Morphology of the Caudal Fossa in Cavalier King Charles Spaniels

Abstract

Chiari malformations and syringohydromyelia are an important disease complex in Cavalier King Charles Spaniels. Although abnormalities in caudal fossa morphology are considered major contributors to the development of this disease, limited information exists on the range of morphologies in Cavalier King Charles Spaniels and on the relationship of these to clinically evident disease. Sixty-four Cavalier King Charles Spaniels were studied. Each underwent a neurologic examination and magnetic resonance imaging of the cervical spine and brain. T2-weighted sagittal images were used to determine both the morphologic characteristics and volume of the caudal fossa in each dog. This volume was also analyzed as a percentage of total cranial cavity volume. Each attribute was correlated with neurological grade and presence of syringohydromyelia. Fifteen dogs had neurologic signs, and 59 had morphologic abnormalities of the craniocervical junction. While 27 dogs had syringohydromyelia, 13 of these were clinically normal. Cerebellar herniation and occipital dysplasia were common findings but were not associated with syringohydromyelia. Dorsal compressive lesions were noted at the first and second cervical vertebral junction. Factors associated with the presence of neurologic signs included syringohydromyelia and the ratio of caudal fossa/total cranial cavity volume; dogs with signs had significantly larger syringohydromyelia than asymptomatic dogs. Caudal fossa size was not associated with syringohydromyelia. A positive association was identified between foramen magnum size and length of cerebellar herniation. The prevalence of craniocervical junction abnormalities is high in Cavalier King Charles Spaniels. While several factors are associated with neurologic signs, occipital hypoplasia appears to be the most important factor.

Syringomyelia and Chiari Malformation in Cavalier King Charles Spaniels – Magnetic Resonance Imaging, Pharmacological and Surgical Treatment

“…The results of MRI examinations performed in the study are consistent with the findings reported in literature (1,4). The results delivered by both treatment models seem to be promising, albeit in a short-term perspective.…”

Increase in Cerebellar Volume in Cavalier King Charles Spaniels with Chiari-like Malformation and Its Role in the Development of Syringomyelia

“…As with Classical Chiari type I malformation in humans, CKCS appear to have a shallower caudal cranial fossa and have abnormalities of the supraoccipital and basioccipital bones when compared to mesaticephalic breeds (breeds with a skull of intermediate length and width) [16]. However, although CCF overcrowding has been demonstrated in CKCS with CM/SM, independent studies have reported no difference in relative CCF volume in CKCS compared to brachycephalic breeds or other small breed dogs [17], [18], or a link between CCF volume and the development of SM [19], [20], [21]. In contrast, a recent study has showed that there is evidence of increased volume of brain parenchyma within the CCF in CKCS with syringomyelia compared to CKCS without syringomyelia [19].…”

Assessment of cerebellar pulsation in dogs with and without Chiari-like malformation and syringomyelia using cardiac-gated cine magnetic resonance imaging

“…However, as it is well documented that humans with CM-I have increased cerebellar pulsation (Wolpert et al, 1994), another explanation for the failure to identify a significant difference is probable. It is possible that an inappropriate control group was selected; clinically normal CKCS could not be recruited due to the extremely high prevalence of CM in the breed (Cerda-Gonzalez et al, 2009a). However, given their similar craniocerebral morphology, brachycephalic dogs are an appropriate control group for the study of CM (Schmidt et al, 2011).…”

“…For each of the 20 bFFE images generated during the cardiac cycle, linear measurements were made using a similar technique to that described previously (Lu et al, 2003;Cerda-Gonzalez et al, 2009a;Upchurch et al, 2011). Measurements included the height of the foramen magnum (measured from the ventral most aspect of the supraoccipital bone to the caudal basisphenoid bone) and the length of cerebellar herniation (measured perpendicular from the line of the foramen magnum to the tip of the cerebellar vermis) (Fig.…”

“…CM is a complex oligogenic trait in the Cavalier King Charles Spaniels (CKCS) (Lewis et al, 2010) with one study finding 92% of CKCS to have at least one morphological feature on magnetic resonance imaging (MRI) consistent with this diagnosis (Cerda- Gonzalez et al, 2009a). Syringomyelia (SM) occurs secondary to CM (Rusbridge and Knowler, 2003).…”