Peripheral neuropathy: an underdiagnosed cause of erectile dysfunction.

OBJECTIVES: • To assess the prevalence of peripheral neuropathy in patients with erectile dysfunction (ED). • To evaluate the reliability of clinical tests such as the five-item version of the International Index of Erectile Function (IIEF-5) and the Neuropathy Symptom Score (NSS) classification system in predicting the concurrence of peripheral neuropathy. PATIENTS AND METHODS: • We studied 90 patients who were consecutively recruited from the Department of Andrology of the Central Hospital of Asturias. • Anamnesis included questions about risk factors related to ED. • The severity of ED was classified according to IIEF-5 scores and symptoms of peripheral neuropathy were assessed using the NSS. • Neurophysiological tests included electromyography, nerve conduction studies, evoked potentials from pudendal and tibial nerves as well as bulbocavernosus reflex. • Small fibre function was assessed using quantitative sensory tests and sympathetic skin response. Statistical analysis was performed using the SPSS-11 program. RESULTS: • Patients with more severe symptoms of peripheral neuropathy showed lower (worse) IIEF-5 scores (P= 0.015) and required more aggressive therapies (P < 0.001). • Neurophysiological exploration confirmed neurological pathology in 68.9% of patients, of whom 7.8% had myelopathy and 61.1% peripheral neuropathy. • Polyneuropathy was found in 37.8% of the patients, of whom 8.9% had pure small fibre polyneuropathy, and pudendal neuropathy was diagnosed in 14.4%. • No association between neurophysiological diagnosis and IIEF-5 score was detected, but a statistical association was found between neuropathy and NSS scores. CONCLUSIONS: • Up to now, the impact of peripheral neuropathy in the pathogenesis of ED has been underestimated. The combination of anamnesis and an ad hoc neurophysiological protocol showed its high prevalence and provided a more accurate prognosis. • In future, clinical practice should optimize the assessment of pelvic small fibre function.

Sympathetic skin response in patients with erectile dysfunction.

OBJECTIVES: To evaluate the role of the sympathetic skin response (SSR) in men with erectile dysfunction (ED), focusing on detecting SSR in the penis. PATIENTS AND METHODS: We assessed the SSR in 82 patients with ED, as an indicator of abnormalities both in amyelinic C-fibres and in autonomic pathways in these patients. The SSR was carried out according to the to the Technical Standards of the International Federation of Clinical Neurophysiology. Electrical stimulation was applied through superficial electrodes over the contralateral median nerve. Values were recorded with superficial electrodes on the skin in the contralateral hand and foot, as well as in the penis. The percentage of SSR (SSR%) was classified into three groups, i.e. 0-20%, 21-89% and 90-100%. Results of latency were also classified into three groups of normal or abnormal (increased) latency, and response blocking (no response), the last two being considered pathological conditions. RESULTS: In the penis, the mean (sd) SSR% was 52.8 (43.19)% and significantly lower than responses in hands and feet. There was a significant correlation of the SSR% between the palm of the hand and the sole of the foot (P = 0.01) and between the sole of foot and penis (P = 0.05). Diabetics showed a significant decrease (P = 0.001) in the mean SSR% in the palm of the hand and sole of the foot. Although not statistically different, the mean SSR% in the penis was lower in diabetics than in patients with other risk factors for ED. Likewise, the mean SSR% in hand, foot and penis increased with an increase in the International Index of Erectile Function. In the penis, latency was normal (<1.5 ms) in 14 and abnormal in 37 patients. There was a significant association between pathological chronic re-innervation in the bulbocavernosus muscle and SSR latencies in the foot (P = 0.002) and penis (P = 0.03). Bulbocavernosus muscle electromyography showed a higher frequency of chronic bilateral axonomnesis in patients with abnormal latencies (28%) than in patients with normal SSR latencies in the penis. CONCLUSION: These results establish an indication of the SSR in patients with ED, registering responses not only in classic locations like the palm of the hand or sole of the foot, but also in the penis. The SSR% was useful as an indicator of the effect on efferent C fibres. Despite SSR being a polysynaptic potential of long latency and regulated by the cerebral cortex, the present results show that it is advisable to record the latencies of SSR in the three areas registered, and especially in the penis, where it seems be more useful as a marker of lumbosacral and/or pudendal alterations.

[Neurogenic etiology in patients with erectile dysfunction]. / Etiología neurógena en pacientes con disfunción eréctil.

OBJECTIVES: Erectile dysfunction (ED) is a disorder with a high prevalence that increases with age. It is estimated that 18.9% of men's between 25 and 70 years suffer it in Spain. Most cases have a multifactorial origin and it is admitted the influence on its pathogenesis of systemic diseases, different kind of drugs, psychogenic factors, cardiovascular, endocrinological and neurological diseases. Neurologic cause erectile dysfunction may have its origin in the central or peripheral nervous system. Among possible process of neurogenic erectile dysfunction of central origin would be tumors, cerebral vascular accidents, encephalitis, Parkinson disease, multiple sclerosis and other demyelinization diseases, dementias, olivopontocerebellar degeneration and epilepsy. Myelopathies of any etiology may be, depending on their localization and extension, cause of erectile dysfunction. At the peripheral level, disorders of the sensitive tracts constituting the afferent limb of the erection spinal reflex, and the efferent vegetative or somatic tracts mediating arterial vasodilatation, cavernous smooth muscle relaxation or pelvic floor striated muscle contraction. The aim of this work is to review in detail the most relevant causes of neurogenic erectile dysfunction, their etiopathogenic mechanisms and therapeutic approaches currently considered more adequate for each particular case. CONCLUSIONS: The correct diagnostic approach to patients with erectile dysfunction passes through identification, if possible, of the etiopathogenic factors implied. Regarding this, detection and identification of a possible neurogenic risk factor will contribute to a better understanding of the physiopathologic mechanisms, and more adequate diagnostic, prognostic and therapeutic approaches, mainly in those patients refractory to first line therapy.