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Posttraumatic erectile potential of spinal cord injured men: How physiologic recordings supplement subjective reports
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Posttraumatic Erectile Potential of Spinal Cord Injured Men: How Physiologic Recordings Supplement Subjective Reports Frkdckique J. Courtois, PhD, Manon C. Go&et, BSc, Kathleen l? Charvier, MD, Albert Leriche, MD ABSTRACT. 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: 1268-72. Objective: To investigate by means of a neurophysiologic model the remaining erectile function in spinal cord injured men. Design: A nonrandomized control trial. Setting: A Referred Care Center. Subjects: Forty-seven spinal cord injured men and 7 noninjured controls. Intervention: The subject penile responseswere recorded by a penile strain gauge during two sessions-one to obtain baseline responses, and one with reflexogenic stimulation (masturbation) and psychogenic stimulation (film). Measures: Average tumescence, maximal tumescence, percentage rigidity, and duration of tumescence and rigidity. Results: Significant results were found for subjects with lower lesions using psychogenic stimulation as their optimal mode compared with reflexogenic stimulation as an alternate mode, and for subjects with higher lesions using reflexogenic stimulation as their optimal mode, compared with psychogenic stimulation as an alternate mode. The responses with optimal stimulation modes were comparable to those achieved by controls. Conclusion: The findings validate the neurophysiologic model of posttraumatic erectile potential as a function of the lesion type and stimulation source. The results were comparable to those of noninjured subjects; the potential for normal function is present and may be amenable to sexual rehabilitation or use in conjunction with new oral drug treatments for impotence. 0 1999 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation INCE THE DISCOVERY that pharmacologic agents such S as papaverine, phentolamine, prostaglandin (see Courtois’ for a review), alprostadil: and now sildenafiPm5can treat impotence, few studies have shown interest in assessing the posttraumatic sexual potential of spinal cord injured men. Earlier reports have nevertheless indicated that erectile function is possible for these men, especially those with higher From the DBpartment de sexologic, UniversitC du Quebec ?I Montrkxl (Dr. Courtok); the Institut de r&adaptation de Montr&l (Dr. Courtois); and the DCpartement de Psychologie, UniversitB Concordia (Ms. Goulet), Canada: and Hospices Civils de Lyon, Saint-Gtnis-Laval. France (Drs. Charvier, Leriche). Submitted for publication December 7, 1998. Accepted in revised form April 29, 1999. Supported by Fonds de la Recherche en Sam& du Quebec and Fond&ion And& SBn&cal, Quebec, Canada. The authors have chosen not to select a disclosure statement. Reprint requests to Fr6dtrique Courtois, PhD, D6partement de sexologic, Universitk du QuuCbec 51Mont&d, C.P. 8888, sum. centre ville, Montr&l, Qutbec H3C 3P8, Canada. 0 1999 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation 0003.9993/99/8010-5221$3.00/O
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lesions and incomplete lesions.6-19The results support the neural innervation of the male reproductive system, especially that of the sacral pathway mediating reflexogenic erection.20-22 In addition to showing maintenance of reflexogenic erection, earlier studies have shown that psychogenic erection is possible for subjects with lower lesions, although the data based on subjective reports were much more variable under this condition. Most authors6s14-19 reported from 12% to 44% maintenance of psychogenic erection in subjects with lower motor neuron (LMN) lesions, but a few authorss,9%11 reported more than 50% maintenance of psychogenic erection, and Comarr’O reported up to 83% maintenance of psychogenic erection in LMN subjects with incomplete lesions. Overall, the data therefore suggest that maintenance of psychogenic erection is possible for spinal cord injured men, but the occurence and stability of this response is still open to debate. Whether patients with lower lesions can consistently show psychogenic erection and whether the resulting response can be functional is not clear. The question, however, remains of interest, especially since the recent commercial distribution of sildenafil, a new oral treatment for impotence that requires minimal response to sexual stimulation to be effective.3-s The difficulty in assessingerectile capacity with subjective reports, as used in earlier studies, stems from several factors. In the first place, reports of psychogenic erection require that the individual be aware of this capacity. In a previous publication,23 we showed that spinal cord injured men underestimate their residual erectile potential, especially that related to psychogenic erection. This finding, along with our clinical experience,24 further revealed that many spinal cord injured men are not aware of psychogenic erectile function either because they have not experienced it since their injury or because they experienced psychogenic arousal in social situations where they were not visuaIly (or otherwise) paying attention to their genitals. Consequently, men lacking genital sensation or men lacking reflexogenic erection during masturbation often believe that they are impotent to any kind of stimulation. Knowing that psychogenic erection can anatomically be mediated by the thoracolumbar (TL) pathway originating from the Tll to L2 spinal segments, authors have argued that psychogenic erection was possible for subjects with lesions below these levels or lesions damaging the sacral-reflex pathway. Some authors, t4,15however, have argued that psychogenic erections in human subjects with reported complete lesions could be mediated by clinically undetected residual fibers originating from the sacral pathway. To resolve the issue, we first performed a series of controlled experiments on spinal animals to investigate penile responsesto both psychogenic and reflexogenic stimulation.25 Psychogenic stimulation was operationally defined by hypothalamic stimulation and reflexogenic stimulation by retraction of the penile sheath (a well-known procedure to elicit penile reflexes in rats). Animals were operated for destruction of the sacral pathway and the lesion was verified postmortem. As hypothesized, the results confirmed the hypothesis that psychogenic erection, defined by hypothalamic stimulation, was maintained in spinal animals with verified lesions to the sacral pathway.25
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The same hypotheses were then tested on humans with the specific aim at validating the neurophysiologic model of remaining sexual function after spinal cord injury. While few studies have used physiologic recordings to assessthe posttraumatic sexual function of spinal cord injured men,26-2g our studyz3used such recordings to compare subjective reports and physiologic recordings of erectile responses to psychogenic and reflexogenic stimulation in spinal cord injured men. The results confirmed the hypothesis and showed that up to 80% of men with lower lesions maintained psychogenic erection, while all subjects (100%) with higher lesions maintained reflexogenic erection. In the present study, we further investigated the posttraumatic sexual potential of spinal cord injured men, exploring the quality of the response as a function of the stimulation source and the lesion type. The responses assessedthe individual’s erection potential, his potential for sexual rehabilitation, and the functional quality of his erections. METHOD Subjects The neurophysiologic model of posttraumatic sexual function required that subjects be initially classified according to their potential for psychogenic or reflexogenic erection. Two initial groups were considered: lesions potentially sparing reflexogenic erection, and lesions potentially sparing psychogenic erection. Given the innervation of the male reproductive system-by a sacral (S2-S4) pathway responsible for reflexogenie erection and a thoracolumbar (Tl l-L2) pathway responsible for psychogenic erection-we subdivided