Chronic anorectal pain is a syndrome made up of a complex interaction between neurological, musculoskeletal, and endocrine systems that is further affected by behavioral and psychological factors [1]. The ambiguity of the pathophysiology related to this pain has created several synonyms, but chronic idiopathic perineal pain is an umbrella term used to describe the subgroups of patients who present with chronic anorectal pain [2, 3].

Chronic proctalgia is a term traditionally used for the most common pain syndromes termed proctalgia fugax, levator ani syndrome, and coccygodynia, although the Rome III criteria use only levator ani syndrome and proctalgia fugax in its classification [3]. These syndromes will overlap and pose a diagnostic and therapeutic challenge as they tend to represent variations of the same disorder, and pelvic diagnostic investigations to detect such structural or anatomical pathology are nugatory [4–6].

Pudendal neuralgia is the term used to describe pain secondary to injury to the pudendal nerve, while pudendal pain syndrome refers to pain when there is no obvious injury to the nerve.

Without a thorough understanding of the anatomy and physiology of the pelvic floor it is impossible to understand the pathology of chronic anorectal pain. The pelvic floor is a biomechanical composite of muscles, ligaments, and fascia that creates an opening in the pelvis for the pelvic organs to pass into the perineum. The predominant muscle in the pelvic floor is the levator ani, which is composed of four parts: puborectalis, pubococcygeus, ileococcygeus, and coccygyeus. These muscles confer support to the pelvic organs and are essential to functions such as continence, defacation, micturition, delivery, and sexual function [7]. The levator ani and sphincteric muscles are situated in a state of continuous tonic activity, relaxed only during bowel and bladder motility.

The pudendal nerve arises from the S2, S3, and S4 nerve roots. It passes through the greater sciatic notch before wrapping round the ischial spine/sacrospinous ligament before re-entering the pelvis through the lesser sciatic notch below the levator ani. At this point, it lies within a fascial condensation on the medial aspect of obturator internus called Alcock’s canal. It passes below the pubic symphysis before dividing into three branches: the inferior anorectal nerve, the superficial perineal nerve, and the deep perineal nerve. This anatomy is covered in more detail in Chapter 3.

Thaysen introduced the term proctalgia fugax in the 1950s. It is characterized by sudden, short (less than 30 min), intense pain that is anal in distribution (90%) [8]. In most patients, it occurs less than five times per year. It tends to occur at night (30%) and is self-limiting, affecting 8–18% [9, 10] of the population aged 30-60 years and its prevalence shows similar sex predilection [11]. Unlike levator ani syndrome, patients are asymptomatic during examination and no characteristic clinical findings can be found to support the diagnosis.

Smith used the term levator spasm syndrome associated with perineal pain, and Todd reported symptoms of a dull, pressure sensation or a foreign body feeling [12]. The pain is exacerbated by sitting and lasts for hours to days. The prevalence in the general population is 6–7% between the ages of 30 and 60 years with a female predilection [13]. There is an association with previous pelvic surgery/ injury and psychological stress/anxiety. Clinically there is tenderness on palpation of the levator ani muscles [14].

Simpson described the relation between coccyx injury and coccygodynia over 150 years ago. Thiele used the term coccygodynia to relate the levator spasm with anal pain [15]. It refers to severe rectal, perineal, and sacrococcygeal pain, mainly in women (5:1). The key to diagnosis is manipulation of the coccyx, which will trigger the pain and thus differentiate it from levator spasm syndrome.

Pudendal neuralgia is typically perceived in the perineum from anus to clitoris. Classically, it is a burning pain, worse with sitting, and many patients remain standing [16]. Those with unilateral pain often favor sitting on one buttock. On clinical examination, pain may be elicited by pressure over the path of the pudendal nerve either by rectal or by vaginal examination.

Advanced or high-grade internal rectal prolapse appears to be very commonly associated with chronic idiopathic perineal pain, particularly when symptoms of obstructed defecation are present. Neil and Swash [17] commented on the high prevalence of pelvic floor laxity in patients suffering from chronic rectal pain and the real significance of internal prolapse only began to be addressed seriously much later in the 1990s and 2000s [18]. Chronic anorectal pain is a common symptom in patients with advanced posterior compartment prolapse presenting with defecatory dysfunction. About 50% of such patients will complain of pain at least some of the time. This pain often responds to antiprolapse surgery [19, 20].