Thickening of the Internal Anal Sphincter: Primary Cause or Secondary Effect of Constipation

Constipation is one of the most common abdominal symptoms in childhood. In many cases, no primary cause is found and the condition may be labelled as “idiopathic constipation”. Fortunately, most of these cases respond well to dietary manipulation and laxatives. However, some patients continue to suffer from severe refractory constipation without an obvious primary cause [ [1] Hosie G.P. Spitz L. Idiopathic constipation in childhood is associated with thickening of the internal anal sphincter. J Pediatr Surg. 1997; 32: 1041-1044 Abstract Full Text PDF PubMed Scopus (28) Google Scholar ]. As pediatric surgeons, our main concern is to identify an unrecognized correctable surgical etiology. Among these overlooked potentially correctable surgical causes, internal anal sphincter (IAS) achalasia refers to failure of relaxation of the internal anal sphincter after rectal distension [ [2] Doodnath R. Puri P. Long-term outcome of internal sphincter myectomy in patients with internal anal sphincter achalasia. Pediatr Surg Int. 2009; 25: 869-871 Crossref PubMed Scopus (16) Google Scholar ]. Internal anal sphincter achalasia has a similar presentation to Hirschsprung disease but with the presence of ganglia on rectal biopsy. Others may describe a very similar condition as ultra-short segment Hirschsprung disease [ [3] Meier-Ruge W.A. Bruder E. Holschneider A.M. et al. Diagnosis and therapy of ultrashort Hischsprung's disease. Eur J Pediatr Surg. 2004; 14: 392-397 Crossref PubMed Scopus (30) Google Scholar ]. Both conditions are treated by IAS myectomy or, more recently, by Botox injection. While the definitive diagnosis requires anorectal manometry together with special detailed histochemical biopsy examination, the existence of both conditions is often not appreciated [ [3] Meier-Ruge W.A. Bruder E. Holschneider A.M. et al. Diagnosis and therapy of ultrashort Hischsprung's disease. Eur J Pediatr Surg. 2004; 14: 392-397 Crossref PubMed Scopus (30) Google Scholar ].