Acetylcholinesterase-stained suction rectal biopsies in the diagnosis of Hirschsprung's disease

Associations of Mucosal Nerve Fiber Innervation Density with Hirschsprung-Associated Enterocolitis: A Retrospective Three-Center Cohort Study

OBJECTIVE

 Hirschsprung's disease (HSCR) is a congenital intestinal neurodevelopmental disorder characterized by the absence of enteric ganglion cells in the distal colon. Although Hirschsprung-associated enterocolitis (HAEC) is the most frequent life-threatening complication in HSCR, to date reliable biomarkers predicting the likelihood of HAEC are yet to be established. We established a three-center retrospective study including 104 HSCR patients surgically treated between 1998 and 2019.

MATERIALS AND METHODS

 Patient-derived cryopreserved or paraffin-preserved colonic tissue at surgery was analyzed via βIII-tubulin immunohistochemistry. We subsequently determined extrinsic mucosal nerve fiber density in resected rectosigmoid specimens and classified HSCR patients accordingly into nerve fiber-high or fiber-low groups. We compared the distribution of clinical parameters obtained from medical records between the fiber-high (n = 36) and fiber-low (n = 68) patient groups. We assessed the association between fiber phenotype and enterocolitis using univariate and multivariate logistic regression adjusted for age at operation.

RESULTS

 Enterocolitis was more prevalent in patients with sparse mucosal nerve fiber innervation (fiber-low phenotype, 87%) compared with the fiber-high phenotype (13%; p = 0.002). In addition, patients developing enterocolitis had a younger age at surgery (3 vs. 7 months; p = 0.016). In the univariate analysis, the odds for enterocolitis development in the fiber-low phenotype was 5.26 (95% confidence interval [CI], 1.67-16.59; p = 0.005) and 4.01 (95% CI, 1.22-13.17; p = 0.022) when adjusted for age.

CONCLUSION

 Here, we showed that HSCR patients with a low mucosal nerve fiber innervation grade in the distal aganglionic colon have a higher risk of developing HAEC. Consequently, histopathologic analysis of the nerve fiber innervation grade could serve as a novel sensitive prognostic marker associated with the development of enterocolitis in HSCR patients.

Comparison between Suction Rectal Biopsy and Full-Thickness Rectal Biopsy in the Diagnosis of Hirschsprung's Disease

Aim:

The aim of this study is to compare suction rectal biopsy (SRB) with full-thickness rectal biopsy (FTRB) in suspected cases of Hirschsprung's disease (HD).

Materials and Methods:

Between 2014 and 2018, we enrolled 41 consecutive children with suspected HD. We analyzed demographics, sex, age, clinical symptoms, radiological images, and biopsy reports. All the children had undergone X-ray of the abdomen and pelvis and contrast enema. All of them have undergone both SRB and FTRB, and their results were compared.

Results:

Out of 41 children, 26 were male and 15 were female. The children were aged from 5 days to 12 years. All of them presented with delayed passage of meconium, abdominal distension, and severe constipation. They all were on oral laxatives. The sensitivity and specificity of SRB are 80.95% and 90.00% when compared to FTRB which has 100% and 100%, respectively.

Conclusion:

FTRB is the gold standard test for diagnosing HD. SRB may be a good screening test in suspected HD cases. SRB is not as equal and effective as FTRB for diagnosing HD.

Cholinergic innervation and ganglion cell distribution in Hirschsprung's disease

Background

The diagnostic gold standard of Hirschsprung’s disease (HD) is based on the histopathological assessment of colorectal biopsies. Although data on cholinergic innervation and ganglion cell (GC) distribution exist, only few studies have examined these two key features together. We assessed the pattern of cholinergic innervation and the amount of GCs in colorectal specimens of 14 HD patients.

Methods

We established a semi-quantitative score for cholinergic innervation using acetylcholinesterase (AChE) enzyme histochemistry and quantitatively analyzed the number of GCs via NADH tetrazolium reductase (NADH) enzyme histochemistry. We examined both the entire length of the resected specimens as well as defined areas of the transition zone of both pathological and healthy appearing segment.

