Intestinal Motility Disorders of Developmental Origin

Pediatric surgeons across the world often find themselves confronted with an infant who has not passed meconium, a child battling chronic constipation, or an adolescent with refractory abdominal distention and intermittent obstruction.[1] In these cases, a clinical suspicion lingers – is this a motility disorder? Notably, even in cases where clinical and radiological findings are strongly indicative of Hirschsprung’s disease (HD), coexisting or alternative motility disorders may be present – conditions that may significantly impact long-term outcomes if unrecognized at the time of initial evaluation.[2] This editorial draws from a meticulous 20-year data set spanning 2400 full-thickness biopsies (FTRB), providing a rare and insightful window into how often these suspicions are histologically confirmed and what the biopsy reveals.

THE EVOLUTION OF MOTILITY: A JOURNEY IN THE WOMB

Embryologically, the enteric nervous system begins its cephalocaudal migration from the vagus nerve at the esophagus around the 5^th week of gestation, reaching the anal canal by the 12^th week. Failure or arrest of this migration results in aganglionosis – HD. Meanwhile, the gut musculature forms between the 5^th and 20^th weeks, and the supportive connective tissue matures by the 24^th week. This finely choreographed development is vulnerable to genetic insults, intrauterine infections, immunologic factors, and an unfavorable microenvironment.

THE CLINICAL SUSPICION: WHY AND WHEN?

Intestinal motility is orchestrated by a fine interplay between the smooth muscle layers of the gut, the intrinsic enteric nervous system, and the connective tissue meshwork that binds them. Disruption of any of these components during fetal development may manifest as congenital motility disorders.[3] These conditions are often difficult to differentiate clinically from functional constipation or anatomical obstructions, leading to a relatively low threshold among pediatric surgeons to resort to rectal or colonic biopsy – particularly FTRBs.

Dr. Sudha Sane, Ex Professor, Department of Pathology and Cytology, KEM Hospital and GS Medical College, Parel, Mumbai.

In this extensive audit of 2400 such biopsies referred to a single pathologist between 2002 and 2022 from various Indian states (Maharashtra, Madhya Pradesh, Goa, Gujarat, and Karnataka), the most common clinical suspicion was HD. Prebiopsy investigations included barium enema and radiographs, but histopathology remained the gold standard.

WHAT DOES THE BIOPSY REVEAL?

Of the 2400 biopsies, a remarkable 68% confirmed the clinical suspicion of HD, validating the necessity of histopathological confirmation in these cases. However, a deeper dive into the remaining 32% revealed a fascinating spectrum of motility disorders:

• Intestinal neuronal dysplasia (IND): 6%

• Myopathies: 5%

• Internal sphincter achalasia: 5%

• Desmosis (deficient connective tissue): 5%

• Miscellaneous (mucoviscidosis, immature ganglion cells, short colon, etc.): 3%

• Inadequate biopsies: 8%.

These figures emphasize a crucial reality: while HD is the dominant player, a substantial minority of children present with other less commonly recognized motility disorders–many of which are equally debilitating and require surgical or targeted management.

AGE SPECTRUM AND CLINICAL MANIFESTATIONS

In this series, 60% of cases underwent biopsy during the neonatal period, 35% between 1 and 5 years of age, and 5% beyond 5 years. One patient presented at the age of 18 years. The male-to-female ratio was 4:1, consistent with known epidemiological patterns of HD.

Clinical presentations varied with age:

• Neonates: delayed meconium passage, abdominal distension, and enterocolitis

• Infants and toddlers: chronic constipation, failure to thrive, and abdominal bloating

• Older children and adolescents: Often misdiagnosed or underdiagnosed; some relied on enemas or laxatives for years.

Interestingly, 7% were premature by 2–4 weeks and 6% had associated anomalies including Down syndrome, congenital cardiac lesions, and urinary tract anomalies. Maternal obesity emerged as a subtle risk factor, echoing previous literature.

THE NON-HIRSCHSPRUNG’S SPECTRUM: CLINICAL LESSONS

Neuronal dysplasia

Often overlaps with HD, particularly when located proximal to an aganglionic segment. Its diagnosis requires stringent histologic criteria – especially the presence of giant ganglia in over 15%–20% of submucosal ganglia across 20 serial sections. Management is largely conservative but may require temporary stoma or resection in severe cases.

Desmosis coli

Coined by Meier-Ruge, this condition refers to absent or deficient collagen meshwork between the muscle layers. Patients usually present with chronic constipation and megacolon. Its detection mandates a FTRB; superficial biopsies are inadequate.

Myopathies

Involving the smooth muscle itself, these conditions may present with skip lesions, making segmental evaluation crucial. They are often associated with urinary tract anomalies and tend to be refractory to standard surgical interventions.

Internal sphincter achalasia

This is a functional outflow obstruction mimicking HD but showing normal ganglion cells with hypertrophic nerve bundles and abnormal manometric findings. Most respond well to sphincter myectomy.

