Introduction

Rectal pain has been described in the medical literature for over a century. It is a frustrating medical condition for patients for a variety of reasons. Patients with rectal pain are often embarrassed and hesitant to discuss their pain with their physicians leading to a delay in care. To further compound the problem, rectal pain is often underdiagnosed and not well understood by clinicians. Patients are treated by a variety of specialists including psychiatrists, urologists, gynecologists, gastroenterologists, and proctologists. In the majority of cases, no specific etiology is found. This chapter aims to discuss the clinical features and treatment options for proctalgia fugax and levator ani syndrome, collectively known as functional anorectal pain disorders. Due to patients’ reticence on this topic, healthcare providers should welcome and encourage open discussion with their patients experiencing rectal pain.

Etiology and Pathogenesis

The rectum begins at the S3 level as a continuation of the sigmoid colon and has two major flexures: the sacral flexure and the anorectal flexure. The sacral flexure is an anteroposterior curve that concaves anteriorly while the anorectal flexure is an anteroposterior curve with convexity posteriorly. It is the latter flexure that is the main contributor to fecal incontinence as its tone is provided by the puborectalis muscle. The rectum ends in an expanded section called the ampulla which temporarily stores feces until defecation can occur through the anal canal.

The rectum receives both sensory and autonomic innervations. Autonomic innervation originates via lumbar splanchnic nerves that ultimately terminate in the superior and inferior hypogastric plexuses. Rectal branches from the inferior hypogastric plexus accompany rectal vessels to their destination in the rectum. Somatic afferent and efferent innervation of the rectum involves sacral nerve roots originating from S2–S4. The pudendal nerve primarily provides sensation to the anal canal as well as other structures in the perineal area. Furthermore, S4–S5 nerve roots in the form of the coccygeal plexus distribute afferent and efferent nerve fibers to perianal and perineal skin. It is important to note that when presented with complaints of perianal/rectal pain, clinicians must rule out structural causes that may have a coinciding symptom of rectal pain, such as tumors of the gastrointestinal tract and pelvis. This chapter will focus on proctalgia fugax and levator ani syndrome. They are diagnoses of exclusion and consequently are often misdiagnosed.

Clinical Features

Proctalgia fugax (PF) is a nonmalignant syndrome that causes sharp, severe, intermittent pain that is localized to the anus and lower rectum. This syndrome is characterized by paroxysms of rectal pain with pain-free periods lasting seconds to minutes in between attacks. Patients often report that suppositories or a digit in the rectum can abort an attack. The origin of this pain is unknown; however, it is hypothesized that spasms of the levator ani muscle, anal sphincter, and sigmoid colon may play a role.

PF has equal prevalence in males and females. It is seen more frequently in patients who suffer from other bowel disorders such as irritable bowel syndrome. PF typically does not present before puberty and does not usually have an identifiable trigger, which can be a source of anxiety and depression for patients. Precipitants of pain include sexual activity, stress, constipation, defecation, and menstruation. It has also been associated with sclerotherapy for hemorrhoids and after vaginal hysterectomies.

Levator ani syndrome (LAS) is characterized by frequent, dull, and relatively constant anorectal pain that is unexplained by an organic cause. Frequently, patients are tender to palpation over the levator ani muscle. Other names for this syndrome include levator spasm, puborectalis syndrome, chronic proctalgia, and pelvic tension myalgia. Observations of this syndrome suggest that patients have increased anal pressures measured by increased electromyogram activity. It is unclear if the higher anal pressures are a result of increased external or internal anal sphincter tone. It has also been suggested that the observed inability to relax pelvic floor muscles in this syndrome implicates an underlying pelvic floor dysfunction.

Diagnosis

The diagnosis of PF is based on characteristic symptoms in the absence of pelvic and anorectal pathology. Criteria are 12 weeks of characteristic symptoms accompanied by the following :

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  Recurrent episodes of pain localized to anus or lower rectum

  
  
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  Episodes that last from seconds to minutes

  
  
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  No anorectal pain in between episodes

Laboratory tests are largely normal in patients with PF and accompany the nonspecific physical exam findings described above. As a result, the diagnosis of PF requires the clinician to rule out other causes of anorectal pain including hemorrhoids, cryptitis, ischemia, abscess, anal fissure, rectocele, and malignant disease such as rectal cancer. Screening tests such as CBC, ESR, and stool occult blood testing are indicated to screen for possible malignant disease or hematologic disorders. Magnetic resonance imaging and computed tomography should be pursued if suspicion of other diagnoses is high.

