madman
Super Moderator
Current Techniques for the Objective Measures of Erectile Hardness (2022)
Gabrielle E. Rohrer, MD, Hayley Premo, BS, and Aaron C. Lentz, MD
ABSTRACT
Introduction: One of the most discussed topics in the urology provider’s office is that of the male penile erection. Moreover, this is also a frequent basis for consultation by primary care practitioners. As such, it is essential that urologists are familiar with the various means by which the male erection may be evaluated.
Objectives: This article describes several techniques presently available that may serve to objectively quantify the rigidity and hardness of the male erection. These techniques are meant to bolster information gathered from the patient interview and physical examination to better guide patient management.
Methods: An extensive literature review was performed examining publications in PubMed on this subject, including corresponding contextual literature. Results: While validated patient questionnaires have been routinely employed, the urologist has many additional means available to uncover the extent of the patient’s pathology. Many of these tools are noninvasive techniques that involve virtually no risk to the patient and take advantage of pre-existing physiologic properties of the phallus and its blood supply to estimate corresponding tissue stiffness. Specifically, Virtual Touch Tissue Quantification which precisely quantifies axial and radial rigidity can provide continuous data on how these forces change over time, thus providing a promising comprehensive assessment.
Conclusion: Quantification of the erection allows for the patient and provider to assess response to therapy, aids the surgeon in choice of appropriate procedure, and guides effective patient counseling regarding expectation management.
INTRODUCTION
The male erection is an event commonly discussed in the urologists’ clinic, often with attempts to quantify how erect the patient can become when a sexual encounter is desired. Descriptions of the penile erection and attempts at understanding the physiology of erectile dysfunction have dated back to about 2000 BC when “natural” and “supernatural” etiologies of erectile dysfunction were described in an Egyptian papyrus.1,2 This multifaceted event has been studied and described by the great thinkers Hippocrates, Aristotle, and Leonardo da Vinci.1 While da Vinci was among the first to propose an interaction with blood flow in the physiology of the penile erection, Ambroise Pare accurately outlined the vascular concept in addition to defining penile anatomy. Following this, Dionis noted the importance of retaining penile blood flow to maintain the erection.1,2
Since the 1700s, our understanding of penile anatomy, the physiology of erection, and the pathophysiology of erectile dysfunction have dramatically evolved. Specifically, in the last 6 decades, the study of penile hemodynamics has boomed and resulted in much more information in the field of sexual medicine. The use of cavernosography3 and radiopharmaceutical isotopes4 began in the 1970s to assess the arterial and venous blood flow of the phallus during the erect state. Just a decade later, color duplex ultrasonography was incorporated into this field of study. Along with improved imaging techniques, there was a simultaneous advancement in understanding the physiology of the male erection on the molecular level.
Beyond the primitive functions of sexual pleasure and propagation of the species, the penile erection also serves as an independent predictor of cardiovascular disease5 and death.6 Thus, inquiry regarding erectile function or dysfunction may serve to uncover occult cardiovascular disease. Herein, erectile dysfunction has been defined as the consistent and/or recurrent inability to attain and/or maintain an erection sufficient for sexual function.7 This ailment is of global concern, reportedly affecting more than half of men over the age of 40 years old, according to the Mass Male Aging Study.8 While this was once thought to be a disease of either psychologic or physiologic insult, it is now understood that erectile dysfunction (ED) is multi-factorial and requires a biopsychosocial approach to management.9
ANATOMY AND PHYSIOLOGY OF THE PENILE ERECTION
Knowledge of the anatomy and physiology of the penile erection provides an essential foundation for understanding the advancements in quantifying erection. The human phallus consists of 3 cylindrical bodies- 1 ventral corpus spongiosum containing the urethra and 2 paired dorsal corpora cavernosa, which serve as the erectile bodies (Figure 1). The corpora cavernosa are encased in the tunica albuginea, a paired fibrous sheath, and communicate with one another via an incomplete septum between the bodies. The blood supply to the penis arises from the internal pudendal artery, renamed the penile artery, which is the final branch of the anterior division of the internal iliac artery. This vessel gives off 3 named branches: the bulbourethral artery, the cavernosal artery, and the dorsal artery. The bulbourethral artery supplies the corpus spongiosum, urethra, and glans. The cavernosal artery enters the hilum and gives off tortuous helicine branches as it travels through the center of each erectile body; these branches dilate and straighten with erection.2 Lastly, the dorsal artery travels along the dorsum of the penis between the nerve and vein where it supplies the skin and gives off circumflex arteries to supply the corpora.
