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

Diagnostic work up: Laboratory and biomarkers

This chapter will focus on the diagnostic work around sexual dysfunction in Parkinson's disease, especially laboratory tests and biomarkers. A number of methods to analyze if sexual dysfunction is caused by neural pathology, vascular dysfunction or other mechanisms are now available. Other methods can be used to differentiate between psychogenic/functional reasons behind sexual dysfunction and organic ones. The role of biomarkers for diagnosis, but also for understanding the reason behind and for counteracting sexual dysfunction is becoming more evident. There is also a rich and increasing number of scales and other instruments available for detecting and quantifying sexual hypo- and hyperactivity. When investigating the reason behind sexual dysfunction in patients with Parkinson's disease comorbidities should also be considered. Finally, early and pronounced sexual dysfunction might in some cases be an indication that differential diagnosis, like Multisystem Atrophy, should be thought about. All these aspects of the diagnostic procedures around sexual dysfunction in Parkinson's disease will be covered in this chapter.

Assessment of changes in penile sensation by electrophysiological study after radical prostatectomy: A pilot study

Background:

To evaluate the changes in penile sensation by electrophysiological tests in patients who underwent radical prostatectomy (RP) and to demonstrate the role of dorsal penile nerve injury in postoperative erectile dysfunction.

Materials and methods:

Twenty-six volunteer patients who were eligible for RP were included in the study. Preoperative penile sensory electromyography and the International Index of Erectile Function-5 (IIEF-5) questionnaire were done for each patient. Erectile function assessment and electrophysiological evaluation of penile sensation were repeated at postoperative 3rd and 6th months.

Results:

Postoperative IIEF-5 scores and electromyography values were significantly lower than preoperative findings (p < 0.05). The IIEF-5 scores in the nerve sparing-RP (NS-RP) group were significantly higher than the non-nerve sparing-RP (NNS-RP) group in the postoperative period. Nerve conduction velocity values in the NS-RP group were also higher than the NNS-RP group at the postoperative 3rd and 6th months. However, these changes were not statistically significant (p > 0.05).

Conclusions:

Patients who underwent RP have decreased penile sensation due to cavernous nerve damage and a possible dorsal penile nerve injury. The decrease of penile sensation may be associated with postoperative erectile dysfunction.

Male genital sensation after spinal cord injury: a review

Genital sensation (GS) is an essential component of male sexual function. Genital sensory disturbance (GSD) caused by spinal cord injury (SCI) has a severe impact on the patients' sexual function but has garnered little research focus. Under normal conditions, GS encompasses the erection, ejaculation, sexual arousal, and orgasm courses associated with physiological and psychological responses in male sexual activity. However, in SCI patients, the deficiency of GS makes the tactile stimulation of the penis unable to cause sexual arousal, disturbs the normal processes of erection and ejaculation, and decreases sexual desire and satisfaction. To provide an overview of the contemporary conception and management of male GS after SCI, we review the innervation and sexual function of male GS in this article, discuss the effects of GSD following SCI, and summarize the current diagnosis and treatment of GSD in male SCI patients.

Small fibre pathology is associated with erectile dysfunction in men with type 2 diabetes

AIMS

The aim of this study was to evaluate the contribution of small and large fibre neuropathy to erectile dysfunction (ED) in men with type 2 diabetes (T2D).

METHODS

Measures of small and large fibre neuropathy were evaluated in 49 participants with T2D and 20 age-matched controls.

RESULTS

ED was present in 59% of participants with T2D. There was no difference in age, duration of diabetes, blood pressure, lipid profile, vibration perception threshold (V) (14.3 ± 7.8 vs 11.2 ± 6.6, P = .429), peroneal (41.4 ± 8.2 vs 44.8 ± 4.4, P = .10) and sural (45.4 ± 5.6 vs 47.1 ± 5.8) nerve conduction velocities (m/s), cold (25.1 ± 3.8 vs 26.2 ± 2.9, P = .815) and warm (43.2 ± 4.0 vs 41.0 ± 3.8) perception thresholds (°C), and deep breathing heart rate variability (18 ± 8 vs 18 ± 8) between participants with and without ED. However, intraepidermal nerve fibre density (no./mm² ) (4.6 ± 2.8 vs 13.7 ± 2.7, P < .001), corneal nerve fibre density (no./mm² ) (23.5 ± 6.8 vs 31.3 ± 8.2, P < .001), corneal nerve fibre branch density (no./mm² ) (55.4 ± 35.3 vs 97.7 ± 46.4, P = .004), corneal nerve fibre length (mm/mm² ) (17.6 ± 6.8 vs 27.3 ± 6.8, P < .001), and sural (7.7 ± 6.1 vs 14.6 ± 6.7, P = .003) and peroneal (2.5 ± 2.0 vs 4.7 ± 2.0, P = .003) nerve amplitudes were significantly lower in participants with ED compared with those without ED.

