Search

Patients with idiopathic megarectum (extreme dilatation of the rectum of unknown cause) with or without megacolon (extreme dilation of the colon) may develop symptoms in childhood or adulthood. The major symptoms are abdominal pain, constipation, soiling, and recurrent fecal impaction. Usually medical treatment is successful, but some patients may require surgery. The Duhamel operation, originally developed to treat megacolon that occurs in Hirschsprung's disease, removes the upper rectum and dilated colon, and reconnects the remaining normal segment of bowel at the upper end of the anal canal. A report is presented of the outcome of 20 patients with megarectum and megacolon who underwent the Duhamel operation. Patients were treated over a 17-year period by one surgeon, and there were 14 males and six females. The average age of onset of constipation was three years; the average age at the time of surgery was 25 years. There were many complications soon after surgery; five patients required further surgery for constipation. Most patients had a subjective feeling of improved well-being after surgery, however, soiling, straining, abdominal pain, and distention were common after surgery. Ten patients had improvement in bowel frequency. Given these mixed results, it is recommended that patients with moderately dilated rectum or colon who require surgery undergo colectomy with ileorectal anastomosis. The Duhamel operation should be considered for patients with grossly dilated rectum and distal colon. (Consumer Summary produced by Reliance Medical Information, Inc.)

An increasing number of adults are being seen for severe constipation that does not respond to the usual dietary changes and laxatives. Such constipation may limit the patient's social life by causing abdominal pain and distension. Severe constipation results from various causes and has several medical and surgical treatments. There is a large group of patients with dilated large bowel of unknown cause, or idiopathic megarectum and megacolon. This condition may occur in children or adults and is found equally in men and women. Often long-term treatment with laxatives is successful in treating patients with megarectum and megacolon; although they are effective, magnesium sulfate laxatives have an unpleasant taste. Alternative treatments include the use of oral lactulose and phosphate enemas. Patients who are intolerant of these methods or who do not obtain relief from them will require surgery. Those with a moderately dilated colon may undergo removal of all or part of the colon with a connecting of the ileum (last portion of the small intestine) to the rectum. Other possible procedures include proctocolectomy (removal of the colon with connecting of the ileum and anus), and colostomy (diversion of the colon to an artificial anus created through the abdominal wall). Patients who require surgery for megarectum and megacolon need to be carefully evaluated prior to surgery. Many of these patients have mild intellectual impairment or psychological problems. Studies of the upper gastrointestinal tract and colon transit time should be performed. (Consumer Summary produced by Reliance Medical Information, Inc.)

Time series analysis is being applied to the following geological data: tree rings, Sr isotope data for Phanerozoic seawater, and the El Niño phenomenon. First the data are treated by ARIMA models that enable, for stationary time series, to construct a stochastic model that can be utilized to forecast future values of the series. The subsequent R/Sanalysis allows detection of short or long range dependence in the data, furthermore it can also distinguish random from non-random series. It has been applied for El Niño data as well as to tree rings. For El Niño events we obtain evidence of the presence of “cycles” of nearly 30 years. In the case of tree ring width, their increments are independent random variables. The next technique, Neural Network analysis is a deterministic approach which overcomes the restriction of the ARIMA model and permits the reconstruction of the function that gives rise to the data series. We also outline the last approach, the Local Methods, which takes into account the topological structure of the data and enables predictions that approximate the evolution of a dynamical system generating the data. The long range component in the tree ring width data, as well as in the (Sr) isotope data, has been corrected for by first order subtraction in order to apply the ARIMA model. In these cases the Neural Network approach gives the same past predictions as the ARIMA model. The major contributions of our statistical approach for geological applications are the following: (1) recognition of qualitative changes within a given dataset, (2) evaluation of the (in)dependency of increments, (3) characterization of the random process that describes the evolution of the data, (4) recognition of cycles.

Bowel resection for idiopathic megarectum and megacolon does not always predictably relieve symptoms and has a significant morbidity. We have therefore evaluated the results of stoma formation in this condition. All patients had a bowel frequency of less than one per week, and all had a dilated rectum or colon. Eight patients, six of whom had had a previous unsuccessful operation for their constipation, had a colostomy — this relieved the constipation and the need for laxatives in all six patients with rectosigmoid dilatation, although one patient could not tolerate his stoma. Two patients with dilatation of the whole colon were not helped. An ileostomy was formed in four patients with previous colonic resection, with relief of constipation in all. However pain and abdominal distension were common persistent symptoms in both groups. Four patients with a colostomy and all four patients with an ileostomy felt subjectively improved with a stoma. Stoma formation is a viable alternative to more major surgery, either as a primary procedure or after previous surgery has failed.