When physical exam could trump MRI

Plos One 2024

February 28, 2025

CT-based and manual external skull measurements for Chiari-like malformation and syringomyelia in Pomeranians

Koen M. Santifort ,Sophie Bellekom,Ines Carrera,Paul J. J. Mandigers

Background
Chiari-like malformation (CM) and syringomyelia (SM) are neurological disorders affecting certain dog breeds, including Pomeranians. These conditions result in severe quality-of-life impairments. This study aimed to analyze skull morphometric parameters, using CT-based and manual external measurements, to identify associations with CM/SM in Pomeranians. A focus was placed on determining if manual external measurements could predict CM/SM risk, as they do not require sedation or anesthesia.

Methods
This prospective study included 92 Pomeranians over 12 months of age, assessed between February 2022 and October 2023. Dogs underwent both MRI (to confirm CM/SM status) and CT scans, alongside manual skull measurements under anesthesia. Morphometric parameters, including cranial length, mandible length, and craniofacial ratios, were measured. Statistical analyses, including logistic regression, evaluated associations between measurements and CM/SM status.

Results
-CM/SM Prevalence: 66% of dogs were classified as CM abnormal, and 51% as SM abnormal.

-Key Measurements: Shorter mandible length was significantly associated with SM (p = 0.013). No other cranial measurements or ratios were significantly correlated with CM or SM.

-Predictive Modeling: Logistic regression indicated mandible length as a modest predictor of SM status, with shorter mandibles increasing the likelihood of SM. However, the predictive power was low (McFadden’s pseudo R² = 0.036).

-Intermodality Consistency: Manual external measurements had poor to moderate agreement with CT measurements, with mandible length showing the strongest correlation (Pearson coefficient = 0.65).

Limitations
-Intra- and interobserver reliability of manual measurements was not assessed.
-The sample size, while larger than many similar studies, limited the statistical power.
-Manual measurements are less precise compared to imaging-based methods.
-Additional anatomical or physiological factors influencing CM/SM were not analyzed.

Conclusions
Manual measurement of mandible length provides a simple, non-invasive method for assessing SM risk in Pomeranians but should not replace MRI for definitive diagnosis. While shorter mandible length was associated with increased SM likelihood, the predictive accuracy remains limited, emphasizing the need for further research to enhance diagnostic and breeding strategies.

Manual external measurements.
(a) distance between medial canthi of the eyes (intercanthal distance); (b) distance between the center of both eyes (interpupillary distance); (c) distance from the stop to the external occipital protuberance following the shape of the head (cranial length) (1) lateral view (2) dorsal view; (d) circumference (transverse plane) of the head over the zygomatic arch; (e) length of the mandible (rostral tip of the mandible to the angular process); (f) maximum width of the head at the level of the zygomatic arch (1) rostral view, (2) dorsal view; (g) length of the dorsal aspect of the nose from the planum to the stop (muzzle length).

How did we do?

Login or Subscribe to participate in polls.

Disclaimer: The summary generated in this email was created by an AI large language model. Therefore errors may occur. Reading the article is the best way to understand the scholarly work. The figure presented here remains the property of the publisher or author and subject to the applicable copyright agreement. It is reproduced here as an educational work. If you have any questions or concerns about the work presented here, reply to this email.