Carolyn E. Reed, MD
Medical University of South Carolina, Charleston, South Carolina
The esophageal body consists of an empty tube, approximately 20 cm in length, comprised of two layers of muscle, an inner circular layer and an outer longitudinal layer. Fifty to 60% of the distal esophagus is entirely smooth muscle. Nerve networks lay between the muscle layers. Meissner's plexus is between the muscularis mucosa and the circular muscle layer, and Auerbach's plexus (myenteric plexus) is between the circular and longitudinal muscle layers. The innervation to the smooth muscle is primarily via the vagus nerve with nerve endings in the myenteric plexus. Contractions in the esophageal body are initiated by the voluntary act of swallowing, but perpetuation through the distal esophagus is under the control of the enteric nervous system.
Functional Disorders of the Esophageal Body
Motor disorders of the esophageal body have been classified into aperistalsis (achalasia), diffuse esophageal spasm (DES), nutcracker esophagus, and nonspecific esophageal motor disorders. This classification may have several problems when applied to the clinical situation: 1) it is a lab manometric analysis; 2) it does not quantitate the degree of esophageal dysfunction; 3) the category may not relate to the patient's symptoms; and 4) categories may change on different occasions of study. The development of 24-hour ambulatory manometry allows the evaluation of esophageal body function over an entire circadian cycle and offers new insights into functional disorders.
Achalasia
Achalasia is characterized by a double defect in esophageal function. There is incomplete relaxation of the LES, and there is loss of peristalsis in the lower two-thirds (smooth muscle) portion of the esophagus. Recent reports suggest that the pathogenesis in a defect in the nonadrenergic, noncholinergic inhibitory post ganglionic nervous system (decreased VIP and nitric oxide synthase activity).
Radiography, manometry and esophagoscopy are used in the diagnosis.
Treatment is controversial and includes: Botulinum toxin injection vs pneumatic dilation vs esophagomyotomy (open left thoracotomy vs open abdominal vs thorascopic vs laparoscopic). Pharmacologic therapy with nitrates or calcium channel blockers has not proved reliable. Pneumatic dilatation has achieved good to excellent results in 50% to 80% of patients, is an outpatient procedure, and results in rapid recovery. About 30% of patients require repeat dilatations, and the perforation rate is 5%. A recent cost analysis revealed that the cost of open Heller was 5 times greater than the cost of initial pneumatic dilatation and remained 2.4 times greater when including subsequent treatments of symptomatic patients.1 Subsequent pneumatic dilatations to treat persistent or recurrent symptoms were less beneficial than an initial pneumatic dilatation. Okike and colleagues2 in a retrospective review of 899 patients reported good to excellent results in 65% of patients undergoing dilation compared to 85% of a similar number of patients undergoing esophagomyotomy. In the only prospective randomized study, Csendes et al3 achieved good to excellent results in 67% of patients treated by dilation in contrast to 98% treated surgically.
The open surgical approach for myotomy is either by left thoracotomy or transabdominally. Proponents of the transthoracic approach argue that this approach minimized disruption of the normal GE junction architecture and provides superior exposure to greater length of the distal esophagus. The addition of an anti-reflux procedure remains controversial with this approach. Proponents of the transabdominal route argue that the incision is less morbid and a fundoplication is easily added. A recent review of>5000 patients showed that GE reflux was almost twice as common when the myotomy was performed transabdominally as opposed to transthoracically.4 Total fundoplication should be avoided.
Both thorascopic and laparoscopic approaches to esophagomyotomy have been developed. Follow-up is short term. Extent of the distal myotomy via left thoracoscopy is aided by fiberoptic endoscopy.5 There are several arguments favoring a laparoscopic approach with added partial fundoplication.6,7
Injection of botulinum toxin, a potent inhibitor of the release of acetylcholine from nerve endings, into the LES has been shown to be an effective, safe and simple method to treat achalasia.8 However, frequent injections are needed, and the duration of effect is not long (less than 6 months). At present we reserve botulinum injection for elderly, high risk patients.
Diffuse (DES) and Segmental Esophageal Spasm
This esophageal motor disorder is characterized clinically by substernal chest pain and/or dysphagia. The cause and neuromuscular pathophysiology are unclear.
The classic manometric finding in patients with spasm is the frequent occurrence of simultaneous, mutipeaked, and the repetitive contractions that may be abnormally high amplitude or long duration. When these abnormalities are seen throughout the lower two-thirds of the esophageal body, the spasm is termed diffuse, and if less of the body is involved, the spasm is termed segmental. A key to diagnosis is that the esophageal body does retain peristaltic waveforms. Use of the composite scoring system based on the ambulatory motility record has improved the accuracy of diagnosis.9
Medical therapy (calcium channel blockers, nitrates, hydralazine, etc.) has minimal benefit in the treatment of esophageal spasm. Pneumatic dilatation of the body of the esophagus has been tried, but the results are viable. In DES effective bolus propulsion, a function of contraction amplitude and peristaltic progression, is impeded by the functional obstruction resulting from simultaneous contractions and decreased muscle compliance. A long esophageal myotomy will reduce the simultaneous contractions, but at the expense of abolishing peristalsis. The presence of 75% or more simultaneous waveforms during meals encourages a myotomy to relieve dysphagia. Chest pain along is not an indication of myotomy.10
Nutcracker Esophagus
Manometrically, it is characterized by peristaltic esophageal contractions with peak amplitudes greater than two standard deviations above normal values. Chest pain may not be reliably alleviated by long myotomy despite its proponents, and it renders the esophagus aperistalic. Medical therapy (nifedipine/diltiazem, imipramine) does not have uniformly good results.
