Cremaster muscle thickening: the anatomic difference in men with testicular retraction due to hyperactive cremaster muscle reflex

Abstract

The objective was to assess whether men suffering from testicular retraction secondary to hyperactive cremaster muscle reflex have an anatomic difference in the thickness of the cremaster muscle in comparison to men who do not have retraction. From March 2021 to December 2021, 21 men underwent microsurgical subinguinal cremaster muscle release (MSCMR) on 33 spermatic cord units, as 12 of them had bilateral surgery, at Surgicare of South Austin Ambulatory Surgery Center in Austin, TX, USA. During that same time frame, 36 men underwent subinguinal microsurgical varicocele repair on 41 spermatic cord units, as 5 were bilateral for infertility. The thickness of cremaster muscles was measured by the operating surgeon in men undergoing MSCMR and varicocele repair. Comparison was made between the cremaster muscle thickness in men with testicular retraction due to a hyperactive cremaster muscle reflex undergoing MSCMR and the cremaster muscle thickness in men undergoing varicocele repair for infertility with no history of testicular retraction, which served as an anatomic control. The mean cremaster muscle thickness in men who underwent MSCMR was significantly greater than those undergoing varicocele repair for infertility, with a mean cremaster muscle thickness of 3.9 (standard deviation [s.d.]: 1.2) mm vs 1.0 (s.d.: 0.4) mm, respectively. Men with testicular retraction secondary to a hyperactive cremaster muscle reflex demonstrate thicker cremaster muscles than controls, those undergoing varicocele repair. An anatomic difference may be a beginning to understanding the pathology in men who struggle with testicular retraction.

INTRODUCTION

Chronic orchialgia is a common urologic complaint, and it is estimated to affect around 100 000 men each year.1 Despite its prevalence, the clinical presentation may vary, and an underdiagnosed cause of chronic testicular pain may be a hyperactive cremaster muscle reflex. In these men, significant pain can be caused by vigorous testicular retraction up to the external inguinal ring. The excessive retraction most commonly occurs during sexual activity, exercise, and in cold temperatures. It is typical for the man to have to push the testicle back down to a dependent position in the scrotum at these times, and discomfort or pain may linger following the retraction episode. The diagnosis is made primarily by history, with physical examination supporting the diagnosis.

Testicular retraction due to hyperactive cremaster muscle reflex has been successfully treated with microsurgical subinguinal cremaster muscle release (MSCMR).2 However, this malady remains poorly studied, and an anatomic etiology for this retraction has not been investigated. To elucidate the cause of this bothersome retraction, this study examines cremaster muscle thickness in men with testicular retraction due to a hyperactive cremaster muscle reflex in comparison to a control group.

PATIENTS AND METHODS

From March 2021 to December 2021, 21 men underwent MSCMR on 33 spermatic cord units, as 12 of them required bilateral surgery for cremaster muscle release at Surgicare of South Austin Ambulatory Surgery Center in Austin, TX, USA. During that same time frame, 36 men underwent subinguinal microsurgical varicocele repair on 41 spermatic cord units, as 5 were bilateral, for infertility. Men with varicoceles with associated scrotal pain were excluded. All 65 spermatic cord units were operated on by a single fellowship-trained reproductive urologist (PKK) with an expertise in microsurgery. After obtaining Institutional Review Board (IRB) exemption from St. David’s Healthcare IRB (Approval No. 185492-1), all men had cremaster muscle thickness measured by the operating surgeon. Informed consent for obtaining data for the research study was included in all patients’ surgical consent. The cremaster muscle thickness in men with testicular retraction due to a hyperactive cremaster muscle reflex undergoing MSCMR was compared to the cremaster muscle thickness in men undergoing varicocele repair for infertility with no history of testicular retraction or pain, which served as an anatomic control. For men to be considered as surgical candidates for MSCMR, they had to have a history consistent with hyperactive cremaster muscle reflex, negative urinalysis, negative scrotal ultrasound, the demonstration of vigorous testicular retraction with Valsalva on physical examination, and no other anatomic or pathologically identifiable etiology except the testicular retraction. For candidacy for varicocele repair, the men presented with infertility, abnormal semen parameters, and a clinically palpable varicocele.

The surgical technique for MSCMR has previously been described.2 In brief, a 1.5 cm transverse subinguinal incision is made overlying the external inguinal ring. Dissection is carried down through the subcutaneous tissues and Scarpa’s fascia is incised allowing for the isolation of the spermatic cord. Under microsurgical magnified visualization, the cremaster muscle is divided circumferentially with electrocautery, taking great care to leave all veins, nerves, gonadal arteries, lymphatics, and the vas deferens intact, while taking great efforts to not leave any wisps of muscle intact which could result in failure. After completion of circumferential division of the cremaster muscle, the spermatic cord is dropped back into the anatomic position and the incision is closed in layers. Subinguinal microsurgical varicocele repair has been well described with a very similar approach, except only the anterior cremaster muscle is incised and the dilated varices are ligated and divided.3–7 In both surgeries, the cremasteric arteries may be sacrificed, but the deferential and gonadal arteries are preserved.