CONCLUSION

ED affects almost 2/3 of men with T2D and is associated with small nerve fibre damage but preserved nerve conduction and cardiac autonomic function. Corneal confocal microscopy may serve as a useful non-invasive imaging method to identify small fibre damage in patients with T2D and ED.

Penile Sensory Changes After Plaque Incision and Grafting Surgery for Peyronie's Disease

INTRODUCTION

Plaque incision and grafting (PIG) for Peyronie's disease (PD) is not devoid of complications such as erectile dysfunction and penile sensory changes.

AIM

To define the rate and chronology of penile sensation loss after PIG surgery and to define predictors of such.

METHODS

The study population consisted of patients with PD-associated penile curvature who underwent PIG surgery with at least 6 months of follow-up. Demographics and PD factors were recorded. Patient had preoperative assessment of penile sensation and deformity. Postoperative follow-up occurred at 1 week, 1 month, 6 months, and 1 year after surgery. Neurovascular bundle elevation was conducted with loupe magnification.

MAIN OUTCOME MEASURE

Penile sensation was evaluated with a biothesiometer and graded on a patient-reported visual analog scale (0-10) in which 0 defined a completely numb area and 10 defined perfect sensation. The degree of sensation loss was defined as extensive (any 1 area >5 cm), major (2-5 cm), and minor (≤2 cm). The penile sensation loss distribution was defined as focal (1 site) or diffuse (>1 site).

RESULTS

63 patients were analyzed. Mean age was 56 ± 10 years. Mean duration of PD at the time of PIG was 15 ± 7 (12-38) months. 75% had curvature alone, and 25% had hourglass/indentation deformities. Mean primary curvature was 64˚ ± 28˚. The mean operation duration was 3.5 ± 1.8 hours. 21% had some degree of sensation loss at 1 week, 21% at 1 month, 8% at 6 months, and 3% at 12 months. Only 1 patient (1.5%) at 2 years continued to have extensive sensation loss on the glans and distal shaft with a very elevated sensitivity threshold. Using multivariable analysis, the only predictor of penile sensation loss ≥6 months was a duration of operation >4 hours (odds ratio = 2.1; 95% confidence interval = 1.2-3.0; P < .01).

CLINICAL IMPLICATIONS

The study highlights the need during patient consent to discuss penile sensation loss. Patients should be informed that rates of penile sensation loss ranges from 2-30% and most patients will have complete resolution of any sensation loss within one year of follow-up.

STRENGTH AND LIMITATIONS

To our knowledge no other studies have described the chronology and severity of penile sensation following PIG, our study demonstrates the utility of biothesiometry in measuring penile sensation before and after PIG. Number of patients and absence of control group represent a limitation.

CONCLUSION

Sensation loss is not uncommon after PIG surgery. It decreases in frequency and severity with time with only rare cases occurring >12 months. Longer operations appeared to be more likely associated with sensation loss. Terrier JE, Tal R, Nelson CJ. Penile sensory changes after plaque incision and grafting surgery for Peyronie's disease. J Sex Med 2018;15:1491-1497.

Small-fibre neuropathy in men with type 1 diabetes and erectile dysfunction: a cross-sectional study

AIMS/HYPOTHESIS

The aim of this study was to identify the contribution of small- and large-fibre neuropathy to erectile dysfunction in men with type 1 diabetes mellitus.

METHODS

A total of 70 participants (29 without and 41 with erectile dysfunction) with type 1 diabetes and 34 age-matched control participants underwent a comprehensive assessment of large- and small-fibre neuropathy.

