Gastrointestinal (GI) motility disorders (GMDs) are represented by a spectrum of conditions that range from benign prevalent disorders (gastroesophageal reflux (GER) and childhood constipation) to more rare and severe entities (chronic intestinal pseudo-obstruction (CIP) and Hirschsprung’s disease). Altered GI motility adds considerable co-morbidity to structural anomalies such as intestinal atresia, stenosis, or gastroschisis. Pediatric GMDs are classified according to the results of GI motility testing. It is likely that with advanced methods of studying the brain–gut axis, classification of these disorders will eventually be based on pathophysiology. Within the pediatric population, GMDs are also known to be either congenital or acquired, depending on the presence or absence of symptoms at birth.1,2 Congenital disorders usually cause symptoms within the first 2 months of life and can be sporadic or familial. Acquired motility disorders present later in life and can be secondary to a variety of insults including infections and adverse reactions to medications.3 Within the pediatric population, GMDs account for up to 15% of all intestinal failures.

Based on histopathology and patterns of motility abnormalities, traditionally the causes of GMDs are also classified as visceral neuropathy or visceral myopathy.3 Neuropathic disorders are more common, but myopathies are usually associated with more severe symptoms.2,3 The role of genetic mutations in visceral neuropathies or myopathies has not yet been thoroughly elucidated.

Other possible causes of motility disorders include intrauterine ischemic insults, exposure to amniotic fluid,4 delayed maturation of either the enteric nervous system or the interstitial cells of Cajal,5 and disorder of the mitochondrial electron transport chain enzymes.6 Inflammation within the myenteric ganglia may cause severe progressive neuropathic CIP in conjunction with autoimmune disease and circulating antienteric neuronal antibodies.7 Mitochondrial myopathies are known to be associated with a variety of clinical syndromes including CIP.8 Patients with mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) have GI dysmotility, peripheral neuropathy, and ophthalmoparesis, and muscle biopsy shows histological features of mitochondrial myopathy.1,9,10

While treatment of motility disorders has improved significantly over the last two decades, treatment options remain relatively limited. Motility disorders produce nutritional and electrolyte deficiencies, chronic and recurrent vomiting, fecal incontinence, chronic and recurrent pain or discomfort, reduced independence in daily life, and reduced mobility. A wide range of clinical skills is often required to optimally treat these patients. Centers specializing in this care generally establish a multidisciplinary team approach. As part of the treatment, psychological and social support efforts are extremely necessary to achieve optimal outcomes.

Given the number of pediatric GMDs and the space limitations of this chapter, only the following six motility disorders will be reviewed:

• esophageal achalasia (EA);
  
• motility disorders following repair of congenital intestinal atresias;
  
• motility disorders associated with gastroschisis;
  
• CIP;
  
• motility disorders following intestinal transplantation;
  
• Hirschsprung’s disease.

Definition and Epidemiology

EA is a primary esophageal motility disorder characterized by impaired relaxation of the lower esophageal sphincter (LES) in response to swallowing and by a lack of effective peristalsis. EA rarely occurs in adolescents and is seen even less frequently in younger children.11

Pathogenesis

EA occurs so rarely that little is known about related etiologies and pathogenesis. A study by Gockel et al. showed that a majority of patients with EA had a significantly reduced number of intramural ganglion cells in addition to severe fibrosis of the smooth muscle and myopathic changes of smooth muscle cells.12 The disorder in young children is associated with trisomy 21, the triple A (achalasia–addisonian–alacrima) syndrome, and familial dysautomonia.13,14

Clinical Presentation

The signs and symptoms of EA progress slowly (Table 19–1), and the disorder may remain undiagnosed for several years. Vomiting and difficulty swallowing solids and liquids are the primary clinical features, and some children may experience resultant weight loss. Parents may complain that their child burps frequently or regurgitates during the night. Heartburn is also a common complaint.12

Differential Diagnosis

Both malignant (gastric carcinoma) and nonmalignant disorders (esophageal stricture, esophagitis, and “GER”) may cause pseudo-achalasia (Table 19–2). A patient who has had symptoms for <6 months, has lost weight during that time, or had a difficult endoscopy most likely has a malignancy. Esophageal manometry may not distinguish between achalasia and pseudo-achalasia, and computerized tomography and repeated biopsies may be needed to make this differentiation.15

Diagnosis

Several diagnostic tests are used to differentiate EA (Table 19–3). Typically, an EA esophagram will show a dilated esophagus with retained contrast and a smooth tapering of the distal esophagus (“bird beak” appearance), as seen in Figure 19–1A. Disease onset is gradual, however, and a normal contrast esophagram does not rule out early stage disease. Esophageal manometry showing poor relaxation of the LES and aperistalsis of the esophageal body establishes the diagnosis (Figure 19–1B). The LES may also be hypertensive. Endoscopy may demonstrate a distended esophagus, retaining food without any difficulty advancing the scope to the stomach. But scope passage in the distal esophagus is difficult if there is stricture or mass occluding lesion in distal esophagus.15

Referral to a specialist should be made at the early onset of symptoms, especially for children with a history of:

• Down syndrome because of the increased incidence of achalasia and esophageal motility;
  
• adrenal insufficiency (association with triple A syndrome);
  
• persistent dysphagia;
  
• weight loss (Table 19–4).

