Neurological risk profile in organic erectile impotence

[Diabetic neuropathy: do not only consider distal symmetrical neuropathy]

BACKGROUND

Diabetic neuropathy is a common complication of diabetes mellitus. The length-dependent symmetrical sensorimotor type of neuropathy is the most prevalent form of diabetic neuropathy but other forms of diabetic neuropathy also need to be kept in mind. Their differential diagnosis is often more challenging but implicates specific forms of treatment other than improvement of metabolic control.

AIM OF THE STUDY

This article gives an overview of the less frequent forms of diabetic neuropathy and discusses their impact, diagnostic and therapeutic implications.

RESULTS

Autonomic diabetic neuropathy, diabetic small fiber neuropathy and less frequent forms of diabetic neuropathy, such as diabetic radiculoplexopathy, diabetic neuropathy of cranial nerves, therapy-induced neuropathy and alternative causes of peripheral neuropathy in patients with diabetes are described.

DISCUSSION

Diagnosis of less frequent subtypes of diabetic neuropathy and differentiation towards alternative causes of peripheral neuropathy are often difficult in daily medical routine. Diagnostic clues are helpful in identifying rarer forms of diabetic neuropathy, thus enabling more specific treatment.

Assessing erectile neurogenic dysfunction from heart rate variability through a Generalized Linear Mixed Model framework

BACKGROUND

The low (LF) vs. high (HF) frequency energy ratio, computed from the spectral decomposition of heart beat intervals, has become a major tool in cardiac autonomic system control and sympatho-vagal balance studies. The (statistical) distributions of response variables designed from ratios of two quantities, such as the LF/HF ratio, are likely to non-normal, hence preventing e.g., from a relevant use of the t-test. Even using a non-parametric formulation, the solution may be not appropriate as the test statistics do not account for correlation and heteroskedasticity, such as those that can be observed when several measures are taken from the same patient.

OBJECTIVES

The analyses for such type of data require the application of statistical models which do not assume a priori independence. In this spirit, the present contribution proposes the use of the Generalized Linear Mixed Models (GLMMs) framework to assess differences between groups of measures performed over classes of patients.

METHODS

Statistical linear mixed models allow the inclusion of at least one random effect, besides the error term, which induces correlation between observations from the same subject. Moreover, by using GLMM, practitioners could assume any probability distribution, within the exponential family, for the data, and naturally model heteroskedasticity. Here, the sympatho-vagal balance expressed as LF/HF ratio of patients suffering neurogenic erectile dysfunction under three different body positions was analyzed in a case-control protocol by means of a GLMM under gamma and Gaussian distributed responses assumptions.

RESULTS

The gamma GLMM model was compared with the normal linear mixed model (LMM) approach conducted using raw and log transformed data. Both raw GLMM gamma and log transformed LMM allow better inference for factor effects, including correlations between observations from the same patient under different body position compared to the raw LMM. The gamma GLMM provides a more natural distribution assumption of a response expressed as a ratio.

CONCLUSIONS

A gamma distribution assumption intrinsically models quadratic relationships between the expected value and the variance of the data avoiding prior data transformation. SAS and R source code are available on request.

Sexual dysfunction following surgery for rectal cancer - a clinical and neurophysiological study

Background

Sexual dysfunction following surgery for rectal cancer may be frequent and often severe. The aim of the present study is to evaluate the occurrence of this complication from both a clinical point of view and by means of neurophysiological tests.

Methods

We studied a group of 57 patients submitted to rectal resection for adenocarcinoma. All the patients underwent neurological, psychological and the following neurophysiological tests: sacral reflex (SR), pudendal somatosensory evoked potentials (PEPs), motor evoked potential (MEPs) and sympathetic skin responses (SSRs). The results were compared with a control group of 67 rectal cancer patients studied before surgery. Only 10 of these patients could be studied both pre- and postoperatively. 10 patients submitted to high dose preoperative chemoradiation were studied to evaluate the effect of this treatment on sexual function. Statistical analysis was performed by means of the two-tailed Student's t test for paired observations and k concordance test.