RESULTS

The prevalence of erectile dysfunction in participants with type 1 diabetes was 58.6%. After adjusting for age, participants with type 1 diabetes and erectile dysfunction had a significantly higher score on the Neuropathy Symptom Profile (mean ± SEM 5.3 ± 0.9 vs 1.8 ± 1.2, p = 0.03), a higher vibration perception threshold (18.3 ± 1.9 vs 10.7 ± 2.4 V, p = 0.02), and a lower sural nerve amplitude (5.0 ± 1.1 vs 11.7 ± 1.5 mV, p = 0.002), peroneal nerve amplitude (2.1 ± 0.4 vs 4.7 ± 0.5 mV, p < 0.001) and peroneal nerve conduction velocity (34.8 ± 1.5 vs 41.9 ± 2.0 m/s, p = 0.01) compared with those without erectile dysfunction. There was also evidence of a marked small-fibre neuropathy with an impaired cold threshold (19.7 ± 1.4°C vs 27.3 ± 1.8°C, p = 0.003), warm threshold (42.9 ± 0.8°C vs 39.0 ± 0.9°C, p = 0.005) and heart rate variability (21.5 ± 3.1 vs 30.0 ± 3.7 beats/min, p = 0.001) and reduced intraepidermal nerve fibre density (2.8 ± 0.7 vs 5.9 ± 0.7/mm, p = 0.008), corneal nerve fibre density (12.6 ± 1.5 vs 23.9 ± 2.0/mm2, p < 0.001), corneal nerve branch density (12.7 ± 2.5 vs 31.6 ± 3.3/mm2, p < 0.001) and corneal nerve fibre length (8.3 ± 0.7 vs 14.5 ± 1.0 mm/mm2, p < 0.001) in participants with type 1 diabetes and erectile dysfunction. Erectile dysfunction correlated significantly with measures of both large- and small-fibre neuropathy.

CONCLUSIONS/INTERPRETATION

Small-fibre neuropathy is prominent in patients with type 1 diabetes, and is associated with erectile dysfunction and can be objectively quantified using corneal confocal microscopy. This may allow the identification of patients who are less likely to respond to conventional therapies such as phosphodiesterase type 5 inhibitors.

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.

Histological Correlates of Penile Sexual Sensation: Does Circumcision Make a Difference?

INTRODUCTION

The question of whether removal of sensory receptors in the prepuce by circumcision affects sensitivity and/or sexual pleasure is often debated.

AIMS

To examine histological correlates relevant to penile sensitivity and sexual pleasure.

METHODS

Systematic review of the scientific literature on penile structures that might affect sensitivity and sexual sensation. Articles were included if they contained original data on human male penile histology or anatomy. Individual articles, including reference lists, were evaluated. They were then considered in relation to physiological data from articles retrieved by a previous systematic review.

RESULTS

We retrieved 41 publications on penile structure. Considered in the light of 12 reporting physiological measurements, our evaluation finds that sexual response is unlikely to involve Meissner's corpuscles, whose density in the prepuce diminishes at the time of life when male sexual activity is increasing. Free nerve endings also show no correlation with sexual response. Because tactile sensitivity of the glans decreases with sexual arousal, it is unrelated to sexual sensation. Thermal sensitivity seems part of the reward mechanism of intercourse. Vibrational sensitivity is not related to circumcision status. Observations that penile sexual sensation is higher post circumcision are consistent with greater access of genital corpuscles to sexual stimuli after removal of the prepuce. This is based on the distribution of these corpuscles (which are located in the glans) and, in uncircumcised men, the position of the retracted prepuce during intercourse, rather than any change in the number of genital corpuscles. The scientific literature suggests that any sexual effect of circumcised men may depend solely on exposure of the glans and not on the absence of the prepuce.

CONCLUSION

Based on histological findings and correlates of sexual function, loss of the prepuce by circumcision would appear to have no adverse effect on sexual pleasure. Our evaluation supports overall findings from physiological measurements and survey data.

Normative values of skin temperature and thermal sensory thresholds in the pudendal nerve territory

AIMS

The aim of this study was to define normative values of skin temperature and thermal sensory threshold in the pudendal nerve territory.

METHODS

Warm and cold detection thresholds (using the method of limits) and skin temperature were measured in a group of 41 presumably healthy female volunteers aged 41 years (range: 23-66 years) at left thenar eminence and in the pudendal nerve territory. Outlying data were discarded and 95% normative values were derived assuming Normal distributions.