subjects into those with lesions located above the TL pathway (expected to maintain reflexogenic erection) and those with lesions damaging the sacral pathway (expected to maintain psychogenic erection). Because the subjects were recruited from our clinical consultations, and because clinical practice shows that many patients have lesions directly located within the TL segments, a third group of subjects with TL lesions was considered. In contrast to this group, patients with cauda equina lesions (ie, LMN lesions) often presented complex lesions that could extend from the sacral segments up to the thoracic segments. Since such complex lesions prevented specific hypothesis regarding psychogenic or reflexogenic erectile potential, a separate group of cauda equina lesions was not considered in this study. Rather, subjects with cauda equina lesions limited to a destruction of the sacral pathway but sparing TL transmission were included in the sacral lesions group (since they shared the same hypothesis concerning remaining psychogenic erectile function). Originally, we considered subdividing the groups of subjects in terms of complete and incomplete lesions. However, clinical reality revealed that only the group with lesions above the TL pathway had a sufficient number of subjects with complete and incomplete lesions to allow such subdivision. Except for this group, the subjects were therefore included into single groups of lesions and the hypotheses were based on the maintenance of erectile responses to an optimal source of stimulation, as opposed to an alternate source of stimulation. The final sample consisted of five groups: 18 subjects with complete lesions above the TL pathway of erection (CA); 6 subjects with incomplete lesions above the TL pathway of erection (IA); 7 subjects with lesions located within the TL pathway (TL); 9 subjects with lesions damaging the sacral pathway (SA); and 7 noninjured control subjects (CO) to
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control for the effectiveness of the stimulation procedures in the laboratory condition. The subjects’ characteristics were generally equivalent across groups, with the age ranging from 18 to 60 years (average, 31 yrs). The SA group had a slightly older mean age (36 yrs) than the other groups and had slightly more tumors than traumatic injuries. Nevertheless, all subjects were compared to noninjured controls, whose average age was 32 years (ie, between the average ages of the different spinal injury groups). Procedure The project was submitted and accepted for ethics approval and was offered to patients recruited from our clinical consultations at the Rehabilitation Institute of Montreal (Canada) and Hopital Henry Gabrielle in Lyon (France). Interested patients were submitted to a clinical interview and a neurologic examination and were invited to undergo physiologic recordings of erectile response to psychogenic and reflexogenic stimulation. Clinical interview and neurologic examination. The detailed description of the clinical interview and neurologic examination has been described elsewhere.23 Briefly, the subjects were interviewed for perceived somatic and visceral functions, including erectile and ejaculatory responses to various stimulation conditions. The neurologic examination confirmed the lesion level and extent through evaluation of dermatomes and specific testing of four perineal (sacral) reflexes, namely the bulbocavemosus, bulbo-anal, cutaneousanal, and external anal reflexes.23 Physiologic recordings. After the neurologic examination, the subjects were scheduled for laboratory tests that recorded erectile responses to reflexogenic and psychogenic stimulation. The laboratory setting was a private room equipped with a bed and screen, a videocassette recorder, and electrophysiologic equipment. Upon arrival, the subject was assisted to transfer onto the bed and remove his pants and urological equipment, if any. A penile strain gauge was installed at the base of the subject’s penis. The Rigiscar? was then used (rather than the mercury strain gauge used in our previous study23) to measure both penile tumescence and penile rigidity. Once the subject was comfortably installed, the Rigiscan was turned on for 15 minutes and the subject was instructed to relax and not to stimulate himself as he was left alone in the laboratory room. This baseline trial served as a habituation period and allowed detumescence of any penile response that would have occurred reflexively during the installation of the subject. After the baseline period, the Rigiscan was turned off for 1 minute (to allow marking on the recording chart) and turned back on for 15 minutes, during which time the subject was left alone in the room and instructed to masturbate for the complete duration of the trial, whether or not erection occurred. The Rigiscan was then turned off for 1 minute or more (if the previous erection had not completely abated) and turned back on for a final 15minute period, during which the subject was asked to watch an erotic movie without masturbating or otherwise stimulating his genitals. Originally, separate sessions were planned for the reflexogenie (masturbation) and the psychogenic (film) stimulation session.However, travelling inconveniences made it difficult to require many sessions from the subjects. Both stimulation conditions were therefore tested in a single session, with masturbation being considered first because the lack of (or altered) sensation was thought to have less carryover effect on the following psychogenic erection than psychogenic stimulation would have had on subsequent reflexogenic erection. Arch
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RESULTS The data were analyzed for (1) average increase in penile tumescence, to assessthe individual’s actual erection potential, (2) maximal increase in penile tumescence, to provide a basis for sexual rehabilitation, (3) percentage rigidity, and (4) duration of both tumescence and rigidity, to explore the functional quality of the resulting erection. Statistical analysesused 2 X 4 analysisof variance (ANOVA) with one repeated factor (psychogenic and reflexogenic condition) and one independent factor (the AC, AI, TL, SA, and CO groups). Significant effects were further explored through comparisons using the Newman-Keuls procedure. Figure 1 illustrates the findings for average increase and maximal increase in penile circumference. Spinal cord injured men reached average increasesin penile circumference ranging from 2.4cm to 3.4cm and maximal values ranging from 3Scm to 4.5cm. These data were comparable to control subjects, who exhibited average and maximal values of 3.4cm and 3.5cm, respectively. Statistical analyses on average tumescence yielded a significant interaction between the stimulation and group condition (F(4, 42) = 14.58, p < .OOOl).Post-hoc comparisons exploring the differential effect between optimal and alternate mode of stimulation in each group of subjects further revealed that men with CA lesions (p < .Ol) achieved significantly higher increase in average tumescence with reflexogenic stimulation as an optimal mode than with psychogenic stimulation as an alternate mode of stimulation. Similarly, men with IA (p < .Ol) and TL (p < .Ol) lesions exhibited significantly higher increase in average tumescence with reflexogenic stimulation as an optimal mode than with psychogenic stimulation as an alternate mode. In contrast, men with SA lesions (p < .05) exhibited significantly higher increase in average tumescence using psychogenic stimulation as an optimal mode than with reflexogenie stimulation as an alternate mode. Men in the control
CA
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z co ;
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f 4.0 C 0.z 3,0 e 2,o e 5e 1,o 3 0,o
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Fig 1. (A) Average increases and (B) maximum increases in penile circumference with reflexogenic (m) and psychogenic (M) stimulation. Groups: CA, complete lesion above the dual pathway of erection; IA, incomplete lesion above the dual pathway of erection; TL, lesion to the thoracolumbar pathway of erection; SA, lesion to the sacral pathway of erection; CO, control subjects.
