Reproducibility in Monitoring Nocturnal Penile Tumescence and Rigidity

0022-534 7/92/1483-0311$03.00/0 Vol. 148, 811-814, September l:JS2

THE JOURNAL OF UROLOGY

Printed in US.A.

Copyright© 1992 by AMERICAN UROLOGICAL AsSOClATlON, INC.

REPRODUCIBILITY IN MONITORING NOCTURNAL PENILE TUMESCENCE AND RIGIDITY CATHERINE L. BAIN*

AND

ANDRE T. GUAYt

From the Section of Endocrinology and Metabolism, Lahey Clinic Medical Center, Burlington, Massachusetts

ABSTRACT

The evaluation of sexual dysfunction has improved with the advent of methods to test nocturnal penile tumescence that also monitor penile rigidity. Earlier techniques may not have recorded abnormal rigidity despite normal tumescence. To test the reproducibility of penile tumescence and rigidity, the results of initial and repeat tracings performed a mean of 39 days apart were compared in 17 patients (median age 62 years). Three nocturnal patterns were identified. 1) Among the 17 patients the initial penile tumescence and rigidity pattern was reproduced on repeat testing in 15. 2) Patterns that were not reproduced in the other 2 patients were explained by the ingestion of alcohol or because of a febrile illness during the period monitored. 3) Nocturnal penile rigidity and tumescence tracings from these patients reproduced previous patterns. Monitoring of nocturnal penile tumescence and rigidity is a useful and reproducible tool in the evaluation of male sexual dysfunction. KEY WORDS:

penile erection, impotence

Impotence, or the inability to achieve or maintain an erection of sufficient rigidity to perform sexual intercourse in more than 25% of the attempts, is a problem affecting an estimated 10 million American men. 1' 2 Until recently the evaluation of sexual dysfunction in men relied on questionnaires, the accuracy of which has long been questioned. Use of mercury strain gauges during overnight sleep monitoring helped greatly in the understanding of nocturnal penile tumescence. In this test erectile activity is monitored by transducers that measure changes in the circumference of the penis. Unfortunately, rigidity is not measured. The phenomenon of nocturnal penile tumescence with appreciable expansion but without rigidity sufficient for vaginal penetration has been recognized 3 and underscores the need for accurate assessment of rigidity. Monitoring of nocturnal tumescence at a sleep laboratory attempted to confirm adequate rigidity by assessing penile resistance to buckling under a known weight. This method was cumbersome and often inaccurate if the patient awoke. An effort to identify more convenient and less expensive testing alternatives led to the development of the Snap-Gauge.+ A band of nonstretchable fabric is fitted around the penis and kept intact by self-adhesive attachment. Three plastic snap gauges may release at various incremental pressures that may be attained during erectile activity. Studies of the properties of the Snap-Gauge device under conditions of artificial erection showed that breakage of successive elements required increasingly larger penile expansion. In practical application, however, in some men with relatively little penile expansion all 3 elements were broken, whereas in other men with a satisfactory erection the elements were not broken. 4 Its usefulness is limited because only a single tumescent episode is measured and because rigidity cannot be separated from tumescence. Further refinement led to the development of a nocturnal penile tumescence unit, RigiScan,:j: which measures rigidity as well as tumescence and permits monitoring by the patient in

1a T

0I 15

l

p

B A

s

E

1b

Accepted for publication February 14, 1992. Supported in part by a grant from the Eleanor Naylor Dana Charitable Trust, New York. *Current address: Joslin Diabetes Center, 1 Joslin Place, Boston, Massachusetts 02215. tRequests for reprints: Section of Endocrinology and Metabolism, Lahey Clinic Medical Center, 41 Mall Rd., Burlington, Massachusetts 01805. :j:Dacomed, Minneapolis, Minnesota. 811

rig 1/.

T

I

p

tu~ CM

5)

0

]~~~~-,~-,~,\:~

. 100[ B A

$

rig 1/.

E (UM

f

0t-U,..L--,J

lSI

'" Jt~J~;i:~"" . Screen width: 10 hrs FIG. 1. Tracings obtained 3 weeks apart in patient from group 1 revealed normal findings. rig, rigidity, tum, tumescence.

