Functional
Disorders That Lead to Structural Issues
Oropharyngeal dysphagia is an abnormality in the proximal swallowing
mechanism affecting bolus propulsion from the oral cavity to the level of the
pharyngoesophageal junction, the level of the cricopharyngeal muscle, the upper
esophageal sphincter (UES), or the cervical esophagus. Pharyngonasal
regurgitation results from the retropulsion of the bolus into the nasal cavity,
and laryngeal aspiration is a result of hypopharyngeal stasis and vallecula
pooling. Both are a consequence of a functional or structural obstruction,
impeding bolus propulsion.
Dysphagia due to neurologic injury results from an
injury to the central or peripheral nervous system, regardless of etiology.
Bilateral cortical damage such as that following a cerebrovascular accident can
result in reduced lingual control and loss of initiation of the swallowing
reflex, which results in delayed swallowing and reduced pharyngeal peristalsis.
Infarcts affecting the control centers for the nucleus ambiguus cause
unilateral paralysis of the pharyngeal and laryngeal musculature, resulting in
poor glottic closure complicated by hypopharyngeal stasis and laryngotracheal
aspiration. Amyotrophic lateral sclerosis is a progressive neurodegenerative
disease causing motor neuron degeneration in the brain, brainstem, and spinal
cord. Weakness, muscle atrophy, and fasciculation of the musculature lead to poor
bolus handling, resulting in abnormal swallowing. Delayed or incomplete opening
of the UES leads to hypopharyngeal stasis, vallecular pooling, and, ultimately,
laryngotracheal aspiration. Lesions to the cranial nerves innervating the UES
can cause uncoordinated or reduced sphincter opening, leading to a functional
obstruction of the UES; this obstruction coupled with a contracting pharynx may
cause pharyngooral regurgitation, resulting in pharyngolaryngotracheal
aspiration or nasal regurgitation. Neurogenic swallowing abnormalities are
visualized by videofluoroscopy. The traditional method uses a single form of
liquid barium swallow and is performed by a radiologist. The currently
preferable, modified method uses multiple barium-infused consistencies for swallowing
and is performed by a speech pathologist. The modified barium study has the
oral pharyngeal advantage of being able to capture subtle abnormalities in
bolus transfer from the oral cavity to the pharyngoesophageal border. Treatment
of disordered swallowing secondary to cortical disturbances begins with
education, dietary manipulation, and relearning techniques; alternative
nutrition routes, such as a percutaneously placed feeding tube, are reserved
for advanced disease. Cricopharyngeal myotomy has been tried with some degree
of success in the treatment of cricopharyngeal dysfunction induced by cranial
nerve damage. The goal of this procedure is to provide a less obstructed route
for the bolus to travel through for entrance into the esophagus (see Plate
2-72).
Dysphagia secondary to a primary muscle disease is best
illustrated with a progressive degenerative disease such as muscular dystrophy,
particularly the oculopharyngomuscular variant. Bilateral ptosis is a primary
manifestation of the disease, with dysphagia appearing prior to or
simultaneously with the ptosis. They are both late and progressive
manifestations of the disease. Pharyngooral regurgitation is characteristic of
dysphagia resulting from a weak pharyngeal musculature incapable of peristaltic
contractions of sufficient amplitude to move the bolus through the UES.
Tracheobronchial symptoms occur from poor control of laryngeal muscles,
pharyngeal muscle weakness, and hypopharyngeal stasis. Videofluoroscopy
demonstrates normal initiation of swallowing, impaired barium clearance from
the pharynx with concurrent vallecular pooling, and reduced UES opening due to
incomplete or delayed relaxation, with many demonstrating a cricopharyngeal
bar. Treatment is traditionally supportive and includes dietary manipulation,
education, and counseling, plus alternative nutritional feeding when the
disorder is severe. Cricopharyngeal myotomy has been used with good results in
small patient series. The success of the procedure likely results from
enlargement of the pharyngoesophageal opening following the myotomy. Simply
stated, a path of least resistance is created by the procedure.
Cricopharyngeal achalasia presents with oropharyngeal dysphagia due
to cricopharyngeal dysfunction that may or may not coexist with a pharyngeal
diverticulum (Zenker diverticulum). Cricopharyngeal achalasia is characterized
by incomplete relaxation of the UES or by a lack of coordination between UES
opening and pharyngeal contractions. It can arise from an intrinsic muscle
defect or from underlying neurologic dysfunction producing high UES pressures.
