitro pharmacological studies.

Impaired ascendant central pathways conduction in impotent diabetic subjects

OBJECTIVES

Diabetic impotence is generally due to peripheral neuropathy, but a central pathway impairment has also been suggested. We evaluated somatosensory transmission in a group of impotent diabetic men to assess the role of central nervous system (CNS) involvement.

MATERIALS AND METHODS

Somatosensory evoked potentials (SEPs) of pudendal (pdn) and posterior tibial (ptn) nerves were recorded in 74 patients. Type and duration of diabetes, severity of sexual dysfunction, medium term metabolic control, occurrence of microangiopathic chronic complications and autonomic neuropathy were evaluated.

RESULTS

Our data show an impairment of central conduction times in pdn (25.7%) and ptn (39.2%) greater than peripheral nervous impairment (pdn 12.2%, ptn 8.1%), in impotent diabetic patients without any further major complication. Central nervous conduction delay resulted to be correlated with poor glycemic control. Significant evident autonomic dysfunction was found only in a minority of cases.

CONCLUSION

Our data might suggest that altered conduction along CNS and somatic peripheral neuropathy might develop independently. We confirm the hypothesis of a "central diabetic neuropathy" and suggest that central sensory pathways involvement, not related to peripheral impairment, could play a role in the pathogenesis of erectile dysfunction in diabetic patients.

The effects of long-term oral administration of L-arginine on the erectile response of rabbits with alloxan-induced diabetes

OBJECTIVE

To investigate the effects of the long-term oral administration of L-arginine on the impaired neurogenic and endothelium-dependent relaxation responses of corpus cavernosum smooth muscle from alloxan-induced diabetic rabbits.

MATERIALS AND METHODS

Thirty-two New Zealand white rabbits were used in four groups of eight each. In group 1, the rabbits received no treatment after the induction of diabetes with alloxan hydrochloride given intravenously; in group 2, L-arginine (1 mg/mL) was administered orally after the induction of diabetes; in group 3, 6 U/day of insulin was injected subcutaneously; group 4 was maintained with no treatment (as litter-mate controls) for 8 weeks. Thereafter, the rabbits were killed by exsanguination and the penis removed en bloc. The reactivity of corpus cavernosum strips from the penis was then assessed in organ chambers.

RESULTS

Relaxation and contraction responses of corpus cavernosum strips to sodium nitroprusside and potassium chloride, respectively, were similar in all groups. Relaxation responses of corpus cavernosum strips elicited by electrical field stimulation and carbachol from rabbits in group 1 were less than in controls; the responses to carbachol were not significantly impaired in group 2 and 3, whereas responses to electrical field stimulation were impaired in both groups when compared with the control group.

CONCLUSION

The impairment of endothelium-dependent and nerve-mediated relaxation by diabetes appears to involve an alteration in nitric oxide/cyclic GMP pathway. Administration of oral L-arginine increased endothelium-dependent relaxation, probably through activating nitric oxide synthase. Additionally, decreasing elevated blood glucose concentration and advanced glycosylation products by insulin treatment protected endothelium-dependent relaxation, whereas neither L-arginine nor insulin treatment restored impaired neurogenic relaxation.

Corporal reactivity to adenosine and prostaglandin E1 in alloxan-induced diabetic rabbit corpus cavernosum, and the effect of insulin therapy

OBJECTIVE

To investigate the changes in corporal reactivity to adenosine and prostaglandin E1 (PGE1 ) in corpus cavernosal strips from alloxan-induced diabetic rabbits and to determine the effects of insulin therapy.

MATERIALS AND METHODS

Twenty-four New Zealand white rabbits were studied in three equal groups: group 1, control; group 2, diabetes induced by the administration of alloxan hydrochloride intravenously; group 3, as group 2 but with insulin administered after the induction of diabetes. At the end of 8 weeks, the reactivity of corpus cavernosal strips from the animals was assessed in organ chambers.

RESULTS

The relaxation responses of corpus cavernosal strips to adenosine were similar in all groups, but the response to PGE1 was impaired in groups 2 and 3 compared with that in controls.

CONCLUSION

If vasoactive drugs are to be used for the diagnosis or treatment of diabetic erectile impotence, direct-acting vasodilators, e.g. adenosine, must be used. In alloxan-induced diabetes, the corporal reactivity to PGE1 was impaired and insulin therapy did not restore the relaxation responses.