RESULTS

Room temperature averaged 24.3 ± 1.1°. Skin temperature and cold detection threshold value were greater anteriorly (clitoris, labia) than posteriorly (para-anal). Para-anal skin temperature and cold detection threshold value were also significantly lower on the right side than on the left side. The warm detection threshold was significantly lower at the clitoris level than at left and right labia. A significant positive effect of skin temperature on cold and warm detection thresholds values was noted especially at thenar and para-anal levels. Age had no effect on skin temperature but warm detection thresholds at clitoris were higher in older subjects. The only qualitative abnormalities observed were after-sensation (4.9%) and habituation (2.8%). Allodynia, dysesthesia, radiation, and dyslocalization were not observed. Two-sided normative values were determined for skin temperature, vertical, and horizontal differences, while one-sided values were derived for cold and warm detection thresholds as well as for their difference.

CONCLUSIONS

Normative values for perineal skin temperature and thermal detection thresholds can be used as an alternative non-invasive way to evaluate pudendal neuropathy.

Office-based management of impotence and Peyronie's disease

Erectile dysfunction (ED) impacts more than 50% of men older than 40 years; Peyronie disease (PD) affects up to 10% of men, with an adverse impact on normal sexual function and overall well-being. ED can also be the first sign of other underlying disease. The office-based evaluation of ED and PD is the first step in the management of these devastating conditions of men's health. New and exciting nonsurgical therapies are now available to help treat these conditions and restore sexual function and quality of life.

Clinical autonomic neurophysiology and the male sexual response: an overview

INTRODUCTION

Clinical neurophysiology is the study of the human nervous system through the recording of bioelectrical activity. In the realm of male sexual functioning, this includes using electrophysiologic techniques to study the nerves subserving erection, emission, ejaculation, and orgasm.

AIM

To introduce the reader to the principles of clinical neurophysiology as they relate to the male sexual response, particularly erection.

METHODS

We review the pertinent autonomic neuroanatomy and neurophysiology of reflexes relevant to the male sexual response, as well as summarize the genital electrodiagnostic tests that are being used to interrogate the autonomic innervation pertinent to male sexual functioning.

CONCLUSIONS

The male sexual response is a coordinated series of interactions between the somatic and the autonomic nervous systems. Measurement of the autonomically mediated portions of the sexual reflexes is of great clinical interest, particularly in relation to erection. Advances in clinical electrodiagnostics now allow for consistent recording of evoked and spontaneous intrapenile electrical activity. However, before broad and widespread use of these techniques is possible, more investigations are needed.

Self-ratings of genital anatomy, sexual sensitivity and function in men using the 'Self-Assessment of Genital Anatomy and Sexual Function, Male' questionnaire

OBJECTIVE

To assess the perceptions of healthy men of their genital anatomy and sexual sensitivity, along with the re-test reliability of these ratings, in a new self-reported questionnaire, the Self-Assessment of Genital Anatomy and Sexual Function, Male (SAGASF-M).

SUBJECTS AND METHODS

Eighty-one healthy, sexually active, men aged 22-57 years (median 33), with no history of genital surgery, completed the SAGASF-M. This questionnaire comprises written text and images enabling men to rate details of their genital appearance, overall genital erotic and pain sensitivity, orgasm intensity, and effort required for achieving orgasm through stimulation of specified areas around the glans and shaft of the penis, scrotum and anus, along with the contribution of other sexually sensitive areas of the body. Anatomical locations were compared for the functional ratings by mixed-model analysis of variance (anova). A second sample of 38 healthy men (median age 26 years, range 22-64) from the same source completed the SAGASF-M twice with an interval of 2 weeks.

