1. Chronic anal pain
(1) Levator ani syndrome The etiology and pathogenesis  are often congenital, but also related to physical injuries, including trauma, excessive physical activity, and age. It may also be the result of pelvic muscle spasms or excessive contraction of the levator ani muscle in order to overcome their own incontinence symptoms. Some studies suggest that it is related to mental stress, tension and anxiety, and also related to postoperative complications, including transabdominal rectal resection, anal fistula surgery, and medial anal fissure surgery.
(2) Non-specific functional anorectal pain The etiology and pathogenesis of anorectal pain are unknown, and they are closely related to psychological factors.
The etiology of spastic anal pain is unclear, because the attack time is short and the frequency is small, which brings difficulties to the research. Some studies suggest that smooth muscle spasm may be the cause of spastic rectal pain. Psychological tests showed that 63% of patients had perfectionism, 73% had anxiety, and 40% had hypochondriasis. In addition, 62% of patients had multiple physical symptoms. It suggests that mental and psychological factors may play a role in the occurrence of this disease.
2 Diagnosis and differential diagnosis
(1) Diagnosis of chronic anal pain In the Rome III diagnostic criteria of chronic anorectal pain, chronic anorectal pain is divided into two subtypes according to whether there is tenderness when pulling the puborectal muscle backwards.
1. Chronic anorectal pain (1) Chronic or recurrent anorectal pain (2) Pain lasts for at least 20 minutes (3) Exclude other causes of anorectal pain: ischemia, inflammatory bowel disease, cryptitis, muscle Inter-abscess, anal fissure, hemorrhoids, prostatitis and coccygeal pain (the above symptoms appear at least 6 months before diagnosis and last at least 3 months) Subtype ① Levator ani syndrome: meet the diagnostic criteria for chronic anal pain, and from the back Tenderness can be caused when the puborectal muscle is stretched ②Non-specific functional anorectal pain: It meets the diagnostic criteria for chronic anal pain, and it does not cause pain when the puborectal muscle is stretched from the back.
2. Spasmodic anorectal pain (1) Recurrent pain in the anal area and lower rectum (2) The attack lasts for several seconds to several minutes (3) There is no anorectal pain between episodes (the duration of the diagnosis of PF symptoms must be at least 3 Months; for clinical diagnosis and evaluation, the duration of PF symptoms can be less than 3 months)
Levator ani syndrome Levator ani syndrome (LAS) is also known as levator ani muscle spasm, puborectalis syndrome, chronic rectal pain, piriformis syndrome, and tension pelvic myalgia. In addition to meeting the Rome III diagnostic criteria for chronic anorectal pain (see Table 1), the pain is usually dull, electric shock-like, tear-like, burning-like pain, or it shows increased pressure in the rectum, sitting and lying for a long time Exacerbated from time to time, lasting from several hours to several days. The incidence of women in the overall population is relatively high. More than 50% of the patients are between 30 and 60 years old, and only 29% of them go to the doctor, but work and study are obviously affected. In addition, the occurrence of pain may have a certain physiological cycle. Mild symptoms appear in the morning, and the pain starts to aggravate at noon, and the pain disappears at night.
The diagnosis of LAS can be made based on symptoms alone. If the levator ani muscle is tense, tender or painful when the puborectal muscle is pulled backward, the diagnostic reliability is greatly improved. The tenderness occurs unevenly, mainly on the left side. Massaging this muscle usually causes discomfort. Diagnosis is divided into two levels: if the symptoms are consistent and signs are present, the diagnosis is "highly suspicious"; if the symptoms are consistent but the signs are lacking, the diagnosis is "suspicious". Clinical evaluation usually includes medical history, rectal finger picking, and excludes chronic anal pain caused by other diseases. Many studies have reported that the anal myoelectric activity and internal pressure of the anal canal are increased in patients with LAS. However, the standard of anorectal manometry test is not clear. There are literatures showing that pain reduction is related to lower anal pressure. Studies have been carried out on cases of hypertonic sphincter (menopausal women and patients with perineal descent syndrome). In all cases, the puborectalis muscle pressure is too high and causes pain.
Non-specific functional anorectal pain fully meets the diagnostic criteria for chronic anal pain, and does not cause tenderness when pulling the puborectalis muscle from the back. The current cases are rare.
Spastic anal pain (PF) diagnosis
PF refers to sudden severe pain in the anal area that lasts for several seconds or minutes, and then disappears completely. The mechanism may be due to abnormal smooth muscle contraction, and patients with a family history of PF may be related to internal anal sphincter hypertrophy. The cause of PF is mostly related to psychological disorders. About 60% of patients have multiple organ symptoms, combined with irritable bowel syndrome, peptic ulcer or inflammatory bowel disease. Except for the increase in IASP, the pressure of the anal canal and sigmoid colon increased.
It is reported that only about 10% of patients have pain for more than 5 minutes[8,9]. After the attack, the pain will completely disappear as normal until the next attack. The onset time is uncertain and irregular. It can occur once within a few days or once within a few years. It is infrequent. 51% of patients have less than 5 times a year. The population morbidity is 8%-18%, and only 17%-20% of patients seek medical treatment. The incidence is different between men and women. The age of onset is between 30 and 50 years old.
LAS and spasm PF should be distinguished. The former has a longer duration of onset and more frequent onsets. There is a clear difference between LAS and pain caused by anal fissures and hemorrhoids. The nature of the pain is a vague dull sensation. The patient will say that sitting is easier than standing. Pain can be relieved by hot bath.