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Fig 2. Average rigidity genie; n , psychogenic).
TL Group obtained Groups
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co
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group (CO) obtained similar tumescence levels to both types of stimulation. Post-hoc analyses also revealed that the increase in penile tumescence obtained by SA subjects using psychogenic stimulation as an optimal mode of stimulation did not differ significantly from that of other spinal cord injured subjects using reflexogenic stimulation as an optimal mode or from noninjured controls using either mode of stimulation. Statistical analysis on maximal increase in penile tumescence similarly yielded a significant stimulation-by-group interaction (F(4,42) = 14.86, p < .OOOl)allowing further post-hoc analyses. These analyses revealed that men with CA, IA, and TL lesions (each withp < .Ol) achieved significantly higher levels of maximal tumescence with reflexogenic stimulation as an optimal mode of stimulation than with psychogenic stimulation as their alternate mode. In contrast, men with SA lesions and noninjured subjects (CO) showed similar levels of maximal tumescence in response to both types of stimulation. Concerning rigidity measures, the average rigidity obtained by spinal cord injured men using their optimal source of stimulation ranged from 43% to 49% rigidity (fig 2). Noninjured control subjects reached values of 50% to 57% rigidity. Statistical analyses again showed a significant stimulation-bygroup interaction (F(4, 42) = 10.89, p < .OOOl),and post-hoc analyses revealed that men with CA, IA, and TL lesions (each with p < .Ol) obtained significantly higher rigidity levels with reflexogenic stimulation as an optimal mode of stimulation than with psychogenic stimulation as an alternate mode of stimulation. In contrast, men in the SA group (p < .05) obtained better rigidity in response to psychogenic stimulation as an optimal mode than with reflexogenic stimulation as an alternate mode. Noninjured control subjects (CO) obtained erections of similar rigidity to both types of stimulation. Again, it was interesting to note from additional analyses that the rigidity level obtained by SA subjects using psychogenic stimulation (ie, their optimal mode) did not differ significantly from that of the other groups of injured subjects using reflexogenic stimulation (ie, optimal mode of stimulation) or from the control subjects using either mode of stimulation. Figure 3 shows the mean duration of tumescence and rigidity obtained by the different groups of subjects. All spinal cord injured men achieved tumescence and rigidity for 10 to 14 minutes (on a testing procedure of 15 minutes) with their optimal source of stimulation. Noninjured control subjects achieved tumescence and rigidity for 11 to 14 minutes. Statistical analyses on the data showed a significant interaction between the stimulation and the group conditions on the duration of tumescence (F(4, 42) = 18.10, p < .OOOl) and a
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and (B) rigidity
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significant interaction for the duration of rigidity (F(4, 42) = 23.92, p < .OOOl).Post-hoc analyses revealed that men with CA, IA, and TL lesions (each with p < $01) maintained a tumescence and rigidity for a significantly longer period of time using reflexogenic stimulation as an optimal mode of stimulation than with psychogenic stimulation as an alternate mode. In contrast, men with SA lesions (p < .Ol) maintained significantly longer tumescence and rigidity with psychogenic stimulation as their optimal mode than with reflexogenic stimulation as an alternate mode. Men in the control (CO) group exhibited a similar duration of tumescence and rigidity in response to both types of stimulation. DISCUSSION The results from this study clearly support the neurophysiologic model of posttraumatic sexual function in spinal cord injured men. The results thereby show that when the appropriate source of stimulation is used for the lesion type, the resulting tumescence and rigidity are equivalent among spinal cord injured subjects and equivalent to noninjured controls. Furthermore, the duration of the responses (11 to 13 minutes) exhibited by all subjects are within a reasonable range for intercourse. These results generalize previous findings6~8~9~18~19 and specifically show that men with lower lesions can maintain a psychogenic erectile capacity comparable to the reflexogenic capacity maintained by men with higher lesions. Interestingly, the findings on maximal tumescence further show that spinal cord injured men can achieve peaks of tumescence (ie, 3.5cm) identical to the average values (3Scm) exhibited by noninjured controls. These findings indicate that the neurologic potential for normal function is definitely present in these patients (at least as peaks). The initial erectile potential could therefore be used in sexual rehabilitation programs aimed at maximizing its effect, in a way similar to the use of the individual’s initial muscular strength in a general rehabilitation program to design physiotherapy aimed at maximizing its potential. The clinical application of these data therefore suggest that men with spinal cord injury should be educated about their natural posttraumatic function, using optimal stimulation, and be encouraged to experiment with this potential in natural environments. Findings in subjects with incomplete lesions further indicate that optimal stimulation should always be encouraged, and alternate stimulation be discouraged, even if incomplete lesions would have been expected to respond to alternate stimulation. The potential application for clinical practice includes the use of physiologic recordings to assess the posttraumatic sexual potential of paraplegic and tetraplegic individuals. Few studies
