Cricopharyngeal Myotomy Treatment & Management

Cricopharyngeal dysfunction has been largely refractory to medical management, including therapy with muscle relaxants. Botulinum toxin injection into the cricopharyngeus muscle has recently been explored as a possible therapeutic intervention. Although experience with botulinum toxin in this clinical entity is rather limited, it may serve 2 useful purposes.

First, in patients in whom the diagnosis of cricopharyngeal achalasia may be in question, botulinum toxin treatment can be used as a trial of therapy. If the patient's dysphagia symptoms resolve after botulinum toxin injection, the diagnosis of cricopharyngeal achalasia is confirmed, and subsequent cricopharyngeal myotomy may be deemed appropriate.

In addition, patients who are medically infirm and cannot undergo external cricopharyngeal myotomy may be considered for botulinum toxin therapy. Unfortunately, the administration of the botulinum toxin into the cricopharyngeus is technically difficult and somewhat uncomfortable for the patient. Furthermore, because the effective botulinum toxin is temporary, patients are required to undergo repeat injections to maintain therapeutic efficacy. Finally, inadvertent injection outside the cricopharyngeus may result in temporary paralysis of the laryngeal musculature, causing dysphonia and, rarely, aspiration.

Several surgical approaches may be considered for treatment of cricopharyngeal dysfunction.

The classic approach is the external cricopharyngeal myotomy technique. This procedure may be performed with the patient under local or general anesthesia. Position the patient supine on the operating room table. After induction of anesthesia, intubate the cervical esophagus with a relatively large endotracheal tube to provide internal distention of the cervical esophagus at the time of the myotomy. Traditionally, a left-sided surgical approach is used. Make the skin incision in a favorable cervical skin crease roughly overlying the cricoid cartilage. Elevate the subplatysmal skin flaps superiorly and inferiorly to provide exposure to both the superior and inferior limits of the cricopharyngeus, and place self-retaining retractors. Identify the anterior border of the sternocleidomastoid muscle, and reflect it posteriorly to expose the carotid sheath. Develop a plane between the structures of the carotid sheath and the laryngotracheal complex with the greatvesselssubsequently being reflectedposteriorly.

Often, the omohyoid muscle is sectioned to provide additional exposure. Take care to protect the recurrent laryngeal nerve as it enters behind the ala of the thyroid cartilage. Rotate the larynx anteriorly into the right, bringing the internally distended cervical esophagus into view. The cricopharyngeus fibers are seen as a fan-shaped band that emanates from the posterior lateral border of the cricoid cartilage. Magnification with surgical loupes is often helpful in identifying these muscle fibers, which may blend into the surrounding submucosa. Sequentially cut the cricopharyngeus fibers with a sharp No-15 or No-10 blade until the mucosa is seen. Often, when all of the muscle fibers have been appropriately sectioned, the surgeon can see the writing on the endotracheal tube. Many authors have emphasized that the cricopharyngeal myotomy must be extended superiorly and inferiorly to ensure that all of the muscle has been released. This often translates into a myotomy length of 4-5 cm.

Some authors also advocate removing a 3- to 4-mm strip of muscle along the length of the myotomy or elevating and suturing the cut edge of muscle back onto itself. These additional techniques have been advocated to prevent reattachment and subsequent persistent cricopharyngeal dysfunction.

At the conclusion of the procedure, irrigate the wound and place and secure a standard closed suction drain system. Reapproximate the platysma in a watertight fashion. Close the skin according to surgeon preference. Remove the esophageal endotracheal tube before extubation.

Recently, investigators have been exploring a trans-oral approach for endoscopic cricopharyngeal myotomy. However, only limited case series have been published, and follow-up data are rather limited. Initial data suggest that this technique may have applications when the technique is refined and longer follow-up is available. Also, an endoscopic approach has the advantages of avoiding an external neck incision and, to some degree, less risk to surrounding structures.^[4]

Because patients have often had dysphagia for some time prior to surgical intervention, optimizing their nutritional and health status prior to surgical intervention is important. In certain cases, particularly with significant weight loss prior to surgery, a temporary nasogastric feeding tube may be required to administer nutritional supplementation to increased serum protein levels. In those patients with a history of preoperative aspiration, pulmonary insufficiency must also be corrected with appropriate medical consultation.

Patients with a myogenic cause for their CP dysfunction have a higher rate of postoperative complications after CP myotomy, including pulmonary aspiration and lethal respiratory distress. Such patients should be identified and placed under increasing surveillance postoperatively.

Patients are usually observed in the hospital for one night following the procedure. Patients may initiate a standard oral diet the night of the procedure and advance as tolerated. The closed suction drain is usually removed on postoperative day 1, and the patient is discharged home.

Patients are usually seen in routine postoperative follow-up care at 1 week postsurgery for a surgical wound check. In addition to the subjective evaluation of the patients' self-reported swallowing symptoms and improvement, patients also may undergo a follow-up VFSS to objectively assess the impact of the cricopharyngeal myotomy on the cervical dysphagia. Follow-up testing is particularly important in elderly, frail, and pulmonary insufficient patients, particularly when a preoperative history of aspiration exists. Recent follow-up radiologic data suggest that patients with cricopharyngeal dysfunction may continue to have pharyngeal stasis with dysphagia implications after surgery.

