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.

Keywords:
Spinal cord injury, Erectile dysfunction, Sildenafil treatment, Neurophysiological recordings, Urodynamics
1.
Linet OI, Ogriac FG: Efficacy and safety of intracavernosal alprostadil in men with erectile dysfunction. N Engl J Med 1996;334:873–877.
2.
Padma–Nathan H, Hellstrom WJG, Kaiser FE, Labasky RF, Lue TF, Nolten WE, Norwood PC, Peterson CA, Shabsigh R, Tam PU: Treatment of men with erectile dysfunction with transurethral alprostadil. N Engl J Med 1997; 336:1–7.
3.
Montague, DK, Barada JH, Belker AM, Levine LA, Nadig PW, Roehrborn CG, Sharlip ID, Bennett AH: Clinical guidelines panel of erectile dysfunction: Summary report on the treatment of organic erectile dysfunction. J Urol 1996;156:2007–2011.
4.
Anderson KE, Wagner G: Physiology of penile erection: Physiol Rev 1995;75:191–236.
5.
Rajfer J, Aronson WJ, Bush PA, Dorey FJ, Jguarro LJ: Nitric oxide as a mediator of relaxation of the corpus cavernosum in response to nonadrenergic, noncholinergic neurotransmission. N Engl J Med 1992;326:90–94.
6.
Burnett AL: The role of nitric oxide in the physiology of erection. Biol Reprod 1995;52: 485–489.
7.
Boolell M, Allen MJ, Ballard SA, Gepi–Attee S, Muirhead GJ, Naylor AM, Osterloh IH, Gingell C: Sildenafil: An orally active type 5 cyclic GMP–specific phosphodiesterase inhibitor for the treatment of penile erectile dysfunction. Int J Impot Res 1996;8:47–52.
8.
Moreland RB, Goldstein I, Traish A: Sildenafil, a novel inhibitor of phosphodiesterase type 5 in human corpus cavernosum smooth muscle cells. Life Sci 1998;62:309–318.
9.
Goldstein I, Lue TF, Padma–Nathan H, Rosen RC, Steers WD, Wicker PA: Oral sildenafil in the treatment of erectile dysfunction. N Engl J Med 1998;338:1397–1404.
10.
Boolell M, Gepi–Attee S, Gingell JC, Allen MJ: Sildenafil, a novel effective oral therapy for male erectile dysfunction. Br J Urol 1996; 78:257–261.
11.
De Groat WC, Booth AM: Neural control of penile erection; in Maggi CA, Harwood J (eds): The Autonomic Nervous System. London, Academic Publishers, 1993, pp 467–524.
12.
Chapelle PA, Durand J, Lacert P: Penile erection following complete spinal cord injury in man. Br J Urol 1980;52:216–219.
13.
Jänig W, McLachlan EM: Organization of lumbar spinal outflow to the distal colon and pelvic organs. Physiol Rev 1987;67:1332– 1404.
14.
Bors E, Comarr AE: Neurological disturbance of sexual function with special reference to 529 subjects with spinal cord injury. Urol Surv 1960;10:191–222.
15.
Courtois FJ, Charvier KF, Leriche A, Raymond DP: Sexual function in spinal cord injury men. I. Assessing sexual capability. Paraplegia 1993;31:771–778.
16.
Biering–Sörensen F, Sönksen J: Penile erection in men with spinal cord or cauda equina lesions. Semin Neurol 1992;12:98–105.
17.
Maynard FM Jr, Bracken MB, Creasay G, Ditunno JF Jr, Donovan H, Ducker TB, Garber SL, Marino RJ, Stover SL, Tator CH, Waters RL, Wilberger E, Young W: International Standards for Neurological and Functional Classification of Spinal Cord Injury. Spinal Cord 1997;35:266–274.
18.
Sachs BD: Placing erection in context: The reflexogenic–psychogenic dichotomy reconsidered. Neurosci Biobehav 1995;19:211–224.