Results

59.6% of patients operated reported sexual dysfunction, while this symptom occurred in 16.4% in the control group. Moreover, a significantly higher rate of alterations of the neurophysiological tests and longer mean latencies of the SR, PEPs, MEPs and SSRs were observed in the patients who had undergone resection. In the 10 patients studied both pre and post-surgery impotence occurred in 6 of them and the mean latencies of SSRs were longer after operation. In the 10 patients studied pre and post chemoradiation impotence occurred in 1 patient only, showing the mild effect of these treatments on sexual function.

Conclusion

Patients operated showed severe sexual dysfunctions. The neurophysiological test may be a useful tool to investigate this complication. The neurological damage could be monitored to decide the rehabilitation strategy.

The future of the oral pharmacotherapy of male erectile dysfunction: things to come

The convincing clinical data on the use of the orally active phosphodiesterase inhibitors sildenafil, vardenafil and tadalafil for the treatment of male erectile dysfunction have boosted research activities on the physiology of the male erectile mechanism. This included both peripheral intracellular signal transduction in the corpus cavernosum as well as central brain and spinal cord pathways controlling penile erection. This work provided the basis for the development and introduction of several new therapeutic modalities into the management of erectile dysfunction, some of which are already offered to the patients. As the concept of 'taking a pill' as a cure for an illness or the relief of symptoms of a disease has become widely accepted by the consumers, the pharmacologic treatment of erectile dysfunction has primarily focussed on selective, orally available drugs acting by influencing intracellular or central regulatory mechanisms, combining a high response rate and the advantage of an on-demand intake. These agents are regarded as more efficacious, and have a faster onset of drug action in the target tissue and an improved effect to side-effect ratio. The purpose of this review is to describe the major novel and evolving pharmacologic advances in the field of oral pharmacotherapy for the treatment of male erectile dysfunction.

Potential future options in the pharmacotherapy of female sexual dysfunction

Female sexual dysfunction (FSD) is considered a common medical problem estimated to affect millions of women in the westernized countries. FSD has been classified into four different categories including sexual arousal disorder (FSAD), sexual desire disorder (HSDD), orgasmic disorder and sexual pain disorder. The focus of this article is the potential role of pharmacological compounds currently under development, in the treatment of sexual arousal and orgasmic disorders in order to enhance the sexual response in adult females. While a number of potential therapeutic options are available to date, not one of the pharmacological treatment regimens has been yet considered the Gold standard in the management of symptoms of FSD. This article reviews the rationale and potential benefits of using distinct drug formulations in the treatment of FSD.

Therapie der organogen bedingten erektilen Dysfunktion

Erectile dysfunction is a common disease of men. It is associated with various comorbidities and has a prevalence of about 50% in the 7th decade. Erectile dysfunction often affects the quality of life of the patient and his partner, and it is very important to offer adequate therapy that respects the individual circumstances of each patient. The mandatory diagnostic work-up includes a medical and psychosexual history, a physical examination and routine laboratory tests. Besides psychotherapy, oral pharmacotherapy with oral PDE-5 inhibitors (sildenafil, tadalafil, vardenafil) is the most effective therapy for erectile dysfunction and is superior to centrally acting drugs (yohimbine). In cases of failure or contraindication of oral pharmacotherapy, local pharmacotherapy is the second-line therapy. The third-line options are vacuum erectile devices and penile implants, and these have a high patient satisfaction. New therapeutic strategies such as anti-serotoninergic substrates and growth hormone offer a promising future for the therapy of erectile dysfunction but remain to be evaluated.