In LAS, patients often describe the pain as vague, dull, or a pressure sensation high in the rectum. Sitting usually exacerbates the pain and some patients report warm compresses alleviate the pain.

As with PF, it is important to rule out organic anorectal or pelvic pathology (e.g., Crohn’s disease, anal fissures, malignancy). Appropriate testing to exclude these diagnoses should be performed (sigmoidoscopy, ultrasound, pelvic MRI, etc.). Diagnosis is based on meeting the following criteria, with these symptoms lasting at least 12 weeks :

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  Chronic or recurrent dull rectal pain or aching

  
  
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  Episodes lasting 20 min or longer

  
  
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  Other causes of rectal pain ruled out including ischemia, IBD, cryptitis, fissure, hemorrhoids, prostatitis, etc.

Diagnosis is more likely if patients experience the above symptoms with corresponding physical exam findings. The absence of tenderness to levator ani palpation makes the diagnosis less likely. It is important to note that these patients may also have coinciding mood disorders and catastrophizing behavior commonly seen in chronic pain patients.

Physical Exam Findings

A physical exam is largely normal in patients suffering from PF. Patients may appear depressed or anxious as a byproduct of their pain. Along with depression and anxiety, patients with PF may exhibit catastrophizing behaviors manifesting as rumination, magnification, or helplessness about their pain condition. Rectal exams are often normal, but deep palpation may trigger an event.

On physical exam of patients with LAS, the provider may palpate contracted levator ani muscles and patients report tenderness with posterior traction of the puborectalis muscle. In the literature, it is reported that tenderness is asymmetric and the left side may be affected more than the right side. If patients meet clinical criteria for LAS but have absent levator muscle tenderness on palpation, then they are said to have unspecified functional anorectal pain.

Treatment

Treatment of functional rectal pain disorders is challenging due in part to psychosocial comorbid conditions that may hamper progress. When available, multidisciplinary pain rehabilitation programs should be utilized in these patients that integrate teams of physical, occupational, and cognitive-behavioral therapists in an outpatient setting. These programs aim to improve physical deconditioning and eliminate an overreliance on medication or health care systems to manage symptoms. Efficacy has been demonstrated in functional abdominal pain syndromes and shows promise for management of pelvic pain among other chronic pain conditions.

A. Conservative and Behavioral Treatments : During an attack, patients have reported several methods to abort the pain. Dilation of the rectum, either digitally or via rectal suppository, has been used successfully in the treatment of PF. Studies suggest that electrogalvanic stimulation and sitz baths may be helpful in the management of LAS. The electrical stimulation of the levator ani muscle has been used to break the spastic cycle. Hot sitz baths may alleviate pain by reducing anal pressures. Digital massage of levator ani muscles and targeted pelvic physiotherapy have shown to relieve pain from contracted muscles as well. ^,

B. Biofeedback Therapy (BFT) : Biofeedback teaches patients control of autonomic body functions such as heart rate and muscle tension to relieve chronic pain, reduce stress, or achieve other predetermined goals. ^, A landmark trial compared the efficacy of biofeedback therapy, electrogalvanic stimulation, and digital massage in 157 patients with LAS. Patients were divided into two groups, those with LAS “highly likely” and LAS “possible.” The key distinguishing feature was that the latter group did not have tenderness with the traction of the levator ani muscle. Among patients with highly likely LAS, 87% receiving BFT reported adequate pain relief with greater reduction in pain intensity compared to the electrogalvanic stimulation and massage groups. Participants receiving BFT also reported fewer pain days per month compared to the other treatment groups. Clinical improvement was sustained at 12 months. Patients with a “possible” diagnosis of LAS had negligible improvement with any treatment.

C. Pharmacologic Treatment : Initial treatment of proctalgia fugax includes nonsteroidal antiinflammatory agents or cyclooxygenase-2 inhibitors. If initial treatment fails, a tricyclic antidepressant or gabapentin may be added. Selective serotonin reuptake inhibitors have been used to avoid the anticholinergic effects of tricyclic antidepressants but do not confer the same pain relief. Topical treatments such as nitroglycerin suppositories have proven to be successful. Finally, case reports of pain relief using nifedipine, carbamazepine, diltiazem, and salbutamol have been reported in the literature.

