Bulbocavernosus reflex to somatic and visceral nerve stimulation in normal subjects and in diabetics with erectile 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.

Neurophysiology of the pelvic floor in clinical practice: a systematic literature review

Neurophysiological testing of the pelvic floor is recognized as an essential tool to identify pathophysiological mechanisms of pelvic floor disorders, support clinical diagnosis, and aid in therapeutic decisions. Nevertheless, the diagnostic value of these tests in specific neurological diseases of the pelvic floor is not completely clarified. Seeking to fill this gap, the members of the Neurophysiology of the Pelvic Floor Study Group of the Italian Clinical Neurophysiology Society performed a systematic review of the literature to gather available evidence for and against the utility of neurophysiological tests. Our findings confirm the utility of some tests in specific clinical conditions [e.g. concentric needle electromyography, evaluation of sacral reflexes and of pudendal somatosensory evoked potentials (pSEPs) in cauda equina and conus medullaris lesions, and evaluation of pSEPs and perineal sympathetic skin response in spinal cord lesions], and support their use in clinical practice. Other tests, particularly those not currently supported by high-level evidence, when employed in individual patients, should be evaluated in the overall clinical context, or otherwise used for research purposes.

Bulbocavernosus reflex to stimulation of prostatic urethra in patients with lifelong premature ejaculation

INTRODUCTION

Lifelong premature ejaculation (LPE) is a prevalent sexual dysfunction among men, while its precise pathologic mechanisms have remained poorly understood.

AIM

In our study, the correlation between excitability of bulbocavernosus reflex (BCR) to stimulation of the prostatic urethra and LPE was studied.

METHODS

Twenty normal potent male volunteers and 42 patients with LPE were studied by inserting a specially designed Foley catheter with two electrodes mounted on its distal surface (intraurethral catheter electrode) into bladder to evoke the BCR to stimulation of prostatic urethra. Also, sensitivity of glans penis to electrical stimulation was detected by two surface electrodes.

MAIN OUTCOME MEASURES

Sensory thresholds of BCR to stimulation of prostatic urethra, thresholds to evoke stable BCR, latencies of BCR, and sensory thresholds of glans penis to electrical stimulation.

RESULTS

The mean sensory thresholds of BCR to stimulation of prostatic urethra, thresholds to evoke stable BCR, latencies of BCR, and sensory thresholds of glans penis were 12.38±3.71 mA (0.2 ms in duration, 1 Hz), 23.81±5.55 mA (0.2 ms, 1 Hz), 70.48±6.33 ms, and 11.89±2.26 mA (0.04 ms in duration,3 Hz) in the patients with LPE, respectively, and were 18.20±2.68 mA (0.2 ms, 1 Hz), 34.76 ± 4.15 mA (0.2 ms, 1 Hz), 71.20±5.77 ms, and 14.16±1.94 mA (0.04 ms, 3 Hz) in the normal potent men, respectively (mean±SD). Statistically significant differences were seen regarding the sensory thresholds of BCR to stimulation of prostatic urethra, the thresholds to evoke stable BCR and the sensory thresholds of glans penis between the two groups (P<0.001). No statistically significant differences were seen regarding the latencies of BCR between the two groups (P>0.05).

CONCLUSIONS

Patients with LPE might have hyperexcitable BCR to stimulation of prostatic urethra, which is probably one of the important factors for its etiology.

Clinical value of combined electrophysiological and urodynamic recordings to assess sexual disorders in spinal cord injured men

AIMS

To assess the significance of combined neurophysiological and neurourological examinations for diagnosis of neurogenic male sexual dysfunction.

METHODS

This is a prospective study of 32 spinal cord injured men. Each underwent clinical and neurophysiological examinations (sympathetic skin responses (SSR), pudendal somato-sensory evoked potentials (P-SSEP), bulbocavernosus reflex (BCR)) and neuro-urological measurements (urodynamic examination (UE), reflex erections (RE), psychogenic erections (PE) and nocturnal penile tumescence recordings (NPTR)).

RESULTS

Erectile dysfunction due to impairment of RE was associated with loss of BCR and detrusor areflexia (P > 0.001), whereas that due to impairment of PE was associated with loss of perineal SSR (P < 0.001). P-SSEP corresponded in 94% with impairment of penile sensibility and duration of erections in NPTR. The NPTRs were less related to functional sexual impairment. NPTRs in complete and incomplete suprasacral (level > T10) spinal lesion showed sufficient erections despite strongly disturbed PE. NPTRs in lumbosacral lesion revealed significant reduction in or absent erections and underestimated the presence of well excitable PE.

CONCLUSIONS

Combined neurophysiologic and neurourologic testing provides highly relevant diagnostic informations about sexual dysfunction in men with spinal cord injury. Loss of the BCR and detrusor areflexia imply loss of somatic and parasympathetic reflex activity and correlate with loss of RE. Loss of PE correlates with loss of perineal SSR (sympathetic denervation).

