Archives of Sexual Behavior, Vol. 19, No. 1, 1990
Psychophysiological Assessment of Male Sexual Arousal Following Spinal Cord Injury Simon Kennedy, M. Psych., 1 and Ray Over,
Ph.D. 1,2
Adult males with and without permanent damage to the spinal cord were contrasted in terms of their sexual responsiveness to erotic stimulation in film, spoken-text, and fantasy modes. Among the 16 spinal cord injured (SC1) men who were studied, several who had anticipated they would achieve erection failed to do so, whereas others demonstrated penile tumescence during erotic stimulation despite claiming they had lost the capacity for psychogenic erection. Self-report is thus not a valid index of sexual responsivity following spinal cord injury. Levels of tumescence varied across modalities of stimulation in the same manner for SCI and non-SCI men, and within each modality the two groups demonstrated similar rates o f buildup o f arousal over segments of stimulation. The SCI men without erections should not be considered asexual since their subjective arousal paralleled the subjective arousal of the non-SCI men and the SC1 men with erections. KEY WORDS: spinal cord injury; sexual arousal; penile tumescence;psychophysiological;erotic stimulation.
INTRODUCTION Reflexogenic penile erection resulting from tactile stimulation of the genitals, prostate, or urethra occurs through activation of a reflex arc at sacral segments 2 to 4 ( $ 2 - $4), whereas psychogenic erections (induced, for example, by erotic thoughts and fantasies) are initiated by input from the higher central nervous system to thoracolumbar segments T1 2 to L3 (see Burke and Murray, 1975; Karacan et al., 1983). Because these two systems do not func-
IDepartment of Psychology, La Trobe University, Bundoora, Australia 3083. 2To whom correspondence sh•uld be addressed.
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© 1990 Plenum Publishing Corporation
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tion independently, the effects that injury to the spinal cord has on the subsequent capacity of men to achieve erection can be difficult to predict. In general, if the afferent and efferent components of the $2-$4 and T12-L3 systems mediating erection remain intact, the capacity for tumescence is unlikely to be affected by spinal cord injury. At the other extreme, the capacifies for reflexogenic as well as psychogenic erection are lost if both systems become nonfunctional through injury to the spinal cord. The outcome is less certain when injury has resulted in partial rather than complete transsection of the spinal cord, and when not both the sacral and thoracolumbar systems are damaged. It might be anticipated that some men will be incapable of psychogenic but not reflexogenic erection, or vice versa. Further, since pertile erection is a graded response rather than an all-or-none phenornenon, the major consequence of injury to the spinal cord can be that erotic sfimulation will evoke less tumescence after injury than it did before. A number of investigators have sought to correlate the incidence of erection and the type of erection retained following spinal cord injury with lesion site, completeness of the lesion, and whether upper or lower motor neurons were affected. Erectile capabilities were identified in these surveys through reports given by spinal cord injured (SCI) men during interview. In a review covering this literature, Higgins (1979) noted that proportionately more SCI men with lesions above than below T12 reported having erections. Damage below T12 was more likely to result in loss of reflexogenic erection, whereas damage at or above T,2 had more advêrse consequences for psychogenic erection. More SCI men with upper than with lower motor neuron lesions reported erections, and reflexogenic erections were retained more often after upper than after lower motor neuron damage. Finally, proportionately fewer SCI men with incomplete lesions than with complete lesions reported loss of either psychogenic or reflexogenic erection. Not all the surveys reviewed by Higgins (1979) yielded the same pattern of results. In addition, incidence rates reported for seemingly similar groups of SCI men varied substantially. As an example, all men with lesions below T~2 in the sample studied by Fitzpatrick (1974) reported psychogenic erections following spinal cord injury, in contrast to 55% (Comarr, 1970), 42o70 (Hohmann, 1966), 30o70 (Talbot, 1949), 25070 (Talbot, 1955), and 200/0 (Bors and Comarr, 1960) in other studies. As noted by Griffith et al. (1973) and Higgins (1979), the variability in findings across studies may reflect problems associated with the use of survey methodologyù Allowance needs to be made for differences in such subject characteristics as age, marital status, period since injury, physical health, and opportunity for sexual experience. More important, the validity of the retrospective reports obtained from SCI men through interview is not known. Higgins (1979) pointed to the need for erectile capabilities to be assessed through physiological monitoring of sexual arousal.
Male Sexual Arousal Following Spinal Cord Injury
17
Lamid (1985) assessed nocturnal penile tumescence (NPT) across a sample of 24 SCI men (12 tetraplegics and 12 paraplegics) by recording changes in penile circumference during sleep. Tetraplegic men demonstrated a greater mean level of tumescence than paraplegic men, and they also had a longer mean duration of erectile episodes. N P T did not vary significantly with completeness of the spinal lesion, presence of bulbocavernosus reflex, presence of reflexogenic erection, or whether the person reported having experienced sexual dreams during sleep. Lamid nevertheless recommended that N P T measures be used to determine the course of treatment provided to SCI men; in his study, for example, SCI men who were more than 12 months postinjury and did not demonstrate N P T were advised to use a penile prosthesis. However, general concern had been expressed about the reliability and validity of N P T measures in the diagnosis of erectile dysfunction (see Conte, 1986; LoPiccolo and Stock, 1986). False negatives as well as false positives can be expected from classification based on N P T measures. The results reported by Lamid (1985) need to be replicated and supplemented before NPT scores can be used routinely to decide upon treatment for SCI men. In the present study penile tumescence is recorded while fully awake SCI men experience erotic stimulation in three modes of presentation (film, audiotape, fantasy). In order to assess the validity of retrospective reports of erectile capability, the tumescence measures were compared across two groups of SCI men. One group reported retention o f psychogenic erections subsequent to injury to the spinal cord, while the men in the other group claimed loss of psychogenic erections. For further comparative purposes, measures were also obtained for a group of men who had not suffered spinal cord injury (the non-SCI group). Tumenscence was recorded for each group across three modes of stimulation to determine whether there was specificity rather than generality in arousal. With the same erotic stimuli as those used in the present study, Julien and Over (1987) found with non-SCI men that film was more arousing than content-matched audiotape, which in turn was more arousing than content-matched fantasy. Within all three modes, the stimulus events were presented in sequence so that sexual arousal built up over time. By using these same materials in the present study it could be asked whether SCI men who experience erection and non-SCI men demonstrate similar patterns of temporal development and mode-specificity in their sexual arousal. Subjective sexual arousal was assessed in addition to penile tumescence. For non-SCI men tested under the stimulus conditions used in the present study, Julien and Over (1987) found correlations of + 0.27 between subjective and physiological measures for film, + 0.52 for audiotape, and + 0.76 for fantasy. The question of interest was not only whether similar relationships between subjective and physiological arousal would be found for the SCI men demonstrating tumescence, but whether SCI men who did not have
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erections would nevertheless report being subjectively aroused in rauch the same way as the other men in the study. There have been conflicting reports as to whether measures of subjective sexual arousal such as "cognitional eroticism" (Money, 1960), "libido sexualis" (Jochheim and Wahle, 1970), "sexual excitement" (Herman, 1950), "libido" (Talbot, 1955; Bors and Comarr, 1960), "sexual desire" (Tsuji et al., 1961), and sexual feelings (Hohmann, 1966; Weiss and Diamond, 1966) change as a consequence of spinal cord injury. Survey studies, most of which required men to compare their feelings before and after injury, have yielded conflicting findings. Subjective sexual arousal has been reported to decrease markedly (Herman, 1950; Jochheim and Wahle, 1970), decrease slightly (Money, 1960; Tsuji et al., 1961; Hohmann, 1966; Weiss and Diamond, 1966), or not change (Talbot, 1949, 1955; Bors and Comarr, 1960). In the present study the temporal development and mode-specificity of subjective sexual arousal as well as physiological sexual arousal is assessed for both SCI and non-SCI men.
