Small Bowel Dysmotility, Pseudoobstruction, and Functional Correlation with Histopathology: Lessons Learned, 2020, Gonzalez & McCallum

[SNT Gatchaman]

Small Bowel Dysmotility, Pseudoobstruction, and Functional Correlation with Histopathology: Lessons Learned
Gonzalez Z, McCallum R

Purpose of review: Small bowel dysmotility is a broad heterogeneous term that encompasses a wide range of gastrointestinal disorders resulting from abnormal gut motility. Chronic intestinal pseudo-obstruction (CIPO) is a severe, rare, and complex small bowel motility disorder at the extreme end of this spectrum. It is characterized by failure of the intestinal tract to propel contents, which results in signs and symptoms of bowel obstruction albeit in the absence of any obstructive lesion(s). In this article, we discuss up-to-date diagnostic techniques, management options, and histopathological findings in CIPO.

Recent findings: We will emphasize the latest diagnostic methodologies and therapeutic options as well as enteric histopathologic abnormalities in patients with CIPO. CIPO continues to be a clinical challenge. Several novel pharmacological agents hold promise including gastrointestinal hormone agonists and prokinetics. Furthermore, histopathologic findings may help guide therapy and provide further prognostic significance. At present, nutritional support, symptom management, and avoidance of long-term complications are the mainstay of treatment in CIPO.

Link (paywall, Current Gastroenterology Reports)

 

[SNT Gatchaman]

The [Enteric Nervous System] is a large meshwork of up to 600 million neurons embedded within the smooth muscle of the gastrointestinal (GI) tract and has been referred to as a “second brain” because it is able to operate independently from the CNS and peripheral nervous system (PNS).

Small bowel motility disorders encompass illnesses that range from enteric dysmotility (ED) characterized by abnormal intestinal manometry, to life-threatening CIPO with radiographic evidence of small bowel dilation in the absence of a mechanical obstructive lesion.

updated guidelines on histolopathological techniques and diagnostic standardization of GI neuromuscular pathology were published in 2010 by the International Working Group, named The London Classification.

Nevertheless, CIPO remains a clinical and diagnostic challenge. First, clinical symptoms are nonspecific, widely variable and can have significant overlap with functional GI disorders. Secondly, limited awareness of this rare condition by clinicians can often lead to the wrong diagnosis, exhaustive work-ups, and/or inappropriate surgical exploration with progression of the underlying disease. Fourthly, therapeutic options to date have shown limited efficacy. As such, CIPO is associated with high morbidity and mortality and a poor quality of life.

The majority of CIPO cases are idiopathic, but may also be classified as primary or secondary. [...] Approximately 60% of adult CIPO cases are associated with a secondary cause. For example, metabolic disorders such as diabetes mellitus can have an autonomic neuropathy that may present as CIPO.

From a histopathological standpoint, CIPO can be classified into three major groups: neuropathies (inflammatory or degenerative), myopathies, (inflammatory or degenerative), or mesenchymopathies ([Interstitial Cells of Cajal] abnormalities).

There is not one diagnostic test that ascertains the diagnosis of CIPO. Diagnosis of CIPO rests largely on clinical findings, and a pragmatic stepwise diagnostic approach should take place with the exclusion of an underlying organic or mechanical process.

Chronic abdominal pain and distension is a major concern in patients with CIPO and is reported in up to 80% of cases.

Opioid-induced constipation is a well-known side effect of narcotics, including worsening small bowel dysmotility and dilation. It can therefore be a challenge to differentiate between chronic visceral abdominal pain and opioid-induced dysmotility in CIPO patients.

Nutrition optimization is first-line treatment in CIPO. Most patients with CIPO are malnourished and dehydrated due to poor oral tolerance, which eventually leads to intestinal failure defined as “reduction in gut function below the minimum necessary for the absorption of macronutrients and/or water and electrolytes, such that intravenous supplementation is required to maintain health and/or growth.”

At least half of patients with CIPO may not be able to tolerate enteral feeds. However, in trying this approach, it is recommended that a surgically-placed J-tube be utilized so a small bowel muscle biopsy can be obtained at the time of J-tube placement. Eventually, some patients require long-term home parenteral nutrition (HPN). Complications from HPN are many and may include line infection/sepsis, thrombosis, liver disease, among others