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have used such recordings in rehabilitation settings. Sipski and colleagues26 and Whipple and Komisaruk,27 however, have stressed the clinical value of identifying remaining sexual function in spinal cord injured women and have suggested alternative routes to neural transmission of sexual sensations. These studies closed an important gap in the study of spinal cord injured women, and they further revealed applications of physiologic recordings in rehabilitation settings. Along with such applications in our male population, these studies show that it is indeed possible to reassure patients on their natural potential, provide patients with some control over their intimate life, inform clinicians on possible differential diagnoses between purely organic and partially psychogenic erectile dysfunction in spinal cord injured patients, and generally examine unexpected or underestimated sexual capacities (eg, maximal erectile capacity). Furthermore, objective assessmentof posttraumatic sexual function may serve new palliative treatments, such as sildenafil, which requires initial response to sexual stimulation to be effective. Since sildenafil does not directly trigger erection but proceeds by inhibiting the degradation of the molecules responsible for the erection5 new pharmacologic treatments can only benefit from research on posttraumatic erectile function of spinal cord injured men and from sexual rehabilitation programs aimed at maximizing initial responses to sexual stimulation. CONCLUSION The results from this study confirm the neurophysiologic model of posttraumatic erectile function in spinal cord injured men. Men with lower lesion maintain posttraumatic potential using psychogenic stimulation comparable to that of men with higher lesion using reflexogenic stimulation, and they also have a remaining capacity in all casescomparable to that obtained by noninjured control subjects. Data on maximal tumescence reveals that sexual rehabilitation may facilitate normal erectile function in this client population or could be used in conjunction with new oral treatments for impotence (eg, sildenafil) to promote functional responses. These data, although cause for optimism, must be tempered by the understanding that they were obtained from a laboratory setting. Rigidity findings obtained in spinal cord injured subjects failed to reach the 60% value suggested as functional by the Rigiscan literature, and patients in clinical practice report difficulties with the maintenance of rigidity, especially during penetration. Nevertheless, the findings objectify the neurologic potential of individuals, a potential that may be amenable to sexual rehabilitation programs aimed at maximizing the patient’s initially recorded tumescence and rigidity. Arch
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Acknowledgments: The authors thank Serge Raymond and Catherine Mathieu for their valuable collaboration on this report. References 1. Courtois F, Charvier K, Belley C, Leriche A, Monet F, Leduc B, et al. Les injections intracaverneuses et l’approche sexologique aupres des hommes parapltgiques et tetraplegiques. Revue Sexologique 1995;3:69-89. - - 2. Linet 01. Ogrinc FG. Efficacv and safetv of intracavernosal alprostadil inmen with erectile dysfunction. The Alprostadil Study Group. N Engl J Med 1996;334:873-7. 3. Boolell M, Gepi-Attee S, Gingell JC, Allen MJ. Sildenafil, a novel effective oral therapy for male erectile dysfunction. Br J Urol 1996;78:257-61. 4. 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 1998:338:1397-404. 5. Morales A, Gingell C, Collins M, Wickers PA, Osterloh IH. Clinical safety of oral sildenafil citrate (Viagra) in the treatment of erectile dysfunction, Int J Impotence Res 1998;10:69-74. 6. Bors E, Comarr AE. Neurological disturbances of sexual function with special reference to 529 patients with spinal cord injury. Urol Surv 1960;10:191-222. I. Cibeira JB. Some conclusions on a study of 365 patients with svinal cord lesions. Paravleeia 1970:7:249-54. 8. dhapelle PA, Durand >, kacert P. Penile erection following complete spinal cord injury in man. Br J Urol 1980;52:216-9. 9. Comarr AE. Sexual function among patients with spinal cord injury. Urol Int 1970;25:134-68. 10. Comarr AE. Sexual function in patients with spinal cord injury. In: Pierce D, Nickel VN, editors. The total care of spinal cord injuries. Boston (MA): Little Brown; 1977. p 171-80. 11. Fitzpatrick WF. Sexual function in the paraplegic patient. Arch Phys Med Rehabil 1974;55:221-7. 12. Jochheim K-A, Wahle H. A study on sexual function in 56 male patients with complete irreversible lesions of the spinal cord and cauda equina. Paraplegia 1970;8: 166-72. 13. Larsen E, Hejgaard N. Sexual dysfunction after spinal cord or cauda equina lesions. Paraplegia 1984;22:66-74. 14. Munro D, Home H, Paul1 DP. The effect of injury to the spinal cord and cauda equina on the sexual potency of men. N Engl J Med 1948;239:903-11.
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15. Talbot HS. A report on sexual function in paraplegics. J Urol 1949;61:265-70. 16. Talbot HS. Sexual function in paraplegia. J Urol 1955;73:91-100. 17. Taylor TKF, Coolican MJR. Injuries of the corms medullaris. Paraplegia 1988;26:393-400. 18. Tsuji I, Nakajima F, Morimoto J, Nounaka Y. The sexual function in patients with spinal cord injury. Urol Int 1961;12:270-80. 19. Zeitlin AB, Cottrell TL, Lloyd FA. Sexology of the paraplegic male. Fertil Sterill957;8:337-44. 20. Higgins G. Sexual response in spinal cord injured adults: a review of the literature. Arch Sex Behav 1979;8: 173-96. 21. Tarabulcy E. Sexual function in the normal and in the paraplegic. Paraplegia 1972;10:201-8. 22. Yarkony GM. Enhancement of sexual function and fertility in spinal cord-injured males [review]. Am J Phys Med Rehab 1990;69:81-7. 23. Courtois FJ, Charvier KF, Leriche A, Raymond DP. Sexual function in spinal cord injured men. I. Assessing sexual capability. Paraplegia 1993;31:771-84. 24. Courtois FJ, Charvier KF, Leriche A, Raymond DP, Eyssette M. Clinical approach to erectile dysfunction in spinal cord injured men. A review of clinical and experimental data. Paraplegia 1995;33:628-35. 25. Courtois FJ, Macdougall JC, Sachs BD. Erectile mechanism in paraplegia. Physiol Behav 1993;53:721-6. 26. Sipski ML, Alexander CJ, Rosen RC. Orgasm in women with spinal cord injuries: a laboratory based assessment. Arch Phys Med Rehabil 1995;76:1097-102. 27. Whipple B, Komisaruk BR. Sexuality and women with complete spinal cord injury. Spinal Cord 1997;35: 136-8. 28. Lamid S. Nocturnal penile tumescence studies in spinal cord injured males. Paraplegia 1985;26-31. 29. Kennedy S, Over R. Psychophysiological assessment of male sexual arousal following spinal cord injury. Arch Sex Behav 1990;19:15-27. Supplier a. Timm Medical Technologies, 6541 Cilg West Parkway, Eden Prairie, MN 55344.
