Clinical Features and Colonic Motor Disturbances in Chronic Megacolon in Adults

Abstract

Background: Chronic megacolon is a rare disease of the colonic motor function characterized by a permanent increase in colonic diameter.

Methods: We reviewed electronic medical records of all patients diagnosed with chronic megacolon from 1999 to 2014 at Mayo Clinic. Our aim was to summarize clinical and motility features, including colonic compliance and tone measured by colonic barostat-controlled 10-cm-long infinitely compliant balloon. Colonic compliance curves were compared to healthy control (40) and disease (47) control groups.

Results: Among 24 identified patients, the mean maximal colonic diameter on abdominal radiograph was 12.7 ± 0.8 cm. The cause of megacolon was idiopathic in 16 of 24 and secondary in 8 of 24. A relatively high prevalence (10/24) of comorbid pelvic floor dyssynergia was identified. At the time of this report, 16 patients had undergone colectomy. In general, megacolon presented high fasting colonic volume at relatively low pressures (16-20 mmHg), suggesting high colonic compliance; similarly, volumes at operating pressures that ensured apposition of the balloon to the colonic wall suggested low colonic tone. Median balloon volume at 44 mmHg distension was 584 mL (IQR 556.5-600) in patients with megacolon compared to 251 mL (212-281) in healthy, 240 mL (207-286) in functional constipation, and 241 mL (210.8-277.5) in diarrhea-predominant irritable bowel syndrome controls. Colon's tonic response to feeding was generally intact, and there was frequently maintained phasic contractile response to feeding.

Conclusions: Chronic megacolon is a severe colonic dysmotility, manifesting radiologically with increased colonic diameter; it can be proven by measuring colonic compliance and typically requires colectomy because of failed medical therapy.

Conflict of interest statement

Disclosures: The authors have no conflicts of interest.

Figures

Figure 1. Search Strategy to Identify Adults with Chronic Megacolon

Figure 2

Phasic and tonic contractile activity measured under constant pressure conditions in the colon (operating pressure 6mmHg) of patients with a) slow transit constipation and b) chronic megacolon. Note the large colonic volume (indicating low tone) during fasting and the persistence of phasic contractile activity despite the low colonic tone after the ingestion of a 1000kcal liquid nutrient meal.

Figure 3

Colonic compliance in (A) healthy controls, (B) functional constipation/constipation-predominant irritable bowel syndrome and (C) diarrhea-predominant irritable bowel syndrome (IBS-D) control groups; and (D) patients with chronic megacolon. Note the markedly increased volume of the intracolonic balloon (10cm long) in patients with megacolon compared to controls. Note also the marked increase in intraballoon volume (>300mL) at 16mmHg distension in all except one patient with megacolon, which is observed in only one healthy control and in none of the IBS-D patients.

Figure 4

Volume in 10cm long colonic barostat balloon at 8, 16, 20 and 44mHg distension pressures (overall p value