Intestinal neuronal dysplasia as a cause of surgical failure in Hirschsprung's disease: a new modality for surgical management

Intestinal Neuronal Dysplasia Type B: An Updated Review of a Problematic Diagnosis

Context.—

Intestinal neuronal dysplasia type B (IND B) is a controversial histopathologic phenotype that has been associated with intestinal dysmotility, either as an isolated condition or in conjunction with established pathologic disorders (eg, Hirschsprung disease). Many factors contribute to the debate over the existence and/or clinical significance of IND B, including a large body of published data based on inconsistent diagnostic criteria and methods, which have fostered many unwarranted conclusions that lack sufficient scientific basis.

Objective.—

To critically analyze existing published data regarding IND B to provide supporting evidence-based diagnostic practice and to stimulate necessary and scientifically sound research.

Data Sources.—

This update focuses on published literature related to the pathology of IND B because without a reliable pathologic diagnosis, studies of epidemiology, pathogenesis, natural history, management, and outcome are all suspect. Problems with existing data are identified explicitly with suggestions as to how future investigations should be designed and evaluated to better understand this entity.

Conclusions.—

Inconsistencies in diagnostic criteria and methods used to define IND B justifiably encumber the universal acceptance of IND B as a neuropathologic etiology for intestinal dysmotility. IND B will remain a controversial diagnosis until rigorous, well-controlled scientific studies are conducted to establish reproducible and reliable diagnostic criteria that reliably translate from one laboratory to another.

Intestinal Neuronal Dysplasia-Like Submucosal Ganglion Cell Hyperplasia at the Proximal Margins of Hirschsprung Disease Resections

Intestinal neuronal dysplasia type B (IND) denotes an increased proportion of hyperplastic submucosal ganglia, as resolved histochemically in 15-μm-thick frozen sections. IND has been reported proximal to the aganglionic segment in patients with Hirschsprung disease (HSCR) and is putatively associated with a higher rate of postsurgical dysmotility. We developed and validated histological criteria to diagnose IND-like submucosal ganglion cell hyperplasia (IND-SH) in paraffin sections and used the approach to study the incidence and clinical and/or genetic associations of IND-SH at the proximal margins of HSCR pull-through resection specimens. Full-circumference paraffin sections from the proximal margins of 64 HSCR colonic pull-through specimens and 24 autopsy controls were immunostained for neuron-specific Hu antigen, and nucleated ganglion cells in each submucosal ganglion were counted. In controls, an age-related decline in the relative abundance of "giant" ganglia (≥7 nucleated Hu-positive [Hu+] ganglion cells) was observed. A conservative diagnostic threshold for IND-SH (control mean ± 3× standard deviation) was derived from 15 controls less than 25 weeks of age. No control exceeded this threshold, whereas in the same age range, IND-SH was observed at the proximal margins in 15% (7 of 46) of HSCR resections, up to 15 cm proximal to the aganglionic segment. No significant correlation was observed between IND-SH and length of or distance from the aganglionic segment, sex, trisomy 21, RET or SEMA3C/D polymorphisms, or clinical outcome, but analysis of more patients, with better long-term follow-up will be required to clarify the significance of this histological phenotype.

Histopathologic delineation of the transition zone in short-segment Hirschsprung disease

Failure to completely resect the transition zone (TZ) between aganglionic and neuroanatomically normal bowel ("TZ pull-through") is considered one reason for postoperative obstructive symptoms in Hirschsprung disease (HD). Despite years of study, the proximal boundary of the TZ remains nebulous, complicated by discordant, often subjective, histopathologic definitions. In order to objectively delineate the TZ, transverse sections at 1 cm intervals from the rectums of 9 non-HD autopsy subjects and resections from 15 infants with short-segment HD were immunostained with Hu (ganglion cell bodies) and glucose transporter 1 (Glut1) (perineurium of extrinsic nerves), and 6 putative features of TZ were examined: (1) aganglionosis of ≥1/8th circumference; (2) myenteric or submucosal hypoganglionosis; (3) hypertrophic submucosal nerves; (4) Glut1+ submucosal innervation; (5) submucosal hyperganglionosis; and (6) "ectopic" ganglia in lamina propria, muscularis propria, or serosa. In non-HD controls, Glut1+ submucosal innervation, hypertrophic nerves, partial circumferential aganglionosis, and hypoganglionosis were absent or restricted to the distal 2 cm. In contrast, all 6 neuropathologic features of TZ were identified proximal to the aganglionic segment in the majority of HD resections, but the length of the TZ ranged from 0 to 12 cm, depending on which neuropathologic feature was considered. Excluding submucosal hyperganglionosis and ectopic ganglia, the TZ was generally ≤5 cm. Many features of TZ cannot be excluded intraoperatively with a biopsy or a full-circumference frozen section. However, partial circumferential aganglionosis, severe myenteric hypoganglionosis, and hypertrophic submucosal nerves can, and probably should, be assessed in full-circumference frozen sections of the proximal resection margin, to reduce the likelihood of TZ pull-through.