METHOD Subjects
Sixteen men who had experienced traumafic spinal cord injury at least 1 year before were recruited into the study through the assistance of staff at the Spinal Injuries Unit of the Austin Hospital, Melbourne. The men who were approached to participate initially completed a general information questionnaire, which asked the person to report how frequently, if at all, he had experienced even partial penile erection following spinal cord injury through thoughts, fantasies, erotic books, magazines, and films. Subjects were selected on the basis of these reports so that 8 SCI men reporting psychogenic erection following injury could be contrasted with 8 SCI men who claimed that they no longer had this capability. Testing was carried out in a psychophysiological laboratory at La Trobe University. The SCI men ranged in age from 22 to 47 years (median age 29 years), and their injury had occurred 1 to 13 years prior to testing. Each person had been discharged from hospital at least 8 months before. At the time of testing most were employed full-time, and others were engaged full-time in tertiary study. All 16 SCI men were heterosexual, and only 1 had not experienced intercourse prior to injury. In terms of responses given to questions in the Heterosexual Behavior Inventory (Bentler, 1968), the sample was sexually experienced. At the time of testing all but 2 of the 16 SCI men were either married or living in a de facto relationship. Eleven of the 16 SCI men had complete lesions, 11 had incurred lesions at level T~2 or above, and in 11 cases the injury involved up-
Male Sexual Arousal Following Spinal Cord Injury
19
per neuron motor damage. Twelve men were confined to wheelchairs, while 4 walked with some minor difficulties. As assessed by medical examinations within the preceding 6 months, all but 4 were in good general health. No subject was diabetic or currently taking medication or drugs known to impair erectile capabilites. The 8 men in the non-SCI group were recruited from a university population. Ages ranged from 20 to 37 years (median 23 years). The men in this sample were heterosexual, sexually experienced, and sexually active, and none reported sexual problems or an inability to achieve psychogenic erections. As was the case with the $CI men, sufficient information was provided about the requirement of the study so that subjects could make an informed decision concerning participation.
Procedure
Physiological and subjective sexual arousal were measured while subjects were exposed to content-matched erotic material in film, spoken-text, and fantasy formats. In each mode the stimulus materials, which were devised by Julien (1979), entailed presentation of the following sequence of 2-min segments, each followed by a 30-sec interval without stimulation: (1) man and woman undressing each other; (2) mutual fondling; (3) mutual masturbation; (4) cunnilingus; (5) mutual oral sex; (6) fellatio; (7) intercourse in several positions; (8) intercourse terminating in ejaculation. Only one mode of stimulation was presented in a session. The subjects were tested individually across three sessions, each lasting 60 to 90 min and separated by between 1 and 5 days. The sequence in which modes were tested across sessions was counterbalanced through Latin squares (one incomplete). Penile tumescence was measured using a Parks Electronic mercury-inrubber strain gauge modified from the design of Bancroft et al. (1966) in the manner described by Julien and Over (1981, 1984). An open strain gauge 13 cm long was folded in half, and the two unattached ends were clamped 2.0 cm apart using a 1.5 x 2.5 cm perspex clamp with a screw protruding on one side. At the folded end of the gauge a 5 cm soft rubber flap containing four holes was passed around the gauge and glued back onto itself so as not to interfere with the mercury column. As weil as allowing the gauge to be adjusted in size to meet the needs of individual subjects, the modification made possible more accurate measurement of changes in early tumescence, particularly when the penis was of small flaccid circumference. The strain gauge was calibrated using the procedures described by Julien and Over (1984). A session began with 3 min of guided relaxation, followed by a 2-min music excerpt during which the baseline measures were obtained. The eight
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segments of erotic stimulation were then presented. Penile circumference was recorded countinuously over the session. The records were later scored to establish the amplitude of response at each 20th sec over the baseline interval and using each segment of erotic stimulation. These values were averaged across each 2-min interval to produce a mean baseline amplitude and mean amplitude values for each segment within the session. The extent to which a subject had been sexually aroused during a segment was specified by the extent to which penile circumference during the segment differed from the baseline value. Untransformed change scores are an invalid measure of arousal if response levels consequent upon stimulation are correlated with baseline response levels (Wilder, 1958). Julien and Over (1981) have suggested that the law of initial value does not apply for male sexual arousal. Data from the present study were analyzed as a further test of this proposition° The law of initial value applies if the product-moment correlation between prestimulus levels and difference scores is negative, the slope of the best-fit linear regression line relating prestimulus levels to difference scores is negative, or the slope of the best-fit linear regression line relating prestimulus and stimulation levels is less than unity but greater than zero. Since none of these relationships was found to apply for SCI or non-SCI men, data anatysis is based on untransformed change scores. Subjective sexual arousal was measured at the end of each session by asking the subject to position a cross along a line (with the end points tabeled "not sexually exciting" and "wildly sexually exciting") to match what he had experienced. The subject gave separate estimates for the session as a whole and for the eight segments within a session.
RESULTS The question first considered is whether the reports of erectile status given by the SCI men prior to testing were predictive of the tumescence leveis recorded from these subjects during erotic stimulation in the laboratory. In undertaking this analysis the maximum level to which each subject was aroused in a segment relative to baseline was identified for each mode of stimulation. It can be seen from Table I that all eight non-SCI men demonstrated an increase of more than 10 mm relative to baseline in at least one segment of one session. In contrast, three of the eight SCI who reported having lost the capacity for psychogenic erection also showed minimal tumescence, since their penile circumference never increased above baseline by 5 mm or more. However, two men in this category had erections of greater than 5 mm (in one case greater than 10 mm) while viewing the film. These data indicate that self-reports of erectile status from SCI men do not validly predict physiological responsiveness to erotic stimulation.