Current and future trends in the oral pharmacotherapy of male erectile dysfunction

The promising clinical data on the use of the first orally active phosphodiesterase inhibitor sildenafil citrate (Viagra) for treatment of male erectile dysfunction have been accompanied by an increase in research activities on the physiology of the male erectile mechanism. This included both peripheral intracellular signal transduction in the corpus cavernosum as well as central brain and spinal cord pathways that control penile erection. This work provided the basis for the development and introduction of several new therapeutic modalities into the management of erectile dysfunction that is now offered to the patients. Since the concept of 'taking a pill' as a cure for an illness or the relief of symptoms of a disease has become widely accepted by consumers, the pharmacological treatment of erectile dysfunction has primarily focused on selective, orally available drugs that act via influencing intracellular or central regulatory mechanisms, combining a high response rate and the advantage of an 'on-demand' intake. These agents are regarded as more efficacious, have a faster onset of drug action in the target tissue and an improved effect-to-side effect ratio than sildenafil. The purpose of this review is to describe the major novel and evolving pharmacological advances in the field of oral pharmacotherapy for the treatment of male erectile dysfunction.

Cavernous and systemic plasma levels of norepinephrine and epinephrine during different penile conditions in healthy men and patients with erectile dysfunction

OBJECTIVES

To examine and compare the courses of norepinephrine (NE) and epinephrine (E) plasma levels in the systemic and cavernous blood taken during different penile conditions from healthy men and a group of patients with erectile dysfunction (ED). Knowledge concerning the neurophysiology of penile erection has improved tremendously during the past two decades. However, only few in vivo studies on human peripheral neurotransmission have been carried out to date.

METHODS

Fifty-three healthy adult male subjects and 47 patients with ED of different etiologies were exposed to erotic stimuli to elicit penile tumescence and, in the group of healthy subjects, rigidity. Whole blood was simultaneously aspirated from the corpus cavernosum and the cubital vein during different penile conditions. Plasma levels of NE and E were determined by means of a radioimmunoassay.

RESULTS

In the healthy subjects, a significant reduction of NE in cavernous plasma was detected from flaccidity (362 +/- 173 pg/mL) to rigidity (248 +/- 122 pg/mL), followed by an increase in the detumescence phase (336 +/- 199 pg/mL). Changes in NE levels in the peripheral plasma were less pronounced. Cavernous E levels significantly increased from flaccidity (47 +/- 41 pg/mL) to tumescence (130 +/- 106 pg/mL) and dropped from rigidity (113 +/- 67 pg/mL) to detumescence (76 +/- 57 pg/mL). The course of systemic E plasma levels was similar to that in the cavernous blood. In contrast, median NE levels in the systemic and cavernous blood of the ED group slightly increased from flaccidity to tumescence (from 199 +/- 88 pg/mL to 210 +/- 99 pg/mL and from 273 +/- 140 pg/mL to 278 +/- 118 pg/mL, respectively).

CONCLUSIONS

In healthy men, penile erection is accompanied by a reduction of NE in the cavernous blood and a rise in E levels in the peripheral and cavernous blood. That NE levels in the cavernous and systemic blood increase during sexual arousal in patients with ED might be an indication of a somatic dysregulation in sympathetic transmission or alterations of NE reuptake mechanisms as a cause of impaired erectile function.

Cauda equina syndrome

Single or double-level compression of the lumbosacral nerve roots located in the dural sac results in a polyradicular symptomatology clinically diagnosed as cauda equina syndrome. The cauda equina nerve roots provide the sensory and motor innervation of most of the lower extremities, the pelvic floor and the sphincters. Therefore, in a fully developed cauda equina syndrome, multiple signs of sensory disorders may appear. These disorders include low-back pain, saddle anesthesia, bilateral sciatica, then motor weakness of the lower extremities or chronic paraplegia and, bladder dysfunction. Multiple etiologies can cause the cauda equina syndrome. Among them, non-neoplastic compressive etiologies such as herniated lumbosacral discs and spinal stenosis and spinal neoplasms play a significant role in the development of the cauda equina syndrome. Non-compressive etiologies of the cauda equina syndrome include ischemic insults, inflammatory conditions, spinal arachnoiditis and other infectious etiologies. The use of canine, porcine and rat models mimicking the cauda equina syndrome enabled discovery of the effects of the compression on nerve root neural and vascular anatomy, the impairment of impulse propagation and the changes of the neurotransmitters in the spinal cord after compression of cauda equina. The involvement of intrinsic spinal cord neurons in the compression-induced cauda equina syndrome includes anterograde, retrograde and transneuronal degeneration in the lumbosacral segments. Prominent changes of NADPH diaphorase exhibiting, Fos-like immunoreactive and heat shock protein HSP72 were detected in the lumbosacral segments in a short-and long-lasting compression of the cauda equina in the dog. Developments in the diagnosis and treatment of patients with back pain, sciatica and with a herniated lumbar disc are mentioned, including many treatment options available.