Quantitative sensory and autonomic testing in male diabetic patients with erectile dysfunction

OBJECTIVE

To correlate abnormalities of nerve fibres in the lower limbs with erectile dysfunction in male diabetic patients, using a range of quantitative sensory and autonomic function tests.

PATIENTS AND METHODS

The study included 68 male diabetic patients with symptomatic erectile dysfunction and 11 matched diabetics without erectile dysfunction; none had clinical evidence of peripheral vascular disease or psychological disorder. Patients were evaluated with a symptom questionnaire based on the Michigan Neuropathy Screening Instrument questionnaire and examined clinically. Sural and peroneal nerve-conduction studies, and quantitative sensory and autonomic tests (vibration, thermal, light-touch thresholds, sensory and autonomic cutaneous axon-reflexes) were used to detect nerve abnormalities in the lower limbs, which were correlated with erectile dysfunction.

RESULTS

Symptoms of neuropathy were more common in the group with male erectile dysfunction (MED), but statistically significant only for neuropathic pain (53% MED, 18% nonMED, P<0.05, chi-square test) and gastroparesis (44% MED, 0% nonMED, P<0.05). Tests of unmyelinated afferents (warming perception and capsaicin-induced sensory axon-reflex vasodilatation) were most often abnormal, sometimes with no other abnormalities on tests or neurological examination. However, abnormality of warm perception was not significantly different between groups (81% MED, 70% nonMED), suggesting that it is a poorer discriminant than abnormal sensory axon-reflex vasodilatation (89% MED, 22% nonMED, P<0.001). The only other significant test difference was decreased sural nerve action potential (70% MED, 22% non-MED, P<0.01).

CONCLUSIONS

There appeared to be preferential involvement of unmyelinated sensory fibres that mediate axon-reflex vasodilatation in the limbs of diabetic patients with erectile dysfunction. This test appears to be a helpful indicator of neurological involvement in erectile dysfunction, and may be used to monitor the effect of new treatments.

Evaluation and nonsurgical management of erectile dysfunction

The addition of oral drugs to the armamentarium of therapies for erectile dysfunction promises to dramatically increase the number of men seeking treatment for this condition. It is important to have a rational approach to the diagnostic evaluation of erectile dysfunction and to tailor the evaluation to each patient's goals for his sexual function. It is important also to offer each patient the full array of therapeutic options for erectile dysfunction. This article reviews the outpatient diagnostic work-up and current treatment possibilities for erectile dysfunction. The article also discusses clinical research experience with new forms or oral and topical therapies now being developed for future treatment of erectile dysfunction.

New insights into erectile dysfunction: a practical approach

Erectile dysfunction (ED) is the most common sexual problem in men, after premature ejaculation, affecting up to 30 million in the United States. In a society in which sexuality is widely promoted, ED impacts on feelings of self-worth and self-confidence and may impair the quality of life of affected men and their partners. Damage to personal relationships can ensue; and the anger, depression, and anxiety engendered spill over into all aspects of life. Patients are often embarrassed or reluctant to discuss the matter with their primary care practitioners. Unfortunately, many physicians fail to take the opportunity to promote open discussion of sexual dysfunction. They too, may avoid the topic through personal embarrassment. Since the National Institutes of Health (NIH) Consensus Conference on Impotence in 1992, the inadequate level of public and professional understanding of ED has begun to be addressed. As a first step in breaking down the communication barriers between patients and practitioners, it is important that physicians have a thorough understanding of the wide variety of conditions associated with ED and how the different risk factors for ED may be readily identified. This review addresses the diagnosis of ED and identifies diagnostic tests that can be used by primary care physicians to determine the patients most at risk and the treatments most suited to meet the patients' and their partners' goal for therapy.

Intracavernous pressure responses to physical and electrical stimulation of the cavernous nerve in rats

OBJECTIVES

To better define the techniques of nerve-sparing prostate dissection that would result in preservation of erectile function, we characterize the effects of physical pressure on the prostate and cavernous nerve, electrical stimulation of the cavernous nerve, and pharmacologic manipulations on intracavernous pressure (ICP) in normal and diabetic rats.

METHODS

Fischer-34 rats, both normal and diabetic, underwent dissections that isolated the cavernous bodies and cavernous nerves. Cavernous body pressures were characterized during surgical manipulation, during electrical stimulation of the cavernous nerves, and following papaverine hydrochloride injection.