RESULTS

There was little variability in anatomy ratings. Ratings of overall penile sensitivity to sexual stimulation gave higher values of 'sexual pleasure' for penile stimulation by the partner than by self (P = 0.002) and marginally higher ratings of 'orgasm intensity' by partner stimulation (P = 0.077), but there were no corresponding differences on ratings of 'effort needed to reach orgasm' or of 'discomfort/pain'. Overall discrimination between genital areas was highly significant (mixed-model anova, P = 0.001) for ratings of 'sexual pleasure', 'orgasm intensity' and 'orgasm effort', but was not significant for 'discomfort/pain'. Ranked by degree of 'sexual pleasure', the area 'underside of the glans' was highest, followed by 'underside of the penile shaft', 'upper side of the glans', 'left and right sides of the glans', 'one or both sides of the penis', 'upper side of the penile shaft', 'foreskin' (11 subjects), 'skin between the scrotum and anus', 'back side of the scrotum', 'front side of the scrotum', and 'around anus', but not all pair differences were significant. The rank order was similar for 'orgasm intensity', but less similar and with fewer significant pair differences for 'orgasm effort'. Overall discrimination of other body parts that help orgasm when touched/stimulated was also highly significant (P = 0.001) and included (in order of degree) scrotum, ear, skin between scrotum and anus, neck, breast/nipples, buttocks, anus (exterior skin), anus (inside with penetration), wrist, and axilla, but many pair differences were not significant. In the reliability study, which was limited to the 45 function items with sufficient variability and sample size, the re-test reliability values (Pearson r) were distributed as follows: seven were >or=0.80, 16 >or=0.70, 15 >or=0.60, four >or=0.50, two >or=0.40, and one >or=0.30.

CONCLUSION

The SAGASF-M discriminates reasonably well between various genital and nongenital areas in terms of erotic sensitivity, when administered to genitally unoperated men varying widely in age and socio-economic level.

Evoked cavernous activity: normal values

PURPOSE

We present normative data for evoked cavernous activity, an electrodiagnostic test that evaluates the autonomic innervation of the corpora cavernosa.

MATERIALS AND METHODS

We enrolled 37 healthy, sexually active and potent men for the study. Each subject completed an International Index of Erectile Function questionnaire, and underwent simultaneous evoked cavernous activity and hand and foot sympathetic skin response testing. The sympathetic skin response tests were performed as autonomic controls.

RESULTS

A total of 36 men had discernible evoked cavernous activity and sympathetic skin responses. The mean International Index of Erectile Function erectile domain score was 27. Evoked cavernous activity is a low frequency wave that is morphologically and temporally similar in both corpora. The amplitudes of the responses were highly variable. The latencies, although variable, always occurred after the hand sympathetic skin response. There was no change in the quality or the latency of the evoked cavernous activity with age.

CONCLUSIONS

Evoked cavernous activity is measurable in healthy, potent men in a wide range of ages. Similar to other evoked responses of the autonomic nervous system, the measured waveform is highly variable but its presence is consistent. The association between evoked cavernous activity and erectile function is to be determined.

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.

Effect of neonatal circumcision on penile neurologic sensation

OBJECTIVES

To evaluate penile sensory thresholds in neonatally circumcised and uncircumcised men.

METHODS

We evaluated 125 patients, 62 uncircumcised men and 63 neonatally circumcised men. All patients completed the Erectile Function domain of the International Index of Erectile Function questionnaire. Of the 125 patients, 29 (International Index of Erectile Function score of between 25 and 30) were placed in the functional group, and 96 in the dysfunctional group. The patients were tested on the dorsal midline glans of the penis (foreskin retracted). Quantitative somatosensory testing was performed and included vibration, pressure, spatial perception, and warm and cold thermal thresholds.

RESULTS

In the functional group, t-test analysis demonstrated a significant (P <0.001) difference, with worse vibration and better pressure sensation for uncircumcised men. When controlling for age, hypertension, and diabetes, all t-test significance was lost. In the dysfunctional group, circumcised men (49 +/- 16 years) were significantly younger (P <0.01) than uncircumcised men (56 +/- 13 years). For the dysfunctional group, t-test analysis also demonstrated worse vibration sensation for uncircumcised men (P <0.01). Again, when controlling for age, hypertension, and diabetes, all t-test significance was lost.

CONCLUSIONS

We present a comparative analysis of uncircumcised and circumcised men using a battery of quantitative somatosensory tests that evaluate the spectrum of small to large axon nerve fiber function. Our study controlled for factors, including age, erectile function status, diabetes, and hypertension, that have been shown to alter neurologic testing. In our study of neonatally circumcised men, we demonstrated that circumcision status does not significantly alter the quantitative somatosensory testing results at the glans penis.