19.
Bernabe J, Rampin O, Sachs BD, Giuliano F: Intracavernous pressure during erection in rats: An integrative approach based on telemetric recording. Am J Physiol 1999;276:R441– R449.
20.
Rosen RC, Riley A, Wagner G, Osterloh IH, Kirkpatrick J, Mishra A: The International Index of Erectile Function (IIEF): A multidimensional scale for assessment of erectile dysfunction. Urology 1997;49:822–830.
21.
Courtois FJ, Goulet MC, Charvier KF, Leriche A: Posttraumatic erectile potential of spinal cord injured men: How physiologic recordings supplement subjective reports. Arch Phys Med Rehabil 1999;80:1268–1272.
22.
Opsomer RJ, Guerit JM, Wese FX, Cangh PJ: Pudendal cortical somatosensory evoked potentials. J Urol 1986;135:1216.
23.
Courtois FJ, Gonnaud PM, Charvier KF, Leriche A, Raymond DP: Sympathetic skin responses and psychogenic erections in spinal cord injured men. Spinal Cord 1998;36:125.
24.
Ertekin C, Ertekin N, Mutlu S, Almis S, Akcam A: Skin responses (SP) recorded from the extremities and genital regions in normal and impotent subjects. Acta Neurol Scand 1987; 76:28.
25.
Blaivas JG: Urodynamic procedure recommendations of the Urodynamic Society. I. Procedures that should be available for routine practice. Neurourol Urodyn 1982;1:51.
26.
Rossier AB, Fam BA: 5–Microtransducer catheter in evaluation of neurogenic bladder dysfunction. Urology 1986;17:371.
27.
Maytom MC, Derry FA, Dinsmore WW, Glass CA, Smith MD, Orr M, Osterloh IH: A two–part pilot study of sildenafil (Viagra™) in men with erectile dysfunction caused by spinal cord injury. Spinal Cord 1999;37:110–116.
28.
Giuliano F, Hulting C, El Masry WS, Smith MD, Osterloh ICH, Orr M, Maytom M: Randomized trial of sildenafil for the treatment of erectile dysfunction in spinal cord injury. Ann Neurol 1999;46:15–21.
29.
Courtois FJ, Macdougall JC, Sachs BD: Erectile mechanism in paraplegia. Physiol Behav 1993;53(4):721–726.
30.
Root WS, Bard P: The mediation of feline erection through sympathetic pathways with some remarks on sexual behavior after deafferentation of the genitalia. Am J Physiol 1947;151:80–90.
31.
Cruz MR, Liu YC, Manzo J, Pacheco P, Sachs BD: Peripheral nerves mediating penile erection in the rat. J Auton Nerv Syst 1999;76(1): 15–27.
32.
Semens JH, Longworthy OR: Observations on the neurophysiology of sexual function in the male cat. J Urol 1938;40:836–846.
33.
Dail WG, Walton G, Olmsted MP: Penile erection in the rat: Stimulation of the hypogastric nerve elicits increases in penile pressure after chronic interruption of the sacral parasympathetic outflow. J Auton Nerv Syst 1989;28(3): 251–257.
34.
De Groat WC, Steers WD: Autonomic regulation of the urinary bladder and sexual organs; in Loewy AD, Spyer KM (eds): Central Regulation of Autonomous Functions. New York, Oxford University Press, 1990, pp 310–333.
35.
Lowentritt BH, Scardino PT, Miles BJ, Orejuela FJ, Schatte EC, Slawin KM, Elliott SP, Kim ED: Sildenafil citrate after radical retropubic prostatectomy. J Urol 1999;162:1614– 1617.
36.
Morales A, Gingell C, Collins M, Wicker PA, Osterloh IH: Clinical safety of oral sildenafil citrate (Viagra™) in the treatment of erectile dysfunction. Int J Impot Res 1998;10:69–74.
2000
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