Cricopharyngeal achalasia

From Dog
Lateral radiograph of a young dog following barium-swallow, showing delayed emptying of the pharynx and cervical esophageal dilation[1]

Cricopharyngeal achalasia is a rare genetic disease of dogs resulting in a disorder of the cricopharyngeas muscle involved with the swallowing reflex[2].

Although a congenital predisposition is observed with the Cocker Spaniel[3], acquired cricopharyngeal achalasia has also been reported in association with hypothyroidism[4].

This disease is thought to be caused by an underlying neuromuscular disorder of the cricopharyngeus muscle, etiology unknown[5]. Swallowing normally involves three phases (oropharyngeal, esophageal, and the gastroesophageal) and it is in the middle esophageal phase, when the upper esophageal sphincter fails to relax that the disorder manifests[6]. Failure for this muscle to relax can be caused by asynchrony or achalasia.

Cricopharyngeal achalasia occurs when the upper esophageal sphincter fails to relax or when there is asynchrony between contraction of the pharynx during swallowing and relaxation of the sphincter[7][8].

Clinical signs frequently develop in pups at or soon after weaning, with characteristic dysphagia, frequent swallowing, gagging, regurgitation and nasal reflux/discharge. These dogs appear clinically healthy unless there is secondary aspiration pneumonia or emaciation[9].

Diagnosis is one of exclusion of other causes and use of fluoroscopic swallowing studies (using liquid barium or barium soaked kibble) to make a definitive confirmation of the disorder[10][11], showing disturbances to normal bolus formation and contraction of the pharyngeal muscles[12].

Radiographs should be performed to exclude underlying pulmonary disease, esophagitis, megaesophagus, ciliary dyskinesia and bronchoesophageal fistula[13].

Treatment for this condition is either the transection or the complete removal of the muscles that surround the esophagus in this region (cricopharyngeal myotomy); specifically the cricopharyngeus muscle, the thyropharyngeus muscle, or both[14][15][16].

Complications arising from both of these surgical procedures may occur if concurrent aspiration pneumonia or malnutrition are not addressed prior to surgery, and include fibrosis, recurrent laryngeal paralysis, esophageal perforation, recurrence of dysphagia, and pharyngocutaneous fistula[17].

In dogs with achalasia complicated by myasthenia gravis, laryngeal paralysis and esophageal stricture, surgery may not be indicated and conservative medical therapy with prednisolone may be warranted[18].

References

  1. Bélanger M et al (1973) Cricopharyngeal achalasia in a dog. Can Vet J 14(10):252-254
  2. Pfeifer RM (2003) Cricopharyngeal achalasia in a dog. Can Vet J 44(12):993-995
  3. Weaver AD (1983) Cricopharyngeal achalasia in cocker spaniels. J Small Anim Pract 24:209–214
  4. Bruchim Y et al (2005) L-thyroxine responsive cricopharyngeal achalasia associated with hypothyroidism in a dog. J Small Anim Pract 46(11):553-554
  5. Rosin E & Hanlon G (1972) Canine cricopharyngeal achalasia. J Am Vet Med Assoc 160:1496–1499
  6. Shelton GD (1982) Swallowing disorders in the dog. Compend Contin Educ Pract Vet 4:607–613
  7. Sokolovsky V (1967) Cricophayngeal achalasia in a dog. J Am Vet Med Assoc 150:281–284
  8. Ladlow J & Hardie R (2000) Cricopharyngeal achalasia in dogs. Compend Contin Educ Pract Vet 22:750–755
  9. Elliott RC (2010) An anatomical and clinical review of cricopharyngeal achalasia in the dog. J S Afr Vet Assoc 81(2):75-79
  10. Pollard RE et al (2000) Quantitative videofluoroscopic evaluation of pharyngeal function in the dog. Vet Radiol Ultrasound 41(5):409-412
  11. Goring RL & Kagan KG (1982) Cricopharyngeal achalasia in the dog: radiographic evaluation and surgical management. Compend Contin Educ Pract Vet 4:438–444
  12. Niles JD et al (2001) Resolution of dysphagia following cricopharyngeal myectomy in six young dogs. J Small Anim Pract 42(1):32-35
  13. Pollard RE et al (2000) Quantitative videofluoroscopic evaluation of pharyngeal function in the dog. Vet Radiol Ultrasound 41:409–413
  14. Rosin E (1998) Cricopharyngeal dysphagia. In: Bojrab MJ, ed. Current Techniques in Small Animal Surgery. 4th ed. Baltimore: Williams & Wilkins. pp:144–147
  15. Baredes S (1988) Surgical management of swallowing disorders. Otolaryngol Clin North Am 21:711–720
  16. Ross E (1982) Cricopharyngeal myo tomy: management of cervical dysphagia. Otolaryngol Head Neck Surg 90:434–441
  17. Warnock JJ et al (2003) Surgical management of cricopharyngeal dysphagia in dogs: 14 cases (1989-2001). J Am Vet Med Assoc 223(10):1462-1468
  18. Willard MD et al (1983) Progressive oropharyngeal dysfunction in a dog. J Am Vet Med Assoc 183(9):1009-1011