812

BAIN AND GUAY l\7\7

2a rig

rig

1/.

1/.

I

0

T

I p

tu1<1 CM

B

lllll

3a

l'IY 1/.

A

s

tUM CM

I

II

1:b;~· 10 1 I 0

E

I

111

I

11!

II

15f

liili H

T

I

I p

I

tUM CM

B A

s

E tUM CM

J~~7=··;:;·~·-~ 2b

3b

ice

rig

rig 1/.

T

I

p

lllll

01 15

I

1/.

~I

T

01

I

tu1>1 CM

B

B

A

s

A

s

5:~~f

:I

1

:i• I ~111

E

E

I

15

p

tUM

CM

151

I

•

~~

:

k . _ _,. ._. : r-t--

_J~,-~,- - ~ - - - - s

5.,...t-':-1:.....,..._· -~~,-~-d..,...____,_J____~, _1°'"'"'~,

Screen wi,lth:

rn h~,

FIG. 2. Tracings obtained 4 weeks apart in patient from group 2 showed near total absence of activity. rig, rigidity, tum, tumescence.

the privacy of the home. The RigiScan monitor for nocturnal penile tumescence and rigidity has 2 major components, which include an ambulatory nocturnal penile tumescence and rigidity data logging unit, and a microcomputer to process and print data. The ambulatory unit has 2 loop transducers that fit on the penis and self-adjust in length to measure circumferential changes. In the presence of tumescence the loop tightens around the penile shaft to measure rigidity by radial loading. 5 An advantage is the ability to monitor all erectile episodes throughout the night. Although monitoring of nocturnal penile tumescence and rigidity is believed to demonstrate activity at a given time and readings on successive nights have shown similarity,6 the reproducibility of results with time has not been studied. Therefore, our objective was to test the reproducibility of results with time before therapeutic intervention.

Screen width: 10 h!'s FIG. 3. Tracings obtained 6 weeks apart in patient from group 3 revealed decreased rigidity (rig) amplitude or duration of rigidity or dissociation between base and/or tip rigidity. tum, tumescence.

prescription drugs taken routinely), alcohol and caffeine-containing beverages for approximately 6 to 8 hours before each session, and to abstain from sex for 24 hours before each session. Patients were questioned as to compliance on the return visit. Testing of nocturnal penile tumescence and rigidity was repeated 8 to 129 days (mean 39 days) later before initiation of therapeutic maneuvers. If the 2 patients who needed 3 tests were excluded, no testing of the patients exceeded 50 days. Data from initial and repeat monitoring were compared. The 2 patients whose results did not correlate were asked to undergo monitoring a third time. We recommend defining normalcy as at least 60% rigidity at the base and 50% at the tip that lasts 10 minutes each erection and is present in at least 50% of the erectile episodes.7 This definition would be in keeping with an erection that lasts long enough to complete intercourse.

METHODS

The study involved 17 men between 38 and 72 years old (median age 62 years). The subjects were selected from patients who were referred from a general medical population to evaluate impotence. The evaluation consisted of history, physical examination, biochemical profile, complete blood counts and hormonal analysis, which included a minimum level of testosterone, prolactin, luteinizing hormone and follicle-stimulating hormone. Methods of monitoring in the assessment of penile rigidity have been described by Burris et al. 6 Our patients were requested to use the instrument at home for 2 or 3 consecutive nights. They also were asked to abstain from drugs (except for

RESULTS

After evaluation the results were classified into 3 categories. No blinded procedures were used to formulate these classifications. Three general groups were chosen to categorize the extremes of function, with group 3 encompassing all other abnormal tracings. The 4 patients in group 1 showed normal tumescence and rigidity consistent with psychological impotence (fig. 1). The 6 patients in group 2 showed near total absence of rigidity and tumescence (fig. 2). The tracings of the 7 men in group 3 revealed definite but abnormal activity in rigidity and/or tumescence (fig. 3).

