title: The tension-stress effects on growth of the external anal sphincter: animal experiment and its application on treatment of anorectal stenosis.
abstract: OBJECTIVE
  To evaluate the effect of continuous balloon distension on the treatment of anorectal stenosis.
  
  
  METHODS
  Animal experiment on 17 guinea pigs and clinical study on 13 patients with anorectal stenosis were carried out. The procedure of the continuous balloon distension was followed to stimulate the growth of the anus or stenotic segment.
  
  
  RESULTS
  In animal experiment, the procedure induced muscle growth of the external anal sphincter at a rate of 2 mm per day. The grown muscle showed good contractile ability. By histological examination, it was found that the muscle cells were hypertrophic and Schwann's cells of the nerve fibers in the muscle became hyperplastic. Under electron-microscope, the muscle sarcomeres were found splitting both transversely and longitudinally. Twelve of the 13 patients were successfully treated by continuous balloon distension within 5 to 15 days (average: 6.7 days). During 4 to 14 months follow-up, all patients defecated without difficulty.
  
  
  CONCLUSIONS
  Continuous balloon distension may induce growth of the external anal sphincter. This procedure is an acceptable therapy for anorectal stenosis.
authors.affiliation: Department of Pediatric Surgery, Beijing Children's Hospital, Beijing, China.
authors.forename: L
authors.initials: L
authors.lastname: Li
authors.forename: J
authors.initials: J
authors.lastname: Zhang
authors.forename: Y
authors.initials: Y
authors.lastname: Wang
authors.forename: P
authors.initials: P
authors.lastname: Luo
mesh_terms: D000328:Adult; D001003:Anal Canal; D000818:Animals; D001004:Anus Diseases / Q000628:therapy*; D002404:Catheterization; D002648:Child; D002675:Child, Preschool; D003251:Constriction, Pathologic / Q000151:congenital / Q000628:therapy; D005260:Female; D006168:Guinea Pigs; D006801:Humans; D007223:Infant; D008297:Male; D024510:Muscle Development; D009130:Muscle, Smooth / Q000254:growth & development*; D012002:Rectal Diseases / Q000628:therapy*; D013718:Tensile Strength