Penile electrodiagnosis. Value of bulbocavernosus reflex latency versus nerve conduction velocity of the dorsal nerve of the penis in diagnosis of diabetic impotence

Diagnosing Diabetic Neuropathy: Something Old, Something New

There are potentially many ways of assessing diabetic peripheral neuropathy (DPN). However, they do not fulfill U.S. Food and Drug Administration (FDA) requirements in relation to their capacity to assess therapeutic benefit in clinical trials of DPN. Over the past several decades symptoms and signs, quantitative sensory and electrodiagnostic testing have been strongly endorsed, but have consistently failed as surrogate end points in clinical trials. Therefore, there is an unmet need for reliable biomarkers to capture the onset and progression and to facilitate drug discovery in DPN. Corneal confocal microscopy (CCM) is a non-invasive ophthalmic imaging modality for in vivo evaluation of sensory C-fibers. An increasing body of evidence from multiple centers worldwide suggests that CCM fulfills the FDA criteria as a surrogate endpoint of DPN.

Evaluation of young men with organic erectile dysfunction

Erectile dysfunction (ED) in men under the age of 40 was once thought to be entirely psychogenic. Over the last few decades, advances in our understanding of erectile physiology and improvements in diagnostic testing have restructured our understanding of ED and its etiologies. Although psychogenic ED is more prevalent in the younger population, at least 15%-20% of these men have an organic etiology. Organic ED has been shown to be a predictor of increased future morbidity and mortality. As such, a thorough work-up should be employed for any man with complaints of sexual dysfunction. Oftentimes a treatment plan can be formulated after a focused history, physical exam and basic lab-work are conducted. However, in certain complex cases, more testing can be employed. The major organic etiologies can be subdivided into vascular, neurologic, and endocrine. Specific testing should be directed by clinical clues noted during the preliminary evaluation. These tests vary in degree of invasiveness, precision, and at times may not affect treatment. Results should be integrated into the overall clinical picture to assist in diagnosis and help guide therapy.

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

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

The effect of pharmacologic erection on the dorsal nerve of the penis

The dorsal nerve of the penis (DNP) is the primary source of afferent somatic input from the penis and is critical in the male sexual functions of erection and ejaculation. Using genitourinary electrodiagnostic techniques, this study was conducted to investigate the effect of pharmacologic erection on the DNP. Three tests were administered, and the changes in the DNP between flaccid, stretched, and erect states were examined. Calculated nerve conduction velocity (cNCV) measurements of the DNP increased with pharmacologic erection because mechanical straightening of the nerve allowed for a more precise measurement of nerve length. The latencies of the cortical evoked response and the bulbocavernosus reflex were not significantly changed with stretch or pharmacologic erection. In the evaluation of impotence, cNCV DNP measurements should be performed on the erect penis.

[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.

Cerebral-evoked response from stimulation of dorsal nerve in impotent men

Cerebral-evoked responses from 128 uncategorized, impotent men were compared with responses from 17 healthy age-height matched controls, after stimulation of two penile sites, and one tibial nerve at the ankle. Our goal has been to establish a simple screening test to identify neurogenic impotence in patients with normal superficial sensation. High-frequency stimulation at 5.7 c/s and minimal repetitions (300) per trial, allowed thirty to forty minute sessions in alert subjects. With these methods, the amplitudes of cerebral responses at N2 were most informative. All volunteers had measurable amplitude while 11.9 percent of patients did not. An additional 4.5 percent of patients had amplitude suppression of 2 SD compared with the control mean, suggesting that as many as 16.4 percent of such patients may have neural damage. Prolonged latencies alone were rare and not included in this total. Ninety-two of these 128 patients had Doppler flow studies, and only 2 showed both Doppler and electrical abnormalities. This suggests that neurogenic problems may often be independent of vascular disease. This evoked-response screen of the entire genitocerebral neuraxis offers a safe method of identifying a portion of those patients with neurogenic impotence.