Transitional zone pull through: surgical pathology considerations

Incomplete resection of the transitional zone (TZ) between histologically normal and aganglionic bowel in Hirschsprung disease is a putative cause of postoperative dysmotility. A review of literature indicates that diverse histopathological indexes have been used to define the TZ, and validated and reproducible diagnostic criteria have not been established. As a consequence, the proximal margin of the TZ is difficult to delimit, and the length of the TZ in a given patient depends on the diagnostic criteria used. Seromuscular biopsies are inadequate to exclude TZ, as diagnostic indexes may involve only a portion of the bowel circumference or the submucosa. Most published investigations of postoperative outcome after a TZ pull through (TZPT) conclude that the latter can cause persistent obstructive symptoms, which necessitate reoperation. However, the results of these studies are difficult to translate into clinical practice because most lack appropriate controls, and the overwhelming majority provide inadequate histopathological descriptions for reference at the time of intraoperative frozen section analysis. At present, a conservative approach based on frozen section examination of the entire proximal margin of the resection to exclude obvious subcircumferential aganglionosis (contiguous gap between ganglia of more than one-eighth of the circumference), hypoganglionosis (continuous string of myenteric ganglia comprised of 1 or 2 ganglion cells without surrounding neuropil), or hypertrophic submucosal nerves (>2 nerves with widths ≥40 μm per high-power field) seems prudent. Well-controlled studies to correlate proximal margin histology, especially subtle anatomic or immunohistochemical changes, with postoperative outcome are needed.

Pathology of Intestinal Motor Disorders in Children

Varied intestinal neuromuscular pathologies are responsible for Hirschsprung disease and other forms of chronic pseudo-obstruction that are encountered in pediatrics. Pathologically distinct subtypes discussed in this review include aganglionosis, hypoganglionosis, neuronal intranuclear inclusion disease, ganglionitis, degenerative neuropathy, diffuse ganglioneuromatosis, neuronal dysplasia, malformations of the muscularis propria, degenerative leiomyopathy, leiomyositis, and mitochondriopathies. Emphasis is given to the histopathologic features that distinguish these conditions and their differential diagnoses.

Practical pathology and genetics of Hirschsprung's disease

Diagnosis and management of Hirschsprung's disease (HSCR) requires understanding of the malformation's anatomic features and multigenic nature. Rectal biopsies, intraoperative frozen sections, and resection specimens provide invaluable information. Extraction of these data requires thoughtful biopsy technique, adequate histologic sections, histochemistry, and collaboration of surgeon and pathologist. Critical consideration of transition zone anatomy and published studies of "transition zone pull through" indicate that more research is needed to determine how much ganglionic bowel should be resected from HSCR patients. Many HSCR-susceptibility genes have been identified, but mutational analysis has limited practical value unless family history or clinical findings suggest syndromic HSCR.

Patterns of postoperative enterocolitis in children with Hirschsprung's disease combined with hypoganglionosis

OBJECTIVE

The relationship between postoperative enterocolitis (EC) and Hirschsprung's disease (HD) combined with hypoganglionosis (HYP) has not been thoroughly reported elsewhere. The aim of this study was to investigate the incidence of EC after operation in children with HD combined with HYP and to identify new strategies to prevent postoperative EC.

METHODS

From 1998 to 2005, 97 children with HD underwent the modified Swenson's procedure in this institute. They were classified into 2 groups based on pathologic investigation as follows: group A contained 70 patients with HD and group B contained 27 patients with HD complicated with HYP. The mean follow-up time from the time of the operation was 3.4 years (range, 1.5-8 years). The incidence of postoperative EC and anorectal functions were evaluated and compared between these 2 groups.

RESULTS

Eight cases (11.4%) in group A developed postoperative EC, whereas 11 (40.7%) in group B did so. The incidence of postoperative EC in group A was significantly lower than that in group B (P < .005). According to the Rintala scoring system, the percentage of patients with an excellent score in group A (85.7%) was significantly higher than that in group B (P < .05). The recurrence rate of constipation in group B was 14.8% (4/27), whereas it was 2.8% (2/70) in group A.

CONCLUSIONS

Postoperative EC is associated with retained proximal HYP, which suggests that HYP could be, at minimum, a predictive marker for this complication. Complete resection of HYP segment could potentially minimize the incidence of postoperative EC and alleviate the severity of EC.

