Journal of Postgraduate Medicine, Vol. 46, No. 1, January-March, 2000, pp. 52-54
Hirschsprung's Disease: Revisited
Department of Surgery and
Paediatric Surgery, Armed Forces Medical College, Pune - 411 040, India
Code Number: jp00016
The diagnosis and therapy of Hirschsprung's disease has changed in recent times and a firm diagnosis of the entity can be made pre-operatively by immunohisto-chemistry. There has been a recent trend of switching over from the conventional staged surgical procedures to primary pull-through procedures. In this article the newer concepts referring to its aetiology, pathogenesis, and the current technical advancements like stapler anastomosis, laparoscopic assisted pull-through and single one stage operation without colostomy are discussed along with a brief mention of current concepts in intestinal neuronal dysplasia, enterocolitis and total colonic aganglionosis. (J Postgrad Med 2000; 46:52-54)
Key Words: Hirschsprung's disease, Colonic aganglionosis, Intestinal neuronal dysplasia, Pull-through operation.
Hirschsprung's disease (HD) is one of the most common diseases in the field of Paediatric Surgery. It is a congenital condition characterised by the absence of ganglion cells in the submucosal (Meissner's) and myenteric plexus of the distal bowel. It is believed to result from the failure of ganglion cells to migrate fully caudad during the embryonic life. The loss of ganglion cells extends for a variable distance above the anorectal junction. In a recent series the classical HD was found restricted to rectosigmoid junction in 75% cases, long segment disease in 15% cases, ultra short segment disease in 5% cases and variable length was found in 5% of cases 1 . The aganglionic (distal) bowel in Hirschsprung's disease lacks the normal motility, thus the upstream bowel becomes dilated secondary to functional obstruction. Due to the stasis and obstruction there is a great risk of enterocolitis in these patients. There is also a lack of normal internal sphincter relaxation in response to rectal stretch and this is the principle of a diagnostic modality called anorectal manometry. Histologically, there is absence of ganglion cells in neural plexus of the all layers of gut together with hypertrophied nerve fibres or trunks. On histochemical staining increased acetylcholinesterase activity is noticed. There is also absence of non-adrenergic inhibitory nerves, which are required for normal bowel relaxation. This article makes an effort to discuss the newer scientific perceptions regarding its aetiology, pathogenesis, and recent technical modifications in the management of the disease.
The exact cause of Hirschprung's disease is unknown. The recent sophisticated molecular and embryologic studies have established that the aganglionosis results either from a failure of migration of neural crest cells to the correct site, or failure to mature, or degeneration of neural cells, or failure of differentiation in the altered micro-environment 2 . The increased expression of class II antigens found in mucosa and submucosa of HD patients points towards the likely immunologic basis of the entity. The recent studies have also shown that the mutations in the endothelin B receptor gene (EDNRB), endothelin 3 (EDN 3), RET protooncogene and glial cell linked derived neurotrophic factor (GDNF) genes are responsible for occurrence of congenital aganglionosis 3 .
The diagnostic accuracy of various modalities for Hirschprung's disease are radiology (barium enema) with 80% accuracy, manometry with 90% accuracy, biopsy with 95% accuracy and immunohisto-chemistry having 99% accuracy. The current criteria for histochemical diagnosis of the disease are failure to demonstrate ganglion cells in 60 serial sections from a suction rectal mucosal biopsy and positive staining for acetylcholinesterase (AChE) in nerve fibres within lamina propria, muscularis mucosa and subjacent submucosa. The various types of rectal biopsies are full thickness rectal biopsy, submucosal biopsy, seromuscular biopsy, punch biopsy and suction rectal biopsy. Now-a -days the rectal suction biopsy is safe, reliable and the procedure of choice but attention to technique is very important. In children over 6 months, the storz rectal cup biopsy is found to give superior results 4 . The standard full thickness rectal biopsy is indicated in children who had more than one non-diagnostic suction rectal biopsy. The barium enema reveals a transitional zone, which is a funnel shaped dilatation of bowel at junction of aganglionic and ganglionic gut. The retention of barium for 2-3 days and the rectosigmoid index less than 1 is also diagnostic of the disease. The anorectal manometry is a useful screening test in the constipated young child. The rectosphincteric inhibitory reflex is found absent in these patients.