Results

High AChE score values were associated with absence of GCs, and AChE scores were inversely correlated with the number of GCs. Nevertheless, we observed several cases in which one of the two features revealed a normal distribution pattern, whereas the other still displayed pathological features.

Conclusions

Our data support the need for transmural colon biopsies, to enable the best evaluation of both cholinergic innervation and GCs for a reliable assessment of HD.

Diagnostic Accuracy of Combined Acetylcholinesterase Histochemistry and Calretinin Immunohistochemistry of Rectal Biopsy Specimens in Hirschsprung's Disease

BACKGROUND

Acetylcholinesterase (AchE) histochemistry has been established as an accurate diagnostic tool for Hirschsprung's disease (HD). In addition, calretinin immunohistochemistry is also reported as a reliable and adjunctive method to diagnose HD. We investigated the diagnostic value of combined AchE histochemistry and calretinin immunohistochemistry in rectal suction biopsies from HD and non-HD patients.

METHODS

We retrospectively reviewed 99 rectal suction biopsy specimens including 4 repeat biopsies from 95 patients (34 HD and 61 non-HD). Each specimen was evaluated with hematoxylin-eosin, AchE histochemistry, and calretinin immunohistochemistry.

RESULTS

Of 95 patients, only 21 (22.1%) showed some ganglion cells. All 61 non-HD cases revealed no abnormal AchE-positive fibers. Of 34 HD patients, 32 exhibited abnormal AchE fibers, but 2 showed no stained fibers. None of the tissues from the HD patients exhibited calretinin immunoreactivity. Test sensitivity and specificity of AchE histochemistry alone were 93.5% and 100.0%, respectively, while calretinin immunohistochemistry were 100.0% and 85.2%, respectively.

CONCLUSIONS

AchE histochemistry is a good diagnostic method for HD, if feasible, and a combination of AchE histochemistry and calretinin immunohistochemistry will help increase the accuracy of the diagnosis of HD.

Acetylcholinesterase histochemistry (AChE)--A helpful technique in the diagnosis and in aiding the operative procedures of Hirschsprung disease

Background

Hirschsprung’s disease (HD) is an anomaly characterized by the absence of myenteric and submucosal ganglion cells (GC) in the distal alimentary tract. Diagnosis of HD is made by the absence of GC and missing out on even a single ganglion cell can be very devastating. Acetylcholinesterase (AChE) histochemistry, done on frozen sections is said to be a very useful ancillary technique in the diagnosis and in aiding the operative procedures of HD.

Methods

To assess this, 73 samples from 42 suspected/known cases of HD were subjected to frozen section analysis with rapid haematoxylin and eosin, toluidin blue stain along with AChE histochemistry. The remnant sample was paraffin embedded for routine haematoxylin and eosin staining.

Results

On frozen section analysis, 33 samples showed absence of ganglion cells, AChE histochemistry showed a positive staining pattern in 17 samples and paraffin embedded routine, H&E stained sections showed absence of ganglion cells in 19 samples. Sensitivity and specificity of both tests ie frozen section rapid H&E/AChE histochemistry in the diagnosis of HD, were calculated taking paraffin embedded H&E stained sections as the gold standard. Sensitivity of frozen section rapid H&E in the diagnosis of HD is 57.57 % and specificity is 79.10 %. The p-value is <0.0001, which is significant. The sensitivity of AChE histochemistry in the diagnosis of HD is 90.47 % and specificity is 96.36 %. The p-value is <0.0001, which is significant.

Conclusions

Acetylcholineesterase (AChE) histochemistry is a very useful ancillary technique in the diagnosis and in aiding the operative procedures of HD. It acts as a double check in the diagnosis of HD.