Long-term outcome, colonic motility, and sphincter performance after Swenson's procedure for Hirschsprung's disease: a single-center 2-decade experience with 346 cases

BACKGROUND

The aim of this study is to explore the long-term outcome and the colon and sphincter function in children undergoing the Swenson's operation for Hirschsprung's disease (HD).

METHODS

Three hundred forty-six children (266 males and 80 females) undergoing Swenson's operation for HD for 8 to 20 years were followed up. Barium enema and defecography, total and segmental colonic transit time with the simplified radioopaque markers, and the anorectal vector manometry were used.

RESULTS

Stooling patterns were fair in most patients, and the functional examinations were abnormal in few cases.

CONCLUSIONS

The long-term outcome is satisfactory in most of the children undergoing the Swenson's operation for HD, but it is still not as good as what the surgeons have expected. This is probably because of the abnormal colonic motility and/or the dysfunctions of the internal anal sphincter.

Advantages of intraoperative semiquantitative evaluation of myenteric nervous plexuses in patients with Hirschsprung disease

BACKGROUND

The reappearance of an occlusive syndrome after surgical treatment of patients with Hirschsprung disease is often caused by incomplete resection of the affected segment. Intraoperative examination of frozen biopsies assists surgery, but interpretation of biopsies in the transitional zone is difficult.

METHODS

We performed retrospective semiquantitative evaluations of myenteric nervous plexuses at the proximal limits of resection specimens from 41 children who were treated for rectocolic Hirschsprung disease using intraoperative examination of transparietal biopsies. The results of the evaluations were correlated with the postoperative courses of the children.

RESULTS

After formalin fixation, the mean length of the aganglionic segments was 8.9 cm (range, 1-37.5 cm). At the proximal limit, the percentage of the circumference of the muscularis propria that was composed of plexuses with ganglion cells was more than 95% in 7 children, 90% to 95% in 21 children, 40% to 80% in 6 children, and 30% or less in 7 children (17%), 4 of whom subsequently developed occlusive syndromes.

CONCLUSIONS

Semiquantitative intraoperative examination of the entire circumference of resected segments facilitates precise evaluation of intrinsic innervation at the level of the anastomosis and may reduce the frequency of recurrence of occlusive symptoms after surgery.

Intestinal neuronal dysplasia type B: one giant ganglion is not good enough

In this "Current Practice in Pediatric Pathology" article, 2 experts in the field and an associate editor of Pediatric and Developmental Pathology discuss the definition, diagnosis, clinical significance, and management of intestinal neuronal dysplasia type B. Intestinal neuronal dysplasia type B has constituted a diagnostic challenge ever since its first description more than 30 years ago. Intestinal neuronal dysplasia type B is regarded by many as a subtle malformation of the enteric nervous system that is limited to the submucosal plexus of the colon. The precise etiology remains unknown, and, to date, no specific diagnostic test exists other than morphology. Over time, with increasing experience, obligate pathological features have been adapted and refined, leading to contemporary diagnostic criteria that are enunciated in this review and placed into context with prior published data. Rigorous application of these criteria, under standardized laboratory conditions, is crucial for accurate diagnosis and future advances in this field.

An approach to minimize postoperative enterocolitis in Hirschsprung's disease

BACKGROUND/PURPOSE

Enterocolitis (EC) is a common and severe complication after pull-through for Hirschsprung's disease; its pathogenesis remains unclear, but the role of coexistent intestinal neuronal dysplasia (IND) in the proximal colon may be relevant. This study evaluated the relationship between postoperative EC and IND and assessed whether a surgical protocol including resection of coexistent IND could prevent postoperative EC.

METHODS

Between June 1993 and June 2002, 36 patients with aganglionosis were submitted to definitive surgical treatment. There were 2 sequential sets of patients: group I (n = 17), in whom the resection was confined to the aganglionic colon, and group II (n = 19), who were additionally submitted to resection of the coexistent IND segment; excision was restricted to the hepatic flexure in long segmental IND. The prevalence of postoperative EC and anorectal function were evaluated and compared between the 2 groups.

RESULTS

There was no mortality. Fifteen patients had isolated aganglionosis, and 21 presented with aganglionosis plus proximal IND. All 6 children who developed postoperative EC had coexistent IND. In group I, 9 patients had coexistent IND and 5 developed postoperative EC (5/17, 29%). In group II, 12 patients had coexistent IND but only 1 patient, with long segmental IND, developed postoperative EC (1/19, 5%). Among the patients with proximal IND, the prevalence of postoperative EC was 29%; but it was significantly lower in group II than in group I (1/12 or 8% vs 5/9 or 56%; P = .02). Anorectal function was excellent or good in more than 80% of the patients in both groups.

