Motility disorders and diverticula 

Oesophageal motility disorders

Motility disorders may affect the whole gut An oesophageal motility disorder can be readily understood when a patient has dysphagia in the absence of a stricture; a barium impregnated food bolus is seen to stick in the oesophagus and oesophageal manometry shows abnormal contractions in the oesophagus. The problem with oesophageal motility disorders is that the symptoms often seem disproportionately severe in comparison to the abnormality that can be demonstrated by objective investigation and the response to treatment may be so poor that the clinician is driven to questioning the very existence of motility disorders. The greatest difficulty arises when pain is the only symptom. Since surgery is advocated as a treatment for some motility disorders it is essential that the surgeon understands the nature of the condition. Much harm may be done by inappropriate enthusiastic surgery for ill defined conditions. It should also be remembered that there may be a general disturbance of GI function. It is convenient to classify oesophageal motility disorders as in Table 50.2.

Pain in functional gastrointestinal disorders

Pain that is assumed to arise from dysfunction of the GI tract has three components, namely, abnormal motility and ‘spasm’, visceral hypersensitivity in which the gut is relatively intolerant of distension, and psychosocial factors. All three components are still poorly understood and it is therefore impossible to give dogmatic guidelines for treatment. Dealing with these conditions involves more art than science, but scientific understanding is slowly increasing.

Achalasia

Pathology and aetiology

Selective loss of inhibitory neurons in achalasia Achalasia is uncommon, but merits prominence because it is reasonably well understood and responds well to treatment. It is due to loss of the ganglion cells in Auerbach’s plexus. The cause of the ganglion cell loss is unknown, but may be due to neurotropic viruses such as Varicella zoster. In South America chronic infection with the parasite Trypanosoma Cruzi causes Chagas’ disease which has marked similarities to achalasia. Achalasia differs from Hirschsprung’s disease of the colon because the dilated oesophagus usually contains few ganglion cells, whereas the dilated colon contains normal ganglion cells proximal to a constricted a-ganglionic segment. Histology of muscle specimens shows reduction of ganglion cells with a variable degree of chronic inflammation. In so called vigorous achalasia, which may be an early stage of achalasia, there is inflammation and neural fibrosis, but nor­mal numbers of ganglion cells. The neural damage in achalasia is somewhat selective since there is particularly severe loss of inhibitory neurons. The observation of selective loss of inhibitory innervation prompted the first attempts at treat­ment with botulinum toxin (see below). The term achalasia is derived form the Greek word (ctxctXw3tct) which means failure to relax and was coined by Sir Arthur Hurst in 1910. The physiological abnormalities are incomplete or absent relaxation of the lower oesophageal sphincter and absent peristalsis in the body of the oesophagus. The oesophagus empties incompletely, almost always containing residual food and fluid. There is no gas bubble in the stomach because no bolus with its accompanying normal gas bubble ever passes through the sphincter. The oesophagus becomes dilated (‘mega esophagus’) and tortuous with a persistent retention oeso­phagitis due to fermentation of food residues (Fig. 50.62). There is an increased incidence of carcinoma of the oesophagus in patients with achalasia.

Beware pseudoachalasia

Look for tumour

Pseudoachalasia is an achalasia-like disorder which is usually produced by adenocarcinoma of the cardia (Fig. 50.63) and sometimes also by cancers outside the oesophagus such as bronchogenic cancer, especially oat cell cancer, and pancreatic cancer.

Clinical features

The disease is commonest in middle life, but can occur at any age. It typically presents with dysphagia. In patients who have remained untreated for many years regurgitation is frequent and there may be overspill into the trachea, especially at night. In the early stages achalasia may present with retrosternal discomfort and this may lead to a mistaken diagnosis of GORD.

Diagnosis

Achalasia may be suspected at endoscopy by finding a tight cardia and food residue in the oesophagus. Barium radiology may show hold-up in the distal oesophagus, peristaltic dys­function and a tapering stricture in the distal oesophagus often described as a bird’s beak (Fig. 50.62). The gastric gas bubble is usually absent. However, these typical features of well-developed achalasia are often absent, and endoscopy and radiology are often normal. The barium meal may even be reported as showing gastro-oesophageal reflux. A firm diagnosis can only be made by oesophageal manometry. Classically there is a hypertensive lower oesophageal sphincter that does not relax completely on swallowing, a-peristalsis of the oesophageal body and a raised resting pressure in the oesophagus (Fig. 50.64). In practice the LOS pressure is often normal.