21
Male Sexual Arousal Following Spinal Cord Injury Table I. Maximum Mean Increase in Penile Circumference (mm) Above Baseline in a Segment for Each Mode for SCI and non-SCI Men Mode Group and subject
Film
Spoken-text
Fantasy Any mode
18.75 12.50 14.00 18.38 17.63 20.50 17.25 22.88
10.00 17.38 12.38 0.50 17.88 14.63 19.25 21.13
5.57 8.71 12.57 6.71 21.86 6.86 21.00 13.57
18.57 17.38 14.00 18.38 21.86 20.50 19.25 22.88
SCI men reporting psychogenic erections 1 2 3 4 5 6 7 8
5.00 0.13 0.25 2.75 23.00 0.75 0.00 1.00
2.00 0.38 0.25 2.00 2.63 1.00 0.00 0.63
2.00 1.86 0.57 1.00 3.71 1.57 0.00 0.00
5.00 1.86 0.57 2.75 23.00 1.57 0.00 1.00
SCI men reporting no psychogenic erections 1 2 3 4 5 6 7 8
15.00 1.00 12.88 11.88 0.13 3.50 0.00 1.00
21.38 1.38 15.63 4.63 12.75 1.25 2.00 2.25
15.86 0.00 5.57 11.14 0.29 0.00 5.71 0.14
21.38 1.38 16.63 11.88 12.75 3.50 5.71 2.25
Non-SCI men 1 2 3 4 5 6 7 8
Biserial correlations were calculated between reported erectile status a n d m a x i m a l t u m e s c e n c e f o u n d u n d e r each m o d e o f s t i m u l a t i o n i n c o m p a r i s o n s based o n the 16 SCI men. The values were + 0.15 for film, + 0.63 for spokentext, a n d + 0.48 for fantasy. The biserial c o r r e l a t i o n between reported erectile status a n d m a x i m a l physiological arousal irrespective o f m o d e o f erotic s t i m u l a t i o n was + 0.38. These values indicate that the belief o f SCI m e n as to whether they still have psychogenic erections is o n l y a weak predictor o f the level o f t u m e s c e n c e generated w h e n these m e n view a n erotic film, listen to erotic text, or engage in erotic f a n t a s y in the l a b o r a t o r y . The focus i n the next stage o f d a t a analysis is o n differences b e t w e e n SCI a n d n o n - S C I m e n in terms o f a b s o l u t e levels o f tumescence, specificity to m o d e s o f s t i m u l a t i o n , a n d the b u i l d u p in a r o u s a l across segments within a session. The c o m p a r i s o n is between the eight n o n - S C I m e n (each of w h o m had a n erection o f greater t h a n 10 m m in at least o n e segment o f one mode)
Kennedy and Over
22 o--o SC1 Ss producing psychogenic erections ( n = 7 )
15. 14"
non SCI subjects ( n = 8 } [5-
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I0"5
9
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8
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7
o
6
~
5
X
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~ 4 g
3
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5 6 nurnber
7
8
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3 4 5 6 segmeni number
AUDIO
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8
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3 4 5 6 ? segment number
8
FANTASY
Fig. 1, Mean increases in penile circumference (mm) above baseline across segments witlün modes (film, audio, fantasy) for non-SCl m e n and SCI m e n with psychogenic erections.
and the seven SCI men who demonstrated an increase of 5 m m or more in penile circumference above baseline in at least one segment of one mode. This criterion was set to distinguish deviations f r o m baseline due to erection from those reflecting a possible artifact. Figure 1 shows mean tumescence levels for the two groups across modes and segments. Analysis of variance indicated that erotic stimulation produced a higher mean level of tumescence for the non-SCI men than for the SCI men, F(1, 13) = 5.46, p < 0.01. Tumescence levels differed significantly between the three modes of erotic stimulation, F(2, 26) = 7.70, p < 0.01. Comparisons between means by Newman-Keuls test showed that the film was more arousing than fantasy, while spoken-text did not differ significantly in arousal level f r o m either film or fantasy. The significant main effect of segments, F(7, 91) = 5.83, p < 0.05, was shown through multiple comparisons to reflect an increase in arousal level between the first and second segments. None of the interactions involving group, mode, or segment was significant. The objective in the final comparison was to establish whether the nine SCI men with tumescence consistently less than 5 m m were less subjectively aroused by the erotic stimulation than either the non-SCI men or the seven SCI men who had had an erection of 5 m m or more in at least one segment of one mode. In reporting subjective arousal, a subject had marked for each segment a position on a line with the ends labeled "not sexually exciting" and "wildly sexually exciting." These ratings were converted to scores ranging from 0 to 5. Mean values are reported for segments, modes, and groups in Fig. 2.
Male Sexual Arousal Following Spinal Cord Injury
23
SCI Ss producing psychogenic erections (n=T}
g ò
4
~
3
SCI Ss producing no psychogenic erections (n=9) non SCI Ss (n=8)
S
g 2
o
g i o E
I
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3 4 5 6 segment number FILM
7
8
I
2
3 4 5 6 segment number AUD/O
7
I
2
$ 4 5 6 segment number FANTASY
7
8
Fig. 2. Mean ratings of subjectivesexual arousal across segments within modes (film, audio, fantasy) for the three groups.
The mean subjective arousal levels for the three modes of erotic stimulation differed significantly, F(2, 42) = 9.87, p < 0.01, and subjective arousal also varied significantly across segments within a mode, F(7,147) = 25.71, p < 0.01. However, mean values did not differ significantly between groups, F(2, 21) = 0.22, p > 0.05, and none of the interactions involving mode, segments, or group was significant. Thus, among the SCI men subjective sexual arousal was independent of tumescence levels. The SCI men who did not have erections were no less subjectively aroused by the film, spoken-text, and fantasy than were the SCI men with erections (and in fact, the non-SCI men). Further, modality specificity in subjective arousal was comparable for the three groups, and the buildup in subjective arousal over segments occurred at a rate that was independent of whether the erotic stimulation was eliciting erection.
DISCUSSION The results suggest that reports given by SCI men as to whether they had had erections following injury as a result of thoughts, fantasies, reading erotic books or magazines, or seeing films only provide a partly valid index of psychogenic erectile capability. Some men claiming to have experienced postinjury psychogenic erections failed to demonstrate tumescence in the laboratory. This discrepancy could reflect performance pr¢ssure in the laboratory (the men were aware that tumescence was being monitored), biased reporting o f erectile status (for example, a social desirability response set), or
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failure to distinguish whether postinjury erection had been reflexogenic or psychogenic. Further possibilities are that the erotic stimulation in the laboratory was not appropriate for all subjects and segment length (2 min) was too limited for some SCI men. Some SCI men in the present sample who believed they had lost the capacity for erection nevertheless achieved tumescence in the laboratory. In view of the level of sexual experience of the subjects and the extent of self-disclosure evident on other measures (for example, the Sexual Behavior Inventory), it seems unlikely these men were too inhibited to have reported having had postinjury psychogenic erections. There was no ambiguity in the questions that were asked, and written responses on the subject information sheet corresponded with the verbal reports given when the men were first contacted. One possibility is that the SCI men who demonstrated tumescence and reported no postinjury psychogenic erections lacked awareness of these erections through diminished kinesthetic and tactile feedback. However, the men were sexually active following injury, and hence they would have had many opportunities for visual feedback and partner response. A further possibility is that postinjury erections had been perceived as reflexogenic, rather than psychogenic. In fact, the two men who demonstrated psychogenic erections in the laboratory reported in the questionnaire administered at the start of the study that they had experienced reflexogenic erections since injury. Finally, although tumescence is a graded response rather than an all-or.none phenomenon, there is a widely held belief that no level of sexual response below complete tumescence is fully useful, adequate, or satisfying (Gochros and Fischer 