Nasopharyngeal stenosis, popular topic this year....

CT Features of Confirmed Nasopharyngeal Stenosis in 12 Cats

Kevin Kang, Robert Brash

Background
Nasopharyngeal stenosis (NPS) is a narrowing of the nasopharyngeal lumen due to a soft tissue membrane, leading to partial or complete obstruction. It can be congenital or acquired, with potential causes including chronic rhinitis, upper respiratory tract infections, or aspiration rhinitis. NPS is uncommon in cats, representing about 4–6% of cases with nasopharyngeal disease. Diagnosis relies on imaging, with CT providing detailed anatomical assessment. This study aimed to describe the CT features of NPS in cats and identify imaging characteristics that may aid in diagnosis and treatment planning.

Methods
A retrospective review of medical records from 2011 to 2023 identified 12 cats with NPS confirmed by retroflex nasopharyngoscopy. All cats underwent head CT imaging, and scans were reviewed by a board-certified radiologist and a radiology resident. CT features were analyzed, including the location and severity of nasopharyngeal narrowing, contrast enhancement patterns, and associated anatomical abnormalities. Measurements of the stenotic region and surrounding structures were performed to assess the degree of airway obstruction.

Results
All 12 cats had a focal, abrupt narrowing of the nasopharynx due to a soft tissue attenuating band, with one cat exhibiting two separate stenotic areas. NPS was exclusively located in the caudal third of the nasopharynx, resulting in significant luminal reduction. The narrowing was concentric in 11/13 cases and lateral-to-lateral in 2/13 cases. Contrast enhancement of the stenotic tissue was observed in 73% of cases. In 67% of cats, the soft palate was dorsally deviated at the stenosis site, best seen in the sagittal plane. Additional findings included nasal cavity abnormalities (58% of cases), tympanic bulla effusion (33%), and mild lymphadenopathy (17%).

Limitations
The study was retrospective, with a small sample size limiting statistical power. Variability in CT acquisition protocols and image interpretation could have influenced findings. Some stenotic regions were too small for accurate measurement. The absence of long-term follow-up data restricted assessment of treatment outcomes and recurrence rates.

Conclusions
The most consistent CT features of NPS in cats include a marked, focal, contrast-enhancing soft tissue band in the caudal nasopharynx and focal dorsal deviation of the soft palate. These findings, when present in cats with compatible clinical signs, should prompt further evaluation via retroflex nasopharyngoscopy for confirmation and treatment planning. CT plays a crucial role in diagnosing NPS and guiding intervention strategies such as balloon dilation or stenting.

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