Benzalkonium chloride-treated anorectums mimicked endothelin-3-deficient aganglionic anorectums on manometry

The anorectal spasticity in Hirschsprung disease may be caused by the absence of enteric ganglia and/or the presence of hypertrophic nerves. Anorectal manometry of chemically denervated rectums was compared with that of congenital aganglionic rectums that also possessed hypertrophic nerves.

Aganglionic and ganglionic littermates were produced from breeding heterozygous lethal-spotted mice. Benzalkonium chloride was endorectally injected into ganglionic rectums to ablate the neural elements. Anorectal manometry was performed before the injection and on day 14 postinjection. The anorectal resting pressure was calculated based on the manometric tracing. Rectums were retrieved on day 14 for histologic evaluations.

Benzalkonium chloride injection successfully ablated the rectal ganglia. Although ganglionic littermates exhibited regular slow waves on anorectal manometry, aganglionic lethal-spotted mice showed irregular waves. Similar to lethal spotted mice, benzalkonium chloride-treated mice exhibited significantly higher anorectal resting pressure than that of ganglionic mice. The slow waves were absent in benzalkonium chloride-treated mice.

Benzalkonium chloride treatment produced aganglionic rectums that had higher resting pressure similar to the congenital aganglionic rectums. This suggests that hypertrophic nerves in congenital aganglionosis are not necessary to produce the anorectal spasticity.