Neoplasms and Malformations of the CNS Flashcards
Meningioma
Most common CNS tumor (most benign)- cats and dogs
OG in the meninges, close to dura
Grow by expansion compressing
Cats with meningioma
Develop tela choroidea of the 3rd ventricle
Astrocytoma
Affects brain or SC, common in dogs
Malignant (anaplasia)
Oligodendroglioma
Most common in brachy breeds
Well-demarcated or infiltrate parenchyma
Gray to pink/ red, soft hemorr., gelatinous
Ependymoma
OG from ependymal cells lining ventricles and central canal
Common in lateral ventricles
Benign or malignant (usually benign and expansile)
Medulloblastoma
From primitive cells in the roof of the 4th ventricle → external granular cell layer
Most common in cerebellum of puppies
Other names for adenoma of the pars intermedia
Pituitary pars intermedia dysfunction (PPID)/ Equine’s cushings
Adenoma of the pars intermedia
Secondary to loss of dopaminergic inhibition by the hypothalamus to the cells of the pars intermedia
What does pars intermedia produce?
Prio-opiomelanocortin (POMC) cleaves→ produce MSH, B endorphin and ACTH
CS associated with adenoma of the pars intermedia
Hypothalamus compression → hyperhidrosis, hirsutism, disrupted carb metabolism
Which tumors commonly metastasize to the brain?
Melanomas
Sarcomas more the carcinomas
Cholesterol granuloma (cholesteatoma)
Degenerative lesion of the choroid plexus, related to inflamm. changes of old horses
Cholesterol crystals found
Most often in lateral ventricles
Neural tube closure defects
Ancephaly, cranium bifidum and spina bifidum
Ancephaly
Absence of the brain
Primarily cerebral hemispheres (prosencephalic hypoplasia)
How is ancephaly developed?
Vit. A excess and cyclophosphamide in 1st trimester
Meningoencephalocele
Protrusion of brain and meninges through a defect in the cranium (doesn’t close properly)
Cranium bifida: dorsal midline cranial defect
How is meningoencephalocele developed?
Cats: griseofulvin in first week of gestation
Pigs and cats: hereditary
Spina bifida
Dorsal defect of the vertebral arches from failure of the neural tube and dorsal vertebral arches to close
Cd. spine usually affected
Spina Bifida Occulta
Lack of herniation of meninges and SC
Secondary: Meningocele of SC
Spina bifida is hereditary in which animal?
Autosomal dominant in Manx cats (Manx syndrome)
Amymelia
Absence of the SC, may occur with ancephaly
Holoprosencephaly
Failure of bilateral separation of the proencephalic cavity into 2 hemispheres
Cyclopia occurs when severe
Teratogenic clyopic effect
When veratrum californium consumed @ day 14 of gestation (ruminants)
Inhibits sonic hedgehog pathway
Hydrocephalus
↑ CSF in the ventricles of subarachnoid space of the brain
Congenital or acquired
Lateral and 3rd ventricles most severely affected
Noncommunicating hydrocephalus
Internal: fluid within the ventricular system (most common)
External: Fluid in the subarachnoid space
Communicating hydrocephalus
Excess fluid in both locations
Hydrocephalus ex vacuo
From destruction and loss of cerebral tissues around the lateral ventricles
In stroke or brain injury, senescent degeneration and Alzheimer’s
What causes hydrocephalus
↑ production of CSF
Obstruction of the normal CSF flow
Defective absorption of CSF
Congenital hydrocephalus
Pups, foals, calves and piglets
Associated with malformation of the cranium
Acquired hydrocephalus
Less severe
Usually no malformation in the cranium
What causes porencephaly/ hydranencephaly
Akabane dz, BVD, Bluetongue, border dz
________________ are the primary cell type in the brain affected by viruses
Neuroblasts
Syringomyelia
Tubular cavitation (syrinx) of the SC and separate from the central canal
Not lined by ependymal cells
Weimeraner, Cavalier King Charles Spaniels
CS of syrinomyelia
Symmetrical hopping gait
Unable to extend the hindlimbs
Hydromelia
Dilation of the central canal of the SC
Lined by ependymal cells
CSF accumulate in this cavity
Lissencephaly (agyria)
Absence of gyri and sulci
Arrest or defect in neuronal migration during embryogenesis
Which species is Lissencephaly found in?
Normal in rabbits, mice, rats, reptiles and birds
Hereditary in Lhasa Apso
Cerebellar Hypoplasia
Effects primarily on the rapidly dividing external germinal layer of the cerebellum
Inoculated in utero or shortly after birth
What pestiviruses cause cerebellar hypoplasia
BVDV in calves
Hog Cholera in fetal pigs
Border dz in lambs
What causes cerebellar hypoplasia in kittens?
Panleukopenia virus (parvo)