1980). O'Dea (1980) found that the disabled, similarly to the nondisabled, tend to evaluate sexual functioning in quantitative as opposed to qualitative terms. In the present study some SCI men who were still capabte of some degree of psychogenic erection may have used their preinjury tumescence level as the criterion in deciding, and hence reporting, whether they still had psychogenic erections. Further attention needs to be given to this possibility that self-reports of sexual responsiveness by SCI men depend on how physiological states are labeled. Reports of whether ejaculation and orgasm have occurred following injury may be subject to the same sort of blas. Erotic stimulation in the laboratory produced a higher mean level of tumescence for the non-SCI men than for the SCI men who demonstrated erection. There were too few subjects in the SCI sample to determine whether the extent of diminution in tumescence was related to factors such as the site, type, and completeness o f lesion. Consistent with the report by Julien and Over (1987), film elicited significantly larger erections than fantasy, whereas tumescence elicited by spoken-text was at an intermediate leveL There was a similar rate of buildup of arousal across segments within a mode for SCI and non-SCI men. Notwithstanding these similarities between SCI and non-SCI men at the level of group analysis, the SCI men were more variable
Male Sexual Arousal Following Spinal Cord lnjury
25
in their sexual responsiveness than the non-SCI men. Most of the non-SCI men became sexually aroused during the film, spoken-text, and fantasy, whereas for some SCI men tumescence occurred in only a single mode of stimulation. Such a result points to the need to use a fange of erotic stimulation, possibly with variation in content as weil as mode, in direct clinical assessment of the psychogenic erectile capabilities o f SCI men. Irrespective of whether they had demonstrated tumescence, the SCI men had rauch the same levels, mode specificity, and patterns of subjective sexual arousal as the non-SCI men. Such a finding challenges claims (e.g., Hohmann, 1966; Jochheim and Wahle, 1970) that emotional responses, including feelings of sexual arousal, are lessened by spinal cord injury. Further, since some SCI men reported similar levels o f subjective sexual arousal to nonSCI men in the total absence of erectile response, any claim that SCI men who gain erections are more "sexual" than SCI men who do not is untenabie. In contrast to claims in the earlier literature that SCI men are asexual, sexual education and rehabilitation programs designed for SCI men and their partners (e.g., Chipouras, 1979; Brockway et al., 1978) recognize that sexuality has sensual and romantic dimensions, and not just mechanical and secretory components. Men who are unable to engage in intercourse are encouraged to achieve sexual arousal and satisfaction through other activities, none of which is labeled as inferior to intercourse. An obvious implication from our results is that neurological examination and verbal reports from patients, the traditional methods for identifying the effects of a spinal cord injury on penile erection, should be supplemented by psychophysiological measurement. In doing so, however, arousal levels need to be assessed across a range of erotic stimuli. The relationship between tumescence levels established by the methods used in the present study and nocturnal penile tumescence also needs to be evaluated in order to establish the validity of each measure in the diagnosis of erectile capability. Finally, the approach we advocated for assessment of erectile responsiveness following spinal cord injury can be applied more widely. For example, many diabetic men report impotence (Jensen, 1981; Whitehead e t al., 1983). In a follow-up study of 101 insulin-treated diabetic men, Jensen (1986) found that many men with evidence of peripheral neuropathy reported no erectile dysfunction, and that self-reported impotence was often associated with psychological factors. There thus are strong grounds for using a broadly based psychophysiological assessment with this population.
REFERENCES Bancroft, J. H., Jones, H. G., and Pullan, B. R. (1966). A simple transducer for measuring penile erection, with comments on its use in the treatment of sexual disorders. Behav. Res. Ther. 4: 239-241.
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Bentler, P. M. (1968). Heterosexual behavior assessment - I. Males. Behav. Res. Ther. 6: 21-25. Bors, E., and Comarr, A. E. (1960). Neurological disturbances of sexual function with special reference to 529 patients with spinal cord injury. Urol. Surv. 10: 191-222. Brockway, J., Steger, J. C., Berni, R., Ost, V. V. Williamson-Kirkland, T. E., and Peck, C. L. (1978). Effectiveness of a sex education and counseling program for spinal cord patients. Sex. Disabil. 1: 127-136. Burke, D. C., and Murray, D. D. (1975). Handbook ofSpinal CordMedicine, Raven Press, New York. Chipouras, S. (1979). Ten sexuality programs for spinal cord injured persons. Sex. DisabiL 2: 301-321. Comarr, A. E. (1970). Sexual functioning among patients with spinal cord injury. Urol. Int. 25: 134-168. Conte, H. R. (1986). Multivariate assessment of sexual dysfunction. J. Consult. Clin. PsychoL 54: 149-157. Fitzpatrick, W. F. (1974). Sexual functioning in the paraplegic patient. Arch. Phys. Med. Rehabil. 55: 221-227. Gochros, H. L., and Fischer, J. (1980), Treat Yourselfto a Better Sex Life, Prentice-Hall, Englewood Cliffs, NJ. Griffith, E. R., Tomko, M. A., and Timms, R. J. (1973). Sexual function in spinal-cord injured patients: A review. Arch. Phys. Med. Rehabil. 54: 539-543. Herman, M. (1950). Role of somesthetic stimuli in the development of sexual excitation in man. Arch. Neurol. Psychiat. 64: 42-56. Higgins, G. E. (1979). Aspects of sexual response in adults with spinal-cord injury: A review of the literature. Arch. Sex. Behav. 8: 173-196. Hohmann, G. W. (1966). Some effects of spinal cord lesions on experienced emotional feelings. Psychophysiology 3: 143-156. Jensen, S. B. (1981). Diabetic sexual dysfunction: A comparative study of 160 insulin-treated diabetic men and women and an age-matched control group. Arch. Sex. Behav. 10: 493 -497. Jensen, S. B. (1986). Sexual dysfunction in insulin-treated diabetics: A six-year follow-up study of 101 patients. Arch. Sex. Behav. 15: 271-283. Jochheim, K. A., and Wahle, H. (1970). A study on sexual function in 56 male patients with complete irreversible lesions of the spinal cord and cauda equina. Paraplegia 8: 166-172. Julien, E. (1979). Mode specificity and human male sexual arousal. Unpublished Ph.D. thesis, La Trobe University, Australia. Julien, E., and Over, R. (1981). Male sexual arousal and the law of initial value. Psychophsiology 18:709-711. Julien, E., and Over, R. (1984). Male sexual arousal with repeated exposure to erotic stimuli, Arch. Sex. Behav. 13: 211-222. Julien, E., and Over, R. (1987). Male sexual arousal across five modes of erotic stimulation. Arch. Sex. Behav. 17: 131-143. Karacan, 1., Aslan, C., and Hirshokowitz, M. (1983). Erectile mechanisms in man. Science 220: 1080-1082. Lamid, S. (1985). Nocturnal penile tumescence studies in spinal cord injured males. Paraplegia 23: 26-31. LoPiccolo, J., and Stock, W. E. (1986). Treatment of sexual dysfunction. J. Consult. Clin. PsychoL 54: 158-167. Money, J. (1960). Phantom orgasm in the dreams of paraplegic men and women. Arch. Gen. Psychiat. 3: 373-382. O'Dea, J. (1980). The role of cognition in sexual difficulties in the physically disabled. Unpublished Master of Psychology dissertation, La Trobe University, Australia. Talbot, H. S. (1949). A report on sexual function in paraplegics. J. Urol. 61: 265-270. Talbot, H. S. (1955). The sexual function in paraplegia. J. Urol. 73: 91-100. Tsuji, I., Nakajima, F., Morimoto, J., and Nounaka, Y. (1961). The sexual function in patients with spinal cord injury. UroL Int. 12: 270-280.
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Weiss, A. J., and Diamond, M. D. (1966). Sexual adjustment, identification, and attitudes of patients with myetopathy. Arch. Phys. Med. Rehabil. 47: 245-250. Wilder, J. (1958). Modern psychophysiology and the law of initial value. Amer. J. Psychother. 12: 199-221. Whitehead, E. D., Klyde, B. J., Zussman, S., Wayne, N., Shinback, K., and Davis, D. (1983). Male sexual dysfunction and diabetes mellitus. N.Y. Stare J. Med. 83" 1174-1179.
