Colorectal Collaboration: Neurogastroenterology/Motility Disorders

Manometry is a catheter-based study of pressure changes within the lumen of the gut, involving visual pattern recognition of tracings to identify deviations from normal.

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

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

There are three types of constipation: normal transit constipation, slow transit constipation (problem with neuromuscular integrity of colonic wall), and outlet obstruction or withholding (most common in anorectal malformation children).

In a Sitz marker study, a patient should be able to pass all ingested radio-opaque markers in 5 days; markers remaining at 5 days indicate abnormal transit.

When Sitz markers are collected in the dilated rectum at 5 days, 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 studies colonic transit by tracking the geometric center of an ingested isotope and can identify specific colonic locations with transit issues.

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

There are two main types of colonic contractions: phasic (brief) or tonic (sustained), with segmental non-propagated contractions being the most common.

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 (stimulus to colonic motility upon waking) and gastrocolonic reflex (stimulus upon eating) affect the timing of colonic contractions.

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 allows evaluation of colonic mucosa, though interventional radiologists can also place them.

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

Segmental dysmotility on manometry can show HAPCs present in the right colon but absent in the left colon.

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

The management approach at Cincinnati Children's is to maximize medical therapy and understand anatomic and functional issues before resorting to surgical intervention and potential resection.

The first step in management is to maximize stimulant laxatives to ensure evacuation; if that fails, irrigation or enemas are tried before considering surgical interventions.

Resection should not be performed immediately based on one abnormal finding; multiple factors must be considered.

The first step in evaluating a patient with suspected motility disorder is to ensure normal anatomy, which can be assessed with contrast studies.

In the presented case, duodenal and colonic manometry were normal, ruling out widespread dysmotility and confirming gastroparesis as the isolated abnormality.