Pelvic Pain in Males

Andrew Baranowski

This chapter is about pain perceived to be in the male pelvis—the pelvic pain syndromes. For the purpose of this chapter, the pelvis is considered as the anatomical bony pelvis and the structures both within and adjacent to it, including the male external genitalia, nervous system structures, and soft tissue/muscular structures, that is, the pelvis in its broadest sense. Although this chapter focuses primarily on the male urogenital pelvic pain syndromes, the importance of other systems, particularly the musculoskeletal, nervous, and other viscera, is emphasized when appropriate.

There are many well-recognized, well-defined pathologies that may result in pain perceived within the male urogenital system, such as infections of the organs; infiltration of somatic, visceral, and nervous tissue by cancer; and referred sensations from the musculoskeletal system. However, for less defined pathologies, the mechanisms underlying the pains have been less widely appreciated outside of pain medicine. The mechanisms for this second group, which is probably the majority of male pelvic pain patients, involve neurologic mechanisms—in particular, central sensitization that may involve the whole neuraxis. These are the primary chronic pain syndromes.

The latest classification approaches have taken this dichotomy of mechanisms into account. To emphasize the differences, those conditions where the main mechanisms are related to central sensitization are known as the pelvic pain syndromes, and they are considered separately from those conditions with ongoing nociceptive, acute pain mechanisms, such as those due to chronic infection. Pelvic pain syndromes are defined by their symptoms and signs and typically by the presence of sensitization, including visceral hypersensitivity, viscerovisceral hypersensitivity (i.e., cross-organ sensitization), and viscerosomatic hypersensitivity (e.g., expanded area of referred sensation and/or increased sensitivity to palpation). Often, an important part of the process of diagnosing the pelvic pain syndromes is excluding other pathologies.

Classification of the pelvic pain syndromes involves terminology, phenotyping, and taxonomy. The phenotype describes the condition in terms of symptoms, signs, and, where possible, mechanisms. Incorporating the phenotype into a hierarchy of phenotypes produces a taxonomy that allows comparisons between phenotypes. This approach enables appropriate prognosis and treatment. The terminology used can be very emotive, and careful description of the meaning of the terms is often required. The classification of pelvic urogenital pain has been rapidly evolving over the past 15 years and is likely to continue to do so.¹^,²^,³^,⁴^,⁵^,⁶^,⁷^,⁸^,⁹ This ongoing change in classification not only reflects our increasing knowledge but also has caused problems for research and evidence-based treatment. The classification will be covered in depth as it is the key to understanding male pelvic pain syndromes.

The central nervous system mechanisms of central sensitization and the psychological responses that result in the chronic pain syndrome are covered in other chapters within this book; those processes that are specific to urogenital pain are expanded on in this chapter. There are some obvious differences between the male and female urogenital systems that will result in specific pain syndromes; however, it is important to recognize that there is much overlap as well. Those differences due to gender and sex are covered in Chapter 7.

This chapter supports that in most men with chronic pain perceived in the pelvic organs, the cause of the pain is not often due to classical pathologies of infection or infiltration but more commonly due to chronic pain mechanisms involving a number of systems with referred pain, sensory and functional consequences (e.g., urinary and fecal incontinence, urge and urgency, urinary hesitance, impotence), and chronic pain psychological responses.⁸

Taxonomy and Phenotyping Chronic Pelvic Pain

A realization has occurred that pain perceived within the pelvis may be associated with classical pathology of the pelvic structures or that it may result secondary to central nervous system pain mechanisms. It is the latter conditions that this chapter primarily concentrates on.

CLASSICAL PATHOLOGIES

Classical pathologies include infection, inflammation, degeneration, neoplastic, and autoimmune mechanisms of any of the pelvic or adjacent pelvic structures (referred pain). In the case of classical pathology, chronic persistent pain is the result of ongoing local pathology, persistent nociceptor activation with peripheral sensitization, and possibly a central sensitization process. Treatment will primarily be focused on managing the underlying pathology and the use of analgesics where required. Removing the peripheral cause should resolve the pain.