Rectal suction biopsy for the diagnosis of Hirschsprung's disease: a systematic review of diagnostic accuracy and complications

PURPOSE

Rectal suction biopsy (RSB) combined with acetylcholinesterase (AChE) staining is currently the gold standard for the diagnosis of Hirschsprung's disease (HD). However, some pathologists are still reluctant to diagnose HD in RSBs as it requires thick submucosal tissue to confirm the absence of ganglion cells. Furthermore, insufficient specimens and adverse events have been reported. The objective of this study was to determine the diagnostic accuracy and incidence of complications of RSBs in patients suspected of HD based on a systematic review of the published literature.

METHODS

A literature-based search for relevant publications was conducted using multiple online databases. Staining for AChE/hematoxylin and eosin should have been used to evaluate RSBs. The number of true-positive, false-positive, true-negative and false-negative results was recorded and data on RSB-related complications was extracted. Pooled incidence rates and odds ratios (ORs) with 95% confidence intervals (CI) were calculated using standardized statistical methodology.

RESULTS

Fifty-eight studies met defined inclusion criteria, reporting a total of 14,053 RSBs. The median cohort size consisted of 72 patients (range 1-766) with a median age of 14.4 months (range 1 day-66 years) at time of biopsy. In 89.93% (CI 89.11-90.70%), RSB provided adequate tissue for the diagnosis of HD. Insufficient specimens were obtained in 10.07% (CI 9.30-10.89%) and in 8.46 % (CI 7.55-9.46%) RSB was repeated. The incidence of HD was 19.13% (CI 18.25-20.03%). Mean sensitivity of RSB was 96.84% (CI 95.57-97.47%) and mean specificity was 99.42% (CI 99.17-99.57%). The overall complication rate was 0.65% (CI 0.46-0.91%) with persistent rectal bleeding requiring blood transfusion in 0.53% (CI 0.36-0.77%), bowel perforation in 0.06% (CI 0.02-0.18%) and pelvic sepsis in 0.06% (CI 0.02-0.18%). Complications were significantly more frequent in newborns and infants compared to older children (OR 9.00 [CI 4.75-17.07], p < 0.0001).

CONCLUSIONS

RSB combined with AChE staining is a simple, safe and accurate method for the diagnosis of HD. The risk for RSB-related complications is higher in newborns and infants.

Laboratory procedures update on Hirschsprung disease

OBJECTIVES

The detection of ganglion cells in rectal biopsies of infants or toddlers with severe constipation is routinely performed by pediatric pathologists in many institutions. Hirschsprung disease (HD) is defined by the lack of ganglion cells (aganglionosis). The early recognition and the prompt implementation of surgical procedures obviously protect infants affected with HD from potential life-threatening conditions, including enterocolitis and debilitating constipation. Image-based and non-image-based clinical techniques and some laboratory tests have been reevaluated along the years, but often fragmentarily. Immunohistochemical markers have been increasingly used in pathology laboratories to detect ganglion cells and nerve fibers. Recently, calretinin, a vitamin D-dependent calcium-binding protein with expression in ganglion cells and nerves, has been described as an adjunctive or primary diagnostic test in HD. The aim of the present study was to systematically summarize and update laboratory procedures targeting ganglion cells in rectal biopsies.

METHODS

Procedures and tests have been reviewed and values of specificity and sensitivity have been calculated according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

RESULTS

Contrast enema has the lowest sensitivity and specificity of all of the 3-index investigations under the lens: contrast enema, anorectal manometry, and biopsy with histology. The latter procedure seems to have the highest sensitivity and specificity. Acetylcholinesterase staining on fresh-frozen material has been found to have slightly higher rates of sensitivity and specificity when compared with hematoxylin and eosin only. Calretinin staining may be supportive for the diagnosis, although some cases with false-positivity may be of some concern.

CONCLUSIONS

Hematoxylin and eosin with or without acetylcholinesterase remains the criterion standard according to our PRISMA-based data. In our opinion, the number of false-positive results with potential overtreatment may limit the increasing advocacy for calretinin staining. Both the "primum non nocere" dictum and the "loss aversion heuristic" need to be satisfied harmoniously by preventing harm from unnecessary surgery.