Psychophysiological Assessment of Male Sexual Arousal Following Spinal Cord Injury Simon Kennedy, M. Psych., 1 and Ray Over,
Ph.D. 1,2
Adult males with and without permanent damage to the spinal cord were contrasted in terms of their sexual responsiveness to erotic stimulation in film, spoken-text, and fantasy modes. Among the 16 spinal cord injured (SC1) men who were studied, several who had anticipated they would achieve erection failed to do so, whereas others demonstrated penile tumescence during erotic stimulation despite claiming they had lost the capacity for psychogenic erection. Self-report is thus not a valid index of sexual responsivity following spinal cord injury. Levels of tumescence varied across modalities of stimulation in the same manner for SCI and non-SCI men, and within each modality the two groups demonstrated similar rates o f buildup o f arousal over segments of stimulation. The SCI men without erections should not be considered asexual since their subjective arousal paralleled the subjective arousal of the non-SCI men and the SC1 men with erections. KEY WORDS: spinal cord injury; sexual arousal; penile tumescence;psychophysiological;erotic stimulation.
INTRODUCTION Reflexogenic penile erection resulting from tactile stimulation of the genitals, prostate, or urethra occurs through activation of a reflex arc at sacral segments 2 to 4 ( $ 2 - $4), whereas psychogenic erections (induced, for example, by erotic thoughts and fantasies) are initiated by input from the higher central nervous system to thoracolumbar segments T1 2 to L3 (see Burke and Murray, 1975; Karacan et al., 1983). Because these two systems do not func-
IDepartment of Psychology, La Trobe University, Bundoora, Australia 3083. 2To whom correspondence sh•uld be addressed.
15 0004-0002/90/0200-0015506.00/0
© 1990 Plenum Publishing Corporation
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Kennedy and Over
tion independently, the effects that injury to the spinal cord has on the subsequent capacity of men to achieve erection can be difficult to predict. In general, if the afferent and efferent components of the $2-$4 and T12-L3 systems mediating erection remain intact, the capacity for tumescence is unlikely to be affected by spinal cord injury. At the other extreme, the capacifies for reflexogenic as well as psychogenic erection are lost if both systems become nonfunctional through injury to the spinal cord. The outcome is less certain when injury has resulted in partial rather than complete transsection of the spinal cord, and when not both the sacral and thoracolumbar systems are damaged. It might be anticipated that some men will be incapable of psychogenic but not reflexogenic erection, or vice versa. Further, since pertile erection is a graded response rather than an all-or-none phenornenon, the major consequence of injury to the spinal cord can be that erotic sfimulation will evoke less tumescence after injury than it did before. A number of investigators have sought to correlate the incidence of erection and the type of erection retained following spinal cord injury with lesion site, completeness of the lesion, and whether upper or lower motor neurons were affected. Erectile capabilities were identified in these surveys through reports given by spinal cord injured (SCI) men during interview. In a review covering this literature, Higgins (1979) noted that proportionately more SCI men with lesions above than below T12 reported having erections. Damage below T12 was more likely to result in loss of reflexogenic erection, whereas damage at or above T,2 had more advêrse consequences for psychogenic erection. More SCI men with upper than with lower motor neuron lesions reported erections, and reflexogenic erections were retained more often after upper than after lower motor neuron damage. Finally, proportionately fewer SCI men with incomplete lesions than with complete lesions reported loss of either psychogenic or reflexogenic erection. Not all the surveys reviewed by Higgins (1979) yielded the same pattern of results. In addition, incidence rates reported for seemingly similar groups of SCI men varied substantially. As an example, all men with lesions below T~2 in the sample studied by Fitzpatrick (1974) reported psychogenic erections following spinal cord injury, in contrast to 55% (Comarr, 1970), 42o70 (Hohmann, 1966), 30o70 (Talbot, 1949), 25070 (Talbot, 1955), and 200/0 (Bors and Comarr, 1960) in other studies. As noted by Griffith et al. (1973) and Higgins (1979), the variability in findings across studies may reflect problems associated with the use of survey methodologyù Allowance needs to be made for differences in such subject characteristics as age, marital status, period since injury, physical health, and opportunity for sexual experience. More important, the validity of the retrospective reports obtained from SCI men through interview is not known. Higgins (1979) pointed to the need for erectile capabilities to be assessed through physiological monitoring of sexual arousal.
Male Sexual Arousal Following Spinal Cord Injury
17
Lamid (1985) assessed nocturnal penile tumescence (NPT) across a sample of 24 SCI men (12 tetraplegics and 12 paraplegics) by recording changes in penile circumference during sleep. Tetraplegic men demonstrated a greater mean level of tumescence than paraplegic men, and they also had a longer mean duration of erectile episodes. N P T did not vary significantly with completeness of the spinal lesion, presence of bulbocavernosus reflex, presence of reflexogenic erection, or whether the person reported having experienced sexual dreams during sleep. Lamid nevertheless recommended that N P T measures be used to determine the course of treatment provided to SCI men; in his study, for example, SCI men who were more than 12 months postinjury and did not demonstrate N P T were advised to use a penile prosthesis. However, general concern had been expressed about the reliability and validity of N P T measures in the diagnosis of erectile dysfunction (see Conte, 1986; LoPiccolo and Stock, 1986). False negatives as well as false positives can be expected from classification based on N P T measures. The results reported by Lamid (1985) need to be replicated and supplemented before NPT scores can be used routinely to decide upon treatment for SCI men. In the present study penile tumescence is recorded while fully awake SCI men experience erotic stimulation in three modes of presentation (film, audiotape, fantasy). In order to assess the validity of retrospective reports of erectile capability, the tumescence measures were compared across two groups of SCI men. One group reported retention o f psychogenic erections subsequent to injury to the spinal cord, while the men in the other group claimed loss of psychogenic erections. For further comparative purposes, measures were also obtained for a group of men who had not suffered spinal cord injury (the non-SCI group). Tumenscence was recorded for each group across three modes of stimulation to determine whether there was specificity rather than generality in arousal. With the same erotic stimuli as those used in the present study, Julien and Over (1987) found with non-SCI men that film was more arousing than content-matched audiotape, which in turn was more arousing than content-matched fantasy. Within all three modes, the stimulus events were presented in sequence so that sexual arousal built up over time. By using these same materials in the present study it could be asked whether SCI men who experience erection and non-SCI men demonstrate similar patterns of temporal development and mode-specificity in their sexual arousal. Subjective sexual arousal was assessed in addition to penile tumescence. For non-SCI men tested under the stimulus conditions used in the present study, Julien and Over (1987) found correlations of + 0.27 between subjective and physiological measures for film, + 0.52 for audiotape, and + 0.76 for fantasy. The question of interest was not only whether similar relationships between subjective and physiological arousal would be found for the SCI men demonstrating tumescence, but whether SCI men who did not have
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erections would nevertheless report being subjectively aroused in rauch the same way as the other men in the study. There have been conflicting reports as to whether measures of subjective sexual arousal such as "cognitional eroticism" (Money, 1960), "libido sexualis" (Jochheim and Wahle, 1970), "sexual excitement" (Herman, 1950), "libido" (Talbot, 1955; Bors and Comarr, 1960), "sexual desire" (Tsuji et al., 1961), and sexual feelings (Hohmann, 1966; Weiss and Diamond, 1966) change as a consequence of spinal cord injury. Survey studies, most of which required men to compare their feelings before and after injury, have yielded conflicting findings. Subjective sexual arousal has been reported to decrease markedly (Herman, 1950; Jochheim and Wahle, 1970), decrease slightly (Money, 1960; Tsuji et al., 1961; Hohmann, 1966; Weiss and Diamond, 1966), or not change (Talbot, 1949, 1955; Bors and Comarr, 1960). In the present study the temporal development and mode-specificity of subjective sexual arousal as well as physiological sexual arousal is assessed for both SCI and non-SCI men.