Clinical Evaluation of Erectile Dysfunction in the Era of PDE-5 Inhibitors

Erectile dysfunction (ED) is a common disorder that has gained attention since the introduction of relatively safe treatment with phosphodiesterase-5 inhibitors. ED is a multi-factorial disorder and a common presentation for several systemic illnesses,particularly vascular occlusive diseases. The clinical evaluation of ED should be thorough and systematic, with attention to the appropriate use of sexual symptom questionnaires and symptom scales, detailed medical and sexual history, physical examination,and basic screening laboratory tests. Patients should be referred for specialized evaluations when appropriate. The clinician must be familiar with the pathophysiologic mechanisms of ED, its associations with other systemic diseases, the indications for specialist referrals, and the role of specialized testing to diagnose and treat this disorder effectively.

Role of penile electrodermal activity in the evaluation of autonomic innervation of corpus cavernosum

Electrodiagnostic tests measuring the activities of cavernous smooth muscle and sudomotor structures of penile skin are used in order to evaluate autonomic innervation of the penis. Owing to closeness of these tissues, the interference of sympathetic activity during recording is a possibility. In this study, we investigated this possibility in 10 patients whose cavernosal tissues were destroyed during penile prosthesis implantation by comparing the pre- and postoperative penile skin electrodermal activities. Penile electrodermal activities were recorded with surface electrodes before and after the operation. All of the patients had spontaneous and evoked penile electrodermal activity (EDA). The mean amplitude of evoked EDA decreased from 2159+/-700 to 1413+/-515 microV following penile prosthesis surgery (P=0.017). The decrease in the amplitude of penile-evoked EDA following penile prosthesis implantation suggests the contribution of cavernous smooth muscle activity to the sudomotor responses prior to operation. Although corpus cavernosum sympathetic activity contributes to the penile skin recordings, these recordings are mostly the result of penile skin sudomotor sympathetic activity. Therefore, surface potentials recorded from penile skin should not be used for the evaluation of autonomic innervation of corpus cavernosum.

Investigations in erectile dysfunction

PURPOSE OF REVIEW

This is an update of recent developments in the investigation of erectile dysfunction in the period since March 2002.

RECENT FINDINGS

Three developments in the field of medical sexology redirected the approach towards the investigation of erectile dysfunction. First, the emergence of oral pharmacological therapy; second, the notion that sexual relationship issues have an important impact on the successful outcome of pharmacological therapy; and finally, the concept that erectile dysfunction is often a sequel or even a sentinel of cardiovascular disease. Consequently, the current evaluation of men with erectile dysfunction may be divided into two steps: a basic diagnostic evaluation for the majority of men, and specific diagnostic procedures for a small minority. The basic evaluation is aimed at the identification of the underlying pathological condition and erectile dysfunction-associated risk factors. Such screening may diagnose reversible causes of erectile dysfunction and also unmask medical and psychological conditions that manifest with erectile dysfunction. The basic evaluation consists of a comprehensive medical, sexual and psychosocial history and a physical examination. Patients who have failed first-line treatment or complicated cases qualify for specific diagnostic procedures, traditionally performed by urologists.

SUMMARY

Current research into the investigation of erectile dysfunction emphasizes the notion that erectile dysfunction is often a result of an interplay between medical and psychosexual conditions. Recognition of the underlying conditions and an estimation of their relative contribution to the patient's and his partner's sexual problem are key issues in the current evaluation of the man with erectile dysfunction.

Quantitative somatosensory testing of the penis: optimizing the clinical neurological examination

PURPOSE

Quantitative somatosensory testing, including vibration, pressure, spatial perception and thermal thresholds of the penis, has demonstrated neuropathy in patients with a history of erectile dysfunction of all etiologies. We evaluated which measurement of neurological function of the penis was best at predicting erectile dysfunction and examined the impact of location on the penis for quantitative somatosensory testing measurements.

MATERIALS AND METHODS

A total of 107 patients were evaluated. All patients were required to complete the erectile function domain of the International Index of Erectile Function (IIEF) questionnaire, of whom 24 had no complaints of erectile dysfunction and scored within the "normal" range on the IIEF. Patients were subsequently tested on ventral middle penile shaft, proximal dorsal midline penile shaft and glans penis (with foreskin retracted) for vibration, pressure, spatial perception, and warm and cold thermal thresholds.

