Cricopharyngeal Myotomy

The cricopharyngeus muscle, also known as the upper esophageal sphincter (UES), was first described by Valsalva in 1717. Over time, an association between dysfunction of the cricopharyngeus and pharyngeal diverticula was identified.[1] In 1946, Lahey proposed dilatation of the cricopharyngeus for the treatment of pharyngeal diverticula, which greatly added to physicians' understanding of upper esophageal dysphagia disorders.[2] In 1950, Asherson proposed the term cricopharyngeal achalasia to denote a persistent spasm of the UES that causes symptoms of dysphagia. Several subsequent authors have proposed cricopharyngeal myotomy for the management of upper esophageal and pharyngeal dysphagia in the setting of polio, degenerative neurologic disorders, and strokes and after head and neck surgery.

See the image below.

Anatomic location of the cricopharyngeus muscle.

Cricopharyngeal myotomy, or surgical sectioning of the cricopharyngeus muscle, has been advocated for the treatment of cricopharyngeal spasm that causes cervical dysphagia.

Frequency

The exact incidence of cervical dysphagia caused by cricopharyngeal dysfunction is unknown. The lack of epidemiologic data results from the significant controversy regarding the diagnostic criteria required for proper use of the term cricopharyngeal dysfunction (ie, achalasia); some authors base the diagnosis solely on symptoms, while others hinge the diagnosis on highly specialized radiologic and invasive probe studies. Although the exact incidence of cricopharyngeal dysfunction is unknown, the literature reports cricopharyngeal achalasia as the primary cause of or as a contributor to dysphagia in 5-25% of patients being evaluated for clinical symptoms of dysphagia.

Cricopharyngeal achalasia may be primary or secondary. Primary cricopharyngeal achalasia implies that the abnormality that leads to the persistent spasm or failure of relaxation of the cricopharyngeus muscle is confined to the muscle, with no underlying neurologic or systemic cause. This primary group can be further subdivided into primary cricopharyngeal achalasia with no underlying cause (ie, idiopathic) or cricopharyngeal achalasia caused by intrinsic disorders of the cricopharyngeus muscle (eg, polymyositis, muscular dystrophy, hypothyroidism, inclusion body myositis).

In many instances, the cricopharyngeal spasm may be secondary to neurologic disorders such as polio, oculopharyngeal dysphagia, stroke, and amyotrophic lateral sclerosis (ALS). Peripheral neurologic disorders,such as diabetic neuropathy, myasthenia gravis, and peripheral neuropathies, can also cause cricopharyngeal dysfunction.

The pathophysiology of cervical dysphagia, as it relates to cricopharyngeal dysfunction, remains unclear. Three main theories have been proposed to explain the relationship between cricopharyngeal dysfunction and dysphagia. The most widely held theory reasons that the cricopharyngeus, which is normally in a state of tonic contraction, fails to relax to allow the passage of the food bolus into the cervical esophagus. This theory has been supported by radiologic and manometric data. Other investigators have identified patients with hypertensive cricopharyngeus muscles, which are abnormally hypertonic during the swallow. Finally, others have identified a relative lack of coordination between the pharyngeal propulsion and the cricopharyngeal relaxation.

These debates are likely to continue given that the full physiologic measurement of the cricopharyngeus during swallowing is difficult and invasive. Furthermore, the presence of the manometric catheter may actually stimulate cricopharyngeal hypertonicity because the catheter irritates the esophageal lumen. Finally, recent work has elucidated a potential role of gastroesophageal reflux disease (GERD) as a cause for cricopharyngeal spasm.

The clinical presentation of patients with cricopharyngeal achalasia may be quite variable. Most patients primarily experience food sticking or catching in the lower third of the neck. These patients often point to the cricoid region in their description of the dysphagia. Patients may also experience accompanying symptoms of heartburn, choking, and pain with swallowing. Less common symptoms include dysphonia, a globus sensation, and pressure in the neck during deglutition. Symptoms have often been present for months to years. In cases related to neurologic causes, the diagnosis of cricopharyngeal achalasia may postdate the neurologic event or diagnosis by several months or years. A history of pneumonia or aspiration pneumonia should be elicited.

The indications for cricopharyngeal myotomy in the treatment of cervical dysphagia are usually based on a combination of patient symptoms, findings from radiologic studies, and, less frequently, manometric information. Before surgical intervention, if possible, aggressively manage underlying etiologies such as neurologic disorders and gastroesophageal reflux disease (GERD). Myotomy may be considered if conservative measures fail and radiologic evidence exists on the video fluoroscopic swallowing study (VFSS) of cricopharyngeal dysfunction that leads to a hesitation of bolus passage.