Rectal suction biopsy to exclude the diagnosis of Hirschsprung disease

OBJECTIVES

Hirschsprung disease (HD) is defined as the absence of ganglion cells in the Meissner and Auerbach plexuses. Diagnosis depends on demonstrating the absence of ganglion cells in rectal biopsy specimens. Rectal suction biopsy is widely employed as the method of choice in obtaining such specimens. Classically, the diagnosis was made until the 1990s by using the Multipurpose Suction Biopsy Kit, or Rubin Tube. This device was replaced by the Model SBT-100 Suction Biopsy Kit as the exclusive device used to procure rectal tissue. Because the suction devices are known to occasionally yield tissue that is insufficient, the present study was undertaken to determine the efficacy of using this technique to make or exclude the diagnosis of HD.

METHODS

The last 50 biopsy sessions using the Multipurpose Suction Biopsy Kit and the first 46 sessions using the Model SBT-100 were included for review.

RESULTS

Both groups had similar yields (24%) of biopsy sessions with insufficient tissue to allow meaningful interpretation. The predictive value of rectal suction biopsy in excluding HD at the first biopsy session was 65%.

CONCLUSIONS

We conclude that HD can be excluded with a single rectal suction biopsy 65% of the time. A second biopsy session will exclude the diagnosis in an additional 11% of patients. Both devices yield biopsies of comparable quality and are equally useful in excluding the diagnoses of HD.

Histochemical staining for intestinal dysganglionosis: over 30 years experience with more than 1,500 biopsies

PURPOSE

Intestinal dysganglionosis are a group of anomalies of the enteric nervous system that constitute infrequent but severe forms of constipation. Histochemical stainings are the gold standard diagnostic procedure for intestinal dysganglionosis. This study describes our experience with histochemistry in a large series of patients.

METHODS

Between 1977 and 2010, 1,589 biopsies from children with persistent chronic constipation were studied. The specimens were snap frozen, sectioned and stained with acetylcholinesterase (AChE), acetylcholinesterase counterstained with hematoxilin and succinic dehydrogenase (SDH) histochemical stainings.

RESULTS

Among the 1,589 biopsies, 946 (59.5%) were rectal biopsies, 242 (15.2%) were internal sphincter biopsies, 346 (21.8%) were intestinal mapping studies and 42 (2.7%) of them were colon specimens from surgical resections. From the rectal biopsy group, 544 (57.5%) patients were reported as normal. Hirschsprung disease was found in 163 (17.2%) patients with a median age at diagnosis of 8 months and a male to female ratio of 3:1. Intestinal neuronal dysplasia was found in 162 (17.2%) patients, hypoganglionosis in 3 (0.3%) of them and ganglioneuromatosis in 1 (0.1%). In 73 (7.7%) patients, the biopsy was not conclusive for different reasons. 34 out of the 42 resected colon specimens were Hirschsprung disease. Intestinal neuronal dysplasia was found in the proximal segment of the aganglionic bowel in 15 out of 34 (44%) patients. All the aganglionic resected colon specimens had a previous aganglionic rectal biopsy. There were no false positive results in this group.

CONCLUSIONS

Histochemical stainings continue to be the gold standard in the diagnosis of intestinal dysganglionosis. The combination of two histochemical staining techniques provides a high level of accuracy in the diagnosis of intestinal dysganglionosis.

Variability of acetylcholinesterase hyperinnervation patterns in distal rectal suction biopsy specimens in Hirschsprung disease

