Hirschprung's Disease

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General Information

Þ   Described by Harold Hirschsprung in 1886

Þ   It is the most common cause of neonatal obstruction of the colon (33%)

Þ   Overall incidence is about 1 in 5000 live births

Þ   Rare in premature infants

Þ   Males are affected more than females (4:1)

Embryology

In normal embryologic development, neuroenteric cells migrate from the neural crest to the upper end of the alimentary canal and then proceed in a distal direction and thus

By               5^th week :   first nerve cells in the oesophagus

                   7^th week :   nerve cells are at the midgut

                   12^th week : migration to the distal colon

Migration first occurs into the Auerbach’s plexus ( myenteric plexus )  and then into the submucosal plexus.

Migration is believed to be influenced by various neural glycoproteins or fibres. These glycoproteins include fibronectin and hyaluronic acid ( laminar protein ) which seems to create a pathway for neural cell migration.

Why in Hirschsprung’s disease this migration does not occur is not known.

The role of NCAM - Neural Cell Adhesion molecules is being investigated, as they appear to be reduced in patients with Hirschsprung’s disease. Some have also suggested a possible immunologic mechanism.

A deletion in the chromosome 10 has also been postulated as a cause for Hirschsprung’s disease.

Pathology

Gross: The gross features vary with the duration of the disease.

 ·        In the neonatal period the intestines may appear fairly normal.

 ·        As the child ages, the proximal, ganglionic intestine hypertrophies and becomes thicker and longer than normal. The taeniae disappear and the longitudinal muscle layer seem to completely surround the colon.

 ·        The transitional zone represented by the ganglionic and the aganglionic segment may be funnel like and vary in length.                                                                                                                                                                                 

·        The distal intestine appears normal.

 Microscopic Picture:

·        Absence of ganglion cells in the distal intestine is the hallmark of the disease.

·        Ganglion cells are absent both in the submucosal ( Meissner’s plexus ) as well as the intermuscular ( Auerbach’s ) plexus.

·        A marked increase in the nerve fibres which extend into the submucosa.

·        The length of the transitional zone may vary in length and may extend several centimetres.

·        Although ganglionic cells may be present in the transitional zone still the colonic motility may be abnormal.                                     Absent ganglion cells and hypertrophied nerves

Pathophysiology

·        Each of the intrinsic plexuses contains a finely integrated neuronal network that acts to control all the functions of the intestine.

·        Normal intestinal motility is primarily controlled by these intrinsic neurones converging onto each ganglion.

·        These ganglion can cause relaxation and contraction of the intestine although relaxation predominates.

·        Extrinsic control is through:

Þ   Excitatory cholinergic fibres using acetylcholine

Þ   Inhibitory adrenergic fibres using norepinephrine

·        Nitric Oxide (NO) is a mediator causing relaxation of smooth muscles.

·        With absent ganglion cells extrinsic system develops a markedly increased innervation of the intestines.

·        Cholinergic innervation is markedly increased in the aganglionic tissue and is predominantly excitatory causing contraction of that segment of the intestine.

·        A loss of nitric oxide synthase has been noted in patients with Hirshprung’s Disease.

Clinical Presentation

·        Symptoms range from complete acute neonatal obstruction to chronic constipation in the older child, sometimes there is diarrhoea.

·        Hirschsprung’s disease should always be suspected in a child who has a history of constipation dating back to the neonatal period. In the neonate there may be failure of passage of meconium

·        The median age for diagnosis of Hirschsprung’s disease has progressively decreased from 2 to 3 years of age to a mean age of 3 to 6 months (1970’s).

·        The usual presentation of Hirschsprung’s disease in the neonates consist of a history of a delayed passage of meconium within the first 48 hours of life.

·        Most of full term infants will defecate within the first 24 hours of life and the remainder will pass by 48 hours. This history may be absent in 6% to 42%.

·        There may be signs of partial or complete intestinal obstruction with vomiting, abdominal distension.

·        Temporary relief may occur after a rectal examination which is characteristically followed by an explosive discharge of faeces and gas.

·        Other presenting signs and symptoms include constipation, abdominal distension, poor feeding and emesis.

·        Clinical signs beyond the newborn period include constipation, abdominal distension and failure to thrive.

·        Patients may also present with a history of constipation followed by explosive diarrhoea indicating the development of enterocolitis. Clostridium difficle has been implicated in the etiology. Unless energetically treated the condition may be fatal within 24 hours.

·        Physical examination of a child often demonstrates abdominal distension that was absent at birth. A large faecal mass may be palpable in the left lower rectum but on rectal examination the rectum is usually empty of faeces.

·        The stools, when passed may consist of small pellets, be ribbon like or have a fluid like consistency; the large stools and faecal soiling of patients with functional constipation are absent.

·        Hypoproteinemia and edema may result from protein losing enteropathy. Breast fed babies with hirschsprung’s disease tend not to manifest as severe clinical features as infants fed artificial formulae.

·        In severe cases there is likely to be a loss of subcutaneous tissue and failure to grow. The wasted extremeties and large, protruding abdomen may be confused with that of the malabsorption syndromes especially when diarrhoea is present.

·        An assessment of the anal position on the perineum is important. A subtle, low - lying imperforate anus with an opening that is displaced in an anterior direction may also be a cause of constipation.

·        Rectal examination reveals a tight anus that is occasionally diagnosed as anal stenosis.

