Guttural Pouch Mycosis

Guttural Pouch Mycosis



Basic Information image



Definition


Fungal infection within the guttural pouch(es) that affects the neurovascular structures inside of the pouch, causing hemorrhage and neurologic deficits



Epidemiology



Associated Conditions and Disorders


Aspiration pneumonia, laryngeal hemiplegia, Horner syndrome



Clinical Presentation



Disease Forms/Subtypes




• Acute, severe epistaxis (unilateral or bilateral)


• Chronic neurologic deficits: Dysphagia, laryngeal or pharyngeal paralysis, esophageal obstruction, Horner’s syndrome, facial nerve paralysis



History, Chief Complaint




• The most common presenting complaint is moderate to severe epistaxis.


• Dysphagia is the second most common presenting complaint.



Physical Exam Findings




• Acute, moderate to severe epistaxis:


image Unilateral is most common, but it can also be bilateral

image Signs of hypovolemic or hemorrhagic shock

• Tachycardia, tachypnea, pale mucous membranes, weak peripheral pulses, anxious demeanor, weakness


• Neurologic deficits:


image Dysphagia: Horses may present with esophageal obstruction, aspiration pneumonia, or tongue protrusion or have feed material in the nares.

image Laryngeal or pharyngeal paralysis: A respiratory noise may be noted during exercise.

image Horner syndrome: Ptosis, meiosis, enophthalmos, patchy sweating, and nasal mucosa congestion on the affected side.

image Facial nerve paralysis: Ear droop, ptosis, lip droop, and inability to blink on the affected side.

• The inability to blink may lead to the development of corneal ulcers on the affected side.


• Other less common clinical signs: Nasal discharge, colic, blindness, unusual head carriage, parotid area pain, head shyness.



Etiology and Pathophysiology




• The most common etiologic agents recovered from horses with guttural pouch mycosis are Emericella nidulans and Aspergillus fumigatus.


• These fungi are ubiquitous and thrive in warm, moist areas such as bedding material containing urine and water.


• These fungi act as opportunistic pathogens, entering the guttural pouch through the pharyngeal orifice, where they incite an inflammatory response.


• This leads to the formation of a diphtheritic membrane, composed of necrotic tissue, cell debris, bacteria, and fungal mycelia.


• The fungi can penetrate deeper tissues, causing thromboarteritis, aneurysm, and hemorrhage.


image This typically occurs in the internal carotid artery (two thirds of cases).

image The external carotid artery, its branches, or the maxillary artery are affected in the other third of cases.

• Damage may occur to any of the nerves within the guttural pouch because of the acute inflammatory response or because of chronic fibrosis.


image Cranial nerves VII, IX, X, XI, and XII; the pharyngeal branch of the vagus nerve; the cranial cervical ganglion; the cranial laryngeal nerve; and the cervical sympathetic stump may be affected.

image Neurologic deficits are generally seen in the more chronic stages of the disease.


Diagnosis image



Differential Diagnosis




• Trauma to the nasal passages or sinuses


• Rupture of the ventral straight muscles of the head


• Masses of the nasal passages, sinuses, or guttural pouches


image Progressive ethmoidal hematomas

image Neoplasia: Squamous cell carcinoma, fibrosarcoma, melanoma, hemangiosarcoma

image Paranasal sinus cysts

• Exercise-induced pulmonary hemorrhage


• Bacterial or fungal sinusitis



Initial Database




• Complete blood count: Normal


• Hematocrit: Normal in the acute stages (<24 hours after hemorrhage); decreased later


• Total protein: Normal in the subacute stages (<4–6 hours after hemorrhage); decreased later


• Fibrinogen: Normal, decreased (if substantial hemorrhage), or increased (chronic inflammation or infection)


• Platelet count: Normal or decreased after substantial hemorrhage


• Serum chemistry: Normal or azotemia (prerenal) if hypovolemic shock is present


• Upper airway endoscopy


• Blood clot at the pharyngeal orifice of the affected pouch
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  3. Pericardial Disease
  4. Regional Limb Perfusion

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Jul 24, 2016 | Posted by in SMALL ANIMAL | Comments Off on Guttural Pouch Mycosis

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