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.