CONCLUSIONS

Postoperative EC was associated with retained proximal IND, suggesting that coexisting IND may be, at least, a predictive marker for this complication. Histochemical characterization of the proximal colon with no radical resection of the IND segment seems to be an effective and safe approach to minimize the prevalence of postoperative EC.

Obstruction due to rectal cuff after laparoscopy-assisted transanal endorectal pull-through for Hirschsprung's disease

We report a case of persistent obstruction after laparoscopy-assisted transanal endorectal pullthrough for Hirschsprung's disease in a 4-week-old boy with biopsy-proven HD. Before pull-through, the posterior rectal cuff was split along its entire length cranially, starting from the dentate line. Initial recovery was uneventful; however, signs of obstruction developed 3 weeks postoperatively. Reoperation through a posterior sagittal approach confirmed a residual rectal cuff surrounding the neo-rectum circumferentially. The dorsal side of the residual rectal cuff was removed completely. At follow-up 5 years later, he defecates 2 to 4 times a day with occasional staining. We hypothesize that the persistent postoperative obstruction was caused by a long residual rectal cuff that spontaneously reapproximated and/or became folded during pull-through. Therefore, a shorter cuff with near-total posterior excision should be strongly considered during laparoscopy-assisted transanal endorectal pull-through for Hirschsprung's disease.

Stooling patterns and colonic motility after transanal one-stage pull-through operation for Hirschsprung's disease in children

BACKGROUND

The transanal one-stage endorectal pull-through operation for Hirschsprung's disease is relatively new and makes assessment of the functional outcome and colonic motility difficult. The aim of this study was to evaluate the stooling patterns and colonic motility after a one-stage transanal pull-through operation for Hirschsprung's disease in children.

METHODS

Twenty-two children who underwent a one-stage transanal pull-through operation for Hirschsprung's disease were followed up for at least 6 months. The children (17 boys and 5 girls) were from 12 months to 13 years of age (mean age, 4 years). All patients had an aganglionic segment confined to the rectosigmoid area (confirmed by preoperative barium enema and postoperative histology). Clinical outcome was assessed by interviews and questionnaires, and children were divided into symptomatic and nonsymptomatic groups. Contrast barium enema and defecography and determination of total and segmental colonic transit time (using radio-opaque markers) were performed on all 22 children.

RESULTS

The stooling patterns were considered satisfactory in 17 children. Of all the children, the mean stool times were 1 to 2 per day and only 2 were 8 to 10 per day; postoperative soiling was found in 4, constipation was observed in 2, and Hirschsprung-associated enterocolitis in 1. There was no incontinence, cuff infection, anastomotic leak, or mortality noted. Barium enema showed that the dilated and spastic colonic segment disappeared in all 22 children. The dilated sigmoid loops decreased in 17 (2 symptomatic, 15 nonsymptomatic) and disappeared in 5 (4 symptomatic, 1 nonsymptomatic). There was a significant difference between the decreasing and disappearing loop group in regard to stooling disorders (P < .05). Postoperative defecography showed that the anorectal angle of all children was open, fixed, and significantly larger than that of the preoperative and control groups (123.3 degrees +/- 15.1 degrees vs 84.7 degrees +/- 8.3 degrees vs 79.0 degrees +/- 11.6 degrees, P < .01) and larger in the symptomatic group when compared with the nonsymptomatic group (135.6 degrees +/- 15.9 degrees vs 111.0 degrees +/- 14.3 degrees, P < .05). Postoperatively, the total gastrointestinal transit time, left colonic transit time, and rectosigmoid colonic transit time of all the children were shorter than preoperatively (26.8 +/- 8.2 vs >188 hours, P < .01; 6.3 +/- 4.1 vs >60 hours, P < .01; 11.8 +/- 4.4 vs >120 hours, P < .01) and similar to controls. The total gastrointestinal transit time and rectosigmoid colonic transit time of the symptomatic group were significantly shorter than the nonsymptomatic group (25.2 +/- 5.6 vs 28.1 +/- 10.1 hours, P < .05; 12.2 +/- 6.7 vs 9.8 +/- 4.0 hours, P < .05).

CONCLUSIONS

The stooling pattern and colonic motility are satisfactory in most children after the one-stage transanal pull-through operation for Hirschsprung's disease. Normalization of colon appearance and total and segmental colonic transit time are signs of recovery of colonic motility. Stooling disorders were noted in a few cases and may be related to decrease or disappearance of the sigmoid loop, dysfunction of the "neorectosigmoid", an open and fixed anorectal angle, and ischemia of the pull-through segment.