Variability in cholinergic innervation may contribute to false-negative and false-positive evaluations for Hirschsprung disease (HD). We compared intraspecimen variability of histochemical acetylcholinesterase (ACE) activity in 62 distal rectal mucosal biopsy specimens from 33 patients with short-segment HD (SSHD), 14 patients with short-segment HD/Down syndrome (SSHD/DS), 10 patients with total colonic aganglionosis (HDTC), and 45 ganglionated control specimens obtained because of clinical suspicion for HD. Specimens were evaluated in 1-mm linear segments for abnormal distribution and abnormal intensity of staining reaction in the lamina propria (LP), muscularis mucosae (MM), numerical excess of small submucosal nerves (SSN), and presence or absence of large submucosal nerves (LSN) defined as >35 microns in diameter. Patients with HD and controls were predominantly infant males. Aggregate length of specimens was 186 mm in HD and 136 mm in controls. We defined multiple patterns and relative frequencies of normal and abnormal ACE reactivity in the muscularis mucosae, submucosal nerves, and innervation in the lamina propria. We verified a hyperinnervation pattern more common in neonates within each subset of HD. Large submucosal nerves >35 microns in diameter are relatively less common in SSHD/DS and HDTC. Eleven of 57 patients with HD had at least 1 mm of normal muscularis mucosae accounting for 19/186 mm examined. Ten percent of control mm had at least 1 submucosal nerve >35 microns in diameter. Intraspecimen variability in ACE patterns, when extreme, can usually be resolved by findings elsewhere in an adequate specimen, minimizing the need for repeat procedures.

Histochemical staining of rectal suction biopsies as the first investigation in patients with chronic constipation

Rectal suction biopsy (RSB) is the gold standard diagnostic procedure for disorders of bowel motility. This study describes our experience with RSB stained with histochemistry as the first diagnostic approach in a large series of patients presenting with chronic constipation. Between 1993 and 2005, 766 children underwent RSB for persistent chronic constipation. The specimens were snap frozen, sectioned and stained with conventional hematoxylin and eosin (H&E) and with nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) and acetylcholinesterase (AChE) histochemical stainings. Adequate amount of submucosa was present in 655 (85.5%) out of 766 cases and formed the basis of this study. RSB in 540 (82%) patients were reported as normal. Hirschsprung's disease was found in 47 (7.2%) patients with characteristic features of absence of ganglion cells, increased AChE activity in the lamina propria and muscularis mucosae, thick nerve fibers in the submucosa, and a lack of NADPH-d-positive fibers in muscularis mucosae. RSB in 59 (9%) patients presented features of intestinal neuronal dysplasia such as submucosal hyperganglionosis, giant ganglia, ectopic ganglia and increased AChE activity in lamina propria. Hypoganglionosis was suspected in nine (1.3%) children because of sparse or absent ganglion cells and low AChE and NAPDH-d activity in muscularis mucosae. Three patients (0.4%) developed bleeding following RSB, requiring diathermy of the bleeding point. Thus, we conclude that RSB is a simple and safe method when used as the first diagnostic approach in patients with chronic constipation. The combination of two histochemical stainings techniques provides a high level of accuracy in the diagnosis of intestinal dysganglionosis.

Acetylcholinesterase in Hirschsprung's disease

The association between the congenital absence of colonic ganglion cells and an increased acetylcholinesterase (AChE) expression in the affected tissue is of diagnostic importance in Hirschsprung's disease (HSCR). Investigation of AChE's function in development may also help unravel some of the complex pathophysiology in HSCR. Normal nerves do not stain for AChE, but increased AChE expression is associated with the hypertrophied extrinsic nerve fibres of the aganglionic segment in HSCR. Although a high degree of histochemical diagnostic accuracy exists, results are not always uniform, and false positives and false negatives are reported. False negative results are primarily related to age, and an absence of AChE reaction does not exclude HSCR in neonates within the first 3 weeks after birth. AChE staining results may lack uniformity, resulting in a number of technical modifications that have been made to improve standardization of AChE staining. At least two distinct histological patterns are described, types A and B. The interpretation of increased AChE staining patterns in ganglionated bowel at the time of surgical pull-through remains a problem in patients with HSCR. The development of rapid staining techniques has helped to identify normal ganglionated bowel with greater certainty. The presence of fine AChE neurofibrils in the ganglionated segment has contributed to the debate surrounding intestinal neuronal dysplasia. Quantitative assay of cholinesterase activity confirms the pattern of histochemical staining. AChE is particularly increased in relation to butrylcholinesterase, with one molecular form, the G4 tetrameric form, predominating. It is likely that the raised levels of AChE in aganglionic tissue are the transcriptional consequence of the abnormalities in signalling molecules that characterize HSCR. Evidence suggests that this AChE is functioning in a nonenzymatic capacity to promote cell adhesion and differentiation and that the hypertrophied nerves and neurofibrils may be the result of this increased AChE expression.

