Colorectal Collaboration: Neurogastroenterology/Motility Disorders

Manometry is a catheter-based study of pressure changes within the lumen of the gut that entails visual pattern recognition of tracings and identifying deviations from normal.

Colonic motility has four key components: the diameter of the colon, the tone, the compliance of the colon wall, contraction pressures (how strong the contractions are), and the length of the colon.

In megacolon, the tone and compliance are usually abnormal, but colonic manometry may still show normal high amplitude propagated contractions and the transit may be normal.

There are three types of constipation: normal transit constipation, slow transit constipation (where there is a problem with the neuromuscular integrity of the colonic wall), and outlet obstruction or withholding (the most common in the pediatric population including anorectal malformation children).

A patient should be able to pass all Sitz markers in 5 days; markers remaining at the end of 5 days indicates that transit may be abnormal.

When Sitz markers are collected down in the rectum at 5 days with a dilated rectum, this is indicative of outlet obstruction or withholding.

When Sitz markers are scattered all over the colon at 5 days, this is indicative of slow transit constipation.

Scintigraphy allows identification of a specific location in the colon that is having transit issues by tracking the geometric center of an ingested isotope.

The smart pill is a large-sized capsule that measures pH, temperature, and pressure to assess gastrointestinal transit, but its size limits use to children approximately 10-12 years old or older.

Colonic contractions include phasic (brief) or tonic (sustained) contractions, segmental non-propagated contractions (the most common), and propagated contractions.

High amplitude propagated contractions (HAPCs) move stool along the length of the colon and correspond to what radiologists see on contrast enema as mass movement.

The orthocolonic reflex is a stimulus to colonic motility that occurs when waking up in the morning.

The gastrocolonic reflex is a stimulus to colonic motility that occurs when eating.

The majority of HAPCs originate in the proximal colon, and most do not propagate beyond the midcolon; fewer than 5% reach the rectum.

Manometry catheters are typically placed during endoscopy, which provides the opportunity to evaluate the colonic mucosa while placing the catheters; interventional radiologists can also place these catheters.

The rectal motor complex appears as multiple small spikes on manometry tracings at the level of the rectum.

If there is more than 40 to 50 centimeters of colon that does not have HAPCs, that is considered a dysfunctional colon.

Management at Cincinnati Children's for colonic dysmotility involves maximizing medical therapy and understanding anatomic and functional issues before resorting to surgical intervention and potential resection.

The first step in managing colonic dysmotility is to maximize stimulant laxatives and ensure evacuation; if that fails, irrigation or enemas can be tried; if that doesn't help, other surgical interventions can be considered.

Resection should not be pursued immediately just because of one abnormal finding; multiple factors must be considered.

The first step in evaluating a patient with suspected motility disorder is to ensure normal anatomy.