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.

Somatic innervation of the human bulbocavernosus muscle

OBJECTIVE

To demonstrate the somatic reflex innervation of the bulbocavernosus muscle (BCM), the principal muscle for ejaculation.

METHODS

Genitourinary electrodiagnostic testing utilizing modifications of the standard bulbocavernosus reflex was performed in 13 healthy male volunteers ages 20-43.

RESULTS

Bulbocavernosus muscle contraction was elicited by stimulation of the dorsal nerve of the penis, from both the penile skin and from the anterior urethra, and following stimulation of the perineal nerve. Latencies were variable depending on the point of stimulation.

CONCLUSIONS

All 3 afferent pathways synapse on pudendal motoneurons in the conus medullaris, and provide for peripheral reflex control of BCM contractions. Based on the latencies of the urethral evoked responses, urethral innervation differs from penile shaft innervation, each having a distinct population of the dorsal nerve of the penis (DNP) fibers. The presence of an electrically-defined pathway from the anterior urethra to the BCM suggests that somatic afferents from the anterior urethra are involved with the ejaculatory reflex. These somatic reflexes are components of normal ejaculatory function. The findings contribute to understanding the neurophysiology of ejaculation, and may be applicable to the evaluation of ejaculatory disorders.

Autonomic nerve involvement and venous leakage in diabetic men with impotence

OBJECTIVE

To determine the neurophysiological and vascular factors in diabetic impotence, particularly the role of autonomic neuropathy on venous leakage and erectile impotence.

PATIENTS AND METHODS

Thirty-four diabetic men with impotence were investigated using various neurophysiological and radiological methods. The results were compared with those from patients with idiopathic penile venous leakage for autonomic neuropathy, especially for spontaneous cavernosal activity (SCA).

RESULTS

Of the neurophysiological tests, the SCA was most frequently abnormal, with the loss of normal periodic oscillations. Penile venous leakage, either alone or with arterial insufficiency, was the most frequent vascular problem (67%) in patients with diabetic impotence, in whom the SCA was absent in most (83%). Conversely, the SCA was normal in all impotent patients with idiopathic venous leakage.

CONCLUSION

Venous leakage in diabetic patients is probably produced by autonomic dysfunction of the penile vascular innervation or degeneration of penile smooth muscles, because the SCA was absent more often in these patients.

[Penile neuropathy: clinical and electrophysiologic study. Report of 186 cases]

Penile neuropathy is a common disease due to lesion of the sensory branch of the pudendal nerve, ie, the dorsal nerve of the penis. Sexual disorders (deterioration of erection) and sensory signs (hypoesthesia or paresthesia of the penis) are noted in patients with penile neuropathy. Electrophysiological recordings help guide the diagnosis (reduction of the sensory velocity of the dorsal nerve of the penis). Many etiologies can be found (traumatic, toxic, compressive), but the most common lesion is neuropathy related to diabetes.

Evoked potential testing

Electrophysiologic tests of the sacral neuromuscular system and its suprasegmental control may be divided into EMG and methods involving stimulation (i.e., evoked potential and sacral reflex testing). The latter group of methods tests the function of defined parts of the motor or sensory nervous system, or reflex arcs. There already is ample experience with testing the somatic sensory pathways (pudendal SEP) and the (somatic) sacral reflex arc, whereas other methods (testing the motor system and tests involving visceral afferents and sympathetic efferents) need further study to establish their proper place in everyday clinical diagnostics. The application of these methods in research has led to important advances in our understanding of nervous system involvement in different pathologic conditions leading to neurogenic sacral dysfunctions. If applied in individual patients, these methods should however, be used and interpreted with restraint; they should be considered in patients with probable or proved nervous system lesions, those in whom additional clarification regarding proof of, localization of, and the nature (i.e., axonal versus demyelinative) of the lesion is relevant for diagnosis and prognosis. If applied in patients with central nervous system involvement, evoked potential studies may be used on their own; but, in the author's opinion, in patients with putative peripheral nervous system involvement these tests should be considered, as a rule, only as an extension of a needle EMG exploration. It is expected that further experience will clarify the sensitivity and specificity of the available methods. The already available methods certainly will gain a place in the operating room helping the surgeon in selected procedures involving the pelvis and particularly conus and cauda equina better to identify neuromuscular structures and to monitor their function throughout the operation in order to prevent subsequent development of lesions.