Transanal pull-through for Hirschsprung disease

Hirschsprung (HSCR) disease is a relatively common neonatal developmental disorder of the enteric nervous system and is characterized by the absence of ganglion cells in the myenteric and submucosal plexuses of the distal intestine. This results in absent peristalsis in the affected bowel, and the development of a functional intestinal obstruction. The pathogenesis and genetic basis of the disease is yet unclear. The surgical treatment of HSCR has evolved significantly since 1949 when Swenson first proposed a trans-abdominal pull-through procedure. The transanal pull-through consists of a rectal mucosectomy, resection of the aganglionic bowel and a colo-anal anastomosis. Recent literature and clinically controversies of this minimally invasive one-stage procedure are reviewed. Although follow up is still relatively short the preliminary results appear very favorable and cost effective.

Reliability of intraoperative frozen sections in the management of Hirschsprung's disease

BACKGROUND

The use of a 1-stage pull-through for Hirschsprung's disease (HD) is dependent on accurate identification of the normally innervated bowel on intraoperative frozen sections (IOFS). The authors wished to determine the incidence and sources of error during this process.

METHODS

All HD patients undergoing IOFS over a 15-year period were reviewed.

RESULTS

Three hundred four patients underwent a total of 700 IOFS. In 9 cases (3%), there was discrepancy between IOFS and permanent sections. Two of these were false-positive (ganglion cells incorrectly believed to be present at IOFS); both required a second operation as a result of the error. Seven were false-negative (presence of ganglion cells not recognized at IOFS); none required a subsequent operation, but 2 had a significantly more extensive colonic resection than was necessary. Responsible factors included sampling from the transition zone, freezing artifact, and misinterpretation of ganglion cells in very young patients owing to pathologist inexperience. There was significant variability in the error rate among the 11 pathologists. However, the numbers were too small for statistical analysis to determine whether there was a correlation between the rate of errors and the volume of cases done or years of experience.

CONCLUSIONS

Error in reading of IOFS is rare but can have significant repercussions in patient care. Multiple factors, including technical issues and pathologist experience, may have a role in contributing to these errors.

The constipated child: how likely is Hirschsprung's disease?

The incidence of Hirschsprung's disease (HD) was determined in children who presented with constipation to a specialist paediatric surgical unit. During a 5-year period, 355 rectal biopsies were performed on 182 neonates, infants and children presenting with chronic constipation or intestinal obstruction: 25 (14%) were diagnosed HD. One hundred and four patients had suction and 78 had full-thickness rectal biopsies. Haematoxylin-eosin (HE) staining and acetylcholinesterase (AChE) histochemistry was used. In 13 cases (8%) of suction and 2 cases (2.5%) of full thickness rectal biopsies, specimens were inadequate to diagnose HD. The mean age of all patients was 2.9 years and that of patients diagnosed with HD was 3.64 months. Nineteen patients with HD were diagnosed in the first month, 5 in 1-12 months and 1 at 4 years of age (Fig. 1). The authors found that along with onset of constipation convincing indications for rectal biopsy to exclude HD were as follows: those infants and children who do not pass meconium within 48 hours, have low intestinal obstruction of unknown cause, severe constipation, chronic abdominal distension and failure to thrive. A diagnostic accuracy of 94% was achieved with AChE histochemistry for suction rectal biopsy. After this review, referring paediatricians were advised that screening of other common organic causes of constipation with the least invasive investigations, including laboratory, dietary and paediatric gastroenterology advice, should be undertaken to avoid unnecessary rectal biopsy to exclude HD and related disorders.