813

NOCTURNAL PENILE TUMESCENCE AND RIGIDITY

rn~

4a l'ig

T

X

I

0I, 15

p !UM CM

~I

~. 1,JI~ ,~ ~

5a rig

:~ I:~

X

I

I

T

I

p

. !'lg X

B

B

0,t_ _ _ ____.ll.,-L-J..._--,-1--..,-----,,...---,---.--

1001

A

s

A

s

t~

E

E

J~l----~·~,~~-,uk,__L·~-~-~--1

CM

51

4b T

I

p

B A

s

E

Screen width: 10 hl'S 4c

5c

T I

T

1001 ~ig

I

p

IIi

0I

Ull1,

15

p tuM CM

B

B

A

s

A

s

E

E

. !'lg

1001 J

Y.

---'"!-•l-.-.,........11.ll__lt..mllL.. .,-_ _ _~

Q1UL-~

!UM

151

I

I

I

I

I

CM

Sc!'een width: 10 hl's

5 - ~ Sc!'een width: 10 hl's

FIG. 4. First nonverified result. a, intermittent but mostly decreased rigidity (rig) after high intake of alcohol (8 ounces or 232 ml.). b, normal result when no alcohol had been ingested for several days. c, intermittent decreased rigidity when less alcohol (3 ounces or 87 ml.) was ingested. tum, tumescence.

FIG. 5. Second nonverified result. a, almost total absence of activity after viral illness with fever of 102F (38.8C). b, repeat tracing 11 days later shows decreased rigidity (rig) amplitude at base and tip. c, repeat tracing 4 months later shows decreased rigidity amplitude at base and tip. tum, tumescence.

Of the 17 men nocturnal patterns were reproduced in 15 on repeat testing. Dissimilar patterns on repeat testing occurred in 2 men. One patient had ingested 8 ounces (232 ml.) of alcohol (whiskey) before tracing 1, which revealed dissociation (fig. 4). Tracing 2, after no consumption of alcohol, revealed normal findings, which prompted tracing 3. The patient again drank a

lesser volume of alcohol (3 ounces or 87 ml.) earlier in the evening. The tracing pattern in the early hours was that of abnormal tumescence and rigidity, whereas later the pattern was normal, presumably as the effects of the alcohol waned. In the other patient the nonreproduced pattern was the result of a febrile illness and revealed almost total absence of activity

814

BAIN AND GUAY

(fig. 5). Results of repeat tracings revealed definite but abnormal activity. DISCUSSION

The RigiScan monitor is a useful and convenient tool in the evaluation of male sexual dysfunction. It enhances earlier studies of nocturnal penile tumescence by providing information on rigidity. It should be recognized that this is a clinical tool and not a quantitative research tool. After assessment for and treatment of hormonal, medication-induced or medical causes of impotence, monitoring of nocturnal penile tumescence and rigidity helps to define psychological versus organic causes. Completely normal tumescence and rigidity confirm the probability of normal function and that the impotence is psychological. Conversely, abnormality of tumescence and rigidity suggests organic dysfunction. However, as in patient 2 whose initial tracing was not reproduced, abnormal findings can be influenced by other factors, such as illness and sleeping disorders. The usefulness of monitoring of nocturnal penile tumescence and rigidity in the evaluation of impotence is based on the findings of Karacan8 and Fisher9 et al that erections occur at night during rapid eye movement sleep. However, obtaining an erection requires that sleep be uninterrupted and patients with sleeping disorders, such as sleep apnea, nocturnal myoclonus, disturbing dreams and medications that disrupt rapid eye movement sleep,8•10• 11 may show abnormal activity on monitoring even when erectile potential is normal. On questioning, when patients indicate they have symptoms of disturbed sleep, monitoring may be performed in a sleep laboratory to ensure adequacy of rapid eye movement sleep. In fact, whether monitoring itself disturbs sleep has been questioned. Although 2 or 3 successive nights of monitoring were obtained on each occasion to circumvent this problem, polysomnographic recordings during monitoring have confirmed that the technique does not disturb sleep. 12 Patients were monitored for 4 to 6 nights with concordance between successive and interval readings. The 2 patterns that did not reproduce confirm the sensitivity of monitoring of nocturnal penile tumescence and rigidity to variables that affect sexual function, that is alcohol, illness or medication. Because of the sensitivity of the device it is important to educate patients on abstinence from caffeine, alcohol and medications before monitoring. Voluntary reporting of any abnormal events or failure to abstain on monitored nights is encouraged. The role of the physician in assessing patient compliance with instructions is also important. Tracings of nocturnal penile tumescence and rigidity that are reproducible when repeated before therapeutic intervention further validate the usefulness of the information that the tracings provide. Data from monitoring of nocturnal penile tumescence and rigidity have been used not only to categorize causes of sexual dysfunction but also to provide a guideline of