The most common complication of external cricopharyngeal myotomy is inadvertent entry into the lumen of the cervical esophagus. Although thoroughly sectioning the entire cricopharyngeus muscle is important, the margin for error is small because the esophageal submucosa and mucosa are very thin. If the cervical esophageal lumen is entered, repair it with a watertight closure in a single layer. Avoid a double-layer closure because it may predispose the patient to stenosis in this area, defeating the original purpose of the procedure. In the setting of an inadvertent esophagotomy, maintain wound drainage and monitor the patient for evidence of salivary fistula through the drain site. Maintain perioperative and postoperative antibiotics to cover oral flora. If no evidence of air leakage or salivary fistula is present, the patient may resume a gradually advancing diet on postoperative day 3, with anticipated discharge 1-2 days later.

Other complications may occur during cricopharyngeal myotomy. A relatively uncommon occurrence is injury to the recurrent laryngeal nerve, which most often manifests as hoarseness after extubation and most often is due to a stretch injury to the nerve. Most injuries such as this resolve with time; however, recovery may require several months. During the recovery phase, monitor the patient for aspiration and pulmonary complications. If the main trunk of the recurrent laryngeal nerve is accidentally sectioned during the procedure, perform a primary neural anastomosis. If this occurs, the patient will likely have a permanent vocal cord weakness that results in dysphonia. This may be rehabilitated with vocal cord augmentation techniques or medialization thyroplasty.

Overall complication rates after cricopharyngeal myotomy are relatively small considering the generalized poor nutrition of many patients preoperatively. Pulmonary complications occur relatively commonly (5-10% of patients), particularly in those who suffer from myogenic CP dysfunction. Nine percent of patients may exhibit a transient fluid collections/inflammation in the retro pharyngeal space and 1.2% of patients may develop frank fistula formation.^[5]

Reported success rates for cricopharyngeal myotomy and management of cervical dysphagia vary widely. To some degree, this variability may be caused by differences in the patient populations that undergo myotomy. Although some studies report results in patients who undergo cricopharyngeal myotomy for neuromuscular disease, other studies report on cricopharyngeal myotomy as a treatment of idiopathic cervical dysphagia. In properly selected patients, success rates that approach 75% may be expected. The chance of success usually decreases when an underlying neuromuscular disorder is present.

The one exception is found in patients with oculopharyngeal dysphagia; these patients generally have a good result from myotomy alone. More recently, reasonably positive outcomes have been achieved by treating patients who have oculopharyngeal dysphagia with simple repeated dilatation of the upper esophageal sphincter. Furthermore, patients with dysphagia secondary to inclusion body myositis within the CP muscle also have a relatively poorer prognosis than those with other causes for CP dysfunction.^[6]

In general, the prognosis for dysphagia without treatment is unfavorable; few patients demonstrate spontaneous improvement in their cervical dysphagia. This forces many patients to opt for a chance of cure with surgery. Untreated patients with inclusion body myositis, for example, will often progress to death from aspiration pneumonia.

Future work in the area of cervical dysphagia and cricopharyngeal dysfunction will likely center on more accurate and physiologic diagnostic techniques. Recent work has focused on integration of data from VFSS and manometric studies to more thoroughly define the entity of cricopharyngeal achalasia. Until this is performed, controversy is likely to continue with respect to the underlying pathophysiology or dysfunction of the cricopharyngeal muscle in this disease. Unfortunately, no randomized trials of treatment alternatives for cricopharyngeal dysfunction have been published. Furthermore, although medical and surgical treatments have evolved, published studies that use objective and validated outcomes measures are lacking; this should be addressed in the near future.

A role for botulinum toxin in the diagnosis and management of cricopharyngeal dysfunction has also emerged. Botulinum toxin may allow better patient selection by accurately identifying patients with cervical dysphagia in whom a cricopharyngeal myotomy would improve symptoms. The approach that has recently been validated is the primary use of botulinum toxin injections (in doses of 5-10 units per injection confirmed by electromyography). Cricopharyngeal myotomy is then reserved for patients with dysphagia that persists after 2 botulinum toxin injection failures. Success rates of about 40% have been reported for endoscopic botulinum toxin injection.

Other authors have reported on limited patient series that describe individuals who have undergone cricopharyngeal myotomy via an endoscopic technique. Using the potassium titanyl phosphate laser, investigators have successfully sectioned the cricopharyngeus muscle via the endoscope, obviating the need for an external incision. However, these clinical series are quite small, and follow-up data to this point are limited. In a recent series of 29 patients (mean age 62 y) after a mean follow-up of 18 months, investigators reported on the use of the CO₂ laser to section the cricopharyngeus muscle endoscopically. Patients reported a significant subjective improvement in swallowing function, although not according to a validated scale. Similar corresponding radiographic improvements were noted based on swallowing videofluoroscopy. No complications were noted. Thus, with further confirmatory studies, an endoscopic laser myotomy approach may be feasible.

Several recent series that also had small sample sizes suggested that an endoscopic approach is feasible and safe. However, more long-term follow-up data are seriously lacking with respect to the effectiveness of the procedure, especially as it compares with the open cricopharyngeal myotomy approach. Investigators have also adapted the endoscopic approach to cricopharyngeal myotomy for those patients with swallowing dysfunction after extensive resection of oral and pharyngeal cancer. Such a procedure may improve dysphagia in up to 80% of those suffering from cricopharyngeal dysfunction and dysphagia after extensive resection of oral or oral pharyngeal cancer.^{[7, 8]}

Another area of interesting research concerns the treatment of inflammatory myopathies that involve the cricopharyngeal muscle, such as inclusion body myositis and eosinophilic myositis. As further research develops concerning the pathogenesis of these entities, certain patients may benefit from percutaneous injection techniques for the delivery of anti-inflammatory medications or from the deposition of intraoperative time-release medications to inhibit the inflammatory myopathy.