D. Local Injections : For patients who continue to have attacks and pain despite medical therapy, injections of local anesthetic into levator ani muscles may be warranted. Local botulinum A toxin has also been injected with success in case studies. The purported mechanism of pain relief is by relaxation of the internal anal sphincter that interrupts the painful spasms. Success rates are higher in LAS compared to PF due to palpable contraction of levator ani muscles in the former condition.

E. Pudendal Nerve Block: Patients who have pudendal nerve compression along with PF have seen relief with pudendal nerve blocks. Pudendal nerve blocks can be approached via a transvaginal or transperineal approach. Both utilize the lithotomy position and the target is the loss of resistance (LOR) after engaging through the sacrospinous ligament. In the transvaginal approach, the iliac spine is palpated through the lateral vaginal wall, and the needle is advanced into the sacrospinous ligament. The needle is passed 1 cm caudally until LOR and a local anesthetic is injected. In the transperineal approach, the iliac spine is identified, and the needle is advanced transperineally in a posterolateral direction until the ischial spine is reached. The sacrospinous ligament is then engaged, and the needle is advanced 1 cm in a medial inferior direction and a local anesthetic is deposited after negative aspiration. ^, With fluoroscopy or CT guidance, the patient is placed in the prone position and the needle is advanced to the tip of the ischial spine. The needle is slightly withdrawn after contact with the ischial spine is made, and medication is administered after negative aspiration rules out the intravascular injection.

F. Ganglion Impar Block : The ganglion impar is the fused terminal portion of the sympathetic chain. It is a retroperitoneal structure that lies just anterior to the sacrococcygeal ligament. It innervates the perineum, distal rectum, anus, and portions of the distal urogynecological system as well. Blocking this ganglion may provide benefits for sympathetically mediated rectal and perineal pain. The most common technique used for this block is a transcoccygeal approach with fluoroscopic guidance. With the patient in the prone position, the C-arm is rotated to the lateral position and the coccyx and sacrococcygeal ligament are visualized. The needle is advanced such that the tip reaches the ventral aspect of the sacroccygeal space. Radiopaque contrast injection should show spread along the ventral aspect of the sacrum and coccyx. The injection is then performed with a local anesthetic and steroid mixture. For patients with refractory pain, radiofrequency ablation may be offered. Radiofrequency ablation has been done for coccydynia at 80°C for 90 s, and it is reasonable to consider these parameters when proceeding with this treatment option for functional rectal pain.

G. Superior H ypogastric P lexus B lock : The superior hypogastric plexus is part of the abdominal and pelvic autonomic system. Blocking this plexus provides pain relief in patients with perineal pain and may have a role in PF and LAS. Located along the anterior border of the fifth lumbar vertebrae, it carries sympathetic nerve fibers from the rectum, colon, prostate, and other pelvic organs. ^, The superior hypogastric plexus is typically performed in the prone position. Under fluoroscopic guidance, the needle is inserted with a paramedian approach and advanced anterolaterally until the tips sit at the anterior margin of the L5–S1 interspace.

H. Sacral Nerve Stimulation : Sacral nerve stimulator systems provide electrical current to sacral nerves to modulate pelvic pain. The neuroelectrode usually exits at the S3 foramen and like other spinal cord stimulators/peripheral nerve stimulator (PNS) systems attaches to an implantable pulse generator. Although used for a variety of GI and urological conditions, there is a paucity of literature utilizing this therapy for the treatment of functional rectal pain disorders. Govaert and colleagues did a retrospective study of patients treated with sacral nerve stimulation between 2005 and 2008 for functional anorectal pain disorders. All patients had test stimulation to assess sacral neuromodulation outcomes before permanent implantation and had to achieve >50% pain improvement during the trial. Of the nine patients included in the study, four had successful test stimulation and went on to receive permanent implantation. All patients had a significant reduction in pain score through a 24-month follow-up period and improved global perceived effect. Although the preliminary evidence is promising, additional studies are needed to validate this therapy for rectal pain disorders.