The penile erection is a psycho-neuro-endo-vascular event whereby sexual stimulation causes the release of neurotransmitters such as nitric oxide, which results in blood accumulation into the sinusoidal spaces of the corpora cavernosa and corpus spongiosum as well as erectile smooth muscle tissue relaxation.11 As arterial inflow increases, sinusoids engorge, the surrounding tunica expands, and venules within the tunica layers become occluded.12 This venous compression limits outflow and propagates the erection by maintaining intracavernosal pressure. This pressure gives rise to the radial rigidity of the phallus, which allows it to resist deformation when circumferential pressure is applied such as with compressive vaginal forces. Another essential biomechanical property of the phallus is axial rigidity, a function of erectile tissue mechanical properties and penile geometry, which allows the penis to withstand compact loads such as with intromission and pelvic thrusting.
Another key component of the penile erection is parasympathetic innervation via the cavernous nerves, which are branches of the pelvic plexus, originating from S2 through S4.2 Conversely, excitation of the sympathetic pathway, originating between T11 and L2, results in detumescence by way of the superior hypogastric nerve plexus to the pelvic plexus via the hypogastric nerve. This overview of key functional anatomy is irrespective of the many other components driving sexual function such as the various brain centers involved in desire and hormonal effects on libido.
MEASURES OF ERECTILE HARDNESS
*Validated Questionnaires
*Intracavernosal Injection Therapy Testing
*Duplex Ultrasound
*Nocturnal Penile Tumescence Testing
*Assessment of Axial Rigidity With Digital Inflection Rigidometer
*Shear Wave Elastography
*Virtual Touch
*NIRS & Photoplethysmography
*Additional Considerations
CONCLUSION
At present time, there is no single questionnaire or imaging technique that is perfect and all-encompassing. Axial and radial rigidity is synergistic and critical components of the penile erection. Both measures provide information regarding the ability of the erect penis to successfully withstand the penetrative and compressive forces required for sexual intercourse. Virtual Touch Tissue Quantification (VTTQ) is a promising technology that provides information regarding these two aspects of penile rigidity. In the future, it may be a particularly useful tool in the accurate assessment of penile hardness. With further testing and generalization, VTTQ, along with the continued use of validated questionnaires presents an encouraging future for the objective assessment of erectile hardness.
Gabrielle E. Rohrer, MD, Hayley Premo, BS, and Aaron C. Lentz, MD
ABSTRACT
Introduction: One of the most discussed topics in the urology provider’s office is that of the male penile erection. Moreover, this is also a frequent basis for consultation by primary care practitioners. As such, it is essential that urologists are familiar with the various means by which the male erection may be evaluated.
Objectives: This article describes several techniques presently available that may serve to objectively quantify the rigidity and hardness of the male erection. These techniques are meant to bolster information gathered from the patient interview and physical examination to better guide patient management.
Methods: An extensive literature review was performed examining publications in PubMed on this subject, including corresponding contextual literature. Results: While validated patient questionnaires have been routinely employed, the urologist has many additional means available to uncover the extent of the patient’s pathology. Many of these tools are noninvasive techniques that involve virtually no risk to the patient and take advantage of pre-existing physiologic properties of the phallus and its blood supply to estimate corresponding tissue stiffness. Specifically, Virtual Touch Tissue Quantification which precisely quantifies axial and radial rigidity can provide continuous data on how these forces change over time, thus providing a promising comprehensive assessment.
Conclusion: Quantification of the erection allows for the patient and provider to assess response to therapy, aids the surgeon in choice of appropriate procedure, and guides effective patient counseling regarding expectation management.
INTRODUCTION
The male erection is an event commonly discussed in the urologists’ clinic, often with attempts to quantify how erect the patient can become when a sexual encounter is desired. Descriptions of the penile erection and attempts at understanding the physiology of erectile dysfunction have dated back to about 2000 BC when “natural” and “supernatural” etiologies of erectile dysfunction were described in an Egyptian papyrus.1,2 This multifaceted event has been studied and described by the great thinkers Hippocrates, Aristotle, and Leonardo da Vinci.1 While da Vinci was among the first to propose an interaction with blood flow in the physiology of the penile erection, Ambroise Pare accurately outlined the vascular concept in addition to defining penile anatomy. Following this, Dionis noted the importance of retaining penile blood flow to maintain the erection.1,2
Since the 1700s, our understanding of penile anatomy, the physiology of erection, and the pathophysiology of erectile dysfunction have dramatically evolved. Specifically, in the last 6 decades, the study of penile hemodynamics has boomed and resulted in much more information in the field of sexual medicine. The use of cavernosography3 and radiopharmaceutical isotopes4 began in the 1970s to assess the arterial and venous blood flow of the phallus during the erect state. Just a decade later, color duplex ultrasonography was incorporated into this field of study. Along with improved imaging techniques, there was a simultaneous advancement in understanding the physiology of the male erection on the molecular level.