Manometry may also lend some information, and those patients with clear-cut cricopharyngeal spasm with manometric evidence of hypertonic contraction of the cricopharyngeus tend to have better outcomes. Cricopharyngeal myotomy may also be considered in the absence of clear-cut radiologic data when patients present with significant aspiration or weight loss caused by clinically evident cervical dysphagia, especially when other methods of treatment have failed.

The cricopharyngeus muscle is a true sphincter composed of striated muscle. Arising from the lateral borders of the cricoid cartilage, the muscle fibers form a sling around the wall of the superior aspect of the cervical esophagus. The cricopharyngeus muscle is bordered superiorly by the inferior constrictor muscle and merges inferiorly with the muscular layers of the cervical esophagus. The muscle is innervated primarily by the vagus nerve, both by branches from the pharyngeal plexus and by neuronal branches from the recurrent laryngeal nerve. Therefore, the recurrent laryngeal nerves lie in close proximity within the surgical.

The main trunk of the recurrent laryngeal nerve lies in a triangle bound laterally by the common carotid artery, the internal jugular vein, and the vagus nerve and medially by the trachea and esophagus. The recurrent nerve passes under the posterior suspensory ligament of Berry (located on either side of the trachea, extending from the cricoid cartilage and the first 2 tracheal rings to the posteromedial aspect of the thyroid gland), before entering the larynx (see the image below).

Relation of the recurrent laryngeal nerve to the cricoid cartilage.

For more information about the relevant anatomy, see Vagus Nerve Anatomy and Esophagus Anatomy.

Cricopharyngeal myotomy is contraindicated when the patient has a known tumor that involves the cervical esophagus or an otherwise correctable mucosal disease that involves the cervical esophagus or hypopharynx. Cricopharyngeal myotomy is also relatively contraindicated in patients who have undergone radiation therapy for head and neck cancer because the cricopharyngeus may be fibrotic and less apt to release when sectioned. Other authors consider cricopharyngeal myotomy to be relatively contraindicated in patients with progressive neurologic disorders such as bulbar palsy.

Traditionally, cricopharyngeal myotomy has been thought to afford limited success in the setting of oculopharyngeal muscular dystrophy. However, recent data suggest that it can be effective for several years after surgery with acceptable rates of recurrent dysphagia at 3 years.[3] Finally, cricopharyngeal myotomy may also be relatively contraindicated in the setting of significant gastroesophageal reflux disease (GERD). Although this is controversial, massive reflux may predispose the patient to significant laryngopharyngitis and subsequent dysphonia.

Video fluoroscopic swallowing study

Traditionally, this study has been the primary tool in the diagnosis of cricopharyngeal achalasia. During VFSS, the patient is asked to swallow barium-coated material of different varieties, including liquid barium, while cineradiographic data are collected as the bolus is followed from swallow initiation in the oral cavity to the delivery of the bolus to the stomach. This provides real-time dynamic assessment of the swallow; the video can subsequently be slowed down and analyzed in more detail.

The classic finding on a diagnostic VFSS of cricopharyngeal achalasia is the presence of the horizontal bar (often called the cricopharyngeal bar) at the level of the cricoid cartilage. This makes a posterior indentation in the barium column that persists throughout the swallow. The VFSS also provides information about the presence or absence of laryngeal spillover, aspiration, nasopharyngeal regurgitation, and pharyngeal stasis, each of which may accompany cricopharyngeal dysfunction.[10]

Recent interest in manometric study of the upper esophageal sphincter (UES) has surfaced in the literature. Lack of data and standardization for this study has prevented the widespread use of manometry in the assessment of cricopharyngeal dysfunction. This is further complicated because manometric measurements may be taken in the anteroposterior direction, lateral direction, or as a radial force. In addition, the presence of the manometer may stimulate cricopharyngeal spasm. Several studies have also demonstrated that the results of UES manometry may contradict findings on VFSS examination. At this point, the diagnostic value of UES manometry has not been thoroughly assessed in the literature.

In most instances, a muscle biopsy is not taken during a standard cricopharyngeal myotomy. However, because some authors advocate removing a strip of muscle to prevent reattachment of the sectioned fibers, some data are available on the histopathology of the cricopharyngeus in cricopharyngeal dysfunction. In most cases, the cricopharyngeus muscle is normal on light microscopy. Patients with cricopharyngeal dysfunction related to neuromuscular disorders may demonstrate variable pathology including atrophy, hypertrophy, replacement with fibrotic tissue, or evidence of frank myositis. Special cases of myositis include muscle inflammation associated with dermatomyositis or inclusion body myositis.

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 two 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]   Recent data examining operative and postoperative outcomes for endoscopic versus open cricopharyngeal myotomy techniques have demonstrated similar success rates between the two techniques with improvements in surgical time and postoperative outcomes in the endoscopic group.[5]  

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.[6]

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.[7]

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.[8, 9]

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.