the minimal dose of intracorporeal vasodilators required and the probability of success or failure when this therapeutic option is chosen.13 Monitoring of nocturnal penile tumescence and rigidity is not intended to replace clinical judgment and it should be regarded as 1 aspect of a comprehensive evaluation. Its limitations have been outlined by the criticisms cited and demonstrated by the 2 patients whose initial patterns were not reproduced. In these 2 patients repeat tracings resulted in recategorization of the underlying problem. In patients who complied with given instructions the monitored results were consistent. We conclude that monitoring of nocturnal penile tumescence and rigidity is a valuable and valid tool to assess impotence. However, when clinical suspicion does not correlate with results of monitoring, detailed questioning about lack of compliance or disturbed sleep patterns and even repeat monitoring may provide added insight. REFERENCES 1. Masters, W. H. and Johnson, V. E.: Human Sexual Inadequacy. Boston: Little, Brown & Co., p. 157, 1970. 2. Shabsigh, R., Fishman, I. J. and Scott, F. B.: Evaluation of erectile impotence. Urology, 32: 83, 1988. 3. Wein, A. J., Fishkin, R., Carpiniello, V. L. and Malloy, T. R.: Expansion without significant rigidity during nocturnal penile tumescence testing: a potential source of misinterpretation. J. Urol., 126: 343, 1981. 4. Condra, M., Fenemore, J., Reid, K., Phillips, P., Morales, A., Owen, J. and Surridge, D.: Screening assessment of penile tumescence and rigidity: clinical test of Snap-Gauge. Urology, 29: 254, 1987. 5. Bradley, W. E., Timm, G. W., Gallagher, J. M. and Johnson, B. K.: New method for continuous measurement of nocturnal penile tumescence and rigidity. Urology, 26: 4, 1985. 6. Burris, A. S., Banks, S. M. and Sherins, R. J.: Quantitative assessment of nocturnal penile tumescence and rigidity in normal men using a home monitor. J. Androl., 10: 492, 1989. 7. Bain, C. L. and Guay, A. T.: Classification of sexual dysfunction for management of intracavernous medication-induced erections. Letter to the Editor. J. Urol., 146: 1379, 1991. 8. Karacan, I., Goodenough, D. R., Shapiro, A. and Starker, S.: Erection cycle during sleep in relation to dream anxiety. Arch. Gen. Psychiatr., 15: 183, 1966. 9. Fisher, C., Gross, J. and Zuch, J.: Cycle of penile erection synchronous with dreaming (REM) sleep: preliminary report. Arch. Gen. Psychiatr., 12: 29, 1965. 10. Pressman, M. R., DiPhillipo, M. A., Kendrick, J. I., Conroy, K. and Fry, J. M.: Problems in the interpretation of nocturnal penile tumescence studies: disruption of sleep by occult sleep disorders. J. Urol., 136: 595, 1986. 11. Schmidt, H. S. and Wise, H. A., II: Significance of impaired penile tumescence and associated polysomnographic abnormalities in the impotent patient. J. Urol., 126: 348, 1981. 12. Morales, A., Condra, M. and Reid, K.: The role of nocturnal penile tumescence monitoring in the diagnosis of impotence: a review. J. Urol., 143: 441, 1990. 13. Fein, R. L.: Classification of sexual dysfunction for management of intracavernous medication-induced erection. J. Urol., 143: 298, 1990.