Pharynx

Cricopharyngeal dysphagia, although an uncommon condition, is considered in the differential diagnosis of persistent dysphagia of young dogs. This condition is characterized by inadequate or asynchronous relaxation of the cricopharyngeal sphincter that prevents the normal movement of food from caudal portions of the pharynx into the cranial esophagus. The etiologic basis of this failure of reflex relaxation has not been established. Dogs with cricopharyngeal dysphagia usually have a history of dysphagia persisting since weaning. Attempts to swallow solid food result in anxiety, gagging, and expulsion of food from the mouth by forward movements of the tongue. After repeated ingestion of the masticated food, the entire meal passes into the stomach.

Diagnosis

Except for slight nasal exudate and occasional coughing, physical examination reveals no abnormality. Examination of the pharynx reveals no inflammatory or obstructive lesions. While the patient is under anesthesia, an esophagoscope can be passed into the stomach without difficulty. The resting pressure provided by the closed sphincter, as encountered by passage of the endoscope and as measured by manometry, is normal.

Radiographs of a barium swallow study reveal contrast material remaining in the pharynx. In some dogs, barium is aspirated into the lungs. Fluoroscopic examination of a barium swallow demonstrates normal movement of the barium bolus into the oropharynx by elevation of the tongue and contraction of the pharyngeal musculature. Despite the presence of sufficient force to distend the caudal pharyngeal wall, inadequate or asynchronous relaxation of the cricopharyngeal sphincter prevents normal movement of the barium bolus into the proximal esophagus. The thin stream of barium that passes through the sphincter moves into the stomach with no evidence of failure of reflex relaxation of the gastroesophageal sphincter. This cycle is repeated in rapid succession until all the barium is swallowed. As the epiglottis, which closes the glottis in normal fashion during swallowing attempts, opens during inspiration, the residual barium filling the caudal pharyngeal region may be aspirated into the trachea and discharged by coughing.

Immediate relief of the dysphagia is achieved by cricopharyngeal myectomy. Complete division of muscle fibers of the cricopharyngeal muscle is essential for permanent elimination of the condition.

Technique for Cricopharyngeal Myectomy

The dog is anesthetized, intubated, and placed in dorsal recumbency. A midline incision is made from the cranial aspect of the larynx to the thoracic inlet. Exposure of the trachea and esophagus is by midline dissection of the ventral neck musculature. Partial incision of the insertion of fibers of the sternohyoid muscle on the basihyoid bone may be necessary. The bisected sternohyoid muscle is retracted to expose the trachea. Dissection is continued to the left of the trachea by transection of the insertion of the left sternothyroid muscle to the lateral surface of the thyroid lamina. The left thyroid gland is exposed between the trachea and the sternothyroid muscle. Several small branches of the cranial thyroid artery that supply the upper aspect of the left thyroid gland are ligated and transected (Figure 15-1). The left recurrent laryngeal nerve should be preserved.
 

The cricopharyngeal muscle and dorsal proximal esophagus can be exposed by grasping the larynx and rotating it. The cricopharyngeal muscle can be identified as a bundle of transverse muscle fibers converging on the dorsal midline and blending into the longitudinal muscle fibers of the cranial esophagus. Two parallel incisions, approximately 2 mm apart, are made on the dorsal midline through the cricopharyngeal muscle and onto the cranial esophageal musculature (Figure 15-2). The esophageal mucosa is not incised. The incised muscle fibers are separated from the mucosa and are excised. Bleeding is controlled by use of gauze and pressure; the myectomy is not sutured. Closure of the incision is initiated by apposition of the sternohyoid muscle with simple interrupted 3-0 absorbable sutures. Suturing the transected insertion of the sternothyroid muscle is not necessary. The subcutaneous tissue and skin are sutured routinely. Although other tissue planes that were separated for exposure are not sutured, seroma formation is uncommon.
 

Postoperative Care

No special postoperative care is required. Patients tolerate solid food the day after the operation. Recurrence of dysphagia because of fibrosis and constriction at the myectomy site is prevented by adequate removal of sphincter muscle fibers during the original surgical procedure.