Clinical outcome in children after transanal 1-stage endorectal pull-through operation for Hirschsprung disease

BACKGROUND/PURPOSE

Recently, the transanal 1-stage pull-through operation has been widely used in Hirschsprung disease (HD), and it is obviously superior to traditional approach in early term for its noninversion. However, the procedure is relatively so new that it makes assessment of the functional outcome and stooling patterns difficult. The aim of this study was to evaluate the clinical outcomes of the transanal 1-stage endorectal pull-through operation in the management of rectosigmoid HD.

METHODS

Fifty-eight children (39 boys and 19 girls) aged 12 months to 13 years (mean, 2 years) who underwent transanal 1-stage endorectal pull-through operation for HD were followed up from 6 to 24 months. Clinical outcome was assessed by interviews and questionnaires. All patients had an aganglionic segment confined to the rectosigmoid area which was confirmed by the preoperative barium enema and postoperative pathological examination.

RESULTS

Forty-six patients had satisfactory results without complications. In all the children, the mean stool times were 1 to 2 per day; only 4 had mean stool times of 8 to 10 per day. Postoperative soiling was present in 9, constipation in 5, and HD-associated enterocolitis in 3. There were no incontinence, cuff infection, anastomotic leak, and mortality in any of the patients. In the 12 symptomatic patients, there were 4 children with length of aganglionic segment less than 30 cm, and 8 had 30 cm or more. In the 46 asymptomatic patients, 42 had length of aganglionic segment less than 30 cm, and 4 had 30 cm or more. There was a significant difference between the group with less than 30 cm and the group with 30 cm or more of aganglionic segment. For statistical analysis, the Fisher exact test showed P < .05.

CONCLUSIONS

The transanal 1-stage endorectal pull-through is a feasible and safe procedure in children with rectosigmoid HD. The clinical outcome is satisfactory. A gradual recovery could be noted in the stooling patterns along with the time after surgery. The younger the patient operated on and the shorter the aganglionic segment, the lower do the stooling disorders occur and the faster does the stooling function recover.

[Hirschsprung's disease: practical considerations]

Hirschsprung's disease (1/5000 live births) is defined by the congenital absence of neuronal cells in the nervous plexuses in the distal part of the digestive tract. The disease affects the rectum and sigmoid colon in 80% of cases, or is more extensive. Hirschsprung's disease is suspected in cases of low gastrointestinal obstruction in the neonatal period, or in cases of chronic severe constipation in childhood. It is diagnosed by pathological examination of rectal biopsies that include the submucosa. After standard staining, multiple sections are scrutinized for neuronal cells. Acetylcholinesterase staining is performed on a frozen fragment to demonstrate the hyperplasia of cholinergic fibers that is very suggestive of Hirschsprung's disease. This hyperplasia decreases from the rectum to the splenic flexure of the colon. Hyperplasia of extrinsic nerve fibers and rarefaction of neuromuscular junctions in Hirschsprung's disease may be demonstrated immunohistochemically. Differential diagnosis includes chronic intestinal pseudo-obstructions. The treatment for Hirschsprung's disease is, most often, anastomosis of the normally innervated gut to the anal canal. Peri- or pre-operative biopsies assist surgery, but their interpretation is difficult in the transitional zone. The examination of the surgical specimen allows measurement of the aganglionic segment and transitional zone. Different genes (RET, most often) may be involved in sporadic or familial Hirschsprung's disease. Hirschsprung's disease is associated with other digestive or extra-digestive abnormalities in 5 to 30% of patients. Associated abnormalities may delay the diagnosis and treatment of Hirschsprung's disease.

Paediatric constipation for adult surgeons - article 2: new microscopic abnormalities and therapies

Chronic constipation is a common condition in both adults and children. Children with chronic constipation frequently have symptoms that continue into adulthood. In the second part of the review we describe advances in the identification of abnormalities in the control of motility. The role of neurotransmitters in both paediatric and adult constipation is examined and the radical rethink of colonic dysmotility caused by the re-emergence of interstitial cells of Cajal is discussed. The recognition of chronic constipation as an heterogenous condition has led to the introduction of new therapies. Antegrade washouts through appendix stomas and an exciting new treatment with electrical interferential therapy may, in the future, result in a less invasive approach to the management of chronic constipation. An improved understanding of the assessment and management of chronic constipation in childhood is also likely to reduce the frequency and morbidity of chronic constipation in adults.

