Internal anal sphincter achalasia: data from a nationwide survey of allied disorders of Hirschsprung's disease in Japan.

Abstract

To investigate the incidence and treatment of internal anal sphincter achalasia (IASA) in Japan based on an analysis of data from a nationwide retrospective cohort study of the allied disorders of Hirschsprung's disease. Five cases of definitive IASA were collected from a nationwide retrospective cohort study conducted from 2001 to 2010 and a search of the Japanese literature. Symptoms developed during the neonatal period in two patients, during early childhood in two, and at school age in one. Symptoms included abdominal distension with severe constipation (n=4) and enterocolitis (n=1). Rectocolonography showed megarectum and no narrow segment in most of the patients. All patients were negative for rectosphincteric reflex. The presence of ganglion cells was demonstrated by H&E or AChE staining from rectal mucosal biopsies or resected full-thickness segments. Two patients were treated conservatively, and three were treated surgically by internal anal sphincter myotomy (n=2) or Lynn procedure (n=1), with satisfactory outcomes. IASA is a rare but distinct entity in Japan. Although the clinical features of IASA resemble those of short- and ultrashort-segment HD, characteristic pathological findings include the presence of ganglion cells. The outcomes of both conservative and surgical treatment are good.