RESULTS

In normal rats, baseline cavernous pressures ranged from 5 to 15 cm H2O (mean 12.29). In diabetic rats, the baseline pressure was significantly lower (3 to 7.5 cm H2O). Lateral nerve displacement caused ICP to rise to approximately 35 cm H2O in normal rats, but only to 20 cm H2O in diabetic rats. Electrostimulation resulted in cavernous pressure increases of 10-fold from baseline in normal rats and sevenfold from baseline in diabetic rats. ICPs were not disturbed appreciably with nerve-sparing dissection techniques. Neurotomy resulted in declines in baseline cavernous pressures in all rats. Electrostimulation of the distal end of a severed nerve resulted in pressure rises to 50% of those observed in rats with intact cavernous nerves. Intracavernous papaverine injection before or after nerve stimulation masked subsequent (expected) pressure changes.

CONCLUSIONS

A change in cavernous pressure is a sensitive indicator of cavernous nerve manipulation. Both cavernous pressure measurements and electrostimulation of cavernous nerves may aid surgeons during radical prostatectomy.

Bulbocavernosus reflex studies and autonomic testing in the diagnosis of erectile dysfunction

The electrophysiologic evaluation of patients with erectile dysfunction presents an important diagnostic challenge. The bulbocavernosus reflex (BCR) latency has been commonly used to evaluate these disorders. However, it is a measure of somatic penile innervation, whereas erection is primarily dependent on autonomic function. We evaluated 195 men with erectile dysfunction over a 3 year period. Each had electrophysiologic studies, nerve conduction studies and a BCR. BCR studies were abnormal in only 7%, of which most had diabetes or pelvic trauma. The BCR was the sole electrophysiologic abnormality in only 2%. Autonomic testing (AT) was additionally performed in 19 diabetic and 23 non-diabetic patients. This included sympathetic skin responses and measurement of the Valsalva ratio and heart rate variability with 6/min breathing. In the diabetic group, AT was positive in 63%, and most often was the sole abnormality. The bulbocavernosus reflex is relatively insensitive in the diagnosis of erectile dysfunction. Brief autonomic testing may provide valuable additional data, particularly in diabetics.

The Endocrinologist as the Focus in a Multidisciplinary Approach to Management of Erectile Dysfunction

OBJECTIVE

To present an approach to the complete but cost-effective office evaluation and treatment of erectile dysfunction.

METHODS

The numerous medical, hormonal, and psychologic causes of erectile dysfunction are reviewed, and the various treatment strategies are outlined.

RESULTS

Erectile dysfunction, which might also include libido and ejaculatory disturbances, is the most frequently encountered type of sexual dysfunction seen in office practice. Before 1960, the assessment of this disorder was dominated by psychiatrists; later, urologists assumed a role. More recently, physicians in internal medicine have become involved in the management of this problem. Diabetes mellitus, hypertension, and tobacco abuse are the three most common causes of erectile dysfunction in men older than 50 years of age. In addition to optimizing the management of diabetes, the endocrinologist can treat other endocrine problems associated with erectile dysfunction.

CONCLUSION

A multidisciplinary approach to the evaluation and treatment of erectile dysfunction is logical, and the endocrinologist--because of an extensive background in internal medicine and expertise in hormonal diagnosis and treatment--should be the focal point of this diagnostic and therapeutic team.

Multifactorial evaluation of diabetic erectile dysfunction

We determined arterial venous and sinusoidal factors in 20 patients with insulin dependent diabetes mellitus and erectile dysfunction by performing dynamic infusion cavernosometry (DIC), colour flow Doppler ultrasonography, penile biothesiometry and corpus cavernosum electromyography (CCE). DIC, colour flow Doppler ultrasonography and penile biothesiometry were done in standard fashion except for CCE. Paradoxical increase in the electrical activity of corpus cavernosum after intracavernous (IC) papaverine was called a discoordination that was due to cavernous smooth muscle contraction instead of relaxation. Arterial and accompanying pathologies were found in 10 (50%) patients. In 3 (15%) of them pure arterial pathology, in 6 (30%) patients arterial and veno-occlusive dysfunction (VOD) and in one patient arterial pathology with abnormal biothesiometry were found. VOD and accompanying pathologies were found in 12 (60%) patients. In 6 (30%) of them VOD and arterial, in 4 (20%) patients VOD and discoordination and in 2 (10%) patients VOD and abnormal biothesiometric values were present. A higher frequency and coexistence of VOD and discoordination pattern were observed. In conclusion, patients with diabetic impotence show a wide range pathophysiology of erection and the evaluation of these patients must include multistep techniques.