Objectives: The aim of this study was to evaluate the efficacy and safety of sildenafil in the treatment of erectile dysfunction (ED) in spinal cord–injury (SCI) patients. Moreover, we looked for neurological conditions permitting therapeutic success and for the ideal dose needed to achieve sufficient erections.Methods: 41 SCI patients were prospectively examined. Sexual dysfunction was assessed by means of anamnesis, the International Index of Erectile Function (IIEF) questionnaire, and neurological examination. Psychogenic erection capacity was tested by audiovisual stimulation and reflexive erection using a vibrator device. Neurophysiological recordings and cystomanometry were performed in parallel to clinical examinations. Neurophysiological recordings included sympathetic skin responses (SSR), pudendus somatosensory evoked potentials (pSSEP), and bulbocavernous reflex (BCR). Urodynamics aimed at classifying the neurogenic bladder dysfunction (upper motoneuron lesion versus lower motoneuron lesion). Intracavernous injection tests with PGE1 were performed in all patients to exclude major organic disease. 50 mg sildenafil was first given 3 times. Thereafter, the doses were adapted according to patients’ reports.Results: Clinically, 28 subjects preserved either reflexive erections (24) or psychogenic erections (4), 11 had both types and only 2 presented with a complete loss of erection. 38 patients (93%) had a positive response to sildenafil and reached a penile rigidity sufficient to permit sexual intercourse. 3 patients dropped out because of non–response despite having increased the dosis up to 100 mg. 22 patients (58%) showed functional erections 1 h after 50 mg sildenafil, whereas 14 (37%) required higher doses of 75–100 mg. By comparing the IIEF questionnaire scores before and after therapy, there was a significant improvement in erectile function and intercourse satisfaction from 9.2±4.4 SD) and 4.5 (±2.5 SD) to 25.5 (±4.2 SD) and 10.5 (±2.1 SD) points, respectively (p<0.05). Nearly 10% (4/41) suffered from side effects such as headache or dizziness. Two of them stopped therapy because of the side effects. At least 36 patients (88%) continue treatment with sildenafil. Absence of both psychogenic (nonsomesthetic supraspinally elicited) and reflexive (somesthetic spinally elicited) erections, confirmed by urodynamical and electrophysiological findings (SSR perineum, BCR and pSSEP), seems to exclude a successful treatment. In contrast, SCI male patients with preserved function of at least one component of the erection phenomenon (psychogenic/reflexive) responded well to sildenafil and the dose required to achieve erections sufficient for sexual intercourse did not differ between the two groups.Conclusions: Sildenafil proves to be a valuable and safe therapeutic management in ED of SCI patients. Therefore, patient acceptance and satisfaction are high. The most common dose required to achieve a satisfying erection is 50 mg. The efficacy of sildenafil depends on sparing of either sacral (S2–S4) or thoracolumbar (T10–L2) spinal segments which, in this study, have been shown to be of relevance in mediating psychogenic erections in male SCI patients. Complete disturbance of any neurogenic impulses excludes successful treatment.

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