Editors Note: Suspicion of Cricopharyngeal dysphagia should prompt the primary care veterinarian to refer the case to a specialist. Fluroscopic contrast swallowing studies are indicated to properly diagnose this uncommon condition prior to any surgical intervention.

Suggested Readings

Hurwitz A L, Duranceau A. Upper esophageal sphincter dysfunction: pathogenesis and treatment. Am J Digest Dis 1978;23:275.

Lund WS. The functions of the cricopharyngeal sphincter during swallowing. Acta Otolaryngol (Stockh) 1965;59:497.

Pearson H. The differential diagnosis of persistent vomiting in the young dog. J Small Anim Pract 1970; 11:403.

Rosin E, Hanlon GF. Canine cricopharyngeal achalasia. J Am Vet Med Assoc 1972;160:1496.

Seaman WB. Functional disorders of the pharyngoesophageal junction. Radiol Clin North Am 1969,11:113.

Sokolovsky V. Cricopharyngeal achalasia in a dog. J Am Vet Med Assoc 1967:150:281.

Suter PF, Watrous BJ. Oropharyngeal dysphagias in the dog: a cinefluorographic analysis of experimentally induced and spontaneously occurring swallowing disorders. I. Oral stage and pharyngeal stage dysphagias. Vet Radiol 1980:21:24.

Warnock JJ, Marks SL, Pollard R, et al: Surgical management of cricopharyngeal dyspahgia in dogs: 14 cases (1989-2001), J Amer Anim Hosp Assoc 223 (10): 1462-1468,2003.
 

Introduction

Otopharyngeal polyps, also termed nasopharyngeal polyps or inflammatory polyps, are benign pedunculated growths that arise from the oropharyngeal mucous membranes. The polyp stalk may originate from the nasopharynx, the auditory canal, or the tympanic cavity.^1,2 The polyp may grow into the nasopharynx or tympanic cavity or both. The mucosal lining from the nasopharynx to the tympanic cavity is continuous and histologically similar, so it is difficult to identify the origin of polyps. Polyps are composed of variable amounts of submucosal lymphocytic plasmacytic cellular infiltration with fibroplasia and the epithelium ranges from stratified squamous to ciliated columnar cells.^2,3

The exact cause of the polyps is unknown. The presence of submucosal inflammatory cells suggests that polyps may arise from infection or chronic inflammation. Polyps are also associated with rhinitis or otitis media, suggesting a viral or bacterial etiology. However, any potential role played by infectious agents remains unclear and it may be that the etiology is multifactorial.⁴ Because polyps have been identified in very young kittens, a congenital origin has also been suggested.^5,6

Otopharyngeal polyps occur in cats of any age, although these animals are often less than two years old and may be seen in kittens as young as 4 weeks of age.^1,5,7,8 There is no apparent sex or breed predisposition. Although polyps are most commonly unilateral they can be bilateral. Polyps have also been reported in dogs, but are less prevalent than in cats.^9-11

Clinical signs may be present for weeks to years before a polyp is diagnosed, and the signs vary depending on polyp location.^3,12 Polyps in the nasopharyngeal region may cause obstruction resulting in respiratory stridor, dyspnea, dysphagia, or voice changes.

Respiratory distress, cyanosis and syncopal episodes may also occur. Nasopharyngeal polyps may cause signs of upper respiratory tract infection such as sneezing, coughing, and nasal or ocular discharge. The respiratory signs may be mildly responsive to symptomatic treatment if a secondary bacterial infection is present. Polyps in the external or middle ear may be visible in the external canal and may be associated with infection or cause signs that mimic otitis externa, otitis media, or otitis interna. These signs include head shaking, ear scratching, head tilt, Horner’s syndrome, and nystagmus. Ability to hear may be diminished in the affected ear,¹³ although this may not be clinically apparent. Any cat with chronic upper respiratory tract disease should be evaluated for polyps. The differential diagnoses include upper respiratory tract infections such as feline calicivirus and feline rhinotracheitis virus, nasal foreign bodies, and nasopharyngeal masses such as cryptococcal granuloma and neoplasms.