Mucoviscidosis (cystic fibrosis)

Although rare in the Indian population, 35 cases were diagnosed. In cystic fibrosis, thick mucus can cause functional intestinal obstruction, particularly in neonates with meconium ileus. Constipation is a major issue, often underappreciated in these children.

WHY FULL-THICKNESS BIOPSY MATTERS

Histological evaluation relied on serial sectioning and routine hematoxylin and eosin (H and E) staining. While immunohistochemistry is often employed for neuron-specific markers, this experience shows that an experienced pathologist can extract robust diagnostic insights from conventional staining when coupled with well-oriented, adequate tissue sections.[4,5]

The power of a FTRB lies in its ability to evaluate all the three key components of bowel motility – neuronal plexuses, muscle layers, and intermuscular connective tissue.[6] For example:

• • Desmosis coli, a condition involving partial or total absence of the collagen mesh between muscle layers, would be missed in superficial biopsies

• • Myopathies often manifest as segmental or skip lesions in the muscularis propria and require a panoramic histologic view for detection

• • Internal sphincter achalasia demands both biopsy and anorectal manometry for diagnosis and is easily misinterpreted clinically with HD.[7]

• HD is diagnosed by identifying aganglionosis in rectal biopsy specimens, with FTRB considered the gold standard due to its high accuracy. Suction rectal biopsy, though less invasive, has lower sensitivity and may yield inconclusive results, making it more suitable as a screening tool. While the frequency of inconclusive biopsies from FTRB is generally low, it remains a relevant clinical issue. The use of Immunohistochemistry (IHC) staining – such as S100 and calretinin – can aid in clarifying some inconclusive cases when added to traditional H and E staining, potentially reducing the need for repeat biopsies. However, the overall added value of IHC is limited, and most inconclusive cases still require further investigation.

ROLE OF IMMUNOHISTOCHEMISTRY (IHC) IN DIAGNOSING MOTILITY DISORDERS

Immunohistochemistry (IHC) plays a crucial role in the diagnosis and classification of pediatric gastrointestinal motility disorders, particularly when conventional histology yields nonspecific or inconclusive results.[3] These disorders often arise from abnormalities in the enteric nervous system, smooth muscle, or interstitial cells of Cajal, and IHC enables targeted evaluation of these components. The key markers used include calretinin (for ganglion cell identification, especially in HD), S100 and PGP9.5 (highlighting nerve fibers), and smooth muscle actin and desmin (to assess muscle integrity in suspected myopathies). In addition, CD117 (c-KIT) is used to identify interstitial cells of Cajal, which are essential for gut pacemaker activity and can be depleted in certain motility disorders such as chronic intestinal pseudo-obstruction. Through precise staining, IHC allows pathologists to differentiate between neuropathic and myopathic forms of dysmotility and to detect inflammatory, degenerative, or developmental abnormalities that may otherwise be missed on H and E staining alone. This enhances diagnostic accuracy, guides surgical decision-making, and enables appropriate genetic or syndromic workup where relevant.

WHAT HAPPENS AFTER SURGERY?

Long-term follow-up data were available for 1500 patients over 2–8 years:

• Thirty-three percent of HD patients continued to experience motility disturbances due to compromised ganglionic segments, hypoganglionosis, or lack of gastrocolic reflex

• Patients with myopathies and desmosis faced persistent symptoms due to skip lesions and often required repeat interventions

• IND patients showed variable outcomes depending on disease extent.

These findings remind us that surgery for HD is not always curative.[8] Persistent or recurrent symptoms must prompt re-evaluation for associated proximal enteric pathology.

TAKE-HOME MESSAGES FOR THE PEDIATRIC SURGEON

1. Trust Your Clinical Judgment, but Confirm It with Biopsy. Two-thirds of suspected HD cases are confirmed histologically, and the rest yield equally important diagnoses

2. Full-thickness biopsy is invaluable. Superficial biopsies can miss crucial elements, especially in non-Hirschsprung’s disorders

3. Understand the full spectrum. Neuronal dysplasia, desmosis, myopathies, and functional obstructions such as sphincter achalasia are not rare – they are underdiagnosed

4. Surgery is not always the end. Long-term follow-up is essential to address persistent symptoms and plan second-line interventions

5. Collaborate with your poathologist. A skilled pathologist, supported by clinical insights and imaging data, remains your best ally in the diagnostic journey.

CONCLUSION

This 20-year experience from a dedicated pathologist serves as both a mirror and a lens. A mirror reflecting the diagnostic dilemmas faced by pediatric surgeons, and a lens focusing our attention on under-recognized yet impactful entities. It is a compelling reminder that while HD continues to dominate the landscape, the terrain of pediatric motility disorders is far more diverse, intricate, and demanding of multidisciplinary diligence.