The surgery for Hirschprung's disease is a staged procedure. In 1 st stage, the obstruction is relieved by establishing a loop enterostomy just above the transition zone to allow dilatation and inflammation to resolve and no attempt at resection is made. In 2 nd stage, the definitive surgery is performed when child is 10 months old and 10 lbs. in weight. The basic principle of definitive surgery is the removal of poorly functioning aganglionic bowel and an anastomosis of a normally innervated portion of the intestine to the distal rectum. The various definitive procedures are Swenson's - proctocolectomy, the Duhamel procedure - posterior pull-through with side-to side anastomosis to aganglionic rectum and Soave operation - pull of ganglionated bowel through the sleeve of rectum. There are no important differences with regard to outcome and long-term function in patients treated with these surgical procedures. However, specific problems have been described for each of these procedures. The Swenson operation is most physiological but is a difficult operation and the extensive pelvic dissection leads to trauma to the pelvic nerves. The Duhamel operation requires less pelvic dissection and is safe in infants as well as in adults but problem is of residual spur. The Soave's operation is easy to perform with no pelvic dissection required but the disadvantage is that it needs repeated dilatations. To avoid complications, the ideal muscular cuff required in Soave's procedure is 1-2 cm above the levator complex. The contemporary surgical management of HD is an early repair with few surgical stages. Hence, now-days the primary laparoscopic-assisted endorectal pull through is the procedure of choice 5 . Similarly, the use of GIA stapler for anastomosis in modified Duhamel operation avoids the problem of residual spur 6 . Morikawa Y et al from Japan found the extra anal mucosectomy in conjunction with a laparoscopic assisted prolapsing technique, a safe and reliable modality in the treatment of HD 7 . A transanal mucosectomy, colectomy and pull through (without laparotomy and laparoscopy) is also recommended as an effective and promising treatment modality in recent years 8 . The Albanese et al termed the perineal one-stage operative pull-through as POOP procedure and found it as a quick and easy technique to treat rectosigmoid HD 9 . On comparing the staged pull-through with primary pull-through it is found that staged pull-through is not any safer than primary pull-through for rectosigmoid HD and there is also no difference in complication rates 10 . Hence, the current trend is towards the primary pull-through at an early age with or without laparoscopic assistance. Pull-through operations have some problems and they may require redo operations. The causes of redo-operations are severe anastomotic stricture, rectourethral fistula, anastomotic disruption, enterocolitis and chronic constipation. The Duhamel operation is the best option for a secondary procedure 11 . The obstruction and/or enterocolitis after Hirschprung's surgery depends on the type of operation performed, the residual internal sphincter function, the presence of stricture at anastomotic site, the incomplete resection of aganglionic bowel and presence of neuronal intestinal dysplasia in upstream bowel which is present in approximately 20% cases. In a recent publication, the HD associated intestinal neuronal dysplasia was found in 40% of cases 12 .
Intestinal Neuronal Dysplasia (IND)
Intestinal Neuronal Dysplasia is characterised by decrease in intestinal motility of distal colon. It is found in 0.3 - 40% of suction rectal biopsies performed and the incidence with HD is 10-20%. It is a distinct histopatologic entity and usually presents as long standing constipation after pull-through operation in patients of HD. The diagnosis is usually established by increased acetylcholine esterase staining and increase in the ganglion cell number (larger ganglia with more than seven nerve cells/ganglia). Diagnosis of IND is not made until the patient develops defecation problem after a definitive pull-through procedure. The medical treatment is usually the first line of therapy in the form of cisapride, enemas and cathartics. If there is no response to conservative treatment for six months, internal sphincter myectomy is the procedure of choice 13 .
Enterocolitis is indeed a dreaded complication of Hirschsprung's disease. Its incidence after operation is approximately 33%. The most accepted explanation is that the persistent hypertonic anal sphincter associated with HD results in functional obstruction that leads to infection and inflammation of colon. Clinically it presents with abdominal distension and tenderness, explosive diarrhoea, fever, emesis, lethargy, haematochezia and sometimes with shock. The diagnosis is made with X ray abdomen, which shows presence of a distended bowel loop along the left flank with an abrupt termination in the pelvis, called as "intestinal cut off sign". Conservative treatment includes intravenous fluids, bowel rest, nasogastric aspiration, rectal tube drainage and broad-spectrum antibiotics (vancomycin and metronidazole). If it is the first manifestation then diverting colostomy is indicated. The patients, who are already operated, may benefit from anal dilatations or posterior sphincterotomy; rarely colostomy may be required. A recent report has suggested the usefulness of routine rectal irrigation in the post-operative period to prevent severe enterocolitis after pull-through procedure 14 .
Total Colonic Aganglionosis
Total Colonic Aganglionosis (TCA) is the severe form of HD. Its incidence varies from 5% to 8%. It is more commonly recognized in neonatal period and is more likely associated with enterocolitis. To diagnose the entity a high index of suspicion is required in any neonate who has signs of intestinal obstruction. Till date there is no proven superior surgical treatment in this entity. The use of extensive lengths of aganglionic bowel to maximise fluid absorption is frequently met with substantial morbidity, hence currently a short ganglionic-aganglionic common channel is practiced 15 .
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