In dogs, inflammatory polyps tend to occur in the middle ear rather than the nasophayrngeal region, and they present with clinical signs of otitis media, otitis externa, or bleeding from the external ear canal.¹⁰ The differential diagnoses for signs related to the ear include neoplasia and otitis externa, media, or interna.

Preoperative Considerations

A thorough physical exam should be performed, including complete otoscopic and oropharyngeal evaluations. Polyps may rupture through the tympanic membrane and appear in the external ear canal. Examination of the external ear canal may reveal signs of otitis externa with a visible pink, red or grey, spherical mass occluding the canal. The surface is often smooth and glistens, due to the mucosa that covers the surface. An otoscope or video-otoscope may be needed to visualize a polyp that is causing the tympanic membrane to bulge, or has perforated the membrane and is protruding into the external auditory canal. If the history and physical findings are suggestive of a pharyngeal mass, sedation or general anesthesia is necessary to perform a thorough oral examination. Inspection of the oral cavity may reveal ventral displacement of the soft palate. The nasopharynx can be evaluated by retracting the caudal edge of the soft palate rostrally using a spay hook or stay suture. The nasopharynx can also be visualized by use of a flexible fiberoptic bronchoscope.

Skull radiographs should be performed with the cat under general anesthesia, with particular attention paid to the nasal cavity and middle ear. A nasopharyngeal polyp may be identified as a soft tissue density in the nasopharynx on the lateral radiographic view. Ventrodorsal, oblique lateral, and frontal open-mouth views are recommended to evaluate the osseous and tympanic bulla and petrous temporal bones. Thickening or sclerosis of the osseous bulla and sclerosis of the petrous-temporal bone indicate chronic middle ear involvement. The tympanic bulla may be best evaluated for increased soft tissue density using frontal open-mouth and lateral oblique radiographic views of the skull. Increased soft tissue density may also be seen within the external canal if a polyp is located there. Most cats with polyps have radiographic changes compatible with middle ear infection.

However, radiographic evaluation is not a highly sensitive method for diagnosing otitis media so a high level of suspicion for otitis media should be maintained in cats diagnosed with otopharyngeal polyps even with a lack of radiographic evidence.^2,14 Compared to skull radiographs, both computed tomography and magnetic resonance imaging provide more accurate assessment of soft tissue opacities and changes in the osseous bulla.

Surgical Technique

The treatment of choice is a ventral bulla osteotomy performed on the side associated with the polyp, along with polyp extraction. Regardless of whether the polyp is in the external ear canal or the nasopharynx, a ventral bulla osteotomy should be performed before removing the polyp to facilitate removal of inflammatory tissue and detachment of the pedicle.

Performance of a ventral bulla osteotomy is associated with a lower incidence of otic and possibly nasopharyngeal polyp recurrence, supporting the idea that polyps may originate in the middle ear.^1,2 A bulla osteotomy is recommended even if there is no evidence of bulla abnormalities on the diagnostic images.

To perform a ventral bulla osteotomy, the cat is placed in dorsal recumbency with the head and neck extended. The ventral wall of the tympanic bulla can usually be palpated between the angular process of the mandible and the larynx. A paramedian skin incision is made over the bulla beginning near the angle of the mandible and extending about 6 cm caudally, where the linguofacial vein may be identified. The incision is continued through the subcutaneous tissues and cutaneous muscles. Blunt dissection between the digastric muscle laterally and the hyoglossal and styloglossal muscles medially exposes the bulla, which is palpable cranial to the hyoid apparatus. The hypoglossal nerve, and the lingual artery and vein may be identified on the hyoglossal muscle and are retracted medially. The ventral branch of the external carotid artery is located lateral to the bulla. Self-retaining retractors may be used to maintain exposure, with care taken to avoid the hypoglossal nerve and the vessels. Connective tissue and periosteum is bluntly dissected off the ventral aspect of the bulla using a periosteal elevator. A Steinmann pin is used to create a hole in the ventral bulla. The hole should be large enough to accommodate one jaw of a small rongeurs. The ventral aspect of the bulla is then removed with the rongeurs.

