Surgical therapy for swallowing disorders

The anatomy and physiology of normal and abnormal swallowing in oropharyngeal dysphagia

BACKGROUND

Eating and drinking are enjoyable activities that positively impact on an individual's quality of life. The ability to swallow food and fluid is integral to the process of eating. Swallowing occupies a dual role being both part of the enjoyment of eating and being a critically important utilitarian activity to enable adequate nutrition and hydration. Any impairment to the process of swallowing can negatively affect a person's perception of their quality of life. The process of swallowing is highly complex and involves muscles in the mouth, pharynx, larynx, and esophagus. The oropharynx is the anatomical region encompassing the oral cavity and the pharynx. Food must be masticated, formed into a bolus and transported to the pharynx by the tongue whereas fluids are usually held within the mouth before being transported ab-orally. The bolus must then be transported through the pharynx to the esophagus without any matter entering the larynx. The muscles needed for all these steps are coordinated by swallowing centers within the brainstem which are supplied with sensory information by afferent nerve fibers from several cranial nerves. The swallowing centers also receive modulatory input from higher centers within the brain. Hence, a swallow has both voluntary and involuntary physiologic components and the term dysphagia is given to difficult swallowing while oropharyngeal dysphagia is difficult swallowing due to pathology within the oropharynx.

PURPOSE

Problems affecting any point along the complex swallowing pathway can result in dysphagia. This review focuses on the anatomy and physiology behind normal and abnormal oropharyngeal swallowing. It also details the common diseases and pathology causing oropharyngeal dysphagia.

Treatment of Oropharyngeal Dysphagia

Substantial ignorance and controversy surround the management of neuromyogenic pharyngeal dysphagia. The major obstacle to confident recommendations is the lack of high-level evidence supporting most available therapies. There is reasonable evidence supporting cricopharyngeal disruption (myotomy or dilatation) in primary restrictive disorders of this region, but low-level evidence supporting myotomy in pure neuromyogenic dysphagia. There is reasonable evidence supporting current dietary recommendations as aspiration-minimization strategies. There is only low-level evidence, albeit consistent, to support swallow-behavior modification therapies. The type of therapy needs to be tailored to the individual and depends upon many variables, including cognitive ability, severity and mechanics of pharyngeal dysfunction, and the perceived safety of continued oral feeding. One or more of these strategies are recommended where appropriate because where the level of evidence is low, it is at least consistently favorable and such therapies have not been proven to be ineffective.

Synchronized electrical stimulation in treating pharyngeal dysphagia

OBJECTIVE/HYPOTHESIS

The objectives were to test the hypothesis that synchronous contraction of the thyrohyoid muscle by electrical stimulation during swallowing would improve dysphagia resulting from reduced laryngeal elevation and to evaluate the effectiveness of the synchronous electrical stimulator.

STUDY DESIGN

Prospective study.

METHODS

Eleven male and 12 female patients (age range, 35-87 y) with moderate to severe degree of dysphagia resulting from reduced laryngeal elevation who did not respond to medical treatment were treated by stimulating synchronous contraction of the thyrohyoid muscle during swallowing with the synchronous electrical stimulator. Treatment was given daily for 4 hours until criteria for improved swallow were fulfilled or other intervention was deemed necessary. Follow-up was performed monthly (range, 3-33 mo).

RESULTS

Of the 23 patients, 20 showed marked improvement at the first course of treatment. The duration of stimulation varied from 2 to 4 days (median duration, 2 d) in patients with moderate dysphagia and from 3 to 30 days (median duration, 6 d) in patients with severe dysphagia. Three patients showed failed synchronous electrical stimulator treatment, one owing to device failure and two requiring gastrostomy for feeding. Six patients who achieved improved swallow criteria relapsed at 2 to 9 months after the first treatment course and were successfully treated with an additional course of synchronous electrical stimulation.

CONCLUSIONS

The study supports the hypothesis that stimulating synchronous contraction of the thyrohyoid muscle by synchronous electrical stimulator during swallowing improves dysphagia resulting from reduced laryngeal elevation. Synchronized electrical stimulation has the advantages of noninvasiveness and actively assisting swallowing and can be used as an alternative treatment. The synchronized feature of the synchronous electrical stimulator helps to restore normal swallowing mechanism and decreases the incidence of nasogastric tube insertion and gastrostomy.

Management of upper esophageal sphincter disorders: indications and complications of myotomy

Since 1951, when it was first used as a treatment for post-poliomyelitis dysphagia, cricopharyngeal myotomy (CPM) has been used in the treatment of various neurogenic, myogenic, structural, and idiopathic disorders. Yet, the efficacy of CPM in treating patients with upper esophageal sphincter (UES) disorders remains controversial. Despite favorable reports regarding its success, too few studies about indications, complications, and outcomes of CPM have been conducted to quell the controversy. Swallowing is accomplished when three primary conditions exist: (1) the cricopharyngeus muscle (CP) relaxes--that is, it is not tonically contracted, (2) the laryngo-hyoid complex elevates in an anterior-superior direction to open the sphincter, and (3) pharyngeal pressure is sufficient to propel a bolus through the open sphincter. CPM is indicated when the second and third conditions are "adequate" but the first is inadequate, thus resulting in pharyngeal dysphagia associated with a defective opening of the UES. UES dysfunction is determined most often through patient history, physical examination, and testing. Patients with Zenker's (pharyngoesophageal) diverticulum, oculopharyngeal dystrophy, or inclusion body myositis are among those reported to have the most positive responses to CPM. Modified barium swallow is the most common measurement of UES dysfunction; manometry also is used, but to a lesser degree because of catheter motion during swallowing. There are four approaches to CPM, including: (1) the external technique, which is indicated when a muscle biopsy or neck exploration is needed; (2) the endoscopic approach, which is reported to work best with patients with Zenker's diverticulum and offers the choice of electrocautery, laser, or the surgical stapler--the last option being the best choice for high-risk patients; (3) balloon dilatation of the UES, a low-risk option that reportedly works best in patients with fibrosis of the CP; and (4) botulinum toxin injection of the CP transcervically or endoscopically, which offers low risk and minimal or no anesthesia. This approach best serves cases of failed relaxation of the CP. Each approach has potential complications, but reports of such are few and rarely severe. In all cases, massive reflux should be controlled before CPM and the patient should be medically stable. Patient selection for CPM remains inadequate. To assess the efficacy of CPM, more multi-institutional outcome studies need to be conducted. In the meanwhile, clinical judgment and selective testing via modified barium swallow are the best methods for identifying patients who may derive the most benefit from CPM.