Nonspecific Esophageal Motor Disorders
Patients who complain of noncardiac chest pain and dysphagia may have altered morphology of esophageal contractions and abnormal wave progression pattern on manometry that do not meet classic criteria of primary motility disorders. Some will slowly progress to classic DES. In some, a 24-hour pH and motility study will show that the motor abnormality is induced by reflux or gastric juice.
Benign Tumors of the Esophageal Body
Benign tumors of the esophageal body are rare, less than 1% of all esophageal neoplasms. They are often asymptomatic (>85%) and found incidentally at endoscopy. The gastroenterologist is much more likely to encounter a benign tumor than the surgeon!
Benign tumors are classified into epithelial and non-epithelial tissue types. The mucosa of the esophagus can give rise to squamous cell papillomas, mucus retention cysts and fibrovascular polyps. The most common tumors of the submucosa are hemangioma and granular cell tumors. The most common tumor of the muscularis propria is a leiomyoma although rhabdomyoma, neurofibroma and granular cell tumor can occur. Schwannomas may form in the vagus nerve plexus present in the adventitia.
Endoscopic ultrasonography has been used at our institution to aid in the diagnosis of benign tumors. A leiomyoma arising from the echo-poor muscularis propria can be distinguished from other lesions, such as cysts or fibromas, arising from the echo-rich submucosa.
The most common benign tumor of the esophagus is the leiomyoma, accounting for 67% of all benign tumors. It has characteristic radiographic and endoscopic features although occasionally it can be circumferential and obstructing.11 In general surgical removed of a leiomyoma is indicated if it is large (>5 cm), symptomatic, the diagnosis is in doubt, or if the tumor is intraluminal, pedunculated and mobile. Since the lesion is intramural, eccentric and well encapsulated, it can be easily enucleated. Only occasionally should esophageal resection be considered: 1) large annular leiomyoma surround the GE junction, 2) rare giant extramural leiomyoma obstructing the esophagus and compressing other organs, 3) mucosa damaged not repairable during enucleation.
The second most benign tumor is a cyst (22% in the large Mayo series). These epithelial lined fluid-filled developmental defects are usually found within or close to the esophageal wall. EUS is the best method of diagnosis. CT can also be helpful. Congenital esophageal cysts are removed by extramucosal resection. Because many of the less common benign tumors are small and asymptomatic the surgeon will seldom be called to intervene. An exception would be a large intramural fibrovascular polyp that required care surgical excision.12
General
Bremmer RM, DeMeester TR. Current management of patients with esophageal motor abnormalities. Adv Surg 1996;30:349-84
Shamji F, Todd TR. Benign Tumors. In:Pearson FG, Deslauriers J, Ginsberg RJ, Hiebert CA, McKneally MF, Urschel HC (eds). Esophageal Surgery, New York:Churchill Livingstone, 1995:519-38.
Reed CE. Benign tumors of the esophagus. Chest Surg Clin North Am 1994;4:769-83.
Specific
1. Parkman HP, Reynolds JC, Ouyang A, Rosato EF, Eisenberg JM, Cohen S. Pneumatic dilatation or esophagomyotomy treatment of idiopathic achalasia: clinical outcomes and cost analysis. Dig Dis Sci 1993,38:75-85.
2. Okike N, Payne WS, Newfeld DM, et al. Esophagomyotomy versus forceful dilation for achalasia of the esophagus: results in 899 patients. Ann Thorac Surg 1979;28:119-25.
3. Csendes A, Braghetto I, Henriquez A, Cortes C. Late results of a prospective randomized study comparing forceful dilatation and oescophagomyotomy in patients with achalasia. Gut 1989;30:299-304.
4. Andreollo NA, Earlam RJ. Heller's myotomy for achalasia: Is an added anti-reflux procedure necessary? Br J Surg 1987;74:765-69.
5. Patti MG, Pellegrini CA. Endoscopic surgical treatment of primary oesophageal motility disorders. JR Coll Surg Edinb 1996;41:137-42.
6. Swanstrom LL, Pennings J. Laparoscopic esophagomyotomy for achalasia. Surg Endosc 1995;9:286-92.
7. Degado F, Bolufer JM, Martinez-Abad M, et all. Laparoscopic treatment of esophageal achalasia. Surg Laparosc Endosc 1996;6:83-90.
8. Pasricha PJ, Ravich WJ, Hendrix TR, et al. Intrasphincteric botulinum toxin for the treatment of achalasia. N. Engl J Med1995;322:774-78.
9. Eypash EP, DeMeester TR, Klingman RR, Stein HJ. Physiologic assessment and surgical management of diffuse esophageal spasm. J Thorac Cardiovasc Surg 1992;104:659-60.
10. Stein HJ, DeMeester TR, Eypasch EP, Klingman RR. Ambulatory 24-hour esophageal manometry in the evaluation of esophageal motor disorders and non-cardiac chest pain. Surgery 1991;110:753-63.
11. Seremetis MG, Lyon WS, DeGuzman VC, Peabody JW. Leiomyomata of the esophagus: an analysis of 838 cases. Cancer 1976;38:2166-77.
12. Avezzo EA, Fleischer DE, Merida MA, et al. Giant fibrovascular polyps of the esophagus. Am J Gastroenterol 1990:85:299-302.