Posttraumatic Erectile Potential of Spinal Cord Injured Men: How Physiologic Recordings Supplement Subjective Reports Frkdckique J. Courtois, PhD, Manon C. Go&et, BSc, Kathleen l? Charvier, MD, Albert Leriche, MD ABSTRACT. 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: 1268-72. Objective: To investigate by means of a neurophysiologic model the remaining erectile function in spinal cord injured men. Design: A nonrandomized control trial. Setting: A Referred Care Center. Subjects: Forty-seven spinal cord injured men and 7 noninjured controls. Intervention: The subject penile responseswere recorded by a penile strain gauge during two sessions-one to obtain baseline responses, and one with reflexogenic stimulation (masturbation) and psychogenic stimulation (film). Measures: Average tumescence, maximal tumescence, percentage rigidity, and duration of tumescence and rigidity. Results: Significant results were found for subjects with lower lesions using psychogenic stimulation as their optimal mode compared with reflexogenic stimulation as an alternate mode, and for subjects with higher lesions using reflexogenic stimulation as their optimal mode, compared with psychogenic stimulation as an alternate mode. The responses with optimal stimulation modes were comparable to those achieved by controls. Conclusion: The findings validate the neurophysiologic model of posttraumatic erectile potential as a function of the lesion type and stimulation source. The results were comparable to those of noninjured subjects; the potential for normal function is present and may be amenable to sexual rehabilitation or use in conjunction with new oral drug treatments for impotence. 0 1999 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation INCE THE DISCOVERY that pharmacologic agents such S as papaverine, phentolamine, prostaglandin (see Courtois’ for a review), alprostadil: and now sildenafiPm5can treat impotence, few studies have shown interest in assessing the posttraumatic sexual potential of spinal cord injured men. Earlier reports have nevertheless indicated that erectile function is possible for these men, especially those with higher From the DBpartment de sexologic, UniversitC du Quebec ?I Montrkxl (Dr. Courtok); the Institut de r&adaptation de Montr&l (Dr. Courtois); and the DCpartement de Psychologie, UniversitB Concordia (Ms. Goulet), Canada: and Hospices Civils de Lyon, Saint-Gtnis-Laval. France (Drs. Charvier, Leriche). Submitted for publication December 7, 1998. Accepted in revised form April 29, 1999. Supported by Fonds de la Recherche en Sam& du Quebec and Fond&ion And& SBn&cal, Quebec, Canada. The authors have chosen not to select a disclosure statement. Reprint requests to Fr6dtrique Courtois, PhD, D6partement de sexologic, Universitk du QuuCbec 51Mont&d, C.P. 8888, sum. centre ville, Montr&l, Qutbec H3C 3P8, Canada. 0 1999 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation 0003.9993/99/8010-5221$3.00/O
Arch
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Vol 80, October
1999
lesions and incomplete lesions.6-19The results support the neural innervation of the male reproductive system, especially that of the sacral pathway mediating reflexogenic erection.20-22 In addition to showing maintenance of reflexogenic erection, earlier studies have shown that psychogenic erection is possible for subjects with lower lesions, although the data based on subjective reports were much more variable under this condition. Most authors6s14-19 reported from 12% to 44% maintenance of psychogenic erection in subjects with lower motor neuron (LMN) lesions, but a few authorss,9%11 reported more than 50% maintenance of psychogenic erection, and Comarr’O reported up to 83% maintenance of psychogenic erection in LMN subjects with incomplete lesions. Overall, the data therefore suggest that maintenance of psychogenic erection is possible for spinal cord injured men, but the occurence and stability of this response is still open to debate. Whether patients with lower lesions can consistently show psychogenic erection and whether the resulting response can be functional is not clear. The question, however, remains of interest, especially since the recent commercial distribution of sildenafil, a new oral treatment for impotence that requires minimal response to sexual stimulation to be effective.3-s The difficulty in assessingerectile capacity with subjective reports, as used in earlier studies, stems from several factors. In the first place, reports of psychogenic erection require that the individual be aware of this capacity. In a previous publication,23 we showed that spinal cord injured men underestimate their residual erectile potential, especially that related to psychogenic erection. This finding, along with our clinical experience,24 further revealed that many spinal cord injured men are not aware of psychogenic erectile function either because they have not experienced it since their injury or because they experienced psychogenic arousal in social situations where they were not visuaIly (or otherwise) paying attention to their genitals. Consequently, men lacking genital sensation or men lacking reflexogenic erection during masturbation often believe that they are impotent to any kind of stimulation. Knowing that psychogenic erection can anatomically be mediated by the thoracolumbar (TL) pathway originating from the Tll to L2 spinal segments, authors have argued that psychogenic erection was possible for subjects with lesions below these levels or lesions damaging the sacral-reflex pathway. Some authors, t4,15however, have argued that psychogenic erections in human subjects with reported complete lesions could be mediated by clinically undetected residual fibers originating from the sacral pathway. To resolve the issue, we first performed a series of controlled experiments on spinal animals to investigate penile responsesto both psychogenic and reflexogenic stimulation.25 Psychogenic stimulation was operationally defined by hypothalamic stimulation and reflexogenic stimulation by retraction of the penile sheath (a well-known procedure to elicit penile reflexes in rats). Animals were operated for destruction of the sacral pathway and the lesion was verified postmortem. As hypothesized, the results confirmed the hypothesis that psychogenic erection, defined by hypothalamic stimulation, was maintained in spinal animals with verified lesions to the sacral pathway.25
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The same hypotheses were then tested on humans with the specific aim at validating the neurophysiologic model of remaining sexual function after spinal cord injury. While few studies have used physiologic recordings to assessthe posttraumatic sexual function of spinal cord injured men,26-2g our studyz3used such recordings to compare subjective reports and physiologic recordings of erectile responses to psychogenic and reflexogenic stimulation in spinal cord injured men. The results confirmed the hypothesis and showed that up to 80% of men with lower lesions maintained psychogenic erection, while all subjects (100%) with higher lesions maintained reflexogenic erection. In the present study, we further investigated the posttraumatic sexual potential of spinal cord injured men, exploring the quality of the response as a function of the stimulation source and the lesion type. The responses assessedthe individual’s erection potential, his potential for sexual rehabilitation, and the functional quality of his erections. METHOD Subjects The neurophysiologic model of posttraumatic sexual function required that subjects be initially classified according to their potential for psychogenic or reflexogenic erection. Two initial groups were considered: lesions potentially sparing reflexogenic erection, and lesions potentially sparing psychogenic erection. Given the innervation of the male reproductive system-by a sacral (S2-S4) pathway responsible for reflexogenie erection and a thoracolumbar (Tl l-L2) pathway responsible for psychogenic erection-we subdivided subjects into those with lesions located above the TL pathway (expected to maintain reflexogenic