Nasopharyngeal stenosis is a pathologic condition in which there is a narrowing within the nasopharynx caudal to the choanae, resulting in variable degrees of inspiratory stertor. See how interventional radiography and endoscopy can help you identify and treat this abnormality in this case study.
Signalment: 8-year-old spayed female domestic shorthaired cat
Presenting complaint: 1.5-year history of inspiratory stertor, intermittent dyspnea and weight loss
Pertinent history: Intermittent nasal discharge started three years before presentation that progressed to static inspiratory noise, requiring the cat to sleep in a separate room from the owner over the past 1.5 years. The cat has a decreased appetite associated with difficulty breathing while eating.
Previous diagnostics performed
—Head and neck radiographs: results normal
—Complete blood count and serum chemistry profile: results normal
—Antibiotic trials: intermittent improvement in discharge, no improvement in breathing
—Computed tomography (CT) (3-mm slices): Evidence of fluid accumulation in both nasal passages and frontal sinus; thickening of nasal turbinates suggestive of chronic rhinitis
—Antegrade rhinoscopy and biopsy: thickened nasal turbinates, moderate lymphoplasmacytic rhinitis
Previous medications: Amoxicillin-clavulanic acid (15 mg/kg orally b.i.d. for 14 days) doxycycline (5 mg/kg orally b.i.d for seven days followed by 10 ml of water orally), and clindamycin (11 mg/kg orally b.i.d. for 21 days). After biopsy results, a tapering course of prednisone was administered per the referring internal medicine specialist (1 mg/kg/day tapered over two months).
Progression: Each course of antibiotics improved the nasal discharge. The prednisone improved the inspiratory noise slightly, but it never fully resolved.
Initial diagnostic evaluation
Physical examination: Bright, alert, good body condition; mucopurulent nasal discharge bilaterally; severe inspiratory stertor with open-mouth breathing; referred upper airway noise over the area of the larynx/pharynx on auscultation
—Severe chronic inspiratory stertor and dyspnea
—Chronic bilateral nasal discharge
—Severe lymphoplasmacytic rhinitis
—Nasal foreign body
• CT with 1-mm slices of the entire head and pharynx (Figure 1)
• Retroflex and antegrade rhinoscopy (Figure 2,)
- Severe nasopharyngeal stenosis
- Moderate chronic lymphoplasmacytic rhinitis
Figure 1: A CT image of the cat in this case with a nasopharyngeal stenosis. A) A transverse image caudal to the nasopharyngeal stenosis (NPS) in the nasopharynx. This is the area where measurements are typically taken for stent and balloon sizing. B) A transverse image of the stenosis. Note the narrowing. C) A transverse image just rostral to the stenosis in the area of the nasopharynx that sits just dorsal to the hard palate. D) A sagittal image of the nasopharynx (rostral to the right and caudal to the left). Note the narrowing at the junction of the hard (HP) and soft (SP) palate inside the nasopharynx (NP).
Figure 2: A retroflex rhinoscopic view of the nasopharynx showing a narrow opening.