PELVIC PAIN SYNDROMES AND NONPELVIC PAIN SYNDROMES

Most of the recent attempts at classification, taxonomy, and phenotyping have tried to separate out the classical pathologies from those conditions without classical pathology that have become known as the pelvic pain syndromes.³^,⁷^,¹⁰ The pelvic pain syndromes are the conditions where there is no peripheral pathology maintaining the pain experience (peripheral stimuli may however maintain the central sensitization). In its attempt to separate out the pelvic pain syndromes from those with a nociceptive cause, the European Association of Urology (EAU) in their 2004 classification system called those conditions associated with classical pathology as “well-defined” conditions and the European Society for the Study of Interstitial Cystitis (ESSIC) called them “confusable diseases.”³^,¹⁰ Both of those terms have a disadvantage. The term well-defined suggests that the pain syndromes are poorly defined; however, as an understanding of chronic pain mechanisms (including visceral pain mechanisms) and central sensitization develops, this is clearly not the case. ESSIC used the term confusable to separate out the pain syndromes from those conditions that they might be confused with, a very difficult concept. In future classifications, one way forward is that chronic pelvic urogenital pain syndromes will become a differential diagnosis with the classical pathologies, and the taxonomy will be divided into pelvic pain syndromes and nonpelvic pain syndromes.¹¹ The World Health Authority working with the International Association for Pain in ICD11 is using the term primary chronic pain. The emphasis is thus on the pelvic pain syndromes, which is probably correct as in most individuals classical disease processes are not present. Table 65.1 illustrates the division of

chronic pelvic pain into pain syndromes and nonpelvic pain syndromes. Table 65.2 provides the definitions for chronic pelvic pain and the pelvic pain syndromes. The latest World Health Organization International Classification of Diseases, 11th Revision, recognizes pain as a condition in its own right, although uses some outdated terminology. The International Continence Society has tried by working with other published guidelines to achieve international consensus. However, their “Standard for Terminology” did not have any pain medicine representation and reverted to older terminology in places.¹² It will take a lot more time for consensus to be reached.

TABLE 65.1 The Division of Chronic Pelvic Pain into Pelvic Pain Syndromes and Nonpelvic Pain Syndromes

Axis I Region		Axis II System	Axis III End Organ as Pain Syndrome as Identified from Hx, Ex, and Ix			Axis IV Referral Characteristics	Axis V Temporal Characteristics	Axis VI Character	VII Associated Symptoms	VIII Psychological Symptoms
Chronic pelvic pain	Pelvic pain syndrome	Urologic	Bladder pain syndrome Urethral pain syndrome Prostate pain syndrome Scrotal pain syndrome Penile pain syndrome	(See Table 65.2 on ESSIC classification) Type A inflammatory Type B noninflammatory Testicular pain syndrome Epididymal pain syndrome Postvasectomy pain syndrome		Suprapubic Inguinal Urethral Penile/clitoral Perineal Rectal Back Buttocks	ONSET Acute Chronic ONGOING Sporadic Cyclical Continuous TIME Filling Emptying Immediate post Late post PROVOKED	Aching Burning Stabbing Electric Other	URINARY Frequency Nocturia Hesitance Poor flow Pis en deux Urge Urgency Incontinence Other GYNECOLOGIC, for example, menstrual SEXUAL, for example, female dyspareunia impotence, anorectal, incontinence, constipation MUSCULAR, for example, hyperalgesia, dysfunction CUTANEOUS, for example, allodynia	Cognitive Behavioral Emotional
		Gynecologic	Vaginal pain syndrome Vulvar pain syndrome	Generalized vulvar pain syndrome Localized vulvar pain syndrome	Vestibular pain syndrome Clitoral pain syndrome
			Other	Endometriosis associated pain syndrome
		Anorectal Neurologic Muscular	Anorectal pain syndrome Pudendal pain syndrome Pelvic floor muscle pain syndrome
	Nonpelvic pain syndromes	Neurologic Urologic	Pudendal neuralgia
From Fall M, Baranowski AP, Elneil S, et al. Guidelines on chronic pelvic pain. Paper presented at: 23rd European Association of Urology Annual Congress; March 2008; Milan, Italy.