erection) and those with lesions damaging the sacral pathway (expected to maintain psychogenic erection). Because the subjects were recruited from our clinical consultations, and because clinical practice shows that many patients have lesions directly located within the TL segments, a third group of subjects with TL lesions was considered. In contrast to this group, patients with cauda equina lesions (ie, LMN lesions) often presented complex lesions that could extend from the sacral segments up to the thoracic segments. Since such complex lesions prevented specific hypothesis regarding psychogenic or reflexogenic erectile potential, a separate group of cauda equina lesions was not considered in this study. Rather, subjects with cauda equina lesions limited to a destruction of the sacral pathway but sparing TL transmission were included in the sacral lesions group (since they shared the same hypothesis concerning remaining psychogenic erectile function). Originally, we considered subdividing the groups of subjects in terms of complete and incomplete lesions. However, clinical reality revealed that only the group with lesions above the TL pathway had a sufficient number of subjects with complete and incomplete lesions to allow such subdivision. Except for this group, the subjects were therefore included into single groups of lesions and the hypotheses were based on the maintenance of erectile responses to an optimal source of stimulation, as opposed to an alternate source of stimulation. The final sample consisted of five groups: 18 subjects with complete lesions above the TL pathway of erection (CA); 6 subjects with incomplete lesions above the TL pathway of erection (IA); 7 subjects with lesions located within the TL pathway (TL); 9 subjects with lesions damaging the sacral pathway (SA); and 7 noninjured control subjects (CO) to
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control for the effectiveness of the stimulation procedures in the laboratory condition. The subjects’ characteristics were generally equivalent across groups, with the age ranging from 18 to 60 years (average, 31 yrs). The SA group had a slightly older mean age (36 yrs) than the other groups and had slightly more tumors than traumatic injuries. Nevertheless, all subjects were compared to noninjured controls, whose average age was 32 years (ie, between the average ages of the different spinal injury groups). Procedure The project was submitted and accepted for ethics approval and was offered to patients recruited from our clinical consultations at the Rehabilitation Institute of Montreal (Canada) and Hopital Henry Gabrielle in Lyon (France). Interested patients were submitted to a clinical interview and a neurologic examination and were invited to undergo physiologic recordings of erectile response to psychogenic and reflexogenic stimulation. Clinical interview and neurologic examination. The detailed description of the clinical interview and neurologic examination has been described elsewhere.23 Briefly, the subjects were interviewed for perceived somatic and visceral functions, including erectile and ejaculatory responses to various stimulation conditions. The neurologic examination confirmed the lesion level and extent through evaluation of dermatomes and specific testing of four perineal (sacral) reflexes, namely the bulbocavemosus, bulbo-anal, cutaneousanal, and external anal reflexes.23 Physiologic recordings. After the neurologic examination, the subjects were scheduled for laboratory tests that recorded erectile responses to reflexogenic and psychogenic stimulation. The laboratory setting was a private room equipped with a bed and screen, a videocassette recorder, and electrophysiologic equipment. Upon arrival, the subject was assisted to transfer onto the bed and remove his pants and urological equipment, if any. A penile strain gauge was installed at the base of the subject’s penis. The Rigiscar? was then used (rather than the mercury strain gauge used in our previous study23) to measure both penile tumescence and penile rigidity. Once the subject was comfortably installed, the Rigiscan was turned on for 15 minutes and the subject was instructed to relax and not to stimulate himself as he was left alone in the laboratory room. This baseline trial served as a habituation period and allowed detumescence of any penile response that would have occurred reflexively during the installation of the subject. After the baseline period, the Rigiscan was turned off for 1 minute (to allow marking on the recording chart) and turned back on for 15 minutes, during which time the subject was left alone in the room and instructed to masturbate for the complete duration of the trial, whether or not erection occurred. The Rigiscan was then turned off for 1 minute or more (if the previous erection had not completely abated) and turned back on for a final 15minute period, during which the subject was asked to watch an erotic movie without masturbating or otherwise stimulating his genitals. Originally, separate sessions were planned for the reflexogenie (masturbation) and the psychogenic (film) stimulation session.However, travelling inconveniences made it difficult to require many sessions from the subjects. Both stimulation conditions were therefore tested in a single session, with masturbation being considered first because the lack of (or altered) sensation was thought to have less carryover effect on the following psychogenic erection than psychogenic stimulation would have had on subsequent reflexogenic erection. Arch
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RESULTS The data were analyzed for (1) average increase in penile tumescence, to assessthe individual’s actual erection potential, (2) maximal increase in penile tumescence, to provide a basis for sexual rehabilitation, (3) percentage rigidity, and (4) duration of both tumescence and rigidity, to explore the functional quality of the resulting erection. Statistical analysesused 2 X 4 analysisof variance (ANOVA) with one repeated factor (psychogenic and reflexogenic condition) and one independent factor (the AC, AI, TL, SA, and CO groups). Significant effects were further explored through comparisons using the Newman-Keuls procedure. Figure 1 illustrates the findings for average increase and maximal increase in penile circumference. Spinal cord injured men reached average increasesin penile circumference ranging from 2.4cm to 3.4cm and maximal values ranging from 3Scm to 4.5cm. These data were comparable to control subjects, who exhibited average and maximal values of 3.4cm and 3.5cm, respectively. Statistical analyses on average tumescence yielded a significant interaction between the stimulation and group condition (F(4, 42) = 14.58, p < .OOOl).Post-hoc comparisons exploring the differential effect between optimal and alternate mode of stimulation in each group of subjects further revealed that men with CA lesions (p < .Ol) achieved significantly higher increase in average tumescence with reflexogenic stimulation as an optimal mode than with psychogenic stimulation as an alternate mode of stimulation. Similarly, men with IA (p < .Ol) and TL (p < .Ol) lesions exhibited significantly higher increase in average tumescence with reflexogenic stimulation as an optimal mode than with psychogenic stimulation as an alternate mode. In contrast, men with SA lesions (p < .05) exhibited significantly higher increase in average tumescence using psychogenic stimulation as an optimal mode than with reflexogenie stimulation as an alternate mode. Men in the control
CA
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co
z co ;
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f 4.0 C 0.z 3,0 e 2,o e 5e 1,o 3 0,o
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Fig 1. (A) Average increases and (B) maximum increases in penile circumference with reflexogenic (m) and psychogenic (M) stimulation. Groups: CA, complete lesion above the dual pathway of erection; IA, incomplete lesion above the dual pathway of erection; TL, lesion to the thoracolumbar pathway of erection; SA, lesion to the sacral pathway of erection; CO, control subjects.
