Overview

Anismus is a form of pelvic floor dysfunction that causes an individual to strain when passing stool and can eventually result in constipation. Your "pelvic floor" is a collection of muscles in your pelvis that help control bowel movements, among other things. Basically, pelvic floor dysfunction means these muscles and their associated nerves are miscoordinated. When stool is unable to progress in a regular bowel movement, it hardens and becomes stuck inside your bowels, making the next movement harder. Other names for anismus include dyssynergic defecation, pelvic floor hypertonicity, anal sphincter dyssynergia, and paradoxical puborectalis dysfunction. 

Anismus may manifest itself in a variety of ways. Most classically, the muscles that usually hold your stool in fail to release as you attempt to have a bowel movement (This is known as a hypertonic pelvic floor). They may even contract instead. This is called paradoxical contraction. Some also cannot coordinate their muscles to an extent that would allow sufficient force to be exerted by these muscles, which would help push stool effectively out of the body. Lastly, about half of these people will also have an impaired sensation of stool or even the urge to defecate.¹

Anismus may affect both sexes and occur during childhood as well as adulthood. There are cases in which it may cause physical defects or occur for other unknown reasons. Finally, anismus with a behavioural cause might share some characteristics or even relate to parcopresis or psychogenic faecal retention.²

Risk factors

Although anismus does not have any direct cause, it generally overlaps with other conditions like:¹

• Rectal ulcers
• IBS-C (Irritable Bowel Syndrome with constipation)
• Slow colonic transit time, which is described as the passage of food through the body
• Chronic constipation from childhood
• Rectal hyposensitivity
• Psychological disorders
• Opioid use

Classification

Anismus falls under a defecatory disorder as a functional disorder, due to a variety of rectal outlet obstructions that are, in turn, a functional outlet obstruction. In cases where Anismus causes constipation, it is a form of functional constipation. Other authors describe an "obstructed defecation syndrome", of which anismus is a cause.³

The Rome classification divides patients with functional defecation disorders into three main groups, although the patients share the same symptoms.

Type I - Paradoxical contraction of the pelvic floor muscles during attempted defecation

Type II: Insufficient Propulsive Forces throughout Defecation Attempted (Insufficient Defecatory Propulsion)

Type III: impaired relaxation with adequate propulsion

The above categorisation demonstrates that many of the terms used interchangeably with anismus are overly specific and ignore the concept of abnormal propulsion. Some of the definitions provided have also been too restrictive.

Causes

This is a functional disorder, since the exact aetiology eludes us; it does not appear to come from organic disease or a neurological disorder, and may itself be a learned adaptation to stress or trauma, and maybe even the stress of preexistent chronic constipation and straining-too-hard competitive realities underlying attitudes and assumptions- are.¹

Symptoms

• A frequency of fewer than three per week
• Excessive straining to poop
• The sensation of not getting everything out
• Hard stools
• The intuitive need to pull out the stools using fingers
• Bloated stomach
• Stomach pain
• Anal pain^1,2

Diagnosis

The catch before diagnosing dyssynergic defecation is that your health professional should rule out common structural and metabolic causes for constipation. This may just involve a few generic rectal exams, including the DRE, or digital rectal exam, which is a physical exam of the rectum using gloved fingers with lubrication. It may also include sigmoidoscopy, which is a little lighted scope. If they don’t lead to any apparent causes, it will then proceed to further investigations.⁴

Diagnosis needs to be positive on two or more of the following tests:

Anorectal manometry

Anorectal manometry is a procedure that measures the well-being of the anal and rectal muscles' function.. It is generally achieved by inserting a small, flexible tube with a balloon attached to the end into the rectum. The healthcare technician will slowly inflate the balloon; it will provoke your muscles to react as they would if you had a stool in your rectum. The free end of the catheter will attach to a machine that measures your activity. The test can identify:

• Whether you can create enough push force
• How well your anal sphincter muscles relax when you bear down. Whether they contract in response to pushing
• Whether your rectal sensation is within the normal range

Balloon expulsion test

This test measures the duration it takes to pass stool from the rectum, using a balloon inflated with warm water to simulate a stool. Your healthcare technician will insert the balloon into your rectum and inflate it up to a fixed level. After that, you will be given some privacy so that you may stand up or lurch forward to expel the 'stool'. If this takes more than a minute, one can infer the dysfunction of the pelvic floor.

