intercourse

International Journal of Impotence Research (2006), 1–4
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ORIGINAL ARTICLE
Are consecutive nightly recordings required for valid evaluation
of sleep-associated erections?
A Greenstein, NJ Mabjeesh, M Sofer, I Kaver, H Matzkin and J Chen
Department of Urology, Tel-Aviv Sourasky Medical Center, Sackler Faculty of Medicine, Tel-Aviv University, Tel Aviv,
Israel
We questioned the need for more than one RigiScan recording for accurate assessment of sleepassociated
penile erections and determine the necessity of consecutive nightly recordings for valid
evaluation of sleep-associated erections. Men complaining of erectile dysfunction (ED) and referred
to RigiScan evaluation for the first time participated. Recordings were performed at the patient’s
home during two consecutive nights, and data on test time, number of erections, erection duration,
minimal and maximal base and tip tumescence and rigidity were retrieved for both nights. Normal
erectile function was defined with the recording of at least one erection (70 out of 100% tip rigidity
lasting for at least 10 min during either night). The main outcome measures were RigiScan
recordings. Group 1 consisted of 29 men (mean age 42.4713.8 years, range 22–71) who had normal
erections, all during the first night. Group 2 consisted of 26 men (mean age 48.6713.5 years, range
25–70) who failed to fulfill both criteria for normal erection. In Group 2, only the values for penile
base rigidity and erection duration were normal during the first night: the parameters of maximal
base tumescence, tip rigidity, number of effective erections and duration of effective erections that
were impaired during the first night were significantly worse (Po0.01) during the second night. The
required information for the diagnosis of psychogenic ED was obtained during the first night
in 450% of the participants. Men with normal erections during the first night can be spared the
inconvenience and cost of re-testing. Consecutive night recording should be reserved for patients
whose recorded data during the first night did not fulfill the criteria for normal erection.
International Journal of Impotence Research advance online publication, 3 August 2006;
doi:10.1038/sj.ijir.3901512
Keywords: RigiScan; sleep-associated erections; erectile function
Introduction
The treatment of men with erectile dysfunction (ED)
is currently based on patients’ preferences and
goals. 1 In selected cases, it is necessary to differentiate
between psychogenic and organic causes of
ED for appropriate patient management. Night
recordings of spontaneous erections not induced
by deliberate sexual stimulation provide objective
data about the integrity of the erectile mechanism
while excluding the psychogenic impact of intercourse.
2 Since its introduction two decades ago, the
NPT-RigiScan (Dacomed Corporation, Minneapolis,
MN, USA) has become the principal tool for
evaluating penile erection. 3 The device provides
data on penile rigidity and tumescence as well as
the number, duration and timing of erections, and
testing can take place in the privacy of the subject’s
home setting. Because of the possibility of variations
in the recorded information as a result of the need to
adapt to the device, 4 recordings are routinely carried
out during several consecutive nights, followed by
downloading of the data after at least two nights of
home recordings.
Given the expense of conducting multiple tests in
an era of cost-oriented medicine, we evaluated the
need for two recordings in accurately assessing
sleep-associated penile erections.
Correspondence: Dr A Greenstein, Department of Urology,
Tel-Aviv Sourasky Medical Center, Sackler Faculty of
Medicine, Tel-Aviv University, 6 Weizman Street, Tel Aviv
64239, Israel.
E-mail: surge04@post.tau.ac.il
Received 15 May 2006; accepted 28 June 2006
Materials and methods
Population
This is a retrospective study of patients referred for
evaluation of nocturnal erections to distinguish

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Optimal evaluation of sleep-associated erections
A Greenstein et al
between psychogenic and organic ED. Men evaluated
at the ED outpatient clinic participated in the
study. They first underwent a medical and sexual
history, physical examination, psychological profile
and endocrine evaluation for the etiology of ED, and,
when deemed necessary, were referred to RigiScan
evaluation. Patients with total testosterone blood
level o4.0 ng/ml, on two blood samples, were
excluded. Patients graded their sexual function
using the International Index of Erectile Function
(IIEF) questionnaire. 5 These patients referred to
RigiScan evaluation reported an erectile function
(EF) score of o26 in the IIEF questionnaire. None
of the participants had been evaluated by the device
in the past.