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g 0) g 5 !? t
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Fig 2. Average rigidity genie; n , psychogenic).
TL Group obtained Groups
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with optimal stimulation as defined for figure 1.
co
(R’, reflexo-
group (CO) obtained similar tumescence levels to both types of stimulation. Post-hoc analyses also revealed that the increase in penile tumescence obtained by SA subjects using psychogenic stimulation as an optimal mode of stimulation did not differ significantly from that of other spinal cord injured subjects using reflexogenic stimulation as an optimal mode or from noninjured controls using either mode of stimulation. Statistical analysis on maximal increase in penile tumescence similarly yielded a significant stimulation-by-group interaction (F(4,42) = 14.86, p < .OOOl)allowing further post-hoc analyses. These analyses revealed that men with CA, IA, and TL lesions (each withp < .Ol) achieved significantly higher levels of maximal tumescence with reflexogenic stimulation as an optimal mode of stimulation than with psychogenic stimulation as their alternate mode. In contrast, men with SA lesions and noninjured subjects (CO) showed similar levels of maximal tumescence in response to both types of stimulation. Concerning rigidity measures, the average rigidity obtained by spinal cord injured men using their optimal source of stimulation ranged from 43% to 49% rigidity (fig 2). Noninjured control subjects reached values of 50% to 57% rigidity. Statistical analyses again showed a significant stimulation-bygroup interaction (F(4, 42) = 10.89, p < .OOOl),and post-hoc analyses revealed that men with CA, IA, and TL lesions (each with p < .Ol) obtained significantly higher rigidity levels with reflexogenic stimulation as an optimal mode of stimulation than with psychogenic stimulation as an alternate mode of stimulation. In contrast, men in the SA group (p < .05) obtained better rigidity in response to psychogenic stimulation as an optimal mode than with reflexogenic stimulation as an alternate mode. Noninjured control subjects (CO) obtained erections of similar rigidity to both types of stimulation. Again, it was interesting to note from additional analyses that the rigidity level obtained by SA subjects using psychogenic stimulation (ie, their optimal mode) did not differ significantly from that of the other groups of injured subjects using reflexogenic stimulation (ie, optimal mode of stimulation) or from the control subjects using either mode of stimulation. Figure 3 shows the mean duration of tumescence and rigidity obtained by the different groups of subjects. All spinal cord injured men achieved tumescence and rigidity for 10 to 14 minutes (on a testing procedure of 15 minutes) with their optimal source of stimulation. Noninjured control subjects achieved tumescence and rigidity for 11 to 14 minutes. Statistical analyses on the data showed a significant interaction between the stimulation and the group conditions on the duration of tumescence (F(4, 42) = 18.10, p < .OOOl) and a
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Pig 3. Average figure 1. -
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and (B) rigidity
after
significant interaction for the duration of rigidity (F(4, 42) = 23.92, p < .OOOl).Post-hoc analyses revealed that men with CA, IA, and TL lesions (each with p < $01) maintained a tumescence and rigidity for a significantly longer period of time using reflexogenic stimulation as an optimal mode of stimulation than with psychogenic stimulation as an alternate mode. In contrast, men with SA lesions (p < .Ol) maintained significantly longer tumescence and rigidity with psychogenic stimulation as their optimal mode than with reflexogenic stimulation as an alternate mode. Men in the control (CO) group exhibited a similar duration of tumescence and rigidity in response to both types of stimulation. DISCUSSION The results from this study clearly support the neurophysiologic model of posttraumatic sexual function in spinal cord injured men. The results thereby show that when the appropriate source of stimulation is used for the lesion type, the resulting tumescence and rigidity are equivalent among spinal cord injured subjects and equivalent to noninjured controls. Furthermore, the duration of the responses (11 to 13 minutes) exhibited by all subjects are within a reasonable range for intercourse. These results generalize previous findings6~8~9~18~19 and specifically show that men with lower lesions can maintain a psychogenic erectile capacity comparable to the reflexogenic capacity maintained by men with higher lesions. Interestingly, the findings on maximal tumescence further show that spinal cord injured men can achieve peaks of tumescence (ie, 3.5cm) identical to the average values (3Scm) exhibited by noninjured controls. These findings indicate that the neurologic potential for normal function is definitely present in these patients (at least as peaks). The initial erectile potential could therefore be used in sexual rehabilitation programs aimed at maximizing its effect, in a way similar to the use of the individual’s initial muscular strength in a general rehabilitation program to design physiotherapy aimed at maximizing its potential. The clinical application of these data therefore suggest that men with spinal cord injury should be educated about their natural posttraumatic function, using optimal stimulation, and be encouraged to experiment with this potential in natural environments. Findings in subjects with incomplete lesions further indicate that optimal stimulation should always be encouraged, and alternate stimulation be discouraged, even if incomplete lesions would have been expected to respond to alternate stimulation. The potential application for clinical practice includes the use of physiologic recordings to assess the posttraumatic sexual potential of paraplegic and tetraplegic individuals. Few studies
