Atlanto-Axial Luxation and Syringohydromyelia Flashcards
where is the axial ligament?
dorsal arches of atlas and axis
what does the apical ligament do?
connects dens to occipital condyles
what are some congenital malformations for atlanto-axial luxation?
aplasia of dens
hypoplasia of dens
absence of ligaments
which breeds usually have atlanto-axial luxation?
toy poodle
chihuahua
yorkshire terrier
pomeranian
shih tzu
dachshund
what should you not do when taking radiographs of an atlanto-axial luxation?
do not flex the neck
what is the prognosis of atlanto-axial luxation with medical treatment?
50% do well
what is done in surgical treatment of atlanto-axial luxation?
definitive re-alignment and decompression
ventral fusion and permanent biological fixation
what are the difficulties with surgical treatment of atlanto-axial luxation?
small dogs: difficult screw placement
young dogs: soft and immature bone
damage of large blood vessels
spinal cord trauma
what are the long term complications of atlanto-axial luxation?
implant failure
infection
dysphagia
what primary spinal cord disorder can cause syringohydromyelia?
spinal arachnoid cysts
what primary brain disorders can cause syringohydromyelia?
brain tumors
CSF overproduction by plexus papilloma
dermoid or epidermoid cyst
what are the diagnostic MRI findings with chiari-like malformation?
rostral displacement of cerebellum
cerebellar coning
kinked medulla
syringohydromeylia
ventricular enlargement
attenuation of subarachnoid space at cervico-medullary junction
where does CSF flow normally during diastole?
rostral
which breed is especially predisposed to chiari-like malformation?
cavalier king charles spaniel: autosomal recessive trait, incomplete penetrance
what correlates best with clinical signs in chiari-like malformation and syringohydromyelia?
maximal diameter of syrinx
what does the transverse ligament of the atlas do?
holds dens against ventral arch of atlas
what do the paired alar ligaments do?
connect dens to ventral foramen magnum and occipital condyles
what trauma can lead to atlanto-axial luxation?
dens fracture
what is atlanto-axial luxation often triggered by?
minor trauma
when is the common onset of clinical signs with atlanto-axial luxation?
<12 months 70%
<24 months 80%
what are clinical signs with atlanto-axial luxation?
wide range
pain
ataxia
tetraparesis
tetraplegia
respiratory compromise
what is medical management like with atlanto-axial luxation?
not re-aligning C1 and C2
just avoid movement and spinal cord compression
secondary fibrosis might help to stabilize
what is done surgically for atlanto-axial luxation?
definitive re-alignment and decompression
ventral fusion and permanent biological fixation
what are some complications immediately post surgery for atlanto-axial luxation?
death
implant causing spinal cord trauma
laryngeal paralysis
hypoventilation due to spinal cord trauma
worsening neurological condition
aspiration pneumonia
what are some predictive factors for good outcome after surgery with atlanto-axial luxation?
mild neurological signs
young dog
short duration of clinical signs
bigger dog
what is the difference between hydromyelia and syrinx?
hydro: central canal and has epithelial lining
syrinx: cavity, no epithelium
what are the general causes of syringohydromyelia?
primary spinal cord disorders
primary brain disorders
chiari-like malformation
what is increased in chiari-like malformation?
cerebellar volume
CSF flow at foramen magnum
fibrous hypertrophy of meninges
what leads to syrinx formation with chiari-like malformation?
cyclic pressure wave into spinal cord
accumulation due to valve effect at foramen magnum
abnormal drainage of CSF from spinal cord into 4th ventricle
unequal spatial vascular pressure above and below stenosis causes nervous tissue damage
what is the age at onset of chiari-like malformation?
11 months- 13 years
mainly young
what brainstem signs can be seen with chiari-like malformation?
head tilt
facial nerve paralysis
tongue weakness
dysphagia
what can you use to lower CSF production in chiari-like malformation?
omeprazole
acetazolamide
