Neurophysiological investigations of two hundred men with erectile dysfunction. Interest of bulbocavernosus reflex and pudendal evoked responses

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.

Clinical classification of cauda equina syndrome for proper treatment

BACKGROUND AND PURPOSE

Cauda equina syndrome (CES) is a severe complication of lumbar spinal disorders; it results from compression of the nerve roots of the cauda equina. The purpose of this study was to evaluate the clinical usefulness of a classification scheme of CES based on factors including clinical symptoms, imaging signs, and electrophysiological findings.

METHODS

The records of 39 patients with CES were divided into 4 groups based on clinical features as follows. Group 1 (preclinical): low back pain with only bulbocavernosus reflex and ischiocavernosus reflex abnormalities. Group 2 (early): saddle sensory disturbance and bilateral sciatica. Group 3 (middle): saddle sensory disturbance, bowel or bladder dysfunction, motor weakness of the lower extremity, and reduced sexual function. Group 4 (late): absence of saddle sensation and sexual function in addition to uncontrolled bowel function. The outcome including radiographic and electrophysiological findings was compared between groups.

RESULTS

The main clinical manifestations of CES included bilateral saddle sensory disturbance, and bowel, bladder, and sexual dysfunction. The clinical symptoms of patients with multiple-segment canal stenosis identified radiographically were more severe than those of patients with single-segment stenosis. BCR and ICR improved in groups 1 and 2 after surgery, but no change was noted for groups 3 and 4.

INTERPRETATION

We conclude that bilateral radiculopathy or sciatica are early stages of CES and indicate a high risk of development of advanced CES. Electrophysiological abnormalities and reduced saddle sensation are indices of early diagnosis. Patients at the preclinical and early stages have better functional recovery than patients in later stages after surgical decompression.

The application of an electrophysiological bulbocavernosus reflex test in male dogs

The electrophysiological bulbocavernosus reflex test consists of recording the electromyographic activity of the bulbocavernosus muscle following electrical stimulation of the glans penis. This study has been carried out to show the applicability of the electrophysiologic bulbocavernosus reflex (EBCR) in dogs and to determine its normal latency value. Ten healthy male dogs were used. Responses to stimulation of the bulbus glandis were recorded from the left bulbocavernosus muscle with a concentric needle-recording electrode. In 10 dogs of maximum size 31 kg and maximum age 3 years, EBCR had response latencies between 17.6 and 28.8 ms with the mean value of 24.4 ms. The results of this study show that the electrophysiological bulbocavernosus reflex test could be employed as a routine diagnostic method in small animal clinics for evaluation of the sacral reflex arc. Among several advantages are easy applicability and the objective result, with the latency exceeding 29 ms not being seen in the dogs used in our study.

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.

Corpus cavernosum electromyography (CC-EMG): a new technique in the diagnostic work-up of impotence

We have studied cavernous electrical activity in 42 subjects, healthy volunteer controls and groups of impotent patients using a nonspecific electromyographic device (PICO-MENFIS) and a specific one, the SPACE-recorder 7500 designed to achieve electric recordings from the corpora cavernosa. In all of the patients, we detected under basal conditions a mean amplitude of 583 +/- 323 microV, a mean duration of 4.9 +/- 7 s, a mean polyphasicity of 3.5 +/- 1.4. It should be emphasized that a significant reduction of potential amplitudes was recorded after pharmacological stimulation in both the controls and the impotent patients. The healthy controls showed amplitudes significantly higher than the impotent patients after radical cystectomy (715 +/- 141 microV versus 381 +/- 227 microV, p < 0.01). The patients after a "nerve-sparing" radical cystectomy with a mean amplitude similar to the controls (500-700 microV) reacted well to the intracavernous drugs in a high percentage of cases. In our experience, CC-EMG seems to be a reliable method which can pinpoint directly lesions to the cavernous smooth muscle and penile autonomic nerves. It has also been able to assess the effects of stress, anxiety and pain on the erectile mechanisms.

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.

Assessment and treatment of impotence

Impotence is a common problem. History is primarily relied on to diagnose psychogenic impotence. Sex therapy is an effective treatment. Antihypertensive and psychiatric medicines often cause impotence, but most medicines should be considered a cause if this is supported by the history. Hormonal causes should be suspected in a patient with decreased libido or decreased testicular size, and testosterone should be measured in these cases. Hormone replacement may restore sexual function in hypogonadal men. Doppler sonogram or arteriography should be used to diagnose vascular impotence for men who would be good surgical candidates. Only young men without other illness are considered. There is little need to test neurologic function because there is no specific treatment for neurogenic impotence. These patients and patients who do not respond to the aforementioned treatments should be offered the vacuum erection device, penile self-injection therapy, or penile prosthesis. Choice depends on comorbid illness as well as patient preference. A basic algorithm for the evaluation and treatment of impotence is given in Figure 2.

Reduced variance of latencies in pudendal evoked potentials after normalization for body height

The value of the Somatosensory Evoked Potentials (SEP) in the assessment and detection of neurological disorders could be considerably enhanced if the normative standards of (SEP) characteristic parameters were normalized taking into account all other systematic sources of variance. The present study examines the influence of body height on the peak and interpeak latencies of the pudendal somatosensory evoked potentials. We examined the peak latency (L1) of the evoked potential recorded at the L1 vertebra and the onset latency (ONc) of the cortical evoked potentials, after stimulation of the pudendal nerve, as a function of body height in 40 normal male subjects (age 20-40 years). Significant positive correlation was found between both (ONc) latency and ONc-L1 interpeak latency and body height (H). Assuming that the latter is proportional to the length of the neural pathways, the experimental data were fitted using a theoretical model representing the conduction in the sensory neuraxis as a function of body height. Using the estimated fitting functions, we normalized our data with regard to a typical value of body height. The normalized values of the aforementioned latencies reveal a significantly reduced variance, as compared to the original ones, and consequently their diagnostic importance is significantly increased. Similar procedures applied to the L1 (spinal) latencies and the latencies of the bulbocavernosus reflex (BCR) reveal no correlation with body height and this is discussed on the basis of neuroanatomical considerations.

Electromyography of cavernous smooth muscle during flaccidity: evaluation of technique and normal values

Objective evaluation of the penile innervation in impotent patients is mostly restricted to examination of the somatic pudendal pathways. These tests provide little information on the pelvic-cavernous autonomic innervation of the corporeal bodies. Electromyography of the flaccid penile smooth muscle is a reproducible and non-invasive method of evaluating these autonomic pathways and the status of intrinsic smooth muscle. Examination techniques and normal values have been studied in 15 young and potent volunteers. Recordings in 13 patients with neuropathology and 57 impotent patients are discussed.