|
 Cerebrospinal
Fluid Flow in Cavalier King Charles Spaniels
Dr. Sofia Cerda-Gonzalez, Neurology Clinical Studies, College of Veterinary
Medicine, NCSU
MORPHOLOGY OF THE CAUDAL FOSSA IN CAVALIER KING CHARLES SPANIELS.
S Cerda-Gonzalez1,
NJ Olby1, TP Pease1,S McCullough2, N Massoud2, R Broadstone2 1North Carolina
State University, Raleigh, NC; 2IAMS Pet Imaging Center, Raleigh, NC.
Chiari-like malformations and syringohydromyelia (SHM) make up a disease
complex recognized in Cavalier King Charles Spaniels(CKCS) with a world-wide
distribution, complex mode of inheritance and serious health implications.
Abnormalities in caudal fossa morphology are considered major contributors
to the development of Chiari-like malformations in this breed. Recognizing
that little information exists on the range of caudal fossa morphologies in
CKCS and on the relationship of specific anatomical components to clinically
evident disease, the aim of this study was to evaluate the caudal fossa
morphology in a group of normal and affected CKCS.
MRI images were obtained in 11 clinically affected and 48 unaffected CKCS,
and in 5 control dogs of different breeds using a Siemens AG 1.5 T MRI. Ages
ranged from 1 to 5 years. Neurological abnormalities were clinically graded
between 0 and 5. Dogs were anesthetized and sagittal T2-weighted image
sequences of the brain and cervical spine, along with T2 3-dimensional SPACE
sagittal images of the same area were obtained. Parameters assessed included
height of the foramen magnum, presence of occipital dysplasia and of SHM,
degree of cerebellar herniation and of cerebellar indentation and
hydrocephalus. Any other abnormalities were also noted. The volumes of the
caudal fossa and the forebrain were measured and the volume of the caudal
fossa was expressed as a percentage of total brain volume. Each of these
parameters was correlated with neurological grade and presence of SHM using
ANOVA (p values of <0.05 considered significant).
Fifty-one of the CKCS were classified as morphologically abnormal; 22 of
these had SHM. Thirteen dogs with SHM did not have clinical signs; 2 dogs
with clinical signs did not have SHM. Observed morphologic abnormalities
included mild to marked cerebellar herniation and occipital dysplasia
(50/59), medullary kinking (39/59), cerebellar crowding and indentation
(55/59) and a dorsal compressive lesion at the level of the first and second
cervical vertebral junction (12/59). The dorsal compressive lesion lay
immediately cranial to the syrinx in several cases. Clinically affected dogs
were more likely to have SHM than unaffected dogs, and the ratio of the
caudal fossa volume to the total brain volume was significantly smaller in
affected dogs. In contrast, the presence of SHM was not significantly
associated with the relative size of the caudal fossa. No single abnormality
was predictive of the presence of SHM or of clinical status.
In conclusion, the incidence of caudal fossa and cervical spinal
abnormalities is high in CKCS showing clinical signs of Chiari malformation
and in unaffected CKCS. The pathogenesis of this disease appears
multifactorial rather than due to a single malformation. Follow up of these
cases over the next three years will enable us to establish whether these
abnormalities predict future development of clinical signs.
CHARACTERISTICS OF CEREBROSPINAL FLUID FLOW IN CAVALIER KING CHARLES
SPANIELS.
S Cerda-Gonzalez1,
NJ Olby1, TP Pease1,S McCullough2, N Massoud2, R Broadstone2 1North Carolina
State University, Raleigh, NC; 2IAMS Pet Imaging Center, Raleigh, NC.
Changes in CSF flow are thought to cause syringohydromyelia (SHM) associated
with Chiari-like malformations. Anatomical changes in the caudal fossa
restrict CSF passage and result in high velocity jets and turbulence,
causing syrinx formation. In humans, Phase Velocity Cine Magnetic Resonance
Imaging (PVC MRI) has become the standard technique for evaluating CSF flow
patterns and velocities in patients with Chiari malformations. PVC MRI has
been used to measure CSF flow in Cavalier King Charles Spaniels (CKCS) with
SHM1, but information available is limited. This study evaluated CSF flow in
a group of affected and unaffected CKCS.
Fifty nine CKCS and 5 control dogs were evaluated. Neurological deficits
were graded from 0-5. Routine T2-weighted and 3-dimensional T2-weighted
SPACE sagittal image sequences of the brain were obtained using a Siemens
1.5 T MRI to note the presence of caudal fossa abnormalities. PVC MRI was
used, along with Flow Quant Syngo, Argus Viewer and Argus Flow software, to
evaluate patterns and peak velocities of CSF flow just caudal to the foramen
and at the level of the C2-C3 intervertebral disc space. The effect of head
position on CSF flow was assessed. Flow characteristics were correlated with
clinical status and morphological abnormalities.
CSF flow measurements were successfully obtained from all dogs. Peak CSF
flow velocities in dogs were lower than those reported in humans and were
affected by head position. Positioning the head to simulate a normal
standing position increased CSF flow in the dorsal subarachnoid space (SAS)
and allowed more consistent measurement within this area. CSF flow was
obvious within syrinxes, and in some cases the peak velocity was highest in
the syrinx. Turbulent flow was mainly present in dogs with SHM and was
detected at the level of the foramen magnum, cervical spinal cord, and
within syrinxes. Preliminary statistical analysis did not reveal a
difference in peak CSF flow velocities between affected and normal CKCS in
the areas analyzed, although a trend towards higher peak CSF velocity was
noted within the dorsal SAS at the level of the foramen magnum in affected
dogs.
In conclusion, CSF flow patterns and velocities are affected by head
position in dogs. Turbulent flow occurs in dogs with SHM and can be found
within syrinxes. CSF flow velocity may be higher within the dorsal
subarachnoid space of affected dogs although additional studies are needed
to determine whether this finding is significant. A longitudinal study of
the long-term clinical outcome of the dogs imaged will be conducted. The
data will be reanalyzed in the light of these findings.
1. March PA, Abramson CJ, Smith M, et al. CSF flow abnormalities in caudal
occipital malformation syndrome (abstr.). J Vet Intern Med 2005;19:418.
|