Measurements
RigiScan measurements were performed at the
individual’s home during two consecutive nights.
Consumption of alcohol and use of medications on
the eve of each evaluation were forbidden. Subjects
were instructed to place the base band at the penile
base and the tip band proximal to the corona. The
recording unit was returned to the clinic following
the second night’s recording. Data of both nights
were downloaded to the clinic’s computer.
Retrieved data consisted of test time, number of
erections, erection duration (minutes), minimal and
maximal base tumescence, base rigidity, minimal
and maximal tip tumescence and tip rigidity.
Rigidity is reported as percentage of a score of
100%, which means that a full rigid erection with
no shortening of the band had been recorded. The
rigidity measurement is reduced from 100% by
2.3% for each 5 mm of band shortening (i.e., less
rigidity). 6 A normal erection was defined as a score
of X70% and lasting for a minimum of 10 min on
the penile tip recording.
Statistics
Data were analyzed using analysis of variance with
repeated measures. Significance was set at Po0.05.
Group 2 consisted of 26 men aged 48.6713.5
years (range 25–70) who had impaired quality of
erection (tip rigidity o70% out of 100% rigidity
and/or an erection not lasting for 10 min) that was
recorded on both nights (documented ED). In this
group, six men had one morbidity (hyperlipidemia,
hypertension, no insulin-dependent diabetes)
potentially contributing to their sexual dysfunction,
and another five had more then one comorbidity.
None of the patients with impaired quality of
erection during the first night exhibited normal
erectile parameters during the second night. Six of
the 26 patients in Group 2 with impaired quality of
erection had 70% out of 100% tip rigidity but not
lasting for 10 min. There was no statistically significant
difference in the ages and comorbidities or
ED scores on the IIEF questionnaire (18.071.8 and
17.072.1, respectively) of both groups. RigiScan
data of Groups 1 and 2 are presented in Tables 1
and 2, respectively.
The first night recordings were better than those
obtained during the second night in both groups,
with maximal base tumescence, base and tip
rigidity, number of effective erections, duration of
effective erections having been significantly worse
during the second night (Po0.01).
Table 1 Normal EF (Group 1, n ¼ 29)
Parameter Night 1 Night 2 P-value
Number of erections 3.271.1 2.371.1 o0.001
Number of effective erections 2.071.2 1.171.1 o0.002
Total test time (minutes) 381.1786.7 285.57103.5 o0.006
Erection time 28.5711.1 19.1714.0 o0.004
Minimal base tumescence 6.970.6 6.870.7 o0.44
Maximal base tumescence 12.371.6 11.371.4 o0.005
Base rigidity 91.177.2 83.2717.9 o0.01
Minimal tip tumescence 6.270.6 6.370.7 o0.66
Maximal tip tumescence 10.471.6 9.771.4 o0.02
Tip rigidity 85.578.51 72.7725.9 o0.021
Abbreviation: EF, erectile function.
Results
A total of 55 men (mean age 45713.5 years, range
22–71) participated in the study.
Group 1 comprised of 29 men (52.7%) aged
42.4713.8 years (range 22–71) who had at least
one normal recorded erection (tip rigidity X70%
lasting for 10 min or more) during the first night of
recording. In this group, five men had one morbidity
(hyperlipidemia, hypertension, no insulin-dependent
diabetes) potentially contributing to their
sexual dysfunction, and another eight had more
then one comorbidity.
Table 2 Pathological EF (Group 2, n ¼ 26)
Parameter Night 1 Night 2 P-value
Number of erections 2.271.2 1.771.2 o0.045
Number of effective erections 0 0
Total test time (minutes) 352.6794.3 290794.6 o0.003
Erection time 14.9713.2 10.5710.9 o0.04
Minimal base tumescence 7.070.7 7.070.8 o0.7
Maximal base tumescence 11.571.8 10.371.5 o0.007
Tip rigidity 53.8731.3 48.8730.3 o0.49
Base rigidity 76.8722.6 69.1724.8 o0.18
Minimal tip tumescence 6.270.7 6.270.6 o0.4
Maximal tip tumescence 9.671.7 8.671.1 o0.003
Abbreviation: EF, erectile function.