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have used such recordings in rehabilitation settings. Sipski and colleagues26 and Whipple and Komisaruk,27 however, have stressed the clinical value of identifying remaining sexual function in spinal cord injured women and have suggested alternative routes to neural transmission of sexual sensations. These studies closed an important gap in the study of spinal cord injured women, and they further revealed applications of physiologic recordings in rehabilitation settings. Along with such applications in our male population, these studies show that it is indeed possible to reassure patients on their natural potential, provide patients with some control over their intimate life, inform clinicians on possible differential diagnoses between purely organic and partially psychogenic erectile dysfunction in spinal cord injured patients, and generally examine unexpected or underestimated sexual capacities (eg, maximal erectile capacity). Furthermore, objective assessmentof posttraumatic sexual function may serve new palliative treatments, such as sildenafil, which requires initial response to sexual stimulation to be effective. Since sildenafil does not directly trigger erection but proceeds by inhibiting the degradation of the molecules responsible for the erection5 new pharmacologic treatments can only benefit from research on posttraumatic erectile function of spinal cord injured men and from sexual rehabilitation programs aimed at maximizing initial responses to sexual stimulation. CONCLUSION The results from this study confirm the neurophysiologic model of posttraumatic erectile function in spinal cord injured men. Men with lower lesion maintain posttraumatic potential using psychogenic stimulation comparable to that of men with higher lesion using reflexogenic stimulation, and they also have a remaining capacity in all casescomparable to that obtained by noninjured control subjects. Data on maximal tumescence reveals that sexual rehabilitation may facilitate normal erectile function in this client population or could be used in conjunction with new oral treatments for impotence (eg, sildenafil) to promote functional responses. These data, although cause for optimism, must be tempered by the understanding that they were obtained from a laboratory setting. Rigidity findings obtained in spinal cord injured subjects failed to reach the 60% value suggested as functional by the Rigiscan literature, and patients in clinical practice report difficulties with the maintenance of rigidity, especially during penetration. Nevertheless, the findings objectify the neurologic potential of individuals, a potential that may be amenable to sexual rehabilitation programs aimed at maximizing the patient’s initially recorded tumescence and rigidity. Arch
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Acknowledgments: The authors thank Serge Raymond and Catherine Mathieu for their valuable collaboration on this report. References 1. Courtois F, Charvier K, Belley C, Leriche A, Monet F, Leduc B, et al. Les injections intracaverneuses et l’approche sexologique aupres des hommes parapltgiques et tetraplegiques. Revue Sexologique 1995;3:69-89. - - 2. Linet 01. Ogrinc FG. Efficacv and safetv of intracavernosal alprostadil inmen with erectile dysfunction. The Alprostadil Study Group. N Engl J Med 1996;334:873-7. 3. Boolell M, Gepi-Attee S, Gingell JC, Allen MJ. Sildenafil, a novel effective oral therapy for male erectile dysfunction. Br J Urol 1996;78:257-61. 4. 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 1998:338:1397-404. 5. Morales A, Gingell C, Collins M, Wickers PA, Osterloh IH. Clinical safety of oral sildenafil citrate (Viagra) in the treatment of erectile dysfunction, Int J Impotence Res 1998;10:69-74. 6. Bors E, Comarr AE. Neurological disturbances of sexual function with special reference to 529 patients with spinal cord injury. Urol Surv 1960;10:191-222. I. Cibeira JB. Some conclusions on a study of 365 patients with svinal cord lesions. Paravleeia 1970:7:249-54. 8. dhapelle PA, Durand >, kacert P. Penile erection following complete spinal cord injury in man. Br J Urol 1980;52:216-9. 9. Comarr AE. Sexual function among patients with spinal cord injury. Urol Int 1970;25:134-68. 10. Comarr AE. Sexual function in patients with spinal cord injury. In: Pierce D, Nickel VN, editors. The total care of spinal cord injuries. Boston (MA): Little Brown; 1977. p 171-80. 11. Fitzpatrick WF. Sexual function in the paraplegic patient. Arch Phys Med Rehabil 1974;55:221-7. 12. Jochheim K-A, Wahle H. A study on sexual function in 56 male patients with complete irreversible lesions of the spinal cord and cauda equina. Paraplegia 1970;8: 166-72. 13. Larsen E, Hejgaard N. Sexual dysfunction after spinal cord or cauda equina lesions. Paraplegia 1984;22:66-74. 14. Munro D, Home H, Paul1 DP. The effect of injury to the spinal cord and cauda equina on the sexual potency of men. N Engl J Med 1948;239:903-11.
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15. Talbot HS. A report on sexual function in paraplegics. J Urol 1949;61:265-70. 16. Talbot HS. Sexual function in paraplegia. J Urol 1955;73:91-100. 17. Taylor TKF, Coolican MJR. Injuries of the corms medullaris. Paraplegia 1988;26:393-400. 18. Tsuji I, Nakajima F, Morimoto J, Nounaka Y. The sexual function in patients with spinal cord injury. Urol Int 1961;12:270-80. 19. Zeitlin AB, Cottrell TL, Lloyd FA. Sexology of the paraplegic male. Fertil Sterill957;8:337-44. 20. Higgins G. Sexual response in spinal cord injured adults: a review of the literature. Arch Sex Behav 1979;8: 173-96. 21. Tarabulcy E. Sexual function in the normal and in the paraplegic. Paraplegia 1972;10:201-8. 22. Yarkony GM. Enhancement of sexual function and fertility in spinal cord-injured males [review]. Am J Phys Med Rehab 1990;69:81-7. 23. Courtois FJ, Charvier KF, Leriche A, Raymond DP. Sexual function in spinal cord injured men. I. Assessing sexual capability. Paraplegia 1993;31:771-84. 24. Courtois FJ, Charvier KF, Leriche A, Raymond DP, Eyssette M. Clinical approach to erectile dysfunction in spinal cord injured men. A review of clinical and experimental data. Paraplegia 1995;33:628-35. 25. Courtois FJ, Macdougall JC, Sachs BD. Erectile mechanism in paraplegia. Physiol Behav 1993;53:721-6. 26. Sipski ML, Alexander CJ, Rosen RC. Orgasm in women with spinal cord injuries: a laboratory based assessment. Arch Phys Med Rehabil 1995;76:1097-102. 27. Whipple B, Komisaruk BR. Sexuality and women with complete spinal cord injury. Spinal Cord 1997;35: 136-8. 28. Lamid S. Nocturnal penile tumescence studies in spinal cord injured males. Paraplegia 1985;26-31. 29. Kennedy S, Over R. Psychophysiological assessment of male sexual arousal following spinal cord injury. Arch Sex Behav 1990;19:15-27. Supplier a. Timm Medical Technologies, 6541 Cilg West Parkway, Eden Prairie, MN 55344.