The middle ear of the cat contains a septum that divides the bulla into a small dorsolateral and a larger ventromedial compartment.^15,16 This septum must be removed to gain access to the dorsolateral compartment of the bulla, where the external auditory meatus and the auditory os of the Eustachian tube are located (Figure 15-3). Removal of the septum is performed as described for removal of the ventral bulla. Both compartments of the bulla should be cultured. The bulla should undergo careful inspection and gentle curettage to remove the epithelial lining and any granulation tissue. Aggressive curettage or direct suctioning of the dorsomedial aspect of the bulla should be avoided to reduce the risk of damaging the postganglionic sympathetic nerve fibers, auditory ossicles, semicircular canals, and cochlea. Damage to these structures can result in Horner’s syndrome and otitis interna. Any tissue removed from the bulla should be submitted for histologic evaluation. Before closing, the bulla is lavaged with sterile saline. Placement of a surgical drain is probably not necessary, but if one is used it should be placed to exit through a separate stab incision. A closed suction drain may be constructed by cutting the end from a butterfly infusion set^a and creating several fenestrations in the tubing. Once the drain has been placed in the bulla and the wound has been closed, the needle is inserted into a vacutainer tube to provide suction. This system is preferable to a Penrose drain because the quantity and character of the drainage can be easily monitored. The cutaneous muscles and subcutaneous tissues are sutured with 3-0 or 4-0 absorbable suture material in a simple continuous pattern. The skin may be closed using 4-0 absorbable suture material in a simple continuous intradermal pattern or using 4-0 nylon for external skin sutures. The drain should be sutured to the skin to prevent premature removal, and a bandage is placed around the head to stabilize the vacutainer tube. The vacutainer should be replaced twice daily to ensure it is providing negative pressure. The drain is removed when fluid production is, minimal which is usually within 3 to 7 days. If a Penrose drain is used, it is necessary to cover it with a bandage that is changed daily to monitor any drainage. The skin sutures may be removed 7 to 10 days postoperatively.
 

Simple traction using an Allis tissue forceps or alligator forceps is usually sufficient to remove the polyp. Hemorrhage is usually minimal and may be controlled by direct pressure. If the polyp is visible in the external canal, it may be extracted by traction after performing a ventral bulla osteotomy. A lateral ear canal resection may be performed to improve exposure, but is rarely necessary. Nasopharyngeal polyps can be removed by traction, using an oral approach. Endoscopy may provide better visualization of the nasopharyngeal region,¹⁷ but is typically not necessary. Retraction of the soft palate rostrally with a spay hook usually provides adequate exposure. If necessary (rarely), exposure may be increased by making a longitudinal incision on the midline of the soft palate (Figure 15-4).
 

Stay sutures may be used to retract the palate while the polyp is being removed. A three-layer closure is performed on the palate by suturing the nasal mucosa, submucosal tissue and oral mucosa separately using 4-0 or 5-0 absorbable suture material in a simple continuous pattern. The polyp should be submitted for histologic evaluation to confirm the diagnosis.

Surgical complications are related to the ventral bulla osteotomy, and the most common is damage to the postganglionic sympathetic nerve fibers, resulting in Horner’s syndrome which is characterized by miosis, ptosis, enophthalmus and prolapse of the third eyelid (Figure 15-5). It usually resolves within one month, although it may be permanent.^2,8 Horner’s syndrome is a rare complication in dogs, probably reflecting anatomical differences in the tympanic bulla between dogs and cats. Damage to the round and oval windows or vestibulocochlear apparatus result in vestibular disturbances, which include head tilt, ataxia, and nystagmus. Nystagmus usually resolves within 24 hours, but head tilt or ataxia may persist.^14,16 Damage to the hypoglossal nerve is less common, and results in deficits of swallowing, prehension, and mastication. Facial nerve paralysis has also been reported.^2,3 Deafness is not a reported complication of ventral bulla osteotomy. However, cats who are deaf prior to surgery may not be improved by it.¹³
 