Treatment

Alone among motility disorders achalasia responds well to treatment. The two main methods are forceful dilatation of the cardia and Heller’s myotomy.

Beware perforation

Forceful dilatation. This involves stretching the cardia with a balloon to disrupt the muscle and render it less competent. The treatment was first described in the Mayo Clinic by Plummer. Many varieties of balloon have been available in the past, but nowadays plastic balloons with a precisely controlled external diameter are used. If the pressure in the balloon is too high the balloon is designed to split along its length rather than expanding further. Balloons of 30—40 mm diameter are available and are inserted over a guide wire (Fig. 50.65). Perforation is the major complication. With a 30-mm balloon the incidence of perforation should be less than 0.5 per cent. The risk of perforation increases with the bigger balloons and they should be used cautiously for progressive dilatation over a period of weeks. Forceful dilatation is curative in 75—85 per cent of cases. The results are best in patients aged more than 45 years.

Beware postoperative reflux

Heller’s myotomy. This involves cutting the muscle of the lower oesophagus and cardia (Fig. 50.66). The major complication is gastro-oesophageal reflux. Reflux may be avoided by limiting the incision to the lower oesophagus and not more than 1 cm of the stomach. If the myotomy is carried further on to the stomach a prophylactic antireflux operation should be done. It is customary to perform a partial rather than a total fundoplication in this situation because of the risk of causing dysphagia in the presence of an    a-peristaltic oesophagus. However, a total fundoplication may be done provided that great care is taken to produce a very short and floppy fundoplication that does not cause obstruction. The proximal extent of the myotomy does not seem to matter provided that the obstructing segment is divided.

Heller’s myotomy is ideally suited to a minimal access approach by either thoracoscopy or laparoscopy. It is successful in more than 90 per cent of cases and may be used after failed myotomy.

Botulinum toxin. This may be given by endoscopic injec­tion into the LOS. This is a new form of treatment whose place is not yet established. It acts by interfering with cholinergic excitatory neural activity at the LOS.

Drugs. Drugs, such as calcium channel antagonists, have been used but are ineffective for long-term use. Sublingual nifedipine may, however, be useful for transient relief of symptoms if definitive treatment has to be postponed.

Other oesophageal motility disorders

Disorders of the pharyngo-oesophageal junction

These are for the most part neurological disorders and surgery has very little place in their management. Rarely, cricopharyngeal myotomy may be performed to reduce dysphagia in a myopathy affecting the pharyngeal muscles. For this to be successful there must be some preserved contraction of the pharynx and a stable neurological condition.

Cricopharyngeal ‘achalasia’ is a condition in which the upper oesophageal sphincter does not open adequately dur­ing swallowing. A cricopharyngeal ‘bar’ may be visible on a barium swallow. The disorder is probably caused by degen­eration of the cricopharyngeal muscle with consequent loss of elasticity. The condition is rare, but responds well to crico­pharyngeal myotomy. A similar abnormality of the cricopharyngeal muscle occurs in Zenker’s diverticulum (see below).

  Disorders of the body of the oesophagus

Diffuse oesophageal spasm is a condition in which there are incoordinate contractions of the oesophagus causing dysphagia and chest pain. The condition may be dramatic with spastic pressures on manometry of 400—500 mmHg, marked hypertrophy of the circular muscle and a corkscrew oesophagus on barium swallow (Fig. 50.67). If chest pain is the only symptom and the abnormality is not particularly dramatic it may be difficult to be sure that the disorder is the cause of the pain and not an epiphenomenon. Prolonged ambulatory oesophageal manometry with a detailed record of the timing of episodes of chest pain may help to make a diagnosis.

Dysphagia due to diffuse spasm may respond to forceful dilatation of the cardia, but the results are not as predictable as in achalasia. In very severe cases extended oesophageal myotomy up to the aortic arch may be required. Surgical treatment of diffuse spasm is more successful in improving dysphagia than chest pain and caution should be exercised in patients in whom chest pain is the only symptom.

Nutcracker oesophagus is a condition in which peristaltic pressures greater than 180 mmHg are developed. It is said to cause chest pain, but there is still some debate as to whether it is a real disorder.

