BRAIN - Malformation Flashcards
Which breed is predisposed for lobar holoprosencephaly? Alobar?
Lobar: miniature Schnauzer
Alobar: Burmese
What is the mechanism for holoprosencephaly?
Failure of initiation of development and bifurcation of forebrain / telencephalic vesicles
What is the single feline breed that has the higher proportion of crowding of the contents of the caudal fossa or cerebellar herniation through the foramen magnum, seen in sagittal brain MRI?
Persian
What are the clinical features associated with syringobulbia?
Small breed
Adult
Concurrent SHM
Neurological deficits cranial to SC (not explained by SHM)
Solitary medulla oblongata syringobulbia
What is the prevalence of olfactory recess dilation (without other abnomaly) in healthy cats?
11%
(Overall: 37% of cats)
Not associated with age, sex, breed, or with the presence of nasal disease.
The CSF flow is unidirectional: true or false?
False
CSF displayed a bidirectional flow pattern on 2D cardiac-gated phase-contrast MRI at each location.
Which of the following statements about supracollicular fluid accumulations in dogs is correct?
1/ Dogs are more likely to have clinical signs if cerebellum and occipital lobes are compressed
2/ Most frequent clinical signs is blindness
3/ Occipital lobe compression of at least 50% was associated with clinical signs
4/ can cause absent pupillary light reflexes
a
Causes of meningoencephalocoele in cat?
Griseofulvin during pregnancy
Burmese cat craniofacial malformation (ALX1)
What are the 2 main clinical signs associated with meningocele and meningoencephalocele in dogs? The 2 main MRI signs?
Signs: seizures and behavioral abnormalities
CSF rhinorrhoea and refractory seizures are indications for surgery.
MRI: porencephaly (100%), meningeal enhancement of the protruded tissue (77%)
In Persians, high grades of brachycephaly are associated with malformations of the calvarial and facial bones as well as dental malformations: true or false?
True
The endocranial volume was significantly lower in doll-face than peke-face Persians,
What breed has been postulated to have a predisposition for 4rth ventricle arachnoid diverticula?
Border Collie
French Bulldog
Pug
None
border collie
What is the percentage of English Bulldogs undergoing MRI with some degree of cerebral ventriculomegaly?
56%
76%
86%
96%
96%
Syringobulbia may evolve from bulbous to slit?
False, only from slit to bulbous
Parietal meningoencephalocele is the most common type in dogs: true or false?
False
No parietal MEC was described in dogs, only parietal MC.
Moreover, intranasal MEC are more common than parietal MC.
Which breeds are affected by sacral OCD?
German Shepherd dogs
Boxer
Rottweiler
Intracranial cysts may enlarge by
secreting cerebrospinal fluid (CSF) into the cyst
by way of an osmotic gradient depending on the cyst contents
by exfoliation of cyst lining or materials into the lumen.
Intracranial intra-arachnoid diverticula:
1. pathophysiology
2. maj breed
3. different forms
4. reason for signs at adult age
5. % incidental finding
6. associated signs
7. % compression associated with signs
8. associated with hydrocephaly?
- congenit: splitting in the arachnoid layer because of aberrant CSF flow or acquired: head injury, intracranial infection/inflammation, neoplasia, or hemorrhage
- Shih tzu
- associated with either the third or fourth ventricle, or may have a loculated appearance and be associated with both third and fourth ventricles.
- intracystic hemorrhage after trauma
- 50%
- seizures, cerebellar/vestibulocerebellar signs
- 14% of occip lobe
- no
epidermoid cyst :
1. localisation
2. origin
3. composition
4. other name
5. age presentation
6. associated complication
7. MRI appearence
- cerebellopontine/medullary angle, never extradur
- aberrant inclusion of nonneural ectoderm with the neural tube
- stratified squamous epithelium and contain keratinocytes, keratinaceous debris, and cholesterol
- cholesteatomas
- often incidental finding, middle age (slow growth)
- Chemical meningitis by the release of keratin/cholesterol breakdown products into the CSF
- hyper T2 and T1, incomplete FLAIR suppression, heterogenous
dermoid cyst:
1. more frequent than epidermoid cyst?
