PATHOLOGY - Central Nervous System Flashcards
List the cells within the central nervous system from more susceptible to injury to least susceptible to injury
Neurones
Oligodendrocytes
Astrocytes
Microglia
Ependymal cells
What are the eight defence mechanisms the central nervous system (CNS) has against disease?
Skin
Bone (cranium and vertebrae)
Meninges
Cerebrospinal fluid (CSF)
Blood brain barrier (BBB)
Blood-cerebrospinal fluid barrier
Local innate immune system
Circulating macrophages
What are gitter cells?
Gitter cells are enlarged phagocytic cells distended by lipids
What are the seven responses the central nervous system (CNS) can have to injury?
Necrosis
Inflammation
Vascular changes
Gliosis
Central chromatolysis
Demyelination
Wallerian degeneration
What is encephalomalacia?
Encephalomalacia is necrosis of the brain
What is gliosis?
Gliosis is the proliferation of neuroglial cells
What is the difference between primary and secondary demyelination?
Primary demyelination is caused by damage to oligodendrocytes whereas secondary demyelination is caused by damage to the axons
What is Wallerian degeneration?
Wallerian degeneration is anterograde degeneration due to damage to an axon independent of the neuronal cell body
Describe the process of Wallerian degeneration
There will be anterograde degeneration of the axon through the formation of axonal spheroids, distention of the myelin sheaths, necrosis of the axon and myelin sheaths and finally phagocytosis of the debris by macrophages
What happens following Wallerian degeneration in the peripheral nervous system?
Following Wallerian degeneration in the peripheral nervous system, there will be regeneration of the axons and re-myelination
What happens following Wallerian degeneration in the central nervous system?
Following Wallerian degeneration in the central nervous system, there will be astrogliosis and scar formation
What are the two vascular injuries that can occur in the central nervous system (CNS)?
Haemorrhage
Ischaemia
What are the four possible causes of haemorrhage in the central nervous system (CNS)?
Spontaneous
Trauma
Neoplasia
Idiopathic
What is one of the common causes of ischaemia in the central nervous system (CNS)?
Fibrocartilaginous embolism
What is meningitis?
Inflammation of the meninges
What is encephalitis?
Inflammation of the brain
What is myelitis?
Inflammation of the spinal cord
What is leukoencephalomyelitis?
Inflammation of the white matter in the brain and the spinal cord
What is polioencephalomyelitis?
Inflammation of the grey matter in the brain and the spinal cord
What does neurotropic mean?
Infectious agents which are preferential to neurones
What are the four portals of entry for infectious agents into the central nervous system?
Direct entry
Haematogenous
Leukocyte trafficking
Retrograde axonal transport
Give an example of bacteria which uses the haematogenous route to enter the central nervous system (CNS)
Histophilus somni
Which disease is caused by histophilus somni?
Thrombotic meningoencephalitis (TME) in cattle
(T/F) Histophilus somni is a commensal bacteria of the skin
FALSE. Histophilus somni is a commensal bacteria of the lungs
Identify this bacterial mediated brain lesion
Brain abscess
Which viruses have the ability to travel haematogenously to the central nervous system (CNS)?
Arboviruses
Feline infectious peritonitis (FIP)
Which type of inflammation is typically caused by arboviruses?
Polioencephalomyelitis
What is the other route of entry into the central nervous system (CNS) used by feline infectious peritonitis (FIP)?
Leukocyte trafficking
How can a feline infectious peritonitis (FIP) infection cause hydrocephalus?
Feline infectious peritonitis (FIP) virus is preferential to the ventricular system and can cause obstruction of cerebrospinal fluid (CSF) through this system, causing hydrocephalus
What type of inflammation would you expect to see on a histological sample of the central nervous system (CNS) infected with feline infectious peritonitis (FIP)?
Pyogranulomatous inflammation
Which two fungi use leukocyte trafficking to reach the central nervous system (CNS)?
Aspergillus
Cryptococcus neoforms (C. neoforms)
What would you see on gross examination of a central nervous system (CNS) with a fungal infection?
Yellow/brown foci
What type of inflammation would you expect to see on a histological sample of the central nervous system (CNS) with a fungal infection?
Pyogranulomatous inflammation
Which route of entry is used by canine distemper virus to enter the central nervous system (CNS)?
Leukocyte trafficking
Give an example of a bacteria which uses retrograde axonal transport to reach the central nervous system (CNS)?
Listeria monocytogenes
Why is listeriosis most common in ruminants?
Listeriosis is most common in ruminants as it arises through ingesting listeria monocytogenes which is found in poor quality silage
What would be the appearance of a histological sample of the central nervous system (CNS) that had been infected with listeria monocytogenes?
Microabscesses
Lymphoplasmacytic meningoencephalitis
What is lymphoplasmacytic meningoencephalitis ?
Inflammation of the meninges and the brain involving lymphocytes
What is one of the most neurotropic viruses seen in veterinary medicine?
Rabiesvirus
Which route of entry is used by the rabiesvirus to enter the central nervous system (CNS)?
Retrograde axonal transport
Describe briefly how the rabiesvirus uses retrograde axonal transport to enter the central nervous system (CNS)?
Rabiesvirus is transmitted through biting, so will initially infect muscle and neuromuscular junctions where the virus can use retrograde axonal transport to bypass the spinal cord and travel to the brain and salivary glands
Why does the rabiesvirus bypass infecting the spinal cord?
To maintain the movement of the host to increase transmission through biting other hosts
What type of inflammation would you expect to see on a histological sample of the brain infected with rabiesvirus?
Polioencephalitis
What are the two forms of immune-mediated meningoencephalitis?
Necrotising immune-mediated meningoencephalitis
Granulomatous immune-mediated meningoencephalitis
List three intrinsic causes of spinal cord trauma?
Intervertebral disc herniation
Spinal malformation
Pathological fracture
What is Hansen type 1 intervertebral disc herniation?
Protrusion of the nucleus pulposus through a tear in the annular fibrosis
What is Hansen type 2 intervertebral disc herniation?
Protrusion of the entire intervertebral disc
What is an explosive disc?
Traumatic rupture of the annular fibrosis associated with intense exercise
What region of the spine in dogs is most susceptible to clinically significant intervertebral disc disease?
Thoracolumbar region
Which vertebrae are affected by static wobblers in horses?
Static wobblers affects C5 - C7 vertebrae
At what age is static wobblers typically seen in horses?
1-4 years old
Which vertebrae are affected by dynamic wobblers in horses?
Dynamic wobblers affects C3 - C5 vertebrae
At what age is dynamic wobblers typically seen in horses?
8-18 months old
Which pattern of lesions would you see when there is a toxic or metabolic insult to the brain?
Symmetrical, bilateral lesions
What are the seven primary neoplasms of the central nervous system (CNS)?
Oligodendoglioma
Astrocytoma
Medulloblastoma
Choroid plexus tumor
Ependymoma
Haemangioma
Meningioma
