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home - Colon - Colonic Motility Disorders - Hirschprungs Disease Written by Dr Sebastian Zeki
Knowledge

Shows understanding of contemporary knowledge of the range of
factors that control gastrointestinal motility, as well as the means by
which symptoms arising from the GI tract are perceived.

In particular, can describe the enteric nervous system and
understands the ways in which drugs can modify its functioning

Can describe the brain-gut axis and the role of psychological factors
in the genesis of symptoms

Can describe the symptomatology and range of clinical presentations
of patients with irritable bowel syndrome

Knows the diagnostic criteria
Realises the importance of careful clinical assessment as well as the
need for appropriate selection of investigations

Knows the evidence-based treatment options for IBS and the
importance of a holistic and individualised approach to patient
management

Skills
Can make an accurate clinical assessment of patients with irritable
bowel syndrome

Uses investigations selectively
Communicates the diagnosis clearly and sympathetically
Appreciates the degree to which functional gut problems can impair
quality of life. Involves patients in making choice of treatment options

Can explain, where appropriate, that a psychological treatment might
be helpful and refer appropriately

Behaviours
Show a sympathetic understanding of the relevance of symptoms to
the individual and never appears dismissive

Takes time to explain nature of the condition, the treatment options
and appreciates their (often) limited effectiveness

AL

Hirschprungs Disease

Hirschsprung's disease DefinitionBowel fails to relax, causing a functional obstruction as neural crest cells (precursors of colonic ganglion cells) fail to migrate completely during development. Treatment: Neural crest cells Neuroblasts RET proto-oncogene Genes implicated GDNF Neurturin RET- codes for a tyrosine kinase receptor Receptor tyrosine kinase (RET)Transduces growth and differentiation signals in neural crest.Receptor ligands are GDNF and Neurturin.Degree of aganglionosis proportionate to RET dosage. The predominant gene affected is the RET proto-oncogene.-RET proto-oncogene polymorphisms are assoc. with HD phenotype. Diagnostic MethodsMucosal suction rectal biopsy show absent ganglion cells.-Rectal biopsy can show hypertrophic nerve fibres and elevated AChesterase activity.-Immunohistochemistry for RET on rectal tissue can help.Anorectal manometry is useful for ultrashort segment disease.Lack of relaxation of the internal anal sphincter with balloon rectal distension is suggestive of Hirschsprung disease.Contrast enema can show a transition zone- often rectosigmoid-often not visible in newborn.Recto-sigmoid index (Ratio of rectal and sigmoid diam-eters) <1 in HD.AXR- shows distal intestinal obstruction. Defect in the craniocaudal migration of neuroblasts from the neural crest -occurs in first 12 wks of gestation.Defects in the differenti-tion of neuroblasts into ganglion cells +inc. intes-tinal ganglion cell destruc-tion also contributes. GDNF or RET roles:Migration and survival of enteric neurons.Differentiation and survival of CNS neurons.Development of the PNS.Development of the kidneys and ureters. Clinical Features: Neonates (usual presentation) Distal intestinal obstruction (delayed first meconium) relieved by passing finger with blast of gas (Blast sign).Enterocolitis or Sigmoid volvulus- can also be caecal volvulus. Childhood (with less severe disease): History of chronic constipation and failure to thrive. Adulthood: Uncommon.Long history of refractory constipation without faecal incontinence. -RET proto-oncogene (majority- esp. if long segment disease)->20 different mutations. -Mutations in Endothelin 3. receptor B, converting enzyme (EDN3, EDNRB, ECE1);(GDNF);SOX10; PHOX2B.-The genetic defect in the remainder is unknown.Chromosomal+ other Associations: Trisomy 21,Cardiac disease (esp. septal defects)Congenital central hypoventilation syndrome;MEN2;Waardenburg syndrome;Smith-Lemli-Opitz syndrome Surgery- Remove aganglionic segment with primary anastomosis - one stagePost-Op Complications1. Constipation — Due to: Mechanical obstruction; Persistent or acquired aganglionosis, A colonic motility disorder (eg, intestinal neuronal dysplasia);Increased internal anal sphincter tone; Stool withholding behavior. In many cases, obstructive symptoms improve or resolve with time.Enterocolitis: Incidence: 30 %; within first post-op year; inc risk with anastomotic stricture/ long segment disease.Mortality<10%Incontinence: Common in early postop. Gradual improvement after 6 months in 95%Due to loss of water-absorptive surface area from colonic resection + anal sphincter dysfunction. Written by Dr Sebastian Zeki Demographics1: 5000 live births; M:F ratio of 3:1 to 4:1; If entire colon is involved 1:1

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