Anomalous/Developmental encephalopathies

Question 1

What is hydrocephalus?

Answer 1

A condition characterized by the accumulation of cerebrospinal fluid (CSF) in the ventricles of the brain

Question 2

What condition is associated with stenosis of the mesencephalic aqueduct?

Answer 2

Congenital hydrocephalus

Also fusion of the rostral colliculi

Question 3

What is the normal height of lateral ventricles measured at the level of the pituitary gland?

Answer 3

0-14% of the dorsoventral height of the brain

Question 4

What percentage indicates moderate ventricular enlargement?

Answer 4

15-25%

Question 5

What percentage indicates severe ventricular enlargement?

Answer 5

> 25%

Question 6

True or False: Ventriculomegaly may always be clinically significant.

Answer 6

False

Question 7

Which dog breeds are reported to have larger ventricular sizes?

Answer 7

English bulldogs and Yorkshire terriers

Question 8

What are some MRI findings associated with hydrocephalus?

Answer 8

• Ventricular enlargement
• Thinning of the cerebral cortices
• Absence of septum pellucidum
• Dilation of olfactory recesses
• Atrophy of the interthalamic adhesion
• Periventricular edema
• Parenchymal hemorrhage

Question 9

What is the ventricle/brain index that indicates clinically relevant hydrocephalus?

Answer 9

> 0.6 on dorsal plane images

Question 10

What condition is characterized by the protrusion of meninges +/- brain tissue through a calvarial defect?

Answer 10

Meningocele and meningoencephalocele

Question 11

What is cranioschisis?

Answer 11

A congenital defect where there is an incomplete closure of the skull

Question 12

What are some MRI findings of cranial defects?

Answer 12

• Calvarial defect with herniation of meninges
• Cribriform plate defect with herniation of meninges
• Concurrent facial/calvarial deformity

Question 13

What is porencephaly?

Answer 13

A congenital condition involving cystic cavities in the brain

Question 14

What is holoprosencephaly?

Answer 14

Failure of the forebrain to sufficiently divide into two hemispheres

Question 15

What are the three types of holoprosencephaly?

Answer 15

• Alobar
• Semilobar
• Lobar

Question 16

What breed is associated with lissencephaly?

Answer 16

Lhasa apso

Question 17

What MRI findings are associated with lissencephaly?

Answer 17

• Smooth cerebral surface
• Thick neocortex with absence of corona radiata

Question 18

What is polymicrogyria?

Answer 18

A condition characterized by small, disorganized gyri in the dorsal and lateral cerebral cortex

Question 19

What are the MRI findings for polymicrogyria?

Answer 19

• Increased numbers of disorganized shallow gyri in the occipital lobes
• Possible ventriculomegaly
• Hydrocephalus
• Thinning of the subcortical white matter

Question 20

What is Dyke-Davidoff-Masson-like syndrome?

Answer 20

A condition characterized by hypoplasia or partial absence of a cerebral hemisphere

Question 21

What are common MRI findings for Dandy-Walker malformation complex?

Answer 21

• Hypoplasia/agenesis of the cerebellar vermis
• Cyst-like dilation of the fourth ventricle
• Enlargement of the caudal fossa

Question 22

What breed is commonly associated with Chiari-like malformation?

Answer 22

Cavalier King Charles Spaniel

Question 23

What are the MRI features of Chiari-like malformation?

Answer 23

• Crowding of the caudal fossa
• Indentation of the caudal margin of the cerebellum
• Herniation of the cerebellar vermis

Question 24

Fill in the blank: Aplasia refers to the _______ of cerebellar tissue.

Answer 24

complete absence

Question 25

Fill in the blank: Hypoplasia refers to the _______ of cerebellar tissue.

Answer 25

uniform paucity

Question 26

What are some potential concurrent abnormalities in congenital cerebellar malformations?

Answer 26

* Lissencephaly * Hydrancephaly