Dysphagia caused by focal guttural pouch mycosis: mononeuropathy of the pharyngeal ramus of the vagal nerve in a 20-year-old pony mare

Abstract

A 20-year-old pony mare was presented to the equine hospital with a ten-day history of dysphagia, regurgitation and coughing. An obstruction of the oesophagus was excluded via endoscopy, but the proximal oesophagus appeared to be distended and circular contractions were missing. A guttural pouch endoscopy revealed a single, black-mottled plaque on the pharyngeal ramus of the vagus nerve in the left guttural pouch, causing a local swelling of this nerve. The pharyngeal ramus seemed to be atrophic distal to the lesion. A biopsy was taken from the lesion and histopathological findings proved the reasonable suspicion of a guttural pouch mycosis with a high degree of purulent-necrotic inflammation and invasion of fungal hyphae. There were no signs of neoplasia, such as melanoma. Daily guttural pouch irrigations with a clotrimazole emulsion (20 g Canesten® Gyn4 solved in 500 ml water), led to a good recovery of the mucosa above the nerve. Periodic endoscopic examination of the left guttural pouch showed that local thickening and distal atrophy of this pharyngeal ramus did not improve, neither did the clinical symptoms. Due to progressive weight loss, acute respiratory distress and aspiration pneumonia, the 20-year-old pony mare unfortunately had to be euthanized three weeks after discharge. This case report emphasizes the enormous importance of a single nerve for the realization of the swallowing process. The one-sided loss of function of the pharyngeal branch of the vagal nerve cannot be compensated neither by the remaining ipsilateral nerves nor by the contralateral normal functioning glossopharyngeal and vagal nerves and thus inevitably leads to severe dysphagia.

Salpingopharyngeal fistula as a treatment for guttural pouch mycosis in seven horses

“…Systemically, treatments with thiabendazole [2,4], itraconazole [5,6] and iodide [7] have been described. Topical treatment of GPM with a range of topical medications can be found in the literature, but their efficacy is not well supported [6,[8][9][10][11][12][13].…”

Guttural pouch mycosis in two foals

“…and other opportunistic fungi are found naturally in the environment and can be found in the upper respiratory tract of healthy horses (Eichentopf et al . ). Prolonged treatment with antimicrobials, as in both foals in this report, or corticosteroids has been proposed as a potential cause for fungal overgrowth (Guillot et al .…”

“…; Eichentopf et al . ). The presence of dorsal pharyngeal collapse in both cases also indicates involvement of the glossopharyngeal nerve as this provides sensory innervation to the nasopharynx and motor innervation to the stylopharyngeus muscle (Borges and Watanabe ; Eichentopf et al .…”

“…The presence of dorsal pharyngeal collapse in both cases also indicates involvement of the glossopharyngeal nerve as this provides sensory innervation to the nasopharynx and motor innervation to the stylopharyngeus muscle (Borges and Watanabe ; Eichentopf et al . ). Both foals maintained residual cranial nerve deficits after resolution of the guttural pouch mycosis; left laryngeal hemiplegia in Foal A and dorsal pharyngeal collapse with inconsistent dysphagia in Foal B .…”

Ex vivo study of vagal branches at risk for iatrogenic injury during laryngoplasty in horses

“…On the other hand, bilateral and unilateral suppressions of the vagal and glossopharyngeal components of the PP have been studied. Dysphagia has been reported after bilateral and unilateral regional anesthesia of the pharyngeal branch of the vagus nerve 33,34 and in unilateral mononeuropathy of the vagus nerve in guttural pouch mycosis 35 . Barakzai et al 9 described a case of bilateral nasal discharge of food one month after laryngoplasty.…”