METHOD Subjects
Sixteen men who had experienced traumafic spinal cord injury at least 1 year before were recruited into the study through the assistance of staff at the Spinal Injuries Unit of the Austin Hospital, Melbourne. The men who were approached to participate initially completed a general information questionnaire, which asked the person to report how frequently, if at all, he had experienced even partial penile erection following spinal cord injury through thoughts, fantasies, erotic books, magazines, and films. Subjects were selected on the basis of these reports so that 8 SCI men reporting psychogenic erection following injury could be contrasted with 8 SCI men who claimed that they no longer had this capability. Testing was carried out in a psychophysiological laboratory at La Trobe University. The SCI men ranged in age from 22 to 47 years (median age 29 years), and their injury had occurred 1 to 13 years prior to testing. Each person had been discharged from hospital at least 8 months before. At the time of testing most were employed full-time, and others were engaged full-time in tertiary study. All 16 SCI men were heterosexual, and only 1 had not experienced intercourse prior to injury. In terms of responses given to questions in the Heterosexual Behavior Inventory (Bentler, 1968), the sample was sexually experienced. At the time of testing all but 2 of the 16 SCI men were either married or living in a de facto relationship. Eleven of the 16 SCI men had complete lesions, 11 had incurred lesions at level T~2 or above, and in 11 cases the injury involved up-
Male Sexual Arousal Following Spinal Cord Injury
19
per neuron motor damage. Twelve men were confined to wheelchairs, while 4 walked with some minor difficulties. As assessed by medical examinations within the preceding 6 months, all but 4 were in good general health. No subject was diabetic or currently taking medication or drugs known to impair erectile capabilites. The 8 men in the non-SCI group were recruited from a university population. Ages ranged from 20 to 37 years (median 23 years). The men in this sample were heterosexual, sexually experienced, and sexually active, and none reported sexual problems or an inability to achieve psychogenic erections. As was the case with the $CI men, sufficient information was provided about the requirement of the study so that subjects could make an informed decision concerning participation.
Procedure
Physiological and subjective sexual arousal were measured while subjects were exposed to content-matched erotic material in film, spoken-text, and fantasy formats. In each mode the stimulus materials, which were devised by Julien (1979), entailed presentation of the following sequence of 2-min segments, each followed by a 30-sec interval without stimulation: (1) man and woman undressing each other; (2) mutual fondling; (3) mutual masturbation; (4) cunnilingus; (5) mutual oral sex; (6) fellatio; (7) intercourse in several positions; (8) intercourse terminating in ejaculation. Only one mode of stimulation was presented in a session. The subjects were tested individually across three sessions, each lasting 60 to 90 min and separated by between 1 and 5 days. The sequence in which modes were tested across sessions was counterbalanced through Latin squares (one incomplete). Penile tumescence was measured using a Parks Electronic mercury-inrubber strain gauge modified from the design of Bancroft et al. (1966) in the manner described by Julien and Over (1981, 1984). An open strain gauge 13 cm long was folded in half, and the two unattached ends were clamped 2.0 cm apart using a 1.5 x 2.5 cm perspex clamp with a screw protruding on one side. At the folded end of the gauge a 5 cm soft rubber flap containing four holes was passed around the gauge and glued back onto itself so as not to interfere with the mercury column. As weil as allowing the gauge to be adjusted in size to meet the needs of individual subjects, the modification made possible more accurate measurement of changes in early tumescence, particularly when the penis was of small flaccid circumference. The strain gauge was calibrated using the procedures described by Julien and Over (1984). A session began with 3 min of guided relaxation, followed by a 2-min music excerpt during which the baseline measures were obtained. The eight
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segments of erotic stimulation were then presented. Penile circumference was recorded countinuously over the session. The records were later scored to establish the amplitude of response at each 20th sec over the baseline interval and using each segment of erotic stimulation. These values were averaged across each 2-min interval to produce a mean baseline amplitude and mean amplitude values for each segment within the session. The extent to which a subject had been sexually aroused during a segment was specified by the extent to which penile circumference during the segment differed from the baseline value. Untransformed change scores are an invalid measure of arousal if response levels consequent upon stimulation are correlated with baseline response levels (Wilder, 1958). Julien and Over (1981) have suggested that the law of initial value does not apply for male sexual arousal. Data from the present study were analyzed as a further test of this proposition° The law of initial value applies if the product-moment correlation between prestimulus levels and difference scores is negative, the slope of the best-fit linear regression line relating prestimulus levels to difference scores is negative, or the slope of the best-fit linear regression line relating prestimulus and stimulation levels is less than unity but greater than zero. Since none of these relationships was found to apply for SCI or non-SCI men, data anatysis is based on untransformed change scores. Subjective sexual arousal was measured at the end of each session by asking the subject to position a cross along a line (with the end points tabeled "not sexually exciting" and "wildly sexually exciting") to match what he had experienced. The subject gave separate estimates for the session as a whole and for the eight segments within a session.
RESULTS The question first considered is whether the reports of erectile status given by the SCI men prior to testing were predictive of the tumescence leveis recorded from these subjects during erotic stimulation in the laboratory. In undertaking this analysis the maximum level to which each subject was aroused in a segment relative to baseline was identified for each mode of stimulation. It can be seen from Table I that all eight non-SCI men demonstrated an increase of more than 10 mm relative to baseline in at least one segment of one session. In contrast, three of the eight SCI who reported having lost the capacity for psychogenic erection also showed minimal tumescence, since their penile circumference never increased above baseline by 5 mm or more. However, two men in this category had erections of greater than 5 mm (in one case greater than 10 mm) while viewing the film. These data indicate that self-reports of erectile status from SCI men do not validly predict physiological responsiveness to erotic stimulation.
