Synonyms: functional anorectal pain, chronic proctalgia, pyriformis syndrome, pelvic tension myalgia, levator ani syndrome
Functional anorectal pain occurs in the absence of any clinical abnormality.It's a relatively common symptom - first described by the Romans. Patients will often delay consulting a healthcare practitioner about this problem, due to embarrassment and fear of a sinister diagnosis, tolerating disturbing symptoms for long periods.
There are two functional anorectal pain syndromes, defined by the Rome III criteria (2006):
- Proctalgia fugax (PF) (fugax = fugitive/fleeting in Latin)
- Levator ani syndrome (LAS)
They are both characteristic, benign, anorectal-pain syndromes of uncertain aetiology. Despite their benign nature, they can cause severe distress to the sufferer.
- They are thought to occur due to spasm of the anal sphincter (in PF) or pelvic floor muscles (in LAS) but are something of an enigma.
- It is important to elicit a precise history of defecation.
- They may be associated with irritable bowel syndrome (IBS).
- The two affected muscles are anatomically contiguous so the two conditions may co-exist, or be different manifestations of the same underlying dysfunction.
- The diagnosis of these conditions can usually be made on the basis of the symptoms. However, more serious diagnoses can present similarly. Thus, it is essential to conduct a thorough clinical assessment to exclude other pathology before offering reassurance.
- A history of anxiety or depression is often associated and this should be evaluated.
- They have been associated with a variety of other pathologies which may have aetiological significance; for example, pudendal nerve neuralgia.
- Proctalgia fugax (PF) is estimated to affect 8-18% of the population in the developed world, and levator ani syndrome (LAS) around 6%.
- LAS seems to affect women more than men whereas PF seems to affect both sexes equally.
- It is thought that only 20-30% of those who experience these conditions consult a healthcare practitioner.[8, 9]
- Irritable bowel syndrome.
- Haemorrhoids ± thrombosis.
- Anal fissure (usually causes intense localised pain associated with and following defecation) - should be visible on proctoscopy.
- Solitary chronic rectal ulcer.
- Colorectal cancer.
- Perirectal abscess or fistula; hidradenitis suppurativa.
- Proctitis (especially gonococcal/chlamydial infection).
- Crohn's disease/ulcerative colitis.
- Rectal foreign body.
- Pruritus ani.
- Diverticular disease.
- Rectal prolapse.
- Coccygodynia (neuralgic pain around the region of the coccyx).
- Retrorectal cysts.
- Condylomata acuminata (anogenital warts).
- Testicular tumours.
- Psychological cause (some hypothesise that these conditions are psychological rather than physical in origin).
- Alcock's canal syndrome (pudendal neuralgia due to entrapment, may present similarly to PF/be aetiologically relevant).[4, 6]
- Hereditary anal sphincter myopathy.
- Bilateral internal iliac artery occlusion.
- Endoscopy (flexible rectosigmoidoscopy or colonoscopy) should be considered in patients with chronic anorectal pain.
- If this is normal and there is tenderness of the puborectalis muscle then other investigations such as anorectal manometry, balloon expulsion test and MRI-Defecography should be considered.
- Depending on the level of clinical uncertainty, other useful investigations can be FBC, pelvic ultrasound and anorectal endosonography.
Intermittent chronic anal pain syndrome: Proctalgia fugax
- Recurrent episodes of sudden, severe cramping pain localised to the anus or lower rectum.
- Last from seconds to minutes and resolve completely.
- The patient is entirely pain-free between the episodes.
- Symptoms often occur at night and may wake the person who has the condition. Attacks are infrequent (<5 times yearly in 51% of patients).
- Attacks may come in clusters (occurring daily) then abate for long periods.
- PF has no signs and the diagnosis is made on the basis of characteristic symptoms and the absence of signs of other pathology.
- Abdominal and digital rectal examination should constitute the minimum assessment of anal pain.
- Ideally, anoscopy/proctoscopy should be carried out.
- Consider gynaecological/scrotal examination if relevant.
- Further examination with a sigmoidoscope or colonoscope may be necessary in selected patients where there is suspicion of pathology higher in the colon.
