9.1 Introduction

Even before the use of penile Doppler ultrasound (PDU) with intracavernous injection of vasoactive agents in the evaluation of erectile dysfunction (ED), audiovisual sexual stimulation (AVSS) was already performed. As previously discussed in Chap. 1, nocturnal penile tumescence (NPT) testing was once the gold standard to ED evaluation. It was thought to be useful in distinguishing psychogenic from organic ED, as it was used to obtain an accurate indication of the quantity and quality of erections that normally occur during the alpha phase of the sleep. In fact, identification of psychogenic ED has always been a concern to clinicians and researchers, who have always tried to distinguish it from organic ED. Then, NPT started to be replaced by penile plethysmography (PP) in awake individuals. Pulse of the dorsal penile artery and changes in penile circumference were measured during erotic film stimuli as showed in Fig. 9.1 [1].

Fig. 9.1
An illustration represents a man seated in front of a T V where his erected penis is connected to a monitoring system and the erection is analyzed.

Penile pletismography [1]. Erection monitored while patient is isolated in front of a video monitor with erotic film

Full size image

Sexually induced erections are distinct from sleep erections. Sexually generated erections are a combination of erotic and reflex erection activity, whereas the mechanism underlying the initiation and maintenance of sleep erections remains unexplained. The primary distinction between sleep and sexually induced erections is neurological, since both erections involve the identical penile and vascular structural components [2]. A complex set of cortical and subcortical brain regions, including the Anterior and Middle Cingulate Cortex, the Insula, the Claustrum, and the Hypothalamus, have been described in a number of neuroimaging studies conducted in healthy volunteers over the last decades using visual sexual stimulation [3]. In 1980, Kockott et al. pioneered the use of erotic movies in the evaluation of sexual disorders [4]. They studied penile response by erotic film stimuli in men with ED in comparison to a control group of men without ED. Variations in blood pressure, penile erection duration, latency, and amplitude were assessed in 42 individuals, and the group of men with ED had considerably worse parameters. After that, other investigators have also advocated the use of AVSS [5, 6], as it may enhance parasympathetic tone by inhibiting sympathetic tone, which leads to a better erection than with a vasoactive agent injection alone [7, 8].

9.2 Audiovisual Sexual Stimulation and Penile Doppler Ultrasound

In order to obtain consistent result in penile hemodynamic evaluation with PDU, it is mandatory to have complete smooth muscle relaxation (CSMR) of the erectile tissue. This is crucial to avoid false positive results [9]. A mistaken diagnosis of arterial insufficiency (AI) and/or corporal venous occlusive disorder (CVOD) may result from excessive sympathetic discharge as it prevents complete CMSR in response to vasoactive drugs [10, 11]. From all possible strategies to allow CSMR, redosing of intracavernous vasodilators was introduced as a pivotal strategy [11]. However, de Meyer and Thibo [12] suggested that occasionally redosing alone was not sufficient to induce CSMR in their prospective study measuring the effect of a redosing protocol on intracavernous pressure.

In this scenario, AVSS has also been described as a means to increase sexual arousal, which could potentially lead to lower rates of false diagnoses on PDU. Katlowitz et al. reported that the majority of men in their sample of 25 patients had improved penile hemodynamic parameters on PDU examination following AVSS [7]. It seems reasonable to infer that the whole environment of PDU to assess erectile function of men with ED is stressful, and AVSS can be considered a tool to simulate an environment closer to the bedroom scenario. From a biological perspective, it is thought that AVSS leads to an increase in parasympathetic output, resulting in better vasodilation and relaxation of the corpora cavernosa and consequently in a more rigid erection than with ICI alone [7, 8].

Montorsi et al. [13] compared the redosing technique versus ICI plus AVSS and reported 87% maximum rigidity with vasoactive injection and AVSS against 47% with up to 1 redosing of alprostadil 10mcg. Similar findings were reported by Pescatori et al. [14], who demonstrated that 80% of the patients with AVSS vs. 33% of the patients without AVSS achieved CSMR after the first ICI. The same study also suggested that AVSS could reduce the need of redosing, possibly reducing the chance of prolonged erections and/or priapism. Interestingly, in this study some non-responders to redosing did still have complete CSMR when AVSS was added.

9.3 Lessons from a Prospective Study

At our institution, we have also conducted a prospective study to evaluate AVSS during PDU tests [15]. The study’s objective was to assess the impact of the AVSS during PDU in ED patients, looking at how this strategy affected hemodynamic parameters and final diagnosis. Men who were heterosexual and older than 18 who had an ED diagnosis were invited to participate. Partnered sexual activity, a history of ED for at least 6 months, and a self-reported poor response to phosphodiesterase type 5 inhibitors were the inclusion criteria. Patients who had previously undergone PDU studies or who were previously or currently using ICI as an ED therapy were excluded. A total of 40 patients were included and each patient underwent2 PDU examinations with and without AVSS 7 days apart from each other with a fixed dose of ICI containing 20 mcg of alprostadil. To avoid sequential bias and minimize the accommodation effect of repeat testing in PDU, sessions were randomized so that half of the patients had AVSS on the first examination and the other half on the second.