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.

Neurophysiological evaluation of sexual dysfunction in patients operated for colorectal cancer

Sexual dysfunction after colorectal cancer surgery may be severe and occurs in 25% to 100% of cases. Thirty-eight patients underwent colorectal resection; eight (21%) who were totally impotent and two (5%) who had ejaculatory failure were therefore studied to better understand the neurophysiological alterations related to this type of surgery. The patients were evaluated after surgery with electrophysiological testing, including examination of the sacral reflex (SR), pudendal somatosensory evoked potential (PEP), and motor evoked potential (MEP) responses. Sudomotor skin response (SSR) was also studied in a group of patients. Of the 38 patients studied, 29 showed abnormalities: six of SR, three of PEP, six of MEP, and fourteen of SSR. Only a combination of all these tests permits correct evaluation of the sexual dysfunction.

Erectile insufficiency as first symptom of HTLV I/II associated myelopathy. Case report

A case of HTLV-I/II myelopathy in which the initial complaint was erectile insufficiency (EI) is reported. The only abnormalities found on the neurological exam were discrete weakness of the psoas and increased knee jerk reflexes. Diagnosis was made by demonstrating antibodies anti-HTLV I/II in the serum and cerebrospinal fluid (with the techniques of ELISA and Western blot), with confirmation by the polymerase chain reaction (PCR). EI can thus be the first symptom of HTLV-I/II infection and patients with EI of unknown etiology should be tested for HTLV-I/II in endemic areas.

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.

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.

Clinical value of the pudendal somatosensory evoked potential

The pudendal evoked potential was recorded in 126 patients who had presented with various uro-genital complaints. The patients were divided into two groups depending on whether or not there were clinical signs of neurological disease. Group I consisted of 83 patients (66%) who on clinical examination were neurologically normal. In group II there were 43 patients (34%) who had physical signs suggesting underlying neurological pathology. The pudendal evoked potential was abnormal in 10 patients from the group with neurological signs (group II) but only 1 patient from group I (a man who had made an excellent recovery from previous transverse myelitis). The conclusion of this study is that the pudendal evoked potential is of no greater value than the clinical examination in the assessment of patients with uro-genital dysfunction. The recommendation that the potential should be recorded as part of the routine assessment of patients suspected of having a neurogenic disorder of the bladder and sexual function should be reconsidered.

Erectile impotence in multiple sclerosis: a neurophysiological study

Pudendal evoked potentials, motor evoked potentials of the bulbocavernosus muscle to magnetic stimulation and bulbocavernosus reflex were recorded in 34 patients with multiple sclerosis (MS). Responses were delayed in 26, 20 and 3 cases respectively. No relationship was found between neurophysiological abnormalities and the presence or severity of erectile dysfunction, showing that these tests have little diagnostic usefulness in MS patients with impotence. Nocturnal penile tumescence was assessed in 14 cases: the test result was normal in 10 patients, including 3 severely paraplegic subjects.

I potenziali evocati pudendi, i potenziali evocati motori del muscolo bulbocavernoso e il test della tumescenza peniena notturna nella diagnosi di impotenza in pazienti con sclerosi multipla

Pudendal evoked potentials, motor evoked potentials of the bulbocavernosus muscle to magnetic stimulation and bulbocavernosus reflex were recorded in 34 MS patients: responses were delayed in 26, 20 and 3 cases respectively. No relationship was found between neurophysiological abnormalities and the presence or severity of erectile dysfunction, showing that these tests have little diagnostic usefulness in MS patients with impotence. Nocturnal penile tumescence test was assessed in 14 cases: the test was normal in 10 patients, with no additional diagnostic help.