Visualization of the human enteric nervous system by confocal laser endomicroscopy in Hirschsprung's disease: An alternative to intraoperative histopathological diagnosis?

Three-Dimensional Imaging of the Enteric Nervous System in Human Pediatric Colon Reveals New Features of Hirschsprung's Disease

BACKGROUND & AIMS

Hirschsprung's disease is defined by the absence of the enteric nervous system (ENS) from the distal bowel. Primary treatment is "pull-through" surgery to remove bowel that lacks ENS, with reanastomosis of "normal" bowel near the anal verge. Problems after pull-through are common, and some may be due to retained hypoganglionic bowel (ie, low ENS density). Testing this hypothesis has been difficult because counting enteric neurons in tissue sections is unreliable, even for experts. Tissue clearing and 3-dimensional imaging provide better data about ENS structure than sectioning.

METHODS

Regions from 11 human colons and 1 ileal specimen resected during Hirschsprung's disease pull-through surgery were cleared, stained with antibodies to visualize the ENS, and imaged by confocal microscopy. Control distal colon from people with no known bowel problems were similarly cleared, stained, and imaged.

RESULTS

Quantitative analyses of human colon, ranging from 3 days to 60 years old, suggest age-dependent changes in the myenteric plexus area, ENS ganglion area, percentage of myenteric plexus occupied by ganglia, neurons/mm2, and neuron Feret's diameter. Neuron counting using 3-dimensional images was highly reproducible. High ENS density in neonatal colon allowed reliable neuron counts using 500-μm2 × 500-μm2 regions (36-fold smaller than in adults). Hirschsprung's samples varied 8-fold in proximal margin enteric neuron density and had diverse ENS architecture in resected bowel.

CONCLUSIONS

Tissue clearing and 3-dimensional imaging provide more reliable information about ENS structure than tissue sections. ENS structure changes during childhood. Three-dimensional ENS anatomy may provide new insight into human bowel motility disorders, including Hirschsprung's disease.

Hirschsprung disease

Hirschsprung disease (HSCR) is a rare congenital intestinal disease that occurs in 1 in 5,000 live births. HSCR is characterized by the absence of ganglion cells in the myenteric and submucosal plexuses of the intestine. Most patients present during the neonatal period with the first meconium passage delayed beyond 24 h, abdominal distension and vomiting. Syndromes associated with HSCR include trisomy 21, Mowat-Wilson syndrome, congenital central hypoventilation syndrome, Shah-Waardenburg syndrome and cartilage-hair hypoplasia. Multiple putative genes are involved in familial and isolated HSCR, of which the most common are the RET proto-oncogene and EDNRB. Diagnosis consists of visualization of a transition zone on contrast enema and confirmation via rectal biopsy. HSCR is typically managed by surgical removal of the aganglionic bowel and reconstruction of the intestinal tract by connecting the normally innervated bowel down to the anus while preserving normal sphincter function. Several procedures, namely Swenson, Soave and Duhamel procedures, can be undertaken and may include a laparoscopically assisted approach. Short-term and long-term comorbidities include persistent obstructive symptoms, enterocolitis and soiling. Continued research and innovation to better understand disease mechanisms holds promise for developing novel techniques for diagnosis and therapy, and improving outcomes in patients.

Opportunities for novel diagnostic and cell-based therapies for Hirschsprung disease

Despite significant progress in our understanding of the etiology and pathophysiology of Hirschsprung disease (HSCR), early and accurate diagnosis and operative management can be challenging. Moreover, long-term morbidity following surgery, including fecal incontinence, constipation, and Hirschsprung-associated enterocolitis (HAEC), remains problematic. Recent advances applying state-of-the art imaging for visualization of the enteric nervous system and utilizing neuronal stem cells to replace the missing enteric neurons and glial cells offer the possibility of a promising new future for patients with HSCR. In this review, we summarize recent research advances that may one day offer novel approaches for the diagnosis and management of this disease.

Expression of the axon guidance factor Slit2 and its receptor Robo1 in patients with Hirschsprung disease: An observational study

ABSTRACT

Hirschsprung disease (HD) is a common form of digestive tract malformation in children. However, the pathogenesis of HD is not very clear. This study aimed to investigate the expression of slit guidance ligand 2 (Slit2) and roundabout 1 (Robo1) in patients with HD.From January 2018 to January 2019, 30 colon specimens from children with HD undergoing surgical resection at the Department of Surgery in Qilu Children's Hospital of Shandong University were obtained. These specimens were divided into the normal segment group, the transitional segment group and the spastic segment group. Immunohistochemical staining, Western blotting, and real-time polymerase chain reaction were used to measure the expression of Slit2 and Robo1 in the intestinal walls of normal, transitional, and spastic segments.Immunohistochemical staining and Western blot analyses showed high levels of the Slit2 and Robo1 proteins in normal ganglion cells in children with HD, lower levels in transitional ganglion cells, and no expression in spastic segments, with significant differences between groups (P < .05). Similarly, the real-time polymerase chain reaction results were consistent with the Western blot analysis results.The expression of Slit2 and Robo1 decreases significantly in the spastic segment of the intestinal tract in patients with HD.

Visualization of the human enteric nervous system by probe confocal laser endomicroscopy: a first real-time observation of Hirschsprung's disease and allied disorders

Background

Our group previously proved that the human enteric nervous system can be visualized with confocal laser endomicroscopy after topical application of cresyl violet using surgically resected intestine specimens. The present report documents the first in vivo visualization of the human enteric nervous system with confocal laser endomicroscopy using local cresyl violet staining. The aim of this study was to evaluate the technical feasibility and clinical efficiency of confocal laser endomicroscopy in patients with Hirschsprung’s disease and allied disorders in vivo.

Methods

Confocal laser endomicroscopy was performed in vivo in two patients to confirm the presence of the enteric nervous system during surgery in patients with Hirschsprung’s disease and allied disorders. Cresyl violet was gently injected from the serosal side into the muscular layer of the intestine, and scanning was performed within 30 min. Then, the scanned intestines were resected, and the visualized area of the specimens was pathologically evaluated.

Results

The ganglion cell nuclei and the enteric nervous system network were clearly visualized intraoperatively in both cases. The morphological findings were similar to the pathological findings of the enteric nervous system in both cases although the period of visibility was brief.

Conclusion

This study demonstrated the first, real-time observation of the enteric nervous system in humans using confocal laser endomicroscopy and suggest the potential to identify the enteric nervous system intra-operatively during surgery for Hirschsprung’s disease and allied disorders.

Advances and Pitfalls in the Diagnosis of Hirschsprung Disease

Surgical pathology for Hirschsprung disease (HSCR) occasionally is difficult, especially for those who encounter the disorder infrequently. This article reviews pathologic features of HSCR, considers various specimens the pathologist is required to evaluate, and discusses useful ancillary tests. Potential diagnostic pitfalls are highlighted, and helpful hints are provided to successfully navigate challenging situations. Finally, the article looks forward to new ancillary tests on the horizon and future topics for HSCR research.