TABLE 65.2 Definitions of Pelvic Pain

Chronic pelvic pain is nonmalignant pain perceived in structures related to the pelvis of either men or women. In the case of documented nociceptive pain that becomes chronic, the pain must have been continuous or recurrent for at least 6 months. If nonacute pain mechanisms and central sensitization mechanisms are well documented, then the pain may be regarded as chronic, irrespective of the time period. In all cases, there often are associated negative cognitive, behavioral, sexual, and emotional consequences.³,¹¹
Pelvic pain syndrome is the occurrence of persistent or recurrent episodic pelvic pain associated with symptoms suggestive of lower urinary tract, sexual, bowel, or gynecologic dysfunction. There is no proven infection or other obvious pathology.³,¹¹

This chapter uses the EAU and International Association for the Study of Pain (IASP) accepted classifications, which the author was involved in.

Male Urogenital Pain Syndromes

Traditionally, pelvic pain conditions would be classified into those of the male, female, or both. This approach is currently being reconsidered, as the mechanisms discussed earlier may be common to both sexes with the only difference being the sex organ that the pain is perceived in. However, as there has been a lot of research looking at the end-organ pain syndromes and their treatment, this is summarized in the following text as relevant for the male.

MALE-SPECIFIC PELVIC PAIN SYNDROMES

The unique male pelvic pain syndromes are those where the pain is perceived in the male sex organs. Table 65.3 summarizes these conditions. The definitions serve to emphasize that classical pathologies are absent.

SUBCLASSIFICATION OF THE PELVIC PAIN SYNDROMES BY ORGAN

Much discussion has been had about whether it is appropriate to divide the pelvic pain syndromes by the end organ that the pain is perceived in. Many would rather maintain a more generic approach and keep to the term pelvic pain syndrome to cover all pains perceived within the pelvis and not associated with a classical pathology. The EAU approach (see Table 65.1) uses a progressive step-by-step approach to classification.³^,¹¹ That is, classification starts at the left end of the table if pain is perceived within the pelvis or the external sex organs. Further subclassification only occurs if there are distinct localizing factors within an end organ. Such an approach to taxonomy is very similar to that used to classify life and the animal and plant kingdoms. For instance, we would progress from animal to mammal to elephant only as the evidence allowed. The primary localizing factor for pelvic pain is pain produced by local physical stimulation, such as palpation. If an end organ is clearly associated with the area of perceived pain, then the pain may be labeled with that end organ name as in Table 65.1. If more than one organ is deemed to be involved, then either two names may be given to the condition, or it may be more appropriate to consider the pain in more generic terms as a pelvic pain syndrome.

TABLE 65.3 Phenotype Classification of the Male Pelvic Urogenital Pain Syndromes

Penile pain syndrome is the occurrence of pain within the penis that is not primarily in the urethra, with the absence of proven infection or other obvious pathology.³,¹¹
Prostate pain syndrome is the occurrence of persistent or recurrent episodic prostate pain, which is associated with symptoms suggestive of urinary tract and/or sexual dysfunction. There is no proven infection or other obvious pathology.³,¹¹ (This definition of prostate pain syndrome was adapted from the National Institutes of Health [NIH] consensus definition and classification of prostatitis⁴ and includes those conditions that they term chronic pelvic pain syndrome. Using their classification system, prostate pain syndrome may be further subdivided into type A, inflammatory, and type B, noninflammatory.)
Scrotal pain syndrome is the occurrence of persistent or recurrent episodic scrotal pain that is associated with symptoms suggestive of urinary tract or sexual dysfunction. There is no proven epididymo-orchitis or other obvious pathology.³,¹¹
Testicular pain syndrome is the occurrence of persistent or recurrent episodic pain localized to the testis on examination that is associated with symptoms suggestive of urinary tract or sexual dysfunction. There is no proven epididymoorchitis or other obvious pathology. (This is a more specific definition than scrotal pain syndrome.)³,¹¹
Postvasectomy pain syndrome is a scrotal pain syndrome that follows vasectomy.³,¹¹
Epididymal pain syndrome is the occurrence of persistent or recurrent episodic pain localized to the epididymis on examination that is associated with symptoms suggestive of urinary tract or sexual dysfunction. There is no proven epididymoorchitis or other obvious pathology (more specific definition than scrotal pain syndrome).³,¹¹