There was a considerable rise in the cavernous artery diameters after ICI in all sessions, but it was more obvious with AVSS scanning, regardless of the session order and laterality. End diastolic velocity (EDV) and resistance index (RI) had better values with AVSS regardless the session order. Those parameters are an indirect way to measure corporal smooth muscle relaxation. The proportion of patients whose final PDU diagnosis was altered due to AVSS intervention was 4/40 (10%, 95% confidence interval [CI]: 2.8–23.7%). Three of the 12 patients diagnosed with CVOD by the PDU without AVSS were considered normal by PDU with AVSS (25.0%, 95% CI: 5.5–87.2%). Among the 4 patients diagnosed with AI by the first PDU without AVSS, one became normal by the second PDU with AVSS (25.0%, 95% confidence interval [CI]: 0.6–80.6%).Out of 28 patients with normal PDU, 50% had negative EDV without AVSS compared to 67.9% with AVSS (P = 0.3). When we split those numbers up by session, we discovered that in the second session, 88.2% of patients with AVSS and 72.7% of patients without AVSS had zero or negative EDVs. In the second session, when we isolated negative EDV, we discovered 76.5% vs. 36.4% of the patients with AVSS and without AVSS, respectively.

Patients who performed the second session without AVSS had higher PSV values, reinforcing the idea that patient accommodation may have an impact on repeat PDU parameters. The erectile tissue relaxation response may not be fully attained even in the presence of AVSS when a patient undergoes PDU investigations for the first time because of an elevated adrenergic tone brought on by apprehension and worry. This is a prevalent source of bias in the PDU research; as such design may unintentionally overestimate the impact of any given intervention. The randomized use of AVSS in various session orders was pertinent addition to the literature, as only one previous study has had a similar design to prevent sequential bias [5].

Additionally, we showed that AVSS led to a higher rise in cavernous artery diameters. Although it is not the best metric to show adequate blood flow to the penis, it could be used as a substitute marker for cavernosal artery vasodilation in response to a similar dose of a vasoactive drug.

Theoretically, improving EDV and RI values would be the most pertinent effect of adding AVSS in the PDU practice because decreased smooth muscle relaxation is more likely to have an impact on intracavernous pressure regardless of PSVs.

Kuo et al. [5] discovered considerably superior penile hemodynamic parameters by combining AVSS and ICI. Pescatori et al. [14] confirmed that patients stimulated with AVSS were at least twice as likely to have normal PSVs, and they also observed similar findings. Better EDV values were also seen with AVSS by Tang et al. [6], but in this study, AVSS sessions were always repeated.

In the PDU session with AVSS, a greater percentage of men had negative EDVs (67.9% vs. 50%). Similar to the proportions of zero or negative EDVs, the second session with the AVSS had a greater absolute value than the second session without the AVSS (88.2% vs. 72.7%).

It is noteworthy to note that even in individuals with EDs that were severe, we discovered negative EDVs and high RI values. Even men with moderate or severe ED may be affected by psychogenic factors and have normal Doppler parameters.

The ability of AVSS to alter PDU diagnosis was the most important finding of our research. We have found 4 patients (25%) had a normal PDU evaluation with ICI plus AVSS, out of the 16 patients with aberrant hemodynamics according to PDU with ICI alone (12 with CVOD and 4 with AI). In a similar vein, Kuo et al. [5] observed that the addition of AVSS resulted in 12% diagnostic change across the board and 18% altered PDU studies. These findings might improve the patient’s prognosis because an abnormal PDU typically necessitates more intrusive treatments.

9.4 Recommendations of AVSS

After discussing multiple potential benefits of AVSS, it is the authors’ recommendation to include AVSS in the routine of penile hemodynamic studies. There are no reported side effects of short time use of this strategy during PDU. However, it is important to highlight that it might be a sensitive issue in some circumstances and PDU examiners must be careful when offering in-office AVSS.

First, there might be religious restrictions to pornography consumption or masturbation. So, it is important to capture some of these patient’s characteristics during initial sexual history. Permission should always be obtained prior to AVSS, and it is important to explain the importance of mimicking a sexual scenario to obtain CSMR and the best possible outcome. An important argument is that AVSS will also decrease the need for redosing and, therefore, the incidence of potential complications such as prolonged erections and priapism.

Another important aspect that should be inquired previously is sexual orientation and/or preferences. Therefore, it is important to have a variety of options for diverse patients and not only heterosexual content. Beware that with the advent of smartphones, some patients might prefer to use their own collection or to visit an online website of preference. Finally, it is important to be cautious about AVSS content, avoiding violence or other unpleasant depicts of sexual activity that might have the opposite effect in some patients. Having a full range of options that any patient can browse through is perhaps the ideal scenario.

9.5 Conclusion

AVSS has been characterized in the literature as beneficial in the evaluation of ED because it places the patient in a more realistic sexual situation and lowers the adrenergic tone, resulting in a higher rate of CSMR during PDU. The combination of ICI and AVSS may be an even more effective erectogenic strategy than high doses of ICI alone in the PDU setting. This helpful tool improves PDU accuracy and may be crucial for a precise diagnosis. It is the authors’ recommendation that AVSS be routinely offered to patients during PDU.