International Journal of Impotence Research

Discussion
Obtaining and maintaining an erection requires
anatomical and physiological integrity of the penile
erectile mechanism. In addition, following an erotic
stimulus, the brain launches a cascade of events
leading to functional erection, thus psychological
inhibitions may inhibit this chain of events, resulting
in psychogenic ED. The RigiScan was introduced
as a practical tool to help establish or rule out
the diagnosis of psychogenic ED by measuring
sleep-associated erections, which are supposedly
free of the psychogenic variables that may be
impeding normal intercourse. Assessment of EF is
now usually carried out by questionnaires rather
than by physiologic tests. 5 There are, however,
clinical situations in which it is important to
distinguish between organic and psychogenic ED.
For instance, psychogenic ED may preclude the
implementation of invasive therapy, such as selfinjections
of vasoactive medications into the penis,
or non-reversible measures, such as penile prosthesis
implantation in otherwise apparently healthy
men.
The RigiScan recording is carried out in an
ambulatory setting at home. Some men find the
recording unit’s attachments and the two penile
bands that apply timed pressure over the penis to
record rigidity cumbersome. Thus, their sleep is of
poorer quality and the results of the recordings may
be spurious and lead to an incorrect diagnosis. For
this reason, it is customary in clinical practice 7 as
well as in research settings 8,9 to obtain recordings
during several consecutive nights in order to
eliminate the ‘first-night effect’ and to allow the
patient to adapt and become accustomed to wearing
the device.
Regardless of the definition of ‘functional erection’
recorded by the RigiScan, 6,7 it is agreed that
a recording of at least one functional erection is
consistent with intact penile erectile mechanism
and that some psychological factor is the main
contributor to the ED. Owing to the difference in
terms of age between the enrolled patients and the
healthy volunteers data reported previously, 9 we
used even more strict criteria for ‘functional erection’.
In our study, we defined ‘functional erection’
as a score of X70% for the rigidity lasting for a
minimum of 10 min on the penile tip recording,
whereas Gingell used 60% rigidity for 4or ¼ 4 min
to define adequate response to sildenafil. 10
The findings of our current study demonstrated
that the required information for establishing the
diagnosis of organic versus psychogenic ED was
obtained during the first night in more than half of
the participants. Patients who failed to have normal
erection during the first night also failed to have
normal erection during the second night. Moreover,
these first-night recorded data on maximal base
tumescence, base and tip rigidity, number of
Optimal evaluation of sleep-associated erections
A Greenstein et al
effective erections and duration of effective erections
were significantly better than the ones
obtained during the second night. Careful and
comprehensive instructions for applying the RigiScan
were given by one of the authors (JC) who is an
expert in the use of this device: it is possible that the
adaptation to the RigiScan was optimal during
the first night of recording of our patients because
they were so well instructed. Moreover, because
testosterone affects sleep-related erections, hypogonadal
patients were excluded from the study. 11
However, when extensive study using a sleep
laboratory setting is used (three nights using
RigiScan in a sleep laboratory), it is possible
that different data will be obtained. 12 However,
when even one ‘functional erection’ is recorded
further recording are of only scientific interest.
Nevertheless, study population needs more extensive
evaluation before precise decisions regarding
ED etiology is made.
Conclusion
Information required for establishing the diagnosis
of psychogenic ED was acquired from the recording
obtained during the first night in more than half of
the participants. We recommend that the recorded
data of the first night be downloaded and evaluated
before routinely using the device a second time.
Consecutive night recordings should be reserved for
those patients whose initial recordings failed to
show any functional erection or had technical
errors. Men with good-quality erections during the
first night’s recording will be spared the inconvenience
of another test, and costs associated with ED
evaluation may be reduced.
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International Journal of Impotence Research