Congenital and Misc Defects of the Neurological System

What is hydrocephalus?

Accumulation of CSF within the ventricular system

How many ventricles do we have?

4

What divides the 3rd and 4th ventricles?

Mesencephalic aqueduct

What does the foramina of Luschka do?

Allows CSF to flow from the subarachnoid space of the 4th ventricle into the central canal

What produces CSF?

80% from the choroid plexus

Rest by ependymal cellsand interstitial fluid.

What does hydrocephalus cause?

Distention of the ventricular system and thus atrophy and necrosis of adjacent structures

What are the most common site for congenital obstruction causing hydrocephalus?

Mesencephalic aqueductand foramina of Monroe

What are the causes of hydrocephaly?

Congenital

Acquired

Compensatory

What can cause an acquired hydrocephaly?

CSF obstruction from tumors or masses

What breeds are more susceptible to congenital hydrocephaly?

Chihuahua or other min dog breeds

Can also be from In utero viral infections

What causes compensatory hydrocephaly?

Secondary to loss of brain tissue due to senescence, intracranial hemorrhage, FIP in cats

What is senescence?

Age-related atrophy

What can quadrigeminal arachnoid cysts cause?

Depends on size and severity of compression of brain stem, cerebellum, and aqueduct

What causes cholesterol granumlomas?

Unknown

What do cholesterol granulomas do?

Obstruct the interventricular foramina causing hydrocephalus

Why does Chiari malformation cause an acquired hydrocephalus?

Chiari malformation is developmental, but the hydrocephalus is acquired

What does Chiari-like malformation do?

Acquired hydrocephalus secondary to obstruction

Crowding and coning of the cerebellum

Syringomyelia

Describe hydrocephalus due to FIP

Due to a combination of compensatory change and acquired change due to partial occlusion of the ventricular system

What is hydranencephaly?

In utero loss of brain tissue with cavitation and replacement by fluid

What is the spectrum of hydranencephaly?

Complete loss of cerebral hemispheres to large cystic cavities

What usually causes hydranencephaly?

In utero neuroteratogenic viral infections

What are some viruses that can cause hydranencephaly?

Bluetongue, Akabane, Schmallenberg, Cache Valley, felin panleukvirus, and Zika virus.

What can cause cerebellar hypoplasia?

FPV, BVDV

Cerebellar hypoplasia

Cerebellar hypoplasia

Cerebellar hypoplasia

Occipital dysplasia

What is occipital dysplasia?

An abnormal finding where the occipital bone is thin, clinically inapparent

What is lissencephaly?

Smooth brain

What are the clinical signs of lissencephaly?

Typically young dogs that have seizures. Also, training difficulty, behavior problems, no menace response

Microencephaly

Microencephaly

What is cranium bifida?

Defect in the boney encasement of the skull

What is spina bifida?

Defect in the bony encasement of the spinal cord

What are meningoencephaloceles?

Meningoceles plus gray/white matter remnants

Black: Cranium bifidum

White: Meningocephalocele

Cranium bifidum

Meningoencephalocele

Spina bifida

What can cause congenital tremors in piglets?

Atypical porcine pestivirus caused by decreased absence of myelination of nerves. Shake constantly while awake and still while asleep

What can cause hairy shaker lamb?

In utero border disease virus infection that causes decreased or absence of myelination of nerves

Meningeal melanosis

Spinal dura osseous metaplasia

What is spinal dura osseous metaplasia?

A senescent change of the meninges that is uncommon

Cholesterol granuloma

T/F cholesterol granulomas are also called cholesteatomas?

False

What is a cholesterol granuloma?

A common finding in the choroid plexus of the lateral ventricle in horses. Incidental finding

What are cholesterol clefts?

Clear clefts of spaces seen on histology of cholesterol granulomas

Cholesterol clefts in a cholesterol granuloma