Beyond the primitive functions of sexual pleasure and propagation of the species, the penile erection also serves as an independent predictor of cardiovascular disease5 and death.6 Thus, inquiry regarding erectile function or dysfunction may serve to uncover occult cardiovascular disease. Herein, erectile dysfunction has been defined as the consistent and/or recurrent inability to attain and/or maintain an erection sufficient for sexual function.7 This ailment is of global concern, reportedly affecting more than half of men over the age of 40 years old, according to the Mass Male Aging Study.8 While this was once thought to be a disease of either psychologic or physiologic insult, it is now understood that erectile dysfunction (ED) is multi-factorial and requires a biopsychosocial approach to management.9
ANATOMY AND PHYSIOLOGY OF THE PENILE ERECTION
Knowledge of the anatomy and physiology of the penile erection provides an essential foundation for understanding the advancements in quantifying erection. The human phallus consists of 3 cylindrical bodies- 1 ventral corpus spongiosum containing the urethra and 2 paired dorsal corpora cavernosa, which serve as the erectile bodies (Figure 1). The corpora cavernosa are encased in the tunica albuginea, a paired fibrous sheath, and communicate with one another via an incomplete septum between the bodies. The blood supply to the penis arises from the internal pudendal artery, renamed the penile artery, which is the final branch of the anterior division of the internal iliac artery. This vessel gives off 3 named branches: the bulbourethral artery, the cavernosal artery, and the dorsal artery. The bulbourethral artery supplies the corpus spongiosum, urethra, and glans. The cavernosal artery enters the hilum and gives off tortuous helicine branches as it travels through the center of each erectile body; these branches dilate and straighten with erection.2 Lastly, the dorsal artery travels along the dorsum of the penis between the nerve and vein where it supplies the skin and gives off circumflex arteries to supply the corpora.
The penile erection is a psycho-neuro-endo-vascular event whereby sexual stimulation causes the release of neurotransmitters such as nitric oxide, which results in blood accumulation into the sinusoidal spaces of the corpora cavernosa and corpus spongiosum as well as erectile smooth muscle tissue relaxation.11 As arterial inflow increases, sinusoids engorge, the surrounding tunica expands, and venules within the tunica layers become occluded.12 This venous compression limits outflow and propagates the erection by maintaining intracavernosal pressure. This pressure gives rise to the radial rigidity of the phallus, which allows it to resist deformation when circumferential pressure is applied such as with compressive vaginal forces. Another essential biomechanical property of the phallus is axial rigidity, a function of erectile tissue mechanical properties and penile geometry, which allows the penis to withstand compact loads such as with intromission and pelvic thrusting.
Another key component of the penile erection is parasympathetic innervation via the cavernous nerves, which are branches of the pelvic plexus, originating from S2 through S4.2 Conversely, excitation of the sympathetic pathway, originating between T11 and L2, results in detumescence by way of the superior hypogastric nerve plexus to the pelvic plexus via the hypogastric nerve. This overview of key functional anatomy is irrespective of the many other components driving sexual function such as the various brain centers involved in desire and hormonal effects on libido.
MEASURES OF ERECTILE HARDNESS
*Validated Questionnaires
*Intracavernosal Injection Therapy Testing
*Duplex Ultrasound
*Nocturnal Penile Tumescence Testing
*Assessment of Axial Rigidity With Digital Inflection Rigidometer
*Shear Wave Elastography
*Virtual Touch
*NIRS & Photoplethysmography
*Additional Considerations
CONCLUSION
At present time, there is no single questionnaire or imaging technique that is perfect and all-encompassing. Axial and radial rigidity is synergistic and critical components of the penile erection. Both measures provide information regarding the ability of the erect penis to successfully withstand the penetrative and compressive forces required for sexual intercourse. Virtual Touch Tissue Quantification (VTTQ) is a promising technology that provides information regarding these two aspects of penile rigidity. In the future, it may be a particularly useful tool in the accurate assessment of penile hardness. With further testing and generalization, VTTQ, along with the continued use of validated questionnaires presents an encouraging future for the objective assessment of erectile hardness.