Diagnosis

·        A rectal biopsy by the punch or suction method that finds absence of ganglion cells in the submucosa and the intermuscular nerve plexuses with or without an increased numbers of nerve fibres is the only conclusive means.

·        Disadvantages of a rectal biopsy include bleeding, scarring and the need for general anesthesia.

·        Because the ganglion cells normally diminish in number in the more distal rectum and the anal canal, biopsies should be taken no closer than 1 cm to the pectinate line.                                        Full Thickness Rectal Biopsy

·        First time rectal examination and washouts before the study should be avoided because they may distort a low transition zone.

·        Diagnostic findings on barium enema are:

1.     An abrupt change in the calibre between the ganglionic and aganglionic section of bowel.

2.     Irregular ‘sawtooth’ contractions of the aganglionic segment.

3.     Parallel transverse folds in the dilated proximal colon.

4.     A thickened, nodular, oedematous proximal colon associated with protein losing enteropathy, if enterocolitis is present.

5.     Failure to evacuate the barium.

·        In infants a small amount of the contrast medium should be injected slowly with the tip of the catheter inserted barely beyond the anal sphincter as otherwise the transition zone may be obliterated. For the same reason the balloon should not be inflated.

Transition Zone:

Þ   Represents the most distal area in which the ganglion are present

Þ   In most patients it is in the rectosigmoid segment of the colon

Þ   The ratio of the diameter of sigmoid colon to the diameter of the rectum on contrast enema is greater than 1 in patients with Hirschsprung’s Disease.

·        The patient should be in an oblique position and be observed under fluoroscopy. If too much barium is injected the transition zone may be missed.

·        In the newborn the transition zone may not be as apparent as there may not have been enough time for the disparity in size to have developed.

·        Intramural gas will indicate enterocolitis and free peritoneal gas a perforation.

·        Anorectal manometry measured by distension of a balloon placed within the rectal ampula shows a fall of pressure in normal individuals but a striking rise in patients with megacolon.

 Differential Diagnosis

Distinguishing Features of Hirschsprung’s Disease and Functional Constipation.

Note the narrowed segment in the patient with Hirschsprung’s Disease and the patulous rectal vault in the constipated patient

Meconium Plug Syndrome: A contrast enema can be both diagnostic as well as curative. Very often after such a study, the child will pass a meconium plug and be relieved of the obstructive symptoms.

Distal Ileal or Colonic Atresia: Such patients will present as low intestinal obstruction as hirschsprung’s disease itself can have an associated atresia, a rectal biopsy becomes essential.

Small Left Colon Syndrome: Barium contrast studies will demonstrate the classical finding of a constricted left colon and the infant may have a diabetic mother.

Prematurity: The large intestine of premature infants also functions poorly and many such infants do not defecate in the first several days of life but subsequently Hirschsprung’s disease is not noted in them.

Meconium Ileus: Often present in a manner similar to those of Hirschsprung’s disease in the first few days of life. Abdominal radiographs demonstrate a ground - glass appearance in the abdomen particularly in the lower right quadrant.

Low Imperforate Anus: Should be ruled out by physical examination.

Sepsis, Electrolyte Imbalance, Hypothyroidism: May mimic as hirschsprung’s disease but can be ruled out by Biochemical investigations and by ruling out infection.

Associated Anomalies

Hirschsprung’s  disease is usually an isolated disorder of full term, otherwise healthy infants. However several associated congenital anomalies have been recognised as:

Down Syndrome, Trisomy 18, Ondine’s Curse, MEN type 2A, Congenital Deafness, Waardenburg Syndrome, Von Recklinghausen Disease, Ventricular Septal Defect, Meckel Diverticulum.

Treatment of Hirschsprung’s Disease

·        Once the diagnosis is established operation is indicated.

·        It is preferable to place a colostomy in the most distal portion of the normally ganglionated colon.

·        Attempts to postpone surgery by repeated colonic irrigations until the infant reaches a satisfactory size are not justified because of the risk of enterocolitis.

·        With early colostomy the mortality from enterocolitis is 4% as compared to 33% if a colostomy is done after the onset of enterocolitis.

·        When the infant is 6-12 months old a definitive  pull-through operation is done using the Swenson (full thickness extraanal colorectal anastomosis), Duhamel (end-to-side colorectal anastomosis) or the modified Soave (everted mucosa-full thickness colorectal anastomosis) procedure.

·        Surgical management consists of excising the agnaglionic segment and pulling the ganglionic intestine down through the anus anastomosing it to the anal canal within 2.5 cm of the pectinate line.

·        Ultrashort Segment Hirschsprung’s Disease: If the aganglionic segment is so short as to give the clinical and roentgenographic picture almost indistinguishable from acquired megacolon, major surgery is unnecessary. Excision of a strip of the internal anal (internal anal myectomy) is all that is required if non operative management is unsuccessful.

·        Total Colonic Aganglionosis: Ileal anal anastomosis is the treatment of choice, preserving a part of the aganglionic segment for adequate water resorption.

Prognosis

 ·        Results of the treatment of Hirschsprung’s Disease are generally satisfactory, with a great majority of patients achieving faecal continence.

·        Post operative problems include stricture, prolapse, cuff abscesses and faecal soiling.

·        Toilet training is delayed and for several years intermittent incontinence with diarrhoea may occur but with time most children become continent. Loperamide is useful in the management of diarrhoea.

  Thank You.

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