(1)
Pediatric Surgery, Al Azher University, Cairo, Egypt
Abstract
Penile torsion is a debatable condition as no consensus exists on its definition, or on its management. This manuscript is designed a state-of-knowledge about the condition
Keywords
Penile torsionChordeePenile curvatureIntroduction
Penile torsion is a debatable condition as no consensus exists on its definition, or on its management. This manuscript is designed a state-of-knowledge about the condition
Definition
Congenital penile torsion is a rotational defect of the penile shaft, resulting in an abnormal curvature of the penis without aberrant position of the meatus. With this condition, the penis appears twisted on its axis [1]. The degree of torsion is measured as the angle between a line passing through the urethral meatus and the midline of the scrotum [2].
Torsion exists as a stand-alone disease, but is very often associated with other congenital penile malformations: Torsion is a classical feature of severe hypospadias, and is described in that context as penile ‘chordee [3]’. Torsion can also be observed in buried penis and epispadias. No clear difference is made in the literature between penile curvature and penile torsion, both terms being frequently used for both bending of the penis or rotation of the penis. Many authors call bending of the penis: curvature, while rotation is more often used when there is torsion on the penis axis. Chordee is usually used in the context of hypospadias, but no consensus exists about those terms. A first step toward a better understanding of the pathology would be to clearly define terms.
In this chapter, we will use the following definitions:
Torsion: Twist, clock-wise or counter-clockwise, of the penis on its axis. The degree of torsion is measured as the angle between a line passing through the urethral meatus and the midline of the scrotum.
Curvature: Bending of the penis in an erect state in any direction. The penis is not rotated on its axis.
Chordee: Retraction of the penis due to under-development of penile tissues. It is observed on the ventral side in hypospadias, and on the dorsal side in epispadias.
12.1 Historical Background
Torsion as a stand-alone condition was first described by Siever in 1926, who mentioned rotation of the penis associated with hypospadias [5]. We would nowadays define it as chordee.
Penile torsion was first described in 1973 by Horton and Devine [6]. They used also the word chordee. They historically described three types of penile torsion: in the first type they described, the corpus spongiosum was absent on the distal part of the penis, with an ectopic meatus, which is nowadays considered as a classical feature of hypospadias [6]. This first type of ‘torsion’ as described by Horton and Devine would nowadays probably be classified as distal hypospadias with important chordee.
In their second type of torsion Horton and Devine described a fully developed urethra and corpus spongiosum but an important bending of the penis on the ventral side, due do ‘retraction of the superficial dartos fascia’ [6]. It would nowadays probably be classified as chordee without hypospadias, or ‘hypospadias sine hypospadias’. Important chordee without ectopic meatus and with a complete prepuce is often considered as a separate condition and has many names: hypospadias without hypospadias, chordee sine hypospadias, and congenital penile curvature. As it is almost always associated with hypoplasia of the corpus spongiosum, even if the meatus is orthotopic, it should probably still be regarded as part of the hypospadias spectrum.
A third type was described by Horton and Devine as ‘skin chordee’, or retraction due to shortage of skin. It would be nowadays probably also be classified as chordee without hypospadias [6].
Later on, a different type of torsion was introduced by Kramer, who firstly proposed a disproportion in corporal bodies as explanation for penile torsion [7]. He also used the word chordee, even if the condition was not related to hypospadias.
Nowadays, the conditions of chordee without hypospadias and torsion remain broadly discussed, without reaching some clear consensus on its stand-alone condition, or associated with hypospadias or other congenital penile pathologies [8, 9]. Many congenital penile malformations are associated with torsion and chordee: hypospadias, buried penis, epispadias,… Epispadias has of course, due to its embryologic origin, an important component of penile torsion, as both corporal bodies are malrotated, but this is beyond the scope of this chapter.
12.2 Incidence
Torsion has debatable incidence, as some authors consider penile torsion and curvature as part of the spectrum of the hypospadias condition and mix it with chordee [10]. Series investigating purely penile torsion without associated condition are very scarce.
As patients are usually asymptomatic and have few complaints, the incidence of penile torsion might be underestimated [11]. Varying studies report incidence ranging from 1.7 % of males, to 27 % [12, 13]. During childhood, some mothers report observing torsion, but usually it is then only noticed when the curvature is very important. Curvature is often recognized quite late during childhood, at the beginning of puberty, as it is most visible in erection.
Besides the congenital condition, torsion might be acquired after penile surgery, where extensive degloving of the penile shaft is undertaken. In this chapter, we will only consider congenital penile torsion/curvature/chordee.
12.3 Pathophysiology
The pathophysiologic mechanisms leading to penile torsion still need to be unveiled. Embryonal studies have shown penile curvature is a normal phase in the genital tubercle development [14–16]. During the masculinization of the primitive genital tubercle, progressive elongation of the penis seems to be asymmetrical, with initial ventral curvature [14]. Kaplan described after anatomical studies of fetuses that 89 % of the fetuses at different gestational ages presented ventral penile curvature [14]. He described it as chordee, even if it was not associated with hypospadias.
Based on further studies, Baskin proposed that chordee without hypospadias, which could also be considered as curvature of the penis downwards, might be the result of an arrest in development [17].
Kramer proposed a different concept and stated that torsion or bending is the result of asymmetrical growth of corporal bodies [7].
Recent studies have shown that the dartos, which is the smooth muscle layer lying under the skin, might be responsible for chordee/curvature, associated or not with other congenital penile malformations [18]. The dartos tissue is considered a superficial fascia, located immediately under the genital skin, originating in Scarpa’s abdominal fascia, and in Colle’s perineal fascia [19]. The composition of fibro muscular dartos tissue along the penile shaft determines elasticity of the subcutaneous tissue and the skin mobility. Any structural change in organization of these components may influence these characteristics, and might therefore be responsible for torsion/chordee.
Resection of the dartos tissue usually makes the penis straight in hypospadias and unhides the penis in buried penis, suggesting the dartos tissue is involved in pathophysiology of penile chordee/torsion. This quite large study, performed on a large prospective cohort of children undergoing primary penile surgery, with healthy children undergoing circumcision as control, proved that the level of disorganization of the dartos tissue in congenital penile malformation strongly correlated with the severity of the clinical penile malformation [18].
We believe chordee and torsion probably have a same pathophysiologic mechanism, induced by dartos tissue aberrant development. We believe also curvature is caused by another mechanism: curvature is caused by an asymmetrical development of the corporal bodies. More studies however are needed to confirm this idea.
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