Exclusion Criteria: They were required to have no evidence of structural or metabolic diseases that could cause constipation, as assessed by colonoscopy/barium enema and routine hematological, biochemical and thyroid function tests. Patients taking drugs known to be constipating, for example opioids were either excluded or were asked to discontinue the drug prior to enrollment. Other exclusion criteria included: severe cardiac or renal disease, previous gastrointestinal, spinal or pelvic surgery except cholecystectomy, hysterectomy or appendectomy, neurologic diseases such as multiple sclerosis, stroke or spinal injury, impaired cognizance (mini-mental score < 15), legal blindness, pregnancy, rectal prolapse, anal fissure, and alternating constipation and diarrhea.