Hypoperistalsis of the oesophagus occurs in the CREST variant of systemic sclerosis (Fig. 50.68), in severe GORD and sometimes for no obvious cause. Simultaneous oesophageal manometry and radiological studies have shown that a peristaltic pressure of about 30 mmHg is required to propel a bolus down the oesophagus. Peristaltic failure may cause dysphagia in its own right, but can also increase dysphagia if there is any organic obstruction. This is common in the CREST syndrome in which reflux is common as a result of the weak muscle in the lower oesophagus and even the must subtle peptic stricture causes severe dysphagia. Treatment aims at excluding organic obstruction and trying to improve the force of peristalsis with prokinetic agents such as cisapride. However, once peristaltic failure occurs it is usually irreversible.

When GORD and dysmotility occur together it is best to treat the reflux and ignore the dysmotility. It is commonly held that weak peristalsis is a contraindication to total fundo­plication, but the author has not found this to be the case provided that care is taken with the construction of the fundoplication.

Eosinophilic oesophagitis is a distinct pathological entity described in patients who have intermittent dysphagia with­out GORD and without anatomical obstruction. Episodes of dysphagia may be severe and painful with bolus obstruction. Between episodes swallowing may be completely normal. Endoscopic biopsies show a dense eosinophilic infiltrate, sug­gesting an allergic response, but no allergens have been identified. Treatment is with antihistamines, sodium chromoglycate or steroids.

Hypertensive lower oesophageal sphincter is defined as an LOS pressure greater than 45 mmHg with normal relaxation during swallowing. It is said to be associated with chest pain and dysphagia.

Oesophageal diverticula

Most oesophageal diverticula are pulsion        diverticula that develop at a site of weakness as a result of chronic pressure against an obstruction. The symptoms are mostly caused by the underlying disorder unless the diverticulum is particularly large. Traction diverticula (Fig. 50.69) are much less common. They are mostly a consequence of chronic granulo­matous disease affecting the tracheobronchial lymph nodes due to tuberculosis, atypical mycobacteria or histoplasmosis. Fibrotic healing of the lymph nodes exerts traction on the oesophageal wall and produces a focal outpouching that is usually small and has a conical shape. There may be associated broncholithiasis and additional complications may occur such as oesophagobronchial fistulation (Fig. 50.70) and bleeding.

Zenker’s diverticulum (pharyngeal pouch) is not really an oesophageal diverticulum as it protrudes posteriorly above the cricopharyngeal sphincter through the natural weak point between the oblique and horizontal fibres of the inferior pharyngeal constrictor (Figs 50.71 and 50.72). Never­theless it is the commonest diverticulum affecting the region of the oesophagus. The underlying abnormality is the same as in cricopharyngeal achalasia. The diverticulum may be large and extend into the posterior mediastinum. Treatment is always necessary sooner or later. The optimum treatment is excision of the diverticulum combined with cricopharyngeal myotomy to deal with the underlying obstruction. In frail patients or those who decline formal operation an endoscopic linear cutting staple gun may be inserted through the mouth and fired to divide the septum between the diverticu­lum and the upper oesophagus producing a diverticulo­oesophagostomy.

Excision and myotomy for Zenker’s diverticulum

Mid-oesophageal diverticula are usually small pulsion diverticula of no particular consequence. The underlying motility disorder does not usually require treatment. The exception to this rule is in areas of the world in which granulomatous diseases of the mediastinum are common, such as parts of the USA, where the possibility of a traction diverticulum should be considered. Some pulsion diverticula may fistulate into the trachea (Fig. 50.70), but this is much more common in granulomatous disease.

Epiphrenic diverticula are situated in the lower oesophagus above the diaphragm (Fig. 50.73). They may be quite large, but cause surprisingly few symptoms. If surgical treatment is required the precise cause of the symptoms, such as GORD, must be defined and corrected at the same time. The diverticulum cannot be assumed to account for the patient’s illness just because it looks dramatic on an X-ray. Large diverticula may be excised and it is usual to perform a myotomy from the site of the diverticulum down to the cardia to relieve the functional obstruction and to reduce the risk of dehiscence of the suture line in the oesophagus.

The diverticulum may not be the cause of the symptoms

Diffuse intramural pseudodiverticulosis is a rare condition in which there are multiple tiny outpouching from the lumen of the oesophagus. The pseudodiverticula are dilated excretory ducts of oesophageal sebaceous glands. It is questionable whether the condition produces any symptoms in its own right.