21
Male Sexual Arousal Following Spinal Cord Injury Table I. Maximum Mean Increase in Penile Circumference (mm) Above Baseline in a Segment for Each Mode for SCI and non-SCI Men Mode Group and subject
Film
Spoken-text
Fantasy Any mode
18.75 12.50 14.00 18.38 17.63 20.50 17.25 22.88
10.00 17.38 12.38 0.50 17.88 14.63 19.25 21.13
5.57 8.71 12.57 6.71 21.86 6.86 21.00 13.57
18.57 17.38 14.00 18.38 21.86 20.50 19.25 22.88
SCI men reporting psychogenic erections 1 2 3 4 5 6 7 8
5.00 0.13 0.25 2.75 23.00 0.75 0.00 1.00
2.00 0.38 0.25 2.00 2.63 1.00 0.00 0.63
2.00 1.86 0.57 1.00 3.71 1.57 0.00 0.00
5.00 1.86 0.57 2.75 23.00 1.57 0.00 1.00
SCI men reporting no psychogenic erections 1 2 3 4 5 6 7 8
15.00 1.00 12.88 11.88 0.13 3.50 0.00 1.00
21.38 1.38 15.63 4.63 12.75 1.25 2.00 2.25
15.86 0.00 5.57 11.14 0.29 0.00 5.71 0.14
21.38 1.38 16.63 11.88 12.75 3.50 5.71 2.25
Non-SCI men 1 2 3 4 5 6 7 8
Biserial correlations were calculated between reported erectile status a n d m a x i m a l t u m e s c e n c e f o u n d u n d e r each m o d e o f s t i m u l a t i o n i n c o m p a r i s o n s based o n the 16 SCI men. The values were + 0.15 for film, + 0.63 for spokentext, a n d + 0.48 for fantasy. The biserial c o r r e l a t i o n between reported erectile status a n d m a x i m a l physiological arousal irrespective o f m o d e o f erotic s t i m u l a t i o n was + 0.38. These values indicate that the belief o f SCI m e n as to whether they still have psychogenic erections is o n l y a weak predictor o f the level o f t u m e s c e n c e generated w h e n these m e n view a n erotic film, listen to erotic text, or engage in erotic f a n t a s y in the l a b o r a t o r y . The focus i n the next stage o f d a t a analysis is o n differences b e t w e e n SCI a n d n o n - S C I m e n in terms o f a b s o l u t e levels o f tumescence, specificity to m o d e s o f s t i m u l a t i o n , a n d the b u i l d u p in a r o u s a l across segments within a session. The c o m p a r i s o n is between the eight n o n - S C I m e n (each of w h o m had a n erection o f greater t h a n 10 m m in at least o n e segment o f one mode)
Kennedy and Over
22 o--o SC1 Ss producing psychogenic erections ( n = 7 )
15. 14"
non SCI subjects ( n = 8 } [5-
/
I0"5
9
c
8
.E
7
o
6
~
5
X
/
/
~ 4 g
3
E 2
I
2
3 4 segment
FILM
5 6 nurnber
7
8
I
2
3 4 5 6 segmeni number
AUDIO
7
8
I
2
3 4 5 6 ? segment number
8
FANTASY
Fig. 1, Mean increases in penile circumference (mm) above baseline across segments witlün modes (film, audio, fantasy) for non-SCl m e n and SCI m e n with psychogenic erections.
and the seven SCI men who demonstrated an increase of 5 m m or more in penile circumference above baseline in at least one segment of one mode. This criterion was set to distinguish deviations f r o m baseline due to erection from those reflecting a possible artifact. Figure 1 shows mean tumescence levels for the two groups across modes and segments. Analysis of variance indicated that erotic stimulation produced a higher mean level of tumescence for the non-SCI men than for the SCI men, F(1, 13) = 5.46, p < 0.01. Tumescence levels differed significantly between the three modes of erotic stimulation, F(2, 26) = 7.70, p < 0.01. Comparisons between means by Newman-Keuls test showed that the film was more arousing than fantasy, while spoken-text did not differ significantly in arousal level f r o m either film or fantasy. The significant main effect of segments, F(7, 91) = 5.83, p < 0.05, was shown through multiple comparisons to reflect an increase in arousal level between the first and second segments. None of the interactions involving group, mode, or segment was significant. The objective in the final comparison was to establish whether the nine SCI men with tumescence consistently less than 5 m m were less subjectively aroused by the erotic stimulation than either the non-SCI men or the seven SCI men who had had an erection of 5 m m or more in at least one segment of one mode. In reporting subjective arousal, a subject had marked for each segment a position on a line with the ends labeled "not sexually exciting" and "wildly sexually exciting." These ratings were converted to scores ranging from 0 to 5. Mean values are reported for segments, modes, and groups in Fig. 2.
Male Sexual Arousal Following Spinal Cord Injury
23
SCI Ss producing psychogenic erections (n=T}
g ò
4
~
3
SCI Ss producing no psychogenic erections (n=9) non SCI Ss (n=8)
S
g 2
o
g i o E
I
2
3 4 5 6 segment number FILM
7
8
I
2
3 4 5 6 segment number AUD/O
7
I
2
$ 4 5 6 segment number FANTASY
7
8
Fig. 2. Mean ratings of subjectivesexual arousal across segments within modes (film, audio, fantasy) for the three groups.
The mean subjective arousal levels for the three modes of erotic stimulation differed significantly, F(2, 42) = 9.87, p < 0.01, and subjective arousal also varied significantly across segments within a mode, F(7,147) = 25.71, p < 0.01. However, mean values did not differ significantly between groups, F(2, 21) = 0.22, p > 0.05, and none of the interactions involving mode, segments, or group was significant. Thus, among the SCI men subjective sexual arousal was independent of tumescence levels. The SCI men who did not have erections were no less subjectively aroused by the film, spoken-text, and fantasy than were the SCI men with erections (and in fact, the non-SCI men). Further, modality specificity in subjective arousal was comparable for the three groups, and the buildup in subjective arousal over segments occurred at a rate that was independent of whether the erotic stimulation was eliciting erection.
DISCUSSION The results suggest that reports given by SCI men as to whether they had had erections following injury as a result of thoughts, fantasies, reading erotic books or magazines, or seeing films only provide a partly valid index of psychogenic erectile capability. Some men claiming to have experienced postinjury psychogenic erections failed to demonstrate tumescence in the laboratory. This discrepancy could reflect performance pr¢ssure in the laboratory (the men were aware that tumescence was being monitored), biased reporting o f erectile status (for example, a social desirability response set), or
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Kennedy and Over
failure to distinguish whether postinjury erection had been reflexogenic or psychogenic. Further possibilities are that the erotic stimulation in the laboratory was not appropriate for all subjects and segment length (2 min) was too limited for some SCI men. Some SCI men in the present sample who believed they had lost the capacity for erection nevertheless achieved tumescence in the laboratory. In view of the level of sexual experience of the subjects and the extent of self-disclosure evident on other measures (for example, the Sexual Behavior Inventory), it seems unlikely these men were too inhibited to have reported having had postinjury psychogenic erections. There was no ambiguity in the questions that were asked, and written responses on the subject information sheet corresponded with the verbal reports given when the men were first contacted. One possibility is that the SCI men who demonstrated tumescence and reported no postinjury psychogenic erections lacked awareness of these erections through diminished kinesthetic and tactile feedback. However, the men were sexually active following injury, and hence they would have had many opportunities for visual feedback and partner response. A further possibility is that postinjury erections had been perceived as reflexogenic, rather than psychogenic. In fact, the two men who demonstrated psychogenic erections in the laboratory reported in the questionnaire administered at the start of the study that they had experienced reflexogenic erections since injury. Finally, although tumescence is a graded response rather than an all-or.none phenomenon, there is a widely held belief that no level of sexual response below complete tumescence is fully useful, adequate, or satisfying (Gochros and Fischer 1980). O'Dea (1980) found that the disabled, similarly to the nondisabled, tend to evaluate sexual functioning in quantitative as opposed to qualitative terms. In the present study some SCI men who were still capabte of some degree of psychogenic erection may have used their preinjury tumescence level as the criterion in deciding, and hence reporting, whether they still had psychogenic erections. Further attention needs to be given to this possibility that self-reports of sexual responsiveness by SCI men depend on how physiological states are labeled. Reports of whether ejaculation and orgasm have occurred following injury may be subject to the same sort of blas. Erotic stimulation in the laboratory produced a higher mean level of tumescence for the non-SCI men than for the SCI men who demonstrated erection. There were too few subjects in the SCI sample to determine whether the extent of diminution in tumescence was related to factors such as the site, type, and completeness o f lesion. Consistent with the report by Julien and Over (1987), film elicited significantly larger erections than fantasy, whereas tumescence elicited by spoken-text was at an intermediate leveL There was a similar rate of buildup of arousal across segments within a mode for SCI and non-SCI men. Notwithstanding these similarities between SCI and non-SCI men at the level of group analysis, the SCI men were more variable