2. composition
3. localisation
4. MRI
- more infrequent
- contain epidermoid tissue and adnexa, which can include hair follicles, sebaceous, apocrine, and sweat glands
- caudal fossa on the midline
- same as epider + hypointensity (calcification, glandular tissue, sweat, or hair)
choroid plexus cyst:
1. localisation
2. origin
3. associated signs
4. MRI
- frequently bilateral, lateral ventricles
- “infolding” of the choroid epithelial; lipid accumulation within the choroid plexus
- rarely associated with CPCs unless obstructive hydrocephalus occurs
- T2 hyper T1 hypo, strong enhanc
CSF production
CSF is formed primarily by the choroid plexus in the lateral, third, and fourth ventricles
at a rate of 0.047 mL/min in dogs and 0.017 mL/min in cats.
+ secreted by the ependymal lining, the external pial-glial membrane on the surface
of the brain, and by the blood vessels in the pia-arachnoid
independent of CSF hydrostatic pressure, depends on osmotic pressure.
breeds with higher risk of hydrocephaly
most common malformation
Maltese, Yorkshire terrier, English bulldog, Chihuahua, Lhasa apso, Pomeranian,
toy poodle, cairn terrier, Boston terrier, pug dog, and Pekingese
stenotic mesencephalic aqueduct at the level of rostral colliculi
complications of ventriculoperitoneal shunting
infection
blockage by debrits, choroid plexus, brain parenchyma, kinking
overdrainage (ventricule collapse)
mechanical failure
overall improvement 72%, death 30%
relation ICP and optic nerve sheat diameter in dog
ICP is positively and non linearly associated with maximum ONSD
persistant fontanelle are associated with
small size
syringomyelia
CM/SM related signs
ventriculomegaly
CCJ overcrowding
where are osmorecept detecting hypernatremia/dehydratation
hypothalamus
lamina terminalis (organum vasculosum)
subfornical organ
median preoptic nucleus
Dandy-Walker malformation:
1. breed and mutation
2. enlarged caudal fossa ?
3. anatomic changes
- Eurasier, VLDLR (fully penetrant recessive) very low density lipoprotein recept, inflence cell migration
- two variant: enlarged or normal to small
- absence of caudal aspect to vermis and cerebellar hemis, retrocerebellar fluid accumul
name of malformation causing opening of cranium
cranioschisis
molecule detected in a dog with CSF fluid rhinirrhea
transferrin, glucose
most common clinical sign associated with
1. cranial meningocoele or meningoencephalocoele
2. porencephaly
- seizures (80%), propriocept def (60%)
- seizures (70-80%)
breeds predisposed + localisation to supracollic fluid accumul
shih-tzu
chihuahua
maltese
3rd ventri 50%
quadrigem cistern 13%
quad cist + 3rd vent 35%
maj form syringobulbia + associated signs
linear (can progress to bulbous)
always associated with syringomyelia
vestibular + carvical hyperesthesia
cat breed with forebrain comissural malformation
oriental-derived crossbred toyger cat, short ear phenotype
ventromegaly, ventricular cyst, midline and callosal malformation, ossif dura matter
risk factor associated with overshunting in ventroperit shunt
+ decrease ventricular size associated with improvement of which signs
incresae ventricular brain ratio
biventricular hydrocephalus
ataxia and obtundation
cause of vision loss in dog with hydrocephaly
optic radiation lesions
ADC/FA definition
ADC: numeric representation of isotropic water diffusivity, positive correl between ADC and age
FA: mesure anisotropic water diffusivity (directionality of water diffusion attribuable to surrounding tissue)
0= complete isotropic
1= complete anisotropic or highly directional dif
FA WM>GM
localisation associated with head tilting elicited by head turning
hypoplastic nodulus and ventral uvula
