The histological hallmark of Hirschsprung's disease is Aganglinosis in the submucosal plexus of Meissner and Hypoganglionosis & 'skip-area' Aganglionosis (may exist or coexist) in the intermyenteric plexus of Auerbach. This leads to unopposed autonomic nervous system functioning which causes;
* Reduced or absent peristaltic activity * Increased intestinal sphincter tone The pathological hallmark is;
• There is marked distension & hypertrophy of gut proximal to the aganglionic segment • There is funnelling (coning) of the gut between the two - transition zone
• Constricted or collapsed gut at & distal to the aganglionic portion
Anatomical Distribution
• 85% - Left colon
• 2% - Total colonic aganglionosis
• Ultra short segment disease- Aganglionosis only at dentate line
C/P
• Chronic constipation since birth (Up to 4 days constipation in an exclusively breast feeding baby could be
normal)
• Delayed passage of meconium • Abdominal distension
• Failure to thrive
• Necrotizing enterocolitis - Bloody diarrhoea, Fever, Sepsis, Bile stained vomitus, Shock
O/E
• Abdominal distension • DRE;
- Increased intestinal sphincter tone - Empty rectum
- Followed by explosive passage of stool & flatus
** Do DRE after Barium meal to prevent stimulating GIT contractions
DDx
• Mechanical intestinal obstruction e.g. Meconium plug syndrome • Intestinal neuronal dysplasia (IND);
- Incidence of <5% that of Hirschsprung's disease. It is estimated that 25% of children with
Hirschsprung's disease have concomitant neuronal intestinal dysplasia, which may explain why some patients continue to have symptoms following definitive surgery.
- Features;
- Ectopic ganglion cells
- Hyperplasia of the submucosal and intermyenteric plexuses
- ± Hypertrophic nerve trunks and aberrant neurofibrils identified by acetylcholinesterase
stain
- C/P - A long-standing history of constipation, often dating from early infancy. - Ix - ↑NADPH & ↑LDH in intermyenteric plexus
• Hypoganglionosis - Ganglion cells are reduced by a factor of 10 & nerve fibres by a factor of 5 • Hollow visceral myopathy e.g. Desmosis of the colon - abnormal connective tissue of the colon. • Metabolic disorders
• Conditions affecting stool composition • Muscular or neurological disorders • Medications administered to the mother
Ix
• Barium meal;
- Massive distension of proximal colon - Funnelling (coning) of transition zone - Shows narrowing/constricted rectum Repeat after 24Hrs to monitor flow of contrast. • Rectal biopsy;
- Suction biopsy - For neonates - Done up to 5cm above the dentate line
- Full thickness biopsy - Under GA for older children - Done from 2cm above the dentate line • Anorectal manometry - To r/o IND - ↑ resting anal pressure ≥25mmHg - Insert balloon & dilate it above
intestinal sphincter - The sphincter normally should relax - rectosphincteric inhibitory reflex is Absent;
Sphincter relaxation may occur without peristaltic waves & instead there is high pressure segmental contractions 2° to normal smooth muscle reflex activity
Mx
Pre-op;• Manage fluid & electrolyte imbalances
• Insert a soft rectal tube & give patient soft enemas - 4.5ml/kg warm NS & irrigate GIT until patient settles. Conservative surgery;
• Levelling colostomy - Colostomy in the normal colon or Ileostomy in total colonic aganglionosis Indications;
- To decompress normal gut to allow normal growth & development until when definitive management can be instituted.
- Avoid - NOT eliminate risk of enterocolitis
3 Serial biopsies are taken & submitted in frozen section to determine the extent of the disease intra-op of the; i) Undilated segment (most affected);
- Absent ganglion cells
- Increased acetyl cholinesterase activity on histochemical staining due to lack of consumption by the ganglion cells
ii) Maximally dilated segment - Presence of hypertrophic nerve bundles iii) Normal gut - Normal anatomy
Definitive surgery;
a) Left colon disease - Resect aganglionated gut then anastomose normal gut at the dentate line i) Soave procedure;
• Mucosectomy of the rectal cuff up to the dentate line
• The anastomosis of normal gut at the dentate line - (modified by Boley) • There is risk of cuff abscess so always drain the cuff.
Original Soave procedure Boley modification ii) Swenson's operation - End-to-End anastomosis at the dentate line
iii) Duhamel-Grob princen procedure;
• End of normal gut anastomosed to the side of rectal cuff at the dentate line
• There is risk of faecaloma forming in the aganglionated rectal cuff - Lester-Martin modification takes care of this complication
Duhamel Procedure Lester-Martin modification Resultant common chamber b) Total colonic aganglionosis - Martin's procedure;
• Some colon is left for absorption of water & storage of faeces. Ileum is anastomosed at the dentate line & a side to side anastomosis of ileum to remaining colon. The ileum will provide peristalsis.
c) Ultra short segment disease - Submucosal myomectomy
Incidence
• 1:4000 - 6000 live births • M>F - 55-65:1
• Low lesions>High lesions
May occur as part of the VACTERL group of anomalies;
• Vertebral body segmentation defects - Hemivertebra, Sacral agenesis, SB, Kypho-scoliosis • Anorectal malformations
• Cardiovascular - PDA, VSD
• Tracheal - Esophageal fistula/ atresia
• Renal agenesis or ectopia, fusion, fistulae, VUR, neurogenic bladder, rec. UTI, _spadias • Limb abnormalities - radial agenesis, CTEV
Embryology
From the 4th to 7th weeks, the Primitive cloaca, derived from the primitive hind gut (endoderm) is divided by the
urorectal septum into;
• Ventral cloaca - gives rise to the urinary bladder, urethra & vestibule of the vagina
• Dorsal cloaca - gives rise to the rectum & anal canal which fuses with the Proctodeum, an invagination of the ectoderm which eventually breaks down by the 8thweek to give rise to the anus
While the gut tube lengthens, the endodermal lining proliferates, occluding the lumen by the 6th week of gestation.
The maturation of mucosa proceeds from a proximal to distal direction as vacuoles form in the gut tube, so it is fully recanalized by 9th week.
The reproductive system is interposed between the ventral & dorsal cloaca.