chronic intestinal pseudo-obstruction

Definition: The chronic intestinal pseudo-obstruction (CIPO) syndrome is an alteration of smooth muscle contractile function characterized by repetitive episodes of bowel obstruction, with radiographic evidence of dilated bowel, but no fixed lumen occluding lesion.

Onset occurs before 1 year in 80% of cases but largely 60% of patients are diagnosed during the ante- or neonatal period.

Antenatal symptoms include hydramnios,megacystis and hydronephrosis but the most common symptoms, namely bilious vomiting, with abdominal distension, and constipation, usually occur soon after birth.

Urinary disorders, including megacystis and uretero-hydronephrosis are present in almost 70% of pediatric CIPOs.

Chronic intestinal pseudo-obstructions are either primary or secondary due to systemic disorders including amyloidosis, diabetes mellitus, drugs intake, metabolic and viral diseases.

Primary forms include myopathic, neuropathic and unclassified CIPOs.

Syndromic CIPOs (syndromal CIPO) include the megacystis-microcolonintestinal hypoperistalsis syndrome (MMIHS) and the syndrome of congenital short gut, malrotation, and dysmotility of the small bowel.

On the other hand, CIPO is sometimes observed in the course of mitochondrial disorders, and the main clinical feature of the mitochondrial neurogastro-intestinal encephalomyopathy syndrome (MNGIE) which is due to mutation in the thymidine phosphorylase gene (TYMP).

Other mitochondrial diseases also reportedly associated with CIPO include the mitochondrial myopathy-encephalopathy-lactic acidosis-stroke-like episodes syndrome (MELAS) due to mutation in the mitochondrial DNA [tRNAleu(UUR) or tRNAlys genes and disorders due to mutation in the DNA polymerase gamma gene (POLG).

Some adult CIPOs could be the presenting symptom of respiratory chain enzyme deficiency.

Pseudoobstruction implies a pathologic state with signs and symptoms of bowel obstruction without a mechanical cause. The chronic state can be congenital (congenital CIPO or primary CIPO) or acquired (acquired CIPO or acquired CIPO).

Types

 primary CIPO

• myopathic CIPO
  • atrophic myopathic CIPO
  • hypertrophic myopathic CIPO

• neuropathic CIPO
• unclassified CIPO (CIPO NOS)
• syndromal CIPO

 secondary CIPO

• amyloidosis
• diabetes
• metabolic diseases
• viral diseases

According to age

 pediatric CIPO (childhood CIPO)
 adult CIPO (adult-type CIPO)

Primary CIPO

In congenital CIPO, both visceral neuropathies (neuropathic CIPO) and myopathies (myopathic CIPO) prevail. The resulting CIP0 can be highly debilitating, lead to intestinal failure, and be fatal.

Treatment of CIP0 depends on the severity of the disease and its correct
diagnostic classification.

The visceral myopathies (VM) include constitutional visceral myopathy (CVM) and inflammatory visceral myopathies (IVM).

 Constitutional visceral myopathy (CVM or myopathic CIPO)

Of the CVM, the cases are either familial or sporadic. They may affect any part of the tubular gastrointestinal tract and also the biliary and urinary systems. The molecular defect is not defined.

Regardless of the inheritance pattern, CVM is overwhelmingly attributed to an atrophic muscularis propria. The atrophy is variable but described as a marked vacuolar degeneration of myocytes, loss of muscle fibers, and with or without a highly characteristic honeycomb fibrosis.

The recognition of the atrophic pattern of injury is the chief diagnostic clue that
a visceral myopathy is likely and other causes of CIP are unlikely.

A hypertrophic pattern in VM, dominating the atrophic pattern, is exceedingly
rare. As a pattern of injury, hypertrophy is almost absent from the description
of visceral myopathy in much of the literature.

See also

 digestive motility diseases

References

 Intestinal transplantation for motility disorders. Millar AJ, Gupte G, Sharif K. Semin Pediatr Surg. 2009 Nov;18(4):258-62. PMID: 19782308

 Chronic Intestinal Pseudoobstruction. Lyford G, Foxx-Orenstein A. Curr Treat Options Gastroenterol. 2004 Aug;7(4):317-325. PMID: 15238207