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.

Rectal biopsy in the investigation of constipation

AIMS

To develop criteria to prevent unnecessary rectal biopsies in constipated children.

METHODS

A retrospective review of 186 rectal biopsies from 141 children, comparing the age at onset of symptoms with the diagnosis of Hirschsprung's disease.

RESULTS

All of the 17 children with Hirschsprung's disease had the onset of symptoms before the age of 4 weeks. Twenty seven children had delayed passage of meconium (more than 48 hours) of whom 10 had Hirschsprung's disease. Three children with Hirschsprung's disease were referred after the neonatal period (2 months, 11 months, and 3 years) but all had the onset of symptoms before 4 weeks of age.

CONCLUSION

If the age at onset of constipation is after the neonatal period, a rectal biopsy is unnecessary.

Neurology and the gastrointestinal system

Both achalasia and Hirchsprung's disease arise from defects of innervation of the oesophagus and distal large bowel respectively. Their consequences are confined to disorders of motility in the relevant part of the gastrointestinal tract. Many neurogenic and primary muscle disorders are associated with abnormalities of gut motility. Stroke, even when unilateral, is commonly associated with dysphagia. Transcranial magnetoelectric stimulation has established that the pharyngeal phase of swallowing tends to receive its innervation principally from one hemisphere. In many neurological disorders, dysphagia is only one part of the clinical picture but in some--for example, the Chiari malformation--dysphagia may be the sole or major feature. Disturbances of small and large bowel motility, when seen in neurogenic disorders, are associated with autonomic neuropathy and are particularly common in diabetes mellitus. Primary muscle disorders can lead to dysphagia (for example, with polymyositis or oculopharyngeal dystrophy) or defects of large bowel motility (for example, with Duchenne's muscular dystrophy). Primary gut disorders particularly associated with neurological disease include pernicious anaemia, nicotinamide and thiamine deficiencies, selective vitamin E deficiency, and coeliac disease. Inflammatory bowel disease is associated with thromboembolic complications which may include the CNS, inflammatory muscle disease, and abnormalities on MRI of the brain of uncertain relevance. Whipple's disease is a rare condition which sometimes is largely or entirely confined to the CNS. In such cases, a particular neurological presentation can indicate the diagnosis.

Hirschsprung's disease: clinical and experimental observations

Hirschsprung's disease (HD) is a relatively common cause of intestinal obstruction in the newborn. It is characterized by an absence of ganglion cells in the distal bowel beginning at the internal sphincter and extending proximally for varying distances. The etiology of HD-associated enterocolitis remains a complex issue. This study has provided further support for a possible infectious etiology of enterocolitis complicating HD.

An immunohistochemical study of neuronal microtubule-associated proteins in Hirschsprung's disease

Neuronal microtubule-associated proteins (MAPs) are important components of neurons and are believed to regulate neuronal function and development by controlling the assembly of microtubules and the interaction of microtubules with other cytoplasmic organelles. We studied the immunohistochemical localization of MAPs 1, 2, 5, and tau in the intestinal tissues of five patients with Hirschsprung's disease and in five normal controls using monoclonal antibodies. Microtubule-associated proteins 5 and tau proved to be excellent enteric neuronal markers; they were specifically located in the nerve cell bodies and processes of normal intestine as well as in the abnormal hypertrophied nerve fibers of aganglionic colon. Fine fibrillar structures in the neuroplasm were revealed in greater detail than were those obtained from studies with conventional markers, including neuron-specific enolase, S-100 protein, and neurofilament protein. A slight reduction of MAPs 5 and tau immunoreactivity was observed in the aganglionic colon compared with normal colon. Microtubule-associated proteins 1 and 2 were absent from the nerve fibers in both normal and aganglionic colon. This study suggests that immunostaining for MAPs 5 and tau may be superior to other immunohistochemical methods for diagnosing Hirschsprung's disease; however, in view of its limited retrospective nature these findings need to be corroborated by a large prospective evaluation.