Colonic transit time in mentally retarded persons
Constipation is frequently seen in patients with mental retardation (MR). Its pathophysiology is poorly understood. Measurement of colon transit time (CTT) differentiates between retentive and non-retentive constipation. To determine total and segmental CTT in MR patients compared to healthy controls. Of 250 residents, 60 patients older then 16, without swallowing disorder or scoliosis, are randomly chosen, 58 participated (intelligence quotient < 50, median age 35.5 year, 29 male). Constipation was defined as less than three defecations a week. Controls are 32 non-constipated age-matched healthy volunteers (median age 29 year, 19 male). CTT is measured by daily administration of ten radio-opaque markers during 6 days and abdominal X-ray on day 7. CTT is calculated using Bouchoucha’s [7] method. Compared to controls, total CTT is significantly (P < 0.001) longer in MR (median 22.8 h vs. 57.6 h, respectively). Of the MR patients, 21/58 (36%) are constipated. The mental retardated and constipated (MRC) have a significant prolonged CTT in all segments (P < 0.01; median right CTT 19.2 h vs. 4.8 h; left CTT 14.4 h vs. 4.8 h; rectosigmoidal CTT 42 h vs. 9.6 h), whereas in mental retarded non-constipated (MRNC) persons, the rectosigmoidal CTT is prolonged (median 21.6 h vs. 9.6 h). Patients with moderate to deep MR have a significantly prolonged total CTT. In MRNC persons, rectosigmoidal CTT prolongation suggests a defecation problem. In MRC, CTT is prolonged in all segments, suggesting diffuse colonic inertia problem.