Male Sexual Arousal Following Spinal Cord lnjury
25
in their sexual responsiveness than the non-SCI men. Most of the non-SCI men became sexually aroused during the film, spoken-text, and fantasy, whereas for some SCI men tumescence occurred in only a single mode of stimulation. Such a result points to the need to use a fange of erotic stimulation, possibly with variation in content as weil as mode, in direct clinical assessment of the psychogenic erectile capabilities o f SCI men. Irrespective of whether they had demonstrated tumescence, the SCI men had rauch the same levels, mode specificity, and patterns of subjective sexual arousal as the non-SCI men. Such a finding challenges claims (e.g., Hohmann, 1966; Jochheim and Wahle, 1970) that emotional responses, including feelings of sexual arousal, are lessened by spinal cord injury. Further, since some SCI men reported similar levels o f subjective sexual arousal to nonSCI men in the total absence of erectile response, any claim that SCI men who gain erections are more "sexual" than SCI men who do not is untenabie. In contrast to claims in the earlier literature that SCI men are asexual, sexual education and rehabilitation programs designed for SCI men and their partners (e.g., Chipouras, 1979; Brockway et al., 1978) recognize that sexuality has sensual and romantic dimensions, and not just mechanical and secretory components. Men who are unable to engage in intercourse are encouraged to achieve sexual arousal and satisfaction through other activities, none of which is labeled as inferior to intercourse. An obvious implication from our results is that neurological examination and verbal reports from patients, the traditional methods for identifying the effects of a spinal cord injury on penile erection, should be supplemented by psychophysiological measurement. In doing so, however, arousal levels need to be assessed across a range of erotic stimuli. The relationship between tumescence levels established by the methods used in the present study and nocturnal penile tumescence also needs to be evaluated in order to establish the validity of each measure in the diagnosis of erectile capability. Finally, the approach we advocated for assessment of erectile responsiveness following spinal cord injury can be applied more widely. For example, many diabetic men report impotence (Jensen, 1981; Whitehead e t al., 1983). In a follow-up study of 101 insulin-treated diabetic men, Jensen (1986) found that many men with evidence of peripheral neuropathy reported no erectile dysfunction, and that self-reported impotence was often associated with psychological factors. There thus are strong grounds for using a broadly based psychophysiological assessment with this population.
REFERENCES Bancroft, J. H., Jones, H. G., and Pullan, B. R. (1966). A simple transducer for measuring penile erection, with comments on its use in the treatment of sexual disorders. Behav. Res. Ther. 4: 239-241.
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Bentler, P. M. (1968). Heterosexual behavior assessment - I. Males. Behav. Res. Ther. 6: 21-25. Bors, E., and Comarr, A. E. (1960). Neurological disturbances of sexual function with special reference to 529 patients with spinal cord injury. Urol. Surv. 10: 191-222. Brockway, J., Steger, J. C., Berni, R., Ost, V. V. Williamson-Kirkland, T. E., and Peck, C. L. (1978). Effectiveness of a sex education and counseling program for spinal cord patients. Sex. Disabil. 1: 127-136. Burke, D. C., and Murray, D. D. (1975). Handbook ofSpinal CordMedicine, Raven Press, New York. Chipouras, S. (1979). Ten sexuality programs for spinal cord injured persons. Sex. DisabiL 2: 301-321. Comarr, A. E. (1970). Sexual functioning among patients with spinal cord injury. Urol. Int. 25: 134-168. Conte, H. R. (1986). Multivariate assessment of sexual dysfunction. J. Consult. Clin. PsychoL 54: 149-157. Fitzpatrick, W. F. (1974). Sexual functioning in the paraplegic patient. Arch. Phys. Med. Rehabil. 55: 221-227. Gochros, H. L., and Fischer, J. (1980), Treat Yourselfto a Better Sex Life, Prentice-Hall, Englewood Cliffs, NJ. Griffith, E. R., Tomko, M. A., and Timms, R. J. (1973). Sexual function in spinal-cord injured patients: A review. Arch. Phys. Med. Rehabil. 54: 539-543. Herman, M. (1950). Role of somesthetic stimuli in the development of sexual excitation in man. Arch. Neurol. Psychiat. 64: 42-56. Higgins, G. E. (1979). Aspects of sexual response in adults with spinal-cord injury: A review of the literature. Arch. Sex. Behav. 8: 173-196. Hohmann, G. W. (1966). Some effects of spinal cord lesions on experienced emotional feelings. Psychophysiology 3: 143-156. Jensen, S. B. (1981). Diabetic sexual dysfunction: A comparative study of 160 insulin-treated diabetic men and women and an age-matched control group. Arch. Sex. Behav. 10: 493 -497. Jensen, S. B. (1986). Sexual dysfunction in insulin-treated diabetics: A six-year follow-up study of 101 patients. Arch. Sex. Behav. 15: 271-283. Jochheim, K. A., and Wahle, H. (1970). A study on sexual function in 56 male patients with complete irreversible lesions of the spinal cord and cauda equina. Paraplegia 8: 166-172. Julien, E. (1979). Mode specificity and human male sexual arousal. Unpublished Ph.D. thesis, La Trobe University, Australia. Julien, E., and Over, R. (1981). Male sexual arousal and the law of initial value. Psychophsiology 18:709-711. Julien, E., and Over, R. (1984). Male sexual arousal with repeated exposure to erotic stimuli, Arch. Sex. Behav. 13: 211-222. Julien, E., and Over, R. (1987). Male sexual arousal across five modes of erotic stimulation. Arch. Sex. Behav. 17: 131-143. Karacan, 1., Aslan, C., and Hirshokowitz, M. (1983). Erectile mechanisms in man. Science 220: 1080-1082. Lamid, S. (1985). Nocturnal penile tumescence studies in spinal cord injured males. Paraplegia 23: 26-31. LoPiccolo, J., and Stock, W. E. (1986). Treatment of sexual dysfunction. J. Consult. Clin. PsychoL 54: 158-167. Money, J. (1960). Phantom orgasm in the dreams of paraplegic men and women. Arch. Gen. Psychiat. 3: 373-382. O'Dea, J. (1980). The role of cognition in sexual difficulties in the physically disabled. Unpublished Master of Psychology dissertation, La Trobe University, Australia. Talbot, H. S. (1949). A report on sexual function in paraplegics. J. Urol. 61: 265-270. Talbot, H. S. (1955). The sexual function in paraplegia. J. Urol. 73: 91-100. Tsuji, I., Nakajima, F., Morimoto, J., and Nounaka, Y. (1961). The sexual function in patients with spinal cord injury. UroL Int. 12: 270-280.
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Weiss, A. J., and Diamond, M. D. (1966). Sexual adjustment, identification, and attitudes of patients with myetopathy. Arch. Phys. Med. Rehabil. 47: 245-250. Wilder, J. (1958). Modern psychophysiology and the law of initial value. Amer. J. Psychother. 12: 199-221. Whitehead, E. D., Klyde, B. J., Zussman, S., Wayne, N., Shinback, K., and Davis, D. (1983). Male sexual dysfunction and diabetes mellitus. N.Y. Stare J. Med. 83" 1174-1179.