Results of a mechanical Duhamel pull-through for the treatment of Hirschsprung's disease and intestinal neuronal dysplasia

BACKGROUND/PURPOSE

The authors analyzed the results of a modified entirely mechanical Duhamel pull-through for the treatment of Hirschsprung' disease or type B intestinal neuronal dysplasia. The aim of the follow-up was to evaluate results of a Duhamel procedure entirely performed with the use of staplers.

METHODS

Fifty-six patients were followed up to detect complications and outcome. Patients were evaluated clinically, and, when symptoms were present, a suction biopsy with histochemical analysis, an x-ray contrast enema, or an endoscopy was performed.

RESULTS

Early complications developed in 4 cases (7%) including a case of leakage (1.8%). No patient experienced recurrence. During a mean follow-up of 49 months, further complications occurred in 16 other patients: 4 adhesive obstructions requiring surgery, 3 strictures, 5 chronic bleeding, 4 fecaloma formation, 2 urinary problems, and 13 postoperative enterocolitis. Four patients (7%) had more than 3 passages of liquid stools per day, and 3 of them who had an ileal pull-through had constant soiling. Thirty-seven children (68.5%) had 1 to 2 bowel movements per day and were continent. Seven (13%) had less than 3 bowel movements per week. Three children who underwent total colectomy were incontinent (5.5%). Three more children (5.5%) have not yet reached the age for continence. Forty-nine parents (87%) judged the outcome satisfactory.

CONCLUSIONS

Follow-up of mechanical Duhamel pull-through showed an acceptable long-term outcome. An increased risk of incontinence is present in case of ileal pull-through, whereas constipation is more frequent after partial colon resection, regardless of the type of intestinal neuronal malformation.

Neuronal dysplasia: A controversial pathological correlate of intestinal pseudo-obstruction

The infant or child with intestinal pseudo-obstruction poses many challenges for geneticists and other specialists. Although a well-defined anatomic diagnosis (e.g., Hirschsprung disease) can be established for a subset of patients, the pathological correlates for many patients are non-existent or controversial. Intestinal neuronal dysplasia (IND) is frequently considered in the differential diagnosis, despite the fact that existence and significance of the abnormal histopathological features that characterize IND are hotly debated. This review highlights some of the concerns regarding this diagnosis including problems with the diagnostic criteria, the manner in which these criteria are applied in contemporary pathology practices, and the likelihood that many of the pathological findings are secondary consequences of impaired motility with no other clear clinical significance. Possible genetic and developmental bases for IND are also discussed.

Enteric nervous system: development and developmental disturbances--part 1

This review, which is presented in two parts, summarizes and synthesizes current views on the genetic, molecular, and cell biological underpinnings of the early embryonic phases of enteric nervous system (ENS) formation and its defects. In the first part, we describe the critical features of two principal abnormalities of ENS development: Hirschsprung's disease (HSCR) and intestinal neuronal dysplasia type B (INDB) in humans, and the similar abnormalities in animals. These represent the extremes of the diagnostic spectrum: HSCR has agreed and unequivocal diagnostic criteria, whereas the diagnosis and even existence of INDB as a clinical entity is highly controversial. The difficulties in diagnosis and treatment of both these conditions are discussed. We then review the genes now known which, when mutated or deleted, may cause defects of ENS development. Many of these genetic abnormalities in animal models give a phenotype similar or identical to HSCR, and were discovered by studies of humans and of mouse mutants with similar defects. The most important of these genes are those coding for molecules in the GDNF intercellular signaling system, and those coding for molecules in the ET-3 signaling system. However, a range of other genes for different signaling systems and for transcription factors also disturb ENS formation when they are deleted or mutated. In addition, a large proportion of HSCR cases have not been ascribed to the currently known genes, suggesting that additional genes for ENS development await discovery.

Neuropathology of paediatric chronic intestinal pseudo-obstruction and related animal models

Chronic intestinal pseudo-obstruction (CIP) in paediatric patients is due to heterogeneous aetiologies that include primary disorders of the enteric nervous system. These conditions are poorly delineated by contemporary diagnostic approaches, in part because the complex nature of the enteric nervous system may shelter significant physiological defects behind subtle or quantitative anatomical changes. Until recently, relatively few experimental animal models existed for paediatric CIP. However, the availability of rodent models, particularly novel mutants created in the last few years by genetic manipulations, has brought unprecedented opportunities to investigate molecular, cellular, physiological, and histological details of enteric neuropathology. Information gleaned from studies of these animals is likely to change diagnostic and therapeutic approaches to paediatric CIP and related conditions.

Laparoscopic full-thickness intestinal biopsies in children

BACKGROUND

Laparoscopy may reduce postoperative pain and hospital stay, compared with laparotomy. The use of laparoscopic surgery to obtain full-thickness intestinal biopsies in children has not been previously reported.