The prognosis is good with complete excision, but recurrence of the polyp may occur from months to years postoperatively.^3,12 Recurrence is less common when surgical removal is combined with bulla osteotomy.^2,14,16 Recurrence is less common for nasopharyngeal polyps than for aural polyps, even if removed by traction with no bulla osteotomy.¹⁹

^a E-Z Set. Becton Dickinson. Sandy, Utah

References

1. Bradley RL, Noone KE, Saunders GK, et al. Nasopharyngeal and middle ear polypoid masses in five cats. Veterinary Surgery 1985;14:141-144.
2. Kapatkin AS, Matthiesen DT, Noone KE, et al. Results of surgery and long-term follow-up in 31 cats with nasopharyngeal polyps. Journal of the American Animal Hospital Association 1990;26:387-392.
3. Lane JG, Orr CM, Lucke VM, et al. Nasopharyngeal polyps arising in the middle ear of the cat. Journal of Small Animal Practice 1981;22:511-522.
4. Klose TC, MacPhail CM, Schultheiss PC, et al. Prevalence of select infectious agents in inflammatory aural and nasopharyngeal polyps from client-owned cats. Journal of Feline Medicine and Surgery 2010;12:769-774.
5. Brownlie SE, Bedford PGC. Nasopharyngeal polyp in a kitten. Veterinary Record 1985;117:668-669.
6. Stanton ME, Wheaton LG, Render JA, et al. Pharyngeal polyps in two feline siblings. Journal of the American Veterinary Medical Association 1985;186:1311-1313.
7. Parker NR, Binnington AG. Nasopharyngeal polyps in cats: Three case reports and a review of the literature. Journal of the American Animal Hospital Association 1985;21:473-478.
8. Trevor PB, Martin RA. Tympanic bulla osteotomy for treatment of middle-ear disease in cats: 19 cases (1984-1991). Journal of the American Veterinary Medical Association 1993;202:123-128.
9. Fingland RB, Gratzek A, Vorhies MW, et al. Nasopharyngeal polyp in a dog. Journal of the American Animal Hospital Association 1993;29:311-314.
10. Pratschke KM. Inflammatory polyps of the middle ear in 5 dogs. Veterinary Surgery 2003;32:292-296.
11. London CA, Dubilzeig RR, Vail DM, et al. Evaluation of dogs and cats with tumors of the ear canal: 145 cases (1978-1992). Journal of the American Veterinary Medical Association 1996;208:1413-1418.
12. Harvey CE, Goldschmidt MH. Inflammatory polypoid growths in the ear canal of cats. Journal of Small Animal Practice 1978;19:669-677.
13. Anders BB, Hoelzler MG, Scavelli TD, et al. Analysis of auditory and neurologic effects associated with ventral bulla osteotomy for removal of inflammatory polyps or nasopharyngeal masses in cats. Journal of the American Veterinary Medical Association 2008;233:580-585.
14. Remedios AM, Fowler JD, Pharr JW. A comparison of radoigraphic versus surgical diagnosis of otitis media. Journal of the American Animal Hospital Association 1991;27:183-188.
15. Ader PL, Boothe HW. Ventral bulla osteotomy in the cat. Journal of the American Animal Hospital Association 1979;15:757-762.
16. Little CJL, Lane JG. The surgical anatomy of the feline bulla tympanica. Journal of Small Animal Practice 1986;27:371-378.
17. Esterline ML, Radlinsky MG, Schermerhorn T. Journal of Feline Medicine and Surgery 2005;7:121-124.
18. Faulkner JE, Budsberg SC. Results of ventral bulla osteotomy for treatment of middle ear polyps in cats. Journal of the American Animal Hospital Association 1990;26:496-499.
19. Anderson DM, Robinson RK, White RAS. Management of inflammatory polyps in 37cats. Veterinary Record 2000;147:684-687