Definition:

Isolated hypoganglionosis (IHG) is an innervation disorder that provides diagnostic and management challenges secondary to ill-defined diagnostic criteria. The symptoms of IHG resemble classical Hirschsprung disease (HD), and include severe acute and chronic constipation, ileus, and enterocolitis. Histologically, it is characterized by very low or absent activity of acetylcholinesterase (AChE) in the mucosa, a significant reduction of nerve cells in the myenteric plexus and the submucous plexus such as hypertrophic muscularis mucosae and circular muscle. Outcomes are highly dependent on the length of the affected bowel, prolonged use of total parenteral nutrition (TPN), and associated infections. IHG has been proposed as a distinct entity with two subtypes: congenital IHG (CIHG) and acquired IHG (AIHG). In most cases, the onset of symptoms of HD and CIHG is in the neonatal period or in infants younger than one year of age. In contrast, AIHG can present at any age, depending to some extent on the underlying etiology.