Research
Syringomyelia is
often referred to, in medical circles, as an enigmatic condition. This description is certainly fitting for a disorder that can develop as a result of several different underlying disease processes, which can
range in severity from mild to severe and which can cause a wide variety of symptoms and physical disabilities.
Until relatively recently the principal difficulty in managing Syringomyelia was making the diagnosis in the first place. Many victims had developed significant disabilities before their underlying disease was eventually discovered. Happily, since the advent of MR imaging, the diagnosis of Syringomyelia has been made much easier and most cases are now discovered at a relatively early stage. Challenges nevertheless remain in terms of understanding the natural history of Syringomyelia, if left untreated, what sort of operation is most appropriate when surgery is required and how we should deal with residual and recurrent symptoms, which often continue to trouble individuals, even after otherwise successful surgical treatment.
There are still a large number of research projects that need to be conducted, to improve our understanding of these matters and the disturbances of body physiology that underlie Syringomyelia. Such studies require specific funding, especially where we need to employ the services of a dedicated research fellow.
Chiari malformation and man’s
best friend - can dogs help us
understand this condition?
Chiari malformation, also known as hind
brain herniation, can occur in many toy
breed dogs in particular in the Cavalier
King Charles spaniels and Griffon Bruxellois.
The condition is characterized by overcrowding
of the back of the skull (posterior
fossa) due to a combination of a
proportionally small volume skull and
large brain. Like humans with chiari
malformation, dogs can suffer pain
especially if they develop
syringomyelia. This condition, where
fluid filled cavities develop in and
damage the spinal cord, is thought to
occur secondary to obstruction of
cerebrospinal fluid through the
foramen magnum. Dr Clare
Rusbridge, a Specialist in Veterinary
Neurology, has been investigating
and treating Canine Chiari malformation since
1997 when she met her first patient, a Cavalier
called Beau, who was presented because of
limb (arm!) weakness, poor balance and
sensitivity to touch. It soon became apparent
that hundreds of pets across the world were
affected by this disease, and with the help of
research assistant Penny Knowler, a database
of affected dogs and DNA was collected. Later
this Stone Lion Veterinary Hospital team was
joined by geneticists Drs Zoha Kibar and Guy
Rouleau. Dr Rouleau is the Director of the CHU
Sainte-Justine Research Center and a
Professor at the Department of Medicine of the
Université de Montréal. His work deals with
various neurological illnesses with a genetic
component, including amyotrophic lateral
sclerosis, cerebrovascular accidents, familial
aneurysms, cavernous hemangiomas, epilepsy,
spinocerebellar ataxia, spastic paraplegia,
autism, Tourette's syndrome, restless legs
syndrome, schizophrenia and bipolar disorders.
Dr Kibar was trained by Dr Rouleau and has a
particular interest in Chiari malformation and
spinal bifida.
Canine Chiari malformation (CM) is the only
known naturally-occurring animal model for the
condition in humans and represents a powerful
tool for deciphering its complex genetic etiology.
The team aims to identify the CM gene(s) in the
dog which will provide an entry point for
identifying equivalent genes involved in CMI in
humans. Understanding the genetics will allow
better understanding of the cause and what
treatment / management would be best.
So far we have conducted a scan of
the whole dog genome on normal
and CM affected Griffon Bruxellois
and other related breeds using the
CanineSNP20 BeadChip array. The
latter represents a multi-sample array
which contains over 22,000 highly
informative single nucleotide
polymorphism probes (SNPs)
developed across the whole dog
genome. Case-control association
studies showed significant
association of the CM disease with
two SNPs on chromosomes 2 and 14. Put more
simply so far the genetic studies have
suggested that the CM gene(s) might be on
chromosomes 2 and/or 14 but we have yet to
prove it definitely. Thanks to generous funding
by the Ann Conroy Trust we are able to take the
next step which is to investigate these two
chromosomal regions for true association to CM
by additional genetic studies in a larger group of
175 Griffon Bruxellois and other breeds with
CM. We are very grateful to the Ann Conroy
trust for enabling this next step in this long road
to identify the defective CM in the dog and
ultimately in humans. I hope that I can update on
the progress in the near future!
Dr Clare Rusbridge
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