By definition, there should be strong pharyngeal contractions acting against a
poorly relaxing UES, a condition that presents as a functional obstruction.
Patients with cricopharyngeal achalasia present with symptoms of dysphagia
primarily for solids, pharyngooral regurgitation resulting from the strong
pharyngeal contractions acting against a noncompliant UES, and resultant
laryngotracheal aspiration. Videofluoroscopy demonstrates barium pooling above
a closed UES with or without the presence of a cricopharyngeal bar. A
restrictive myopathy secondary to fibrosis or an infiltrative process causing
the reduced compliance of the cricopharyngeus muscle has been implicated in the
pathogenesis; however, because the response to successive bougie
pharyngoesophageal dilations is inconsistent, disease at the level of the
muscle is not likely to be the only causative factor in this condition.
Manometric findings of a hypertensive UES and a frequent positive response to
botulinum toxin suggest an imbalance in excitatory inhibition from
acetylcholine receptors and inhibitory neurotransmitters, as seen in classic
achalasia. Botulinum toxin has been shown to be an effective temporary therapy
reducing cricopharyngeal achalasia in adults and children in much the same way
as it has been used in esophageal achalasia. In this condition commercially
manufactured botulinum toxin is diluted with preservative-free normal saline,
and under endoscopic visualization, an injection of the medication is placed in
each of the four quadrants of the UES. Botulinum toxin irreversibly destroys
the treated acetylcholine receptor; however, this treatment is temporary,
lasting only 6 to 9 months, due to growth of new receptors. The correlation of
symptoms with radiologic dysfunction, manometric abnormalities of a
hypertensive UES, and poor pharyngeal clearance favors a positive response to
botulinum injections and a good response to cricopharyngeal myotomy by either
surgical or endoscopic techniques.
Cricopharyngeal bar is a radiographic finding that presents as
a prominent and persistent posterior indentation at the level of the lower
third of the cricoid cartilage; it is best seen on lateral views.
Histologically, degenerative muscle fibers and fibrosis were found on dissected
surgical specimens. They are present in both symptomatic and asymptomatic
individuals. Esophageal dilation has been successfully used to treat dysphagia
in elderly individuals with a cricopharyngeal bar.
Zenker diverticulum is formed in an area of anatomic weakness
known as the Killian triangle, which is bordered inferiorly and posteriorly by
the superiormost fibers of the cricopharyngeal muscle and superiorly by the
inferior fibers of the inferior constrictor muscles of the posterior pharynx.
This diverticulum, or outpouching, is created by strong pharyngeal peristaltic
contractions against a noncompliant upper esophageal or cricopharyngeal
sphincter. This poorly coordinated movement creates high intrabolus pressures
within the hypopharynx, leading to the development of a pulsion diverticulum.
Symptoms and complications of the diverticulum vary with the size of the
lesion. The most common presenting symptoms include dysphagia, regurgitation of
undigested food, especially in the supine position, choking, aspiration, and
halitosis. A small diverticulum is typically asymptomatic and inci- dentally
found on upper endoscopy or during a barium examination. On radiologic
evaluation, the pharyngoesophageal diverticulum is seen as a midline protrusion
at the level of the posterior hypopharyngeal wall, just above the
cricopharyngeal muscle. A large diverticulum can cause considerable anatomic
distortion, leading to a functionally obliterated or closed esophageal lumen.
Because progressive enlargement is rare, in individuals with a small
diverticulum, observation may be the only required intervention; in patients
with large symptomatic diverticula, surgical or endoscopic management is
required. Because the diverticulum developed as a result of a noncompliant
cricopharyngeal muscle, therapeutic intervention involves two steps,
diverticulectomy and cricopharyngeal myotomy. Traditionally, treatment was
surgical with an open or a transoral endoscopic approach using a rigid or
flexible endoscope. Regardless of the mode of entrance, large diverticula can
be inverted, suspended (diverticulopexy), or resected. Today the endoscopic
approach is favored for diverticula of less than 5 cm. A single lumen is
created with ablation of the upper esophageal sphincter by incising the
muscular layer of the septum, which is composed of the posterior esophageal
wall and anterior wall of the diverticulum and includes the upper esophageal
sphincter. Recurrence is rare when a cricopharyngeal myotomy is performed at
the same time as the diverticulectomy. Flexible endoscopic techniques have been
shown to be as safe as rigid endoscopic treatment for diverticula that are less
than 5 cm, and they have the advantage of not requiring general anesthesia.
Myotomy can be done using the needle knife technique, argon plasma coagulation,
and a monopolar forceps.