RESULTS

Mixed models repeated measures analysis of variance controlling for age, diabetes and hypertension revealed that method of measurement (quantitative somatosensory testing) was predictive of IIEF score (F = 209, df = 4,1315, p <0.001), while site of measurement on the penis was not. To determine the best method of measurement, we used hierarchical regression, which revealed that warm temperature was the best predictor of erectile dysfunction with pseudo R(2) = 0.19, p <0.0007. There was no significant improvement in predicting erectile dysfunction when another test was added. Using 37C and greater as the warm thermal threshold yielded a sensitivity of 88.5%, specificity 70.0% and positive predictive value 85.5%.

CONCLUSIONS

Quantitative somatosensory testing using warm thermal threshold measurements taken at the glans penis can be used alone to assess the neurological status of the penis. Warm thermal thresholds alone offer a quick, noninvasive accurate method of evaluating penile neuropathy in an office setting.

Implications of diabetes mellitus in urology

The incidence of DM is rapidly growing among Americans. DM will rival cancer and heart disease in terms of cost and suffering. The National Institute of Health is tripling the research dollars that are spent on diabetic-related research in an attempt to combat this disease. Urologists are on the front line in the diagnosis and treatment of the complications of DM. The complications of DM that we reviewed in this article, diabetic cystopathy and diabetic ED, can occur in the early stage of DM and often progress in a silent fashion. More awareness and interest are needed to improve our understanding of diabetic complications in urology. Exciting new approaches in the treatment of diabetic cystopathy and ED are being investigated.

The neuropathy of erectile dysfunction

These studies were intended to explore the relationship between autonomic neuropathy and erectile dysfunction (ED). Sensory thresholds reflecting the integrity of both large diameter, myelinated neurons (ie pressure, touch, vibration) and small diameter axons (ie hot and cold thermal sensation) were determined on the penis and finger. Data were compared across subjects with and without ED, controlling for age, hypertension and diabetes. The correlation of specific thresholds scores and IIEF values were also examined. Seventy-three patients who visited the academic urology clinics at Montefiore hospital were evaluated. All patients were required to complete the erectile function domain of the International Index of Erectile Function (IIEF) questionnaire: 20 subjects had no complaints of ED and scored within the 'normal' range on the IIEF. Patients were subsequently tested on their index finger and glans penis for vibration (Biothesiometer), pressure (Semmes-Weinstein monofilaments), spatial perception (Tactile Circumferential Discriminator), and warm and cold thermal thresholds (Physitemp NTE-2). Sensation of the glans penis, as defined by the examined sensory thresholds, was significantly diminished in patients with ED and these differences remained significant when controlling for age, diabetes and hypertension. In contrast, thresholds on the index finger were equivalent in the ED and non-ED groups. Threshold and IIEF scores were highly correlated, consistent with an association between diminished sensation and decreasing IIEF score (worse erectile functioning). These relations also remained significant when controlling for age, diabetes and hypertension. The findings demonstrate dysfunction of large and small diameter nerve fibers in patients with ED of all etiologies. Further, the neurophysiologic measures validate the use of the IIEF as an index of ED, as objective findings of sensory neuropathy were highly correlated with worse IIEF scores. The sensory threshold methods utilized represent novel, non-invasive and relatively simple procedures, which can be used in a longitudinal fashion to assess a patient's neurological response to therapies.

Sexual function in men with cauda equina lesions: a clinical and electromyographic study

OBJECTIVE

To investigate the effects of cauda equina lesions on sexual function in men.

METHODS

Sexual function was investigated in 46 men with long standing cauda equina/conus medullaris lesions. All had clinical and radiological findings supporting the diagnosis. The validated Slovene translation of the international index of erectile function (IIEF) was used. The responses were scored and sexual dysfunction categorised as absent, mild, moderate, or severe. The number of patients receiving help for sexual dysfunction was noted. Neurological examination of the trunk and lower limbs, electromyographic (EMG) evaluation of the sacral reflex, and quantitative EMG of the external anal sphincter muscles were done.

RESULTS

Severe sexual dysfunction was reported by 35% of patients, moderate dysfunction by 24%, and slight dysfunction by 26%; normal sexual function was reported by 15%. Orgasmic function was slightly more impaired than erectile function, and sexual desire slightly less. The patients' age, but no findings on clinical neurological or EMG examination, correlated with sexual function. Only five men had received medical attention for sexual dysfunction.

CONCLUSIONS

There is significant sexual impairment in men with lesions of the cauda equina or conus medullaris. This is poorly correlated with neurological and EMG findings and has received insufficient medical attention.