THE IMPORTANCE OF TAXONOMY AND PHENOTYPING

The mentioned taxonomy (hierarchical classification of conditions) and phenotyping (identifying of the physical characteristics—symptoms and signs—and mechanisms of the diseases within the taxonomy) is important.

Appropriate taxonomy and phenotyping is a prerequisite for epidemiology, diagnosis, management, and prognosis. With traditional management of pelvic pain, there has been a tendency to use inappropriate treatments with inappropriate expectations; the result is increased distress and a worse prognosis.⁸

Currently, it is not unusual for inappropriate treatments to be instigated due to a failure to understand the pain syndromes.¹ For example, classic mismanagement would be the recurrent use of antibiotics or the use of surgery for the complaint of pain. Whereas surgery may have a role for functional reasons (e.g., incontinence), there is a serious debate about its use for pain management. Appropriate taxonomy and phenotyping allows appropriate expectation of both the patient and those providing medical care. Unfortunately, many patients and doctors have inappropriate expectations for treatments aimed at cure. This produces distress, and the increased distress is associated with a worse prognosis.¹³^,¹⁴

An appropriate taxonomy and phenotyping encourages interdisciplinary and multidisciplinary management. In the case of most pelvic pain syndromes, where there may be a reduction in symptoms with appropriate treatment, cure is often not possible. The best outcomes in terms of reduced disability and improved quality of life will come from a symptom management approach involving multiple interdisciplinary teams (e.g., urology, pain
medicine, neurology) and multiple members of the team (e.g., nurses, doctors, psychologists, physiotherapists). This is a standard approach for other pain syndromes and should be the standard approach for the urogenital/pelvic pain syndromes.

Epidemiology

Epidemiology requires a clear understanding of the disease that is being studied. Unfortunately, as the phenotyping and taxonomy of male pelvic pain is ongoing, clear-cut epidemiologic data for specific pelvic urogenital pain syndromes are not available.

INCIDENCE/PREVALENCE

Prostate Pain Syndrome

Male pain perceived deep within the pelvis is usually labeled as prostatitis despite the absence of infection and, frequently, the absence of inflammation within fluids extracted from the prostate. The National Institutes of Health (NIH) classification⁴ of “prostatitis” includes pain perceived in the prostate without evidence of inflammation or infection and has reinforced this misnomer. Therefore, most of the data relating to pain perceived within the prostate stems from the “prostatitis” literature. As well as pain, these patients often have urinary urge (constant need to void as a result of a sensory disturbance), frequency (secondary to the urge), hesitancy, and poor flow, but they do not have urgency (need to void because of a fear of incontinence).

Several studies have looked at the demographic distribution of the disease. Prostatitis appears to be more common in men younger than 50 years of age, although there may be a second cohort aged greater than 74 years.¹⁵^,¹⁶^,¹⁷ The Nickel et al.¹⁶ study identified 9.7% of men as having “chronic prostatitis-like” symptoms as defined by the NIH-Chronic Prostatitis Symptom Index. This index includes urinary “irritative” and “obstructive” symptoms as well as measures of quality of life as these are frequently disrupted.¹⁸

Scrotal Pain Syndrome

Testicular pain in isolation and without obvious cause is well defined as an example of chronic visceral pain. It is essential to rule out pain referred to the testis, such as from an adductor enthesitis or from the spine. Thoracic pathology with or without involvement of the nerve roots may also produce pain perceived in the testis.

