Caudal cranial fossa partitioning in Cavalier King Charles spaniels

Abstract

Cavalier King Charles spaniels (CKCS) are notable among dog breeds for their high rate of Chiari-like malformation (CM-characterised by indentation of the cerebellum by the supraoccipital bone and/or herniation of a part of the cerebellum through the foramen magnum (Cappello and rusbridge 2007)) and syringomyelia (SMfluid-filled cavities within the spinal cord (syringes) (rusbridge and others 2000, lu and others 2003). The cause of this painful and heritable disease complex (rusbridge and Knowler 2004, lewis and others 2010) has been attributed to a volume mismatch between the caudal cranial fossa (CCF) and brain parenchyma contained within, mediated by crowding of hindbrain parenchyma and disturbance to cerebrospinal fluid flow dynamics in the caudal occipital region of the skull (levine 2004, rusbridge and others 2006). although the occipital bones of CKCS appear to be malformed (Dewey and others 2004, rusbridge and Knowler 2006, Carrera and others 2009), previous studies that investigated a possible association between reduced CCF volume and CM/SM yielded inconsistent results (Couturier and others 2008, Carrera and others 2009, Carruthers and others 2009, Cerda-Gonzalez and others 2009, Schmidt and others 2009, Driver and others 2010a, b). Furthermore, when CKCS were compared with other small breed dogs (SB), the CCF was appropriate in size but contained parenchyma that was disproportionately large (Cross and others 2009), suggesting that the aetiology of CM/SM in CKCS may be related to increased growth of the hindbrain. The authors of this communication recently reported that CKCS have a relatively larger cerebellum than SB and labradors (lD), and also found that in CKCS there is an association between the development of SM and increased cerebellar volume (Shaw and others 2012). However, this study also showed that increased cerebellar volume was associated with increased crowding in the caudal occipital region, in contrast with the other breeds in which caudal cerebellar crowding was independent of increased cerebellar volume. These are interesting findings as they suggest a multifactorial aetiology for CM/SM in CKCS, dependent on the cumulative effects of increased cerebellar volume and a CCF which does not reach a commensurate size. Here, we report that the morphology of the canine skull is affected by variation in hindbrain volume. important differences exist between CKCS, SB and lD that are pertinent to the pathological mechanisms of CM/SM.Our first hypothesis is that the caudal part of the CCF is relatively smaller in CKCS than in other breeds of dog, and there is an increase in the volume in other part(s) of the CCF. Our second hypothesis is that there is an association between SM in CKCS and reduced volume of the caudal part of the CCF. Our third hypothesis is that the volume of the caudal part of the CCF in CKCS is insensitive to variation in the relative hindbrain volume, and there is increased sensitivity in other part(s) of the CCF. a retrospective study of Mri scans of CKCS, SB and lD was perfor...

Longitudinal Study of the Relationship among Craniocervical Morphology, Clinical Progression, and Syringomyelia in a Cohort of Cavalier King Charles Spaniels

“…As a preliminary hypothesis, it has been suggested that skull morphology in this breed may change in response to the pulsatile movement of the cerebellum against the supraoccipital bone, leading to increased bone resorption surrounding the foramen magnum . Enlargement of the caudal cranial fossa, in turn, has been proposed to cause rostral angling of the tentorium cerebelli in CKCS, in comparison to other breeds . Such alterations in tentorium positioning could play a role in the decrease in rostral cranial fossa volumes observed in our study.…”

“…23 Enlargement of the caudal cranial fossa, in turn, has been proposed to cause rostral angling of the tentorium cerebelli in CKCS, in comparison to other breeds. 35 Such alterations in tentorium positioning could play a role in the decrease in rostral cranial fossa volumes observed in our study.…”

Quantitative Analysis of Chiari-Like Malformation and Syringomyelia in the Griffon Bruxellois Dog

“…It has been shown previously that Cavalier King Charles spaniels with CM have a relatively large volume pars rostralis and relatively small volume pars caudalis [39]. The authors suggested that, in this breed, occipital bone development is insensitive to changes in hindbrain volume and that there is a compensatory bulging of the tentorium cerebelli in a rostral direction [39].…”

“…The authors suggested that, in this breed, occipital bone development is insensitive to changes in hindbrain volume and that there is a compensatory bulging of the tentorium cerebelli in a rostral direction [39]. However, an increase in line AE could also occur because of its dependence on the position of the occipital lobes relative to the cerebellum.…”

Prevalence and Heritability of Symptomatic Syringomyelia in Cavalier King Charles Spaniels and Long‐term Outcome in Symptomatic and Asymptomatic Littermates

“…SM is characterized by the development of fluid‐filled cavities (syringes) within the spinal cord parenchyma and is associated with Chiari I malformation in humans and Chiari‐like malformation (CM) in the CKCS . The pathophysiology of CM involves a decreased caudal fossa volume with overcrowding of the craniocervical junction and caudal descend of the cerebellum into or through the foramen magnum . The pathogenesis of syrinx formation and the association between CM and SM is not fully understood, but it is believed that a multifactorial etiology including a local obstruction of the subarachnoidal space and abnormal cerebrospinal fluid dynamics are involved .…”