Treatment

Although the triggering events of primary achalasia remain undetermined, motility abnormality results from a reduction in the number of inhibitory neurons in the esophageal myenteric plexus.12 Directing treatment of the underlying abnormality would require restoring the damaged neurons of this plexus. As these treatments are not yet available, current treatment is directed at relieving the distal esophageal obstruction in order to allow the passage of food into the stomach by gravity (Table 19–5).

Pneumatic Balloon Dilation

Dilation in EA, which is meant to rupture the muscle fibers of the LES, carries a significant risk (2–15%) of perforation.16 While some practitioners report good long-term results, it is difficult to balance the desire to disrupt the circular muscle fibers of the LES with the desire to avoid esophageal perforation, particularly in young small patients. In adults, a graded dilation for 60 seconds using a 30–35-mm balloon to efface the waist created by the LES is generally recommended. Repeated dilations may be needed to maintain symptomatic improvement. Given the need for long-term results in children and the data from some recent studies demonstrating better outcomes with surgical myotomy,17 dilation is not a primary recommendation in children.

Surgical LES Myotomy

Surgical myotomy relieves the LES obstruction by longitudinal transection of the sphincter. Laparoscopic Heller myotomy is comparable in result to the open procedure and has greatly reduced perioperative morbidity. An antireflux procedure, usually a partial-circumference fundoplication wrap using the Toupet technique, reduces GER symptoms and results in less postoperative dysphagia than full-circumference wrap procedures. Even with this procedure, a significant proportion of patients will experience reflux symptoms and require proton pump inhibitor therapy.

In a large study of adults, Ortiz et al. found that at 1 year, ~97% of patients reported good to excellent results. However, with >15 year follow-up, they found a gradual reduction in the percentage of patients having satisfactory results; at ≥15 years post-procedure, only 75% of patients reported good to excellent results. This reduction in outcome success was primarily due to increased symptoms related to GER. Endoscopic peptic esophagitis developed in 11% of patients, although half of these patients were asymptomatic.18 These results underline the importance of life-long follow-up in patients with achalasia.

The incidence of long-term complications after laparoscopic myotomy for EA in children is unknown, but persistent dysphagia is reported. Possible causes include incomplete myotomy, esophageal dysmotility, and relative obstruction from a fundoplication or post-surgical fibrosis in the distal esophagus. Evaluation should include a barium esophagram to exclude the presence of anatomic obstruction and to evaluate the emptying of the esophagus. If abnormal esophageal emptying is identified, esophageal manometry should be done to evaluate the effectiveness of the myotomy. Post-surgical LES pressures of <10 mm Hg predict a good long-term clinical response. In patients with persistent dysphagia and persistently elevated LES pressures after laparoscopic myotomy (with or without fundoplication), pneumatic dilations of the distal esophagus are considered, followed by repeat surgical intervention only if this fails. Persistent dysphagia after myotomy is reported. No randomized trials have shown that the performance of intraoperative esophageal manometry improves the outcome of surgical repair of achalasia (Heller myotomy). Algorithm for the management of post-surgical dysphagia is outlined in Figure 19–2.19

Pharmacologic Approach

Currently available pharmacologic agents are of very limited usefulness in the treatment of EA, and are used only in patients unwilling or unable to undergo other procedures such as surgical myotomy. Agents that are sometimes used include calcium channel blockers, nitrites, and phosphodiesterase inhibitors (Table 19–5). Two small double-blind, placebo-controlled trials of nifedipine in adults with EA demonstrated modest improvements in esophageal manometry, with either no improvement in clinical symptoms or modest improvements in symptoms.20

Injecting botulinum toxin A into the LES blocks the release of the excitatory neurotransmitter, acetylcholine, from visceral motor efferent nerve terminals. This reduces the pressure in the LES and allows esophageal emptying. Botulinum toxin injection is a relatively low-risk procedure compared to dilations and surgical interventions and can be repeated in responding patients if the effect wears off.21 Response to injections may last 6–12 months in responding patients. Patients who do not respond to the initial injections are unlikely to benefit from repeated injections.

Definition and Epidemiology

Congenital intestinal atresia, a narrowing or absence of a section of the intestine, is surgically corrected soon after birth. The likelihood of long-term complications following surgery depends on the associated anomalies (cardiac, genitourinary, and intestinal) and the remaining intestinal length. Despite high morbidity prior to surgery, survival rates are high. However, some children contend with long-term GI complications such as GER and malabsorption.22

Pathogenesis

Intestinal atresias are caused by an interruption of the normal development of the GI tract. The mechanism varies depending on the number and location of bowel segments affected. Following surgical repair, the prognosis depends on the length and function of the remaining bowel. Patients with atresias and gastroschisis may be at a high risk for short bowel syndrome. Other dysmotilities include anastomotic dysfunction, GER, malabsorption syndromes, stricture, adhesions, and obstruction.23

Clinical Presentation

Most infants with intestinal atresia have surgical repair within the first few days of life. Surgery is often delayed in infants with partial obstruction and delayed symptoms. Motility disorders immediately following surgery may result from anastomotic obstruction or leakage and prolonged adynamic ileus (Table 19–1). Adhesive bowel obstruction, GER, and late duodenal dysmotility are considered late complications.

Infants with duodenal atresia may present with stenosis, while colonic atresia is rarely associated with other abnormalities, such as gastroschisis and Hirschsprung’s disease. Other intraoperative findings include volvulus, malrotation, and meconium peritonitis.23

Differential Diagnosis