METHODS

Eleven children aged 1.6 to 19 years (median, 4.5 years) underwent laparoscopic full-thickness biopsy of the stomach, small bowel, colon, or a combination thereof. Each procedure used one 12-mm and two 5-mm ports.

RESULTS

Eight children with obstructive symptoms after a pull-through for Hirschsprung disease underwent multiple colon and small bowel biopsies (range, 3-6; median, 5); intestinal neuronal dysplasia was found in two. Two patients with cystic fibrosis had diffuse colonic narrowing; a diagnosis of enzyme-induced fibrosing colonopathy was made in one and nonspecific inflammation was found in the other. One child had a thickened stomach, and a gastroscopic-directed full-thickness biopsy revealed plasmacytoma. Nine of the 11 patients had a previous laparotomy, and ports were placed through preexisting scars. Median hospital stay was 2 days. No patient required more than 24 hours of narcotics. There were no leaks, and no other morbidity or mortality occurred. None of the patients required conversion to an open procedure. Biopsy results significantly affected treatment for each patient.

CONCLUSIONS

Laparoscopic full-thickness intestinal biopsy is safe and effective for a variety of gastrointestinal problems in children. This technique is associated with a short hospital stay, minimal pain, and a very low risk of complications and can be performed even in patients who have had a previous laparotomy.

Hypercellular/heterotopic ganglia in omphalomesenteric duct remnants

Omphalomesenteric duct remnants (ODR) including Meckel diverticula often present with symptoms of bowel obstruction. Their histologic features are varied and include heterotopic gastrointestinal mucosa and/or pancreatic tissue within the wall. Abnormalities of the submucosal plexus of Meissner, however, have not been documented in the literature. Thus, we have examined a number of ODR for evidence of ganglion abnormalities. Fifty-three cases of ODR were retrieved from our archives, along with 25 nonduodenal small bowel control specimens obtained from autopsies of patients without clinical or pathologic evidence of enteropathy. Histologic criteria for the diagnosis of abnormal hypercellular/heterotopic ganglia (HHG) in ODR were defined as a single submucosal ganglion/plexus containing > 10 neurons, or > 5 submucosal ganglions per high-power (x 40) field, or heterotopic ganglion cells within the muscularis mucosa or the lamina propria. HHG, histologically indistinguishable from intestinal neuronal dysplasia type B, were found in more than half of the ODR (ODR: 51.9%, n = 50 vs. control: 4%, n = 25, P = 3.6 x 10(-6), particularly those excised for obstructive complications (ODR with acute abdomen: 65.7%, n = 35, vs. ODR without acute abdomen: 33.3%, n = 15, P = 0.035). HHG were present in equal numbers of inflamed and noninflamed ODR (inflamed: 53.6%, n = 28, vs. noninflamed: 59.1%, n = 22, P = 0.70). A similar incidence was found in ODR with heterotopia and without (with heterotopia: 61.1%, n = 18, vs. without: 53.1%, n = 32, P = 0.59). ODR frequently contained HHG histomorphologically similar to those found in intestinal neuronal dysplasia, type B (IND-B). The overrepresentation of HHG in symptomatic ODR patients suggests an association with bowel obstruction. The data did not demonstrate a relationship with either inflammation or heterotopia.

Colonic motility after surgery for Hirschsprung's disease

OBJECTIVE

Years after surgery for Hirschsprung's disease, many children continue to suffer from fecal incontinence or constipation. The purpose of the present investigation was to define the physiology underlying the persistent symptoms in children after surgery for Hirschsprung's disease, and to determine the outcome of interventions based on the results of the motility testing.

METHODS

We studied 46 symptomatic patients (5.5+/-3.3 yr old, 35 male) >10 months after surgery for Hirschsprung's disease. We performed a colonic manometry with a catheter placed with the tip in the proximal colon. We used a structured questionnaire and phone interview to follow up the patients an average of 34 months after the manometry.

RESULTS

We identified four motility patterns: 1) high-amplitude propagating contractions (HAPCs) migrating through the neorectum to the anal sphincter, associated with fecal soiling (n = 18); 2) normal colonic manometry associated with fear of defecation and retentive posturing (n = 9); 3) absence of HAPCs or persistent simultaneous contractions over two or more recording sites (n = 15), associated with constipation (n = 13); and 4) normal colonic motility and a hypertensive internal anal sphincter (>80 mm Hg) (n = 4). We based treatment on results of the motility studies. There was improvement in global health (mean score, 3.9+/-1.1 vs 2.8+/-1.3 at the time of initial evaluation, p < 0.001) and emotional health (3.8+/-1.1 vs 2.6+/-1.1, p < 0.0001). Improvement in the number of bowel movements occurred in 72% of children. Resolution or decreased abdominal pain was reported in 80%.