Despite being well defined, the testicular pain syndrome is poorly researched and information about its incidence is scanty. The majority of the information stems from postvasectomy surgery,¹⁹ where the incidence may be as high as 19% following this operation. Once more, the problem appears to be more frequent in younger men.²⁰^,²¹^,²²^,²³ In a large cohort study of 625 postvasectomy men, the likelihood of scrotal pain after 6 months was 14.7%. The mean pain severity on a VAS score was 3.4/10. In the pain group, 0.9% had quite severe pain, noticeably affecting their daily life. In this cohort, different techniques were used to perform the vasectomy. The risk of postvasectomy pain was significantly lower in the no-scalpel vasectomy group (11.7% vs. the scalpel group 18.8%).²⁴

Penile Pain Syndrome

There are very few data on this condition, which also appears to be unusual in the pain clinic. The condition must not be confused with the penile pain of pudendal neuralgia or pain sensation referred from the bladder or urethra. This condition is also quite different from the psychiatric obsession associated with the sex organs that can occur in certain patients. A painful penis without obvious cause has been seen to follow circumcision and may represent a central sensitization process.

PRECIPITATING FACTORS

Very little is known about the factors that predispose men to urogenital pain syndromes.²⁵^,²⁶ In certain, but probably only a small proportion of, cases, some form of trauma or infection may be the precipitating factor.²⁷ Surgical trauma in the form of vasectomy may result in testicular pain.²⁸ Recurrent minor injury may be a predisposing factor, as for any pain syndrome.

The role of the pudendal nerve is disputed by different experts in the field. There is no doubt that pudendal neuralgia (pain associated with pudendal nerve damage) exists.²⁹ The mechanism(s) presumably will be the same as for all nerves, and the pain would be perceived in the appropriate dermatome. Depending on the site of damage, the pain may be perceived in the anus, perineum, deeper within the pelvis, the bladder base, or the penis.³⁰ Whether the sexual function and the central sensitization of the sexual process imparts any specific properties on the damaged pudendal nerve is not known. As may be expected, the nerve damage may be associated with a range of sensory abnormalities such as dysesthesia, allodynia, or numbness. The pudendal nerve is suggested to be at risk from recurrent injuries (such as cycling or long hours of sitting) and from acute trauma, including surgical interventions, such as for cancer or orthopedics.³¹^,³²^,³³^,³⁴ Sitting while working at a computer appears to be a predisposing factor among young men (personal observation).

The role of the musculature is also highly debated.²⁸^,³⁵^,³⁶^,³⁷^,³⁸^,³⁹^,⁴⁰^,⁴¹ In general, it is now well accepted that the pelvic muscles (including the core muscles of the abdomen and spine) may be involved in the pelvic pain syndromes and that these muscles are subject to the same causes as any other muscle. Trauma, as during sports injury, birth injury for women, and accidents, may produce a muscle-based pain. A report from the Chronic “Prostatitis Cohort Study” showed that 51% of patients with “prostatitis” and only 7% of controls had any muscle tenderness. Tenderness in the pelvic floor muscles was only found in the chronic pelvic pain group.⁴²

Stress is said to be responsible for pelvic muscle tension and hence pain in certain cases, although it must be appreciated that chronic pain will also be associated with psychological responses and even psychiatric disorders.⁴³^,⁴⁴^,⁴⁵

The role of negative sexual encounters (NSE) continues to be disputed.⁴⁶^,⁴⁷ The prevalence of childhood male sexual abuse may be as high as 16% in some countries; in the United Kingdom, it has been estimated as 5%. Three percent of male adults may also have had an NSE. Victims of torture are frequently subjected to sexual abuse. What is not clear is the relationship of this abuse to male urogenital pain syndromes. In our editorial,⁸ it was suggested that there is little sound evidence to support NSEs as a cause of chronic urogenital pain in patients. However, there is no doubt that in a patient who has suffered an NSE, that incident may require management in its own right.

There are now several articles that indicate that the psychological status of the patient is relevant to the pelvic pain experience. Patients exhibiting high distress associated with catastrophizing and poor coping strategies do less well.⁴⁸^,⁴⁹^,⁵⁰^,⁵¹

Mechanisms

DIFFERENCES BETWEEN VISCERAL AND NONVISCERAL SOMATIC PAINS

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