From the European College of Veterinary Neurology Annual Symposium 2009

 

Volumetric Analysis Of Brain Parenchyma Within The Caudal Fossae Of Cavalier King Charles Spaniels  C Driver, C Rusbridge, H Cross, HA Volk.
In a study supported by Cavalier Friends, Colin Driver et al investigated the relationship between hindbrain (i.e. brain) and caudal fossa (skull) volume in the development of SM in dogs. He analysed the MRI scans of 59 CKCS with CM and using medical imaging software undertook a volumetric analysis of a three-dimensional reconstruction of the brain and skull. Volumes of hindbrain parenchyma were analyzed as percentages of caudal fossa volume and caudal fossa volume was analyzed as a percentage of total cranial cavity volume. The volume of the ventricular system was recorded as a percentage of total parenchymal volume. If SM was present syrinx size was measured from T2 weighted MR images from the maximal dorsoventral dimension within the cervical spine. SM was present in 40/59 (68%) dogs. There was no significant age difference between dogs with or without SM. Caudal fossa percentage of the total cranial cavity volume did not differ significantly between dogs without or with SM.  However, there was a significant difference between the two groups looking at hindbrain parenchyma percentage of the caudal fossa. Furthermore, in the SM group a significant positive association was found between the hindbrain parenchyma percentage and syrinx size. No significant difference was found between the two groups for ventricular volume however when a syrinx was present a strong positive correlation was found between ventricular and syrinx size. This work supports recent evidence that caudal fossa size is not associated with SM, but that overcrowding of the caudal fossa leads to SM. The association between ventricle and syrinx dimensions supports the theory that SM develops as a result of altered CSF dynamics.

 

Anatomical Distribution of Syringomyelia in Cavalier King Charles Spaniel With Chiari.Like Malformation.  S Loderstedt, L Benigni, K Chandler, C Lamb, C Rusbridge, HA Volk.
In a poster presentation, Shenja Loderstedt et al described the results of a study investigating the prevalence and anatomical distribution of syringomyelia (SM) in clinically-affected CKCS. It was hypothesised that (1) SM is not restricted to the cervical spine, (2) the maximal syrinx diameter can occur anywhere along the spinal cord, (3) there is an association between cervical syrinx diameter and distribution and SM in other regions of the spinal cord. Thirty-seven CKCS with clinical evidence of SM were studied prospectively. Magnetic resonance (MR) imaging of the brain and the entire spinal cord of each dog were performed at 1.5 Tesla. SM was present in the region of the C1-C4 vertebral bodies in all dogs (100%) however it often was not limited to that area being also found at C5- T1 in 31/37 (84%), T2-L2 in 29/37(78%) and L3-L6 in 21/37 (57%). Maximal SM diameter occurred at C1-C4 in 19/37 (51%) dogs, at C5- T1 in 2/37 (5%), at T2-L2 in 15/37 (41%) and at L3-L6 in 1/37(3%) dogs, respectively. There was no significant difference between the mean syrinx diameter at the region C1-C4, C5- T1 and T2-L2 but mean syrinx diameter was less in the region L3-L6. Mean syrinx diameter at C1-C4 was positively correlated with mean syrinx diameter at C5- T1, T2-L2 and L3-L6 respectively. In conclusion many CKCS with a cranial cervical syrinx also have a syrinx affecting more caudal regions of the spinal cord. Dogs with a large cranial cervical syrinx tend to also have a large syrinx more caudal. MR imaging restricted to the cervical region will underestimate the extent of the syrinx and the severity of the disease process in the majority of dogs.

 

Effect of Middle Ear Effusion On The Brainstem Auditory Response Of Cavalier King Charles Spaniels  T. R. Harcourt-Brown, J. E. Parker, N. D. Jeffery
Tom Harcourt-Brown et al described the effects of middle ear effusion on hearing tests of 23 CKCS. Middle ear effusion (has been previously referred to as PSOMs) was diagnosed if the auditory bulla was completely filled with material that was isointense to brain parenchyma on T1 weighted images and hyperintense on T2 weighted images. Dogs with otitis externa were excluded from the study. Each dog's hearing was considered normal by their owner however Brainstem Auditory Evoked Reponses (BAER) demonstrated a conductive hearing loss in ears affected by middle ear effusion.

 

Recent publications

 

Characteristics of cerebrospinal fluid flow in Cavalier King Charles Spaniels analyzed using phase velocity cine magnetic resonance imaging. Cerda-Gonzalez S, Olby NJ, Broadstone R, McCullough S, Osborne JA.  Vet Radiol Ultrasound. 2009 Sep-Oct;50(5):467-76.
In a study part funded by the American Cavalier King Charles Spaniel Club Charitable Trust, Sofia Cerda-Gonzalez and others investigated cerebrospinal fluid (CSF) flow in Chiari malformation in 59 Cavalier King Charles Spaniels comparing it to 5 normal control dogs of other breeds. The presence of syringomyelia was noted from sagittal MR images. The pattern and velocity of CSF flow were assessed using phase-contrast cine MRI at the foramen magnum, C2-C3 disc space, and within syrinxes. Flow was measured most easily with the neck flexed to mimic standing. CSF flow velocity in the dorsal aspect of the subarachnoid space at the foramen magnum was significantly higher in control dogs than Cavalier King Charles Spaniels. Flow was obstructed at the foramen magnum in 41 of 59 Cavalier King Charles Spaniels. Turbulent flow and jets were associated with syringomyelia presence and severity, and CSF flow velocity at C2/3 dorsally was inversely related to the presence of syringomyelia. Peak dorsal subarachnoid space CSF flow velocity at the foramen magnum and C2-C3 were together highly predictive of syringomyelia. They concluded that CSF flow can be assessed in dogs using phase-contrast cine MRI. Obstruction to flow at the foramen magnum is common in Cavalier King Charles Spaniels and CSF flow pattern and velocity are related to the presence of syringomyelia. http://www3.interscience.wiley.com/journal/122573484/abstract