The cremaster muscle thickness was measured by sharply dividing the muscle to prevent electrocautery energy-induced distortion of the tissue thickness. Three separate areas of each cremaster muscle were sharply divided in each spermatic cord and measured with the mean measured thickness recorded. The measurements obtained were the dimensions from the outer most part of the cremaster muscle, measuring inwards towards the contents of the spermatic cord to the inner limit of the cremaster muscle. The measurements were typically consistent for the muscle thickness throughout each individual spermatic cord in all three measurements. With the men under general anesthesia with no cause for Valsalva, the testis was in the anatomically normal position in the dependent portion of the scrotum during surgery, so there was no artifact of a retracted testis at the time of surgery causing possible bundling or thickening of the muscle. The cremaster muscle thickness of men undergoing MSCMR was compared to the control, men undergoing subinguinal microsurgical varicocele repair. Results are reported as mean ± standard deviation (s.d.). Statistical analyses were performed by Mann–Whitney U test, with P < 0.05 considered statistically significant.

RESULTS

The mean age of the 21 men who underwent MSCMR on 33 spermatic cord units for testicular retraction secondary to hyperactive cremaster muscle reflex was 43 (s.d.: 12) years, and the mean age of the 36 men who underwent subinguinal microsurgical varicocele repair on 41 spermatic cord units for infertility was 33.4 (s.d.: 11.6) years. The cremaster muscle in men with testicular retraction due to a hyperactive cremaster muscle reflex who underwent MSCMR was nearly 4-fold the thickness of those who underwent subinguinal microsurgical varicocele repair for infertility without a history of testicular retraction as an anatomic control (Figure 1). There was a statistically significant greater cremaster muscle thickness in the men who underwent MSCMR in comparison to those undergoing varicocele repair assessed statistically by the Mann–Whitney U test (P < 0.001; Table 1).

Figure 1.

Microsurgical images of measurements of (a) the cremaster muscle in a man undergoing microsurgical cremaster muscle release versus (b) a control in a man undergoing a subinguinal microsurgical varicocele repair, clearly demonstrating a thicker cremaster muscle in a than in b.

Table 1.

Comparison of cremaster muscle thickness in men undergoing microsurgical subinguinal cremaster muscle release versus subinguinal varicocele repair

Treatment	Cremaster muscle thickness (mm), mean±s.d.
Cremaster muscle release (n=33)	3.9±1.2
Varicocele repair (n=41)	1.0±0.4
P	<0.001

s.d.: standard deviation

DISCUSSION

Despite it being a common clinical presentation, chronic orchialgia remains a poorly understood disease process, with varied presentations and often an idiopathic etiology. A careful history and evaluation can identify a hyperactive cremaster muscle reflex in men who only have pain associated with testicular retraction with an otherwise negative evaluation of other causes for orchialgia. Although testicular pain may result in testicular retraction, a careful history-taking can elucidate testicular retraction and the sequelae that follow as a possible etiology for pain. Men suffering from a hyperactive cremaster muscle reflex resulting in testicular retraction during vigorous activities that result in Valsalva, such as sexual activity, heavy lifting, and cold temperatures, do not complain of pain before the retraction episode. They do not complain of testicular pain at random times when they do not experience retraction. They have severe retraction to the point that the testis gets stuck typically above the scrotum at the external inguinal ring and they have to physically push the testis back down to the scrotum, and this sequence of events induces pain which may linger after retraction episodes. Obtaining a careful history can clarify which patients this occurs in and assist with appropriate patient selection.

Data on the management of a hyperactive cremaster reflex in adults remain sparse. In 1999, a case series of three patients was published in which it was postulated that pain in men with retractile testicles could be the result of an attenuated external oblique aponeurosis. The authors found that by reconstructing the external inguinal ring with a mesh, all three men’s testicles returned to a more dependent position in the scrotum and their pain resolved.8 More recently, MSCMR has been shown to be an effective surgical treatment for men who meet these criteria.2 In this series, using the previously described technique, there was a 100.0% resolution of testicular retraction, and pain improved in 92.0% of the cases.

Although an etiology for orchialgia in this subset of men has been identified with outlined diagnostic criteria, until this study, no anatomic findings had been identified to characterize this process. We believe that the identification of cremaster muscle thickening may be the first step in a better understanding of the cause of this troublesome retraction. However, whether the muscular thickening is causative or reactive remains an unanswered question. We are hopeful the data from this study may stimulate further study. This study did not histopathologically evaluate the presence or absence of Wallerian degeneration in the trifecta nerve complex as described by Parekattil et al.,9 as an etiology of chronic orchialgia, to investigate whether there may be correlation. Future studies will further examine this possible association. Werneburg et al.10 reported a diverse set of neuroinflammatory genes with differential expression in tissue in men with chronic orchialgia, including in the cremasteric muscle. This may possibly explain the etiology of the cremasteric muscle thickness in these men with testicular retraction, but further study is needed to definitively elucidate this correlation.10

Men with testicular retraction secondary to hyperactive cremaster muscle reflex have a significantly thickened cremaster muscle in comparison to men who do not suffer from testicular retraction. This anatomic difference may be of help in future efforts to understand the pathology in men who struggle with testicular retraction.

AUTHOR CONTRIBUTIONS

PKK contributed to the research design, and acquisition, analysis, and interpretation of the data. HTH, KH, RMF, and GLM contributed to acquisition, analysis, and interpretation of the data. All authors contributed to drafting and revising manuscript critically, and read and approved the final manuscript.

COMPETING INTERESTS

PKK is on the speaker bureaus for Acerus pharmaceuticals, Halozyme pharmaceuticals, and Clarus therapeutics, none of which are relevant to this work. Other authors declare no competing interests.