CONCLUSIONS

Colonic manometry clarifies the pathophysiology and directs treatment in symptomatic children after surgery for Hirschsprung's disease.

Repeat pull-through surgery for complicated Hirschsprung's disease: indications, techniques, and results

BACKGROUND

Most children with Hirschsprung's disease (HD) do well after a pull-through procedure. In the occasional child in which the operation fails, a repeat procedure may be necessary.

METHODS

Nine children with HD aged 20 months to 9 years underwent repeat pull-through over a 4-year period. Original pull-throughs (six Soave, two Swenson, one Duhamel) were performed elsewhere 12 to 95 months earlier (median, 36 months). Indications for revision were stricture unresponsive to dilatation (n = 3) and acquired aganglionosis (n = 6). One of the latter had associated segmental intestinal neuronal dysplasia. One child with a stricture after a Swenson procedure underwent a repeat Swenson. The other eight underwent reconstruction using a Duhamel technique. Five had a defunctioning stoma before or at the time of repeat surgery.

RESULTS

Median follow-up was 15 months (range, 4 to 40 months). Complications included wound infection (n = 2), anastomotic bleeding (n = 2), stoma leak (n = 1) or stenosis (n = 1), "kinking" at the top of the Duhamel (n = 1), and persistent septum (n = 1). Three patients have had a good outcome with normal stool patterns. One has intermittent soiling, and one has what is believed to be stool-holding behavior. Four have persistent obstructive symptoms caused by sphincter hypertonicity, which are being successfully managed nonoperatively.

CONCLUSIONS

Repeat pull-through surgery can be performed safely in appropriately selected patients. Duhamel reconstruction usually is preferred for technical reasons, and a stoma is not always necessary. Outcome is generally favorable, but anal sphincter hypertonicity may cause persistent symptoms in some patients.

Hirschsprung disease and other enteric dysganglionoses

Hirschsprung disease has become a paradigm for multigene disorders because the same basic phenotype is associated with mutations in at least seven distinct genes. As such, the condition poses distinct challenges for clinicians, patients, diagnostic pathologists, and basic scientists, who must cope with the implications of this genetic complexity to comprehend the pathogenesis of the disorder and effectively manage patients. This review focuses on the anatomic pathology, genetics, and pathogenesis of Hirschsprung disease and related conditions. The nature and functions of "Hirschsprung disease genes" are examined in detail and emphasis is placed on the importance of animal models to this field. Where possible, potential uses and limitations of new data concerning molecular genetics and pathogenesis are discussed as they relate to contemporary medical practices.

Reoperation for Hirschsprung's disease

BACKGROUND/PURPOSE

Reoperation for Hirschsprung's disease traditionally has been used for patients with anastomotic leaks or stricture or with severe constipation from retained aganglionic segment or neuronal dysplasia, but there is little information regarding its use for other complications and the long-term outcome in these patients.

METHODS

In a 23-year period, 107 infants and children underwent Soave (68 patients) or Duhamel (39 patients) pull-through procedures. The age at operation was newborn to 6 years (mean, 10 months). Eighty percent had aganglionosis limited to the rectosigmoid colon. Follow-up was by office visit or telephone (mean, 8.5 years).

RESULTS

Twenty-three of the 68 patients with Soave pull-through (34%) underwent reoperation for intractable enterocolitis (10 patients, all 10 cured); anastomotic stenosis (four patients, three cured, one continued diversion); anastomotic leak (four patients, four cured); retained aganglionic segment (three patients, three cured); one necrosis of pull-through converted to Duhamel and cured; and one rectal prolapse that was diverted. Fifteen of the 39 patients with Duhamel procedure (38%) underwent reoperation for severe constipation (seven patients, six cured, one diverted); persistent rectal septum (four patients, 4 cured); and intractable enterocolitis (four patients, three cured, one diverted). Overall, 21 of 23 patients (91%) with reoperation after Soave procedures were cured, whereas 13 of 15 patients (87%) who underwent reoperation after Duhamel procedure were cured, and four patients remain diverted.

CONCLUSIONS

These data show that aggressive reoperation can result in a high cure rate in Hirschsprung's disease. Although there is no significant difference in the rate of reoperation after Duhamel and Soave procedures, the patients with Soave pull-through required more complex reoperations, with several requiring more than one procedure. An aggressive approach to reoperation in patients with Hirschsprung's disease clearly is justified.