Cerebral responses elicited by stimulation of the vesico-urethral junction (VUJ) in diabetics

To investigate the involvement of the visceral afferent nerves in diabetes mellitus, we enrolled 46 male patients in a study, examining the cerebral potentials evoked by stimulation of the vesico-urethral junction (VUJ CEP) and the pudendal (penile CEP) and posterior tibial nerves (tibial CEP). The age range was 23-67 (mean 45.8) years. The epithelial surface of the vesico-urethral junction was stimulated bipolarly with an electrode attached to a specially produced Foley catheter. Cerebral responses were recorded bipolarly at vertex. VUJ CEPs were absent (27 patients) or protracted and/or of low amplitude (4 patients) (total 31 patients; 67.8%). Penile CEP and/or tibial CEP could be obtained in all cases; however, protracted P1 peak latencies were detected in 15 (32.8%). The abnormalities of VUJ CEP did not correlate with the presence of peripheral neuropathy, while the abnormalities of penile CEP and/or tibial CEP invariably coincided with the presence of peripheral neuropathy. Although neither age nor the duration of diabetes correlated with abnormal CEPs as determined by any of the tests, insulin dependence correlated with abnormal penile CEP and to a lesser extent with VUJ CEP. We conclude that VUJ CEP is informative in evaluating the physiological condition of visceral afferents, and can be used in diagnosis of the early involvement of visceral afferents in diabetes mellitus.

The clinical application of dorsal penile nerve cerebral-evoked response recording in the investigation of impotence

OBJECTIVE

To determine whether recording of penile cerebral-evoked response (CER) is useful in the assessment of men with impotence.

PATIENTS AND METHODS

A total of 280 impotent men underwent CER recording as part of an assessment for a complaint of impotence. They were categorized from findings in the history and examination as having non-neurogenic impotence (n = 106), impotence related to existing neurological disturbance (n = 67), type I diabetes (n = 49) or type II diabetes (n = 58). Increased period of latency or absence of first positive peak (P1) on CER were used as the criteria for an abnormal response with reference to an age-matched control group of potent men (n = 34).

RESULTS

Overall, impotent men with diabetes or a history of neurological disturbance had significantly longer P1 latencies and lower response amplitudes compared with the control group. In contrast the CER recorded from men with non-neurogenic impotence was similar to the control group. Individual results showed an increased period of latency or absence of P1 in 100 (36%) impotent men, 72 (72%) of whom were diabetic or had a history of neurological dysfunction. CER abnormalities were associated with neurological signs on physical or cystometrographic examination in 40 (40%) individuals.

CONCLUSION

Although technically satisfactory, the clinical usefulness of CER recording is limited by the poor discriminatory value of response latencies. Most abnormal results could be predicted by the presence of diabetes or pre-existing neurological dysfunction, or by evidence of neurological deficit on physical examination. The test is not therefore suitable for routine clinical assessment of impotence but may be worthwhile if objective evidence of penile sensory dysfunction is required.

Cerebral evoked potentials after stimulation of the posterior urethra in man

Cerebral evoked potentials (EPs) were recorded in 25 neurologically normal subjects aged 22-73 years (mean 44.0) after stimulation of the posterior urethra (PU) and the pudendal nerve. After maximal PU stimulation 2 different configurations of the potential were found. In 12 cases a simple bi-triphasic wave form was recorded while in 12 cases there was a bifid form of the first negative wave. In 1 case identical EPs were recorded after PU and pudendal nerve stimulation. It was concluded that (1) PU stimulation excites fibres in the pudendal nerve at higher stimulation strength, resulting in a bifid wave form of the cerebral evoked potential in some individuals, (2) the most prominent negative peak, N1, with a latency of 102.1 +/- 13.2 msec, is the most reproducible part of the PU-evoked potential, (3) the N1 is probably transmitted through A delta fibres localized in the pelvic nerves, (4) there are differences between individuals concerning pudendal and pelvic nerve involvement in afferent innervation of the urethra.

Primary erectile dysfunction

We evaluated 67 patients 18 to 60 years old (mean age 28.5 years) with primary erectile dysfunction (absence of full sustained erections since early childhood or puberty) using a multidisciplinary approach. Organic causes of the erectile dysfunction were found in 57 of the 67 patients (85 per cent): 12 (18 per cent) had neurological, 35 (52 per cent) arteriogenic and 35 (52 per cent) venogenic abnormalities. Psychogenic factors were diagnosed in 11 patients (16 per cent), while in 4 (6 per cent) a classification was not possible. Concomitant psychogenic abnormalities were found in 39 of the 57 patients (68 per cent) with organic primary erectile dysfunction. Our results suggest that primary erectile dysfunction is caused mainly by organic factors. However, for successful therapy the frequent secondary psychogenic abnormalities must be considered.

Etiologic aspects of impotence in diabetes

An investigation of 37 diabetics with impotence (15) or erectile difficulties (22) is presented. On average two significant abnormalities per patient were found. Ranked in order of incidence, the causes were as follows: 1) Combination of neuropathy and psychosocial factors, 2) combination of neuropathy and vascular disease, 3) peripheral neuropathy only, 4) combination of hormonal imbalance and psychosocial factors, 5) combination of three or more defects, and 6) penile vascular disease or psychosocial problems only, or hormonal imbalance combined with peripheral neuropathy.