- It is worth checking for signs of anaemia if gastrointestinal bleeding is suspected.
- Once the diagnosis is made, reassurance is usually sufficient.
- The symptoms are so transient that drug therapy is rarely needed.
- In patients who experience frequent, severe, prolonged attacks, inhaled salbutamol has been shown to reduce their duration.
- Most other treatments (such as oral diltiazem, topical glyceryl nitrate and nerve blocks) act by relaxing the anal sphincter spasm but are not supported by randomised controlled trials.
- Co-existent psychological issues should be addressed with behavioural and/or pharmacological therapies.
Chronic anal pain syndrome: Levator ani syndrome
- Vague, aching or pressure sensation high in the rectum often worsened by sitting and relieved by walking.
- Pain tends to be constant or recur regularly and to last >20mins.
- Lasts from hours to days.
- To satisfy diagnostic criteria the symptoms must be present for three months with symptom onset at least six months prior to diagnosis.
- Other causes of similar pain (see 'Differential diagnosis', above) must have been excluded.
- In LAS, posterior traction on the puborectalis reveals tight levator ani muscles and tenderness or pain. (This differentiates between LAS and Unspecified Functional Anorectal Pain).
- Tenderness may be predominantly left-sided and massage of the puborectalis muscle may elicit the characteristic discomfort.
- The recently-published Guidelines on Chronic Pelvic Pain (European Association of Urology) suggest (in decreasing robustness of clinical evidence) :
- Biofeedback treatment
- Botulinum toxin A and electrogalvanic stimulation
- Percutaneous tibial nerve stimuation
- Sacral neurostimulation
- Inhaled salbutamol
- If all functional tests are normal, consider referral to a specialist pain management unit.
- When examining the anogenital area ensure that the patient is fully informed about what to expect and the reasons why the examination is necessary.
- An appropriate chaperone should be offered and be in attendance for intimate examinations.
- Document the presence of a chaperone and their identity along with the examination findings.
- Ensure patient privacy and dignity, and discontinue the examination if at any time you or the patient are unhappy or uncomfortable with the situation.
- Do not assume that because you are the same sex as the patient, a chaperone isn't needed.
- For further information, see separate article Rectal Examination.
Further reading and references
; Patient characteristics and treatment outcome in functional anorectal pain. Dis Colon Rectum. 2011 Jul54(7):870-5. doi: 10.1007/DCR.0b013e318217586f.
; Anorectal and perineal pain: new pathophysiological hypothesis. Tech Coloproctol. 2004 Aug8(2):77-83.
Guidelines on chronic pelvic pain; European Association of Urology (2014)
; Proctalgia fugax: caused by pudendal neuropathy? Dis Colon Rectum. 2005 Jan48(1):114-20.
; Functional and chronic anorectal and pelvic pain disorders. Gastroenterol Clin North Am. 2008 Sep37(3):685-96, ix. doi: 10.1016/j.gtc.2008.06.002.
; Proctalgia fugax: demographic and clinical characteristics. What every doctor should know from a prospective study of 54 patients. Dis Colon Rectum. 2007 Jun50(6):893-8.
; Functional disorders of the anus and rectum. Gut. 1999 Sep45 Suppl 2:II55-9.
; The prevalence of rectal chlamydial infection amongst men who have sex with men attending the genitourinary medicine clinic in Edinburgh. Int J STD AIDS. 2004 Mar15(3):162-4.
; Retrorectal cyst: a rare tumor frequently misdiagnosed. J Am Coll Surg. 2003 Jun196(6):880-6.
; Hereditary vacuolar internal anal sphincter myopathy causing proctalgia fugax and constipation: a new case contribution. Eur J Gastroenterol Hepatol. 2005 Mar17(3):359-61.
; Common anorectal conditions: Part I. Symptoms and complaints. Am Fam Physician. 2001 Jun 1563(12):2391-8.
; Proctalgia fugax. CMAJ. 2013 Mar 19185(5):417. doi: 10.1503/cmaj.101613. Epub 2012 Nov 26.
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