Neurology Congenital Defects Flashcards
What is Hydrocephaly?
- Dilation of ventricles with secondary brain atrophy
What are the types of Hydrocephaly?
- Congenital
- Acquired
- Compensatory
What is congenital Hydrocephaly?
- Ventricular system malformation beginning in the fetus
- Can be the result of an In utero viral infections
- Breed: Chihuahua, miniature dog breeds
- Mesencephalic aqueduct is the most common site for congenital obstruction and development of hydrocephalus
What is acquired Hydrocephaly
- CSF obstruction later in life
- Causes: Tumors/Masses that obstruct CSF flow
What is Compensatory Hydrocephaly?
- Secondary to loss of brain tissue (hydrocephalus ex-vacuo)
- Causes:
- Senescence (age related atrophy)
- Intracranial hemorrhage/trauma
- FIP infection in cats
How does FIP infections in cats lead to hydrocephaly?
Periventricular inflammation ⇢ loss of brain tissue ⇢ compensatory expansion of the ventricular system
What is Hydranencephaly?
- In utero loss of brain tissue with cavitation & replacement by fluid
- Morphologic change can range from complete loss of cerebral hemispheres to large cystic cavities
- Causes:
-
In utero Neuroteratogenic viral infections
- Bluetongue, Akabane, Schmallenberg, Cache Valley, FeLV
-
In utero Neuroteratogenic viral infections
What are some causes of cerebellar hypoplasia?
-
In utero infections
- BVDV (Ox)
- FPV (Cat)
- CSF (Pigs)
What is occipital dysplasia?
- Congenital
- Occipital bone is thin - most often clinically inapparent
- Considered an abnormal finding
What is going on in this picture and what is a common cause?
What is going on in this picture and what is a common cause?
- Microencephaly
- Cause: In utero viral infection (BVDV, Bluetongue, Cache Valley…)
What is Lissencephaly?
- lack of gyri and sulci of the brain
- “smooth brain”
- Normal in Avian species !
What are the clinical signs of Lissencephaly?
- Typically young dogs
- Most have seizures
- difficulty training
- Behavioral abnormalities
- absence of menace response
- Possible visual impairment
What is a ‘bifida’/’bifidum’
- defect in the boney encasement of the CNS
- Spina bifida - defect affects the spinal cord
- cranium bifidum - defect affects the skull
What is a meningeoceles?
- Outpouchings of fluid cavities lined by meninges
- Fluid inside is CSF
What is a Meningoencephalocele?
- Meningocele + grey/white matter remnants
- need histo to confirm
What does hypomyelination look like at necropsy?
- Brain has very little white matter
What is going on in this picture?
- meningeal melanosis
- NORMAL in dark furred cows
What is going on in this picture?
- Spinal dura osseous metaplasia
- a senescent change
- Uncommon finding in older dogs
What is a cholesterol granuloma?
- Commonly arise whin the choroid plexus of lateral ventricles in horses
- Lesion is typically an incidental finding
- NOT the same as a cholesteatoma
- Represent collections of macrophages mixed with lymphocytes and plasma cells (granulomatous inflammation) along with pigment (hemosiderin, hematoidin) and abundant cholesterol clefts (clear clefts or spaces seen throughout this lesion
What is the pathogenesis of Cholesterol granulomas?
- Unknown
- Estimated 15-20% of older horses
How does a cholesterol granuloma cause hydrocephalus?
- Large cholesterol granulomas ⇢ Obstruction of the interventricular foramina ⇢ hydrocephalus