Defecography

A defecography test takes X-ray or MRI images to observe the internal mechanics of your body in motion when you activate them to have a bowel movement. You will be asked to pass a medical paste that mimics stool while projections of the X-rays or MRIs are being taken on a screen in private. It can demonstrate, for example, pelvic floor dysfunction and other structural abnormalities that might lead to this issue of incomplete evacuation.

Sitz marker study

This test uses small markers to observe the rate of food movement through your intestines. You will first receive a pill from the health provider. It has a few markers seen in X-rays. Five days from the day you took that pill, you'll have your appointment; then your provider will do X-rays to see if the little markers are still in the colon. It will also indicate that the waste does not move through your large intestine as fast as it should, in case the markers are still in your system.

Complications

1. Chronic failure to fully evacuate stool may result in retention of a stool mass in the rectum (faecal loading) that may cohere and solidify, forming a faecal impaction or even a fecalith
2. Liquid stool components can leak around the retained mass of stool, which causes the phenomenon of paradoxical diarrhoea/faecal leakage (commonly referred to as encopresis in children and faecal leakage among adults)
3. In some cases, anismus presents in the setting of intractable encopresis, and resolution of anismus does not result in resolution of the encopresis. For these reasons, and because biofeedback training is invasive, high-priced, and labour-intensive, it cannot be recommended for the treatment of encopresis with anismus
4. The wall of the rectum can stretch, and that is nicknamed a megarectum⁵

Treatment 

Treatments include:⁴

Biofeedback

This is a mind-body physiotherapy technique that allows guided training using graded exercises to contract and relax your sphincter muscles at will. Biofeedback utilises painless electrodes on the skin to monitor factors such as heart rate, breathing, skin temperature, muscle tension, and brain activity. The results are shown on a screen for you and your provider to see.

In the course of a session, your therapist will walk you through different ways to contract your muscles or engage them and then relax or lengthen them to find out what works best. Through practice, you will learn how to push effectively and relax enough to move your bowels.

Biofeedback can also be used to train your sensory awareness. If rectal hyposensitivity is contributing to your problem, this training will help you to recognise the need to move your bowels earlier.

Lifestyle remedies

Even when you're not undergoing biofeedback therapy, general lifestyle changes that your doctor may recommend to assist you in having regular bowel movements are:

• Avoiding constipating agents
• Drinking enough water
• Eating enough fibre
• Take a walk after every meal
• Getting up and going to the bathroom at that very instant, you feel the urge
• Hopefully, pass stool at an expected time each day
• Laxative medications: Your health care provider may recommend laxatives and medications to handle constipation if other approaches do not do the trick. Although these medications have not been recommended specifically for dyssynergic defecation, they are effective for chronic constipation in general. Although they may not correct your muscle abnormality, they can at least prevent stool from getting too hard and impacted to pass

Botox

Botox Trial studies administering toxin for botulism in anismus patients gave mixed results. Theoretically, Botox could force the required muscles to relax, as it does with wrinkles. In reality, the ultimate result is that improvement occurs in about 50% of anismus cases. Maybe that is because anismus is more complicated than straightforward muscle tension. It certainly proves somewhat more successful with children. 

Summary

Anismus is one of the numerous pelvic floor dysfunctions that have been found to cause chronic constipation due to poor muscle and nervous coordination in the defecation process. It is common among many children and adults, although females are more affected than males. Anismus can result from physical defects, ulcers, IBS, and anomalous psychological conditions. Symptoms include bowel obstruction, straining during passage, pain, and feelings of bloating. Diagnosis is established through the process of exclusion of other conditions. Treatment options do exist for this disorder, ranging from biofeedback to lifestyle changes and drugs, and, in extreme cases, Botox injections are used.