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− | [[Central Nervous System Inflammation Overview]]
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− | [[Central Nervous System Infectious Inflammation]]
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− | ==Routes of Entry==
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− | * CNS inflammation is usually the result of infection.
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− | ** This may be caused by:
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− | *** Bacteria
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− | *** Fungi
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− | *** Protozoa
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− | *** Viruses
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− | * Organisms must first enter the CNS in order to establish infection.
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− | ** There are several routes of entry that allow this:
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− | **# '''Haematogenous entry'''
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− | **#* This is the most common route.
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− | **# '''Entry via the peripheral nerves'''
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− | **#* Organisms track within the axoplasm of axons.
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− | **#* For example, ''Listeria monocytogenes''.
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− | **# '''Penetrating trauma'''
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− | **#* For example, dehorning wounds, skull fracture or tail docking.
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− | **# '''Direct spread of infection'''
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− | **#* From the nasal cavity, middle ear or paranasal sinuses.
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− | ==Localisation of Infectious Organisms==
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− | * After entry, organisms may establish in one or more of four main areas:
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− | *# '''Epidural space'''
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− | *#* Infection tends to manifest as abscess formation.
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− | *# '''Subdural space'''
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− | *#* Manifests as abscess formation.
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− | *#* Fairly uncommon.
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− | *# '''Leptomeninges'''
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− | *#* Causes leptomeningitis, which may be:
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− | *#*# Suppurative
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− | *#*#* The most common form.
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− | *#*#* Neutrophils are the predominant cell type.
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− | *#*#* Caused by bacteria
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− | *#*#** E.g. ''E. coli'' and ''Streptococcus''
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− | *#*#* There are often no gross lesions, but the brain may appear swollen and the meninges opaque.
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− | *#*#* Usually results in death.
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− | *#*# Eosinophilic meningoencephalitis
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− | *#*#* The classic example of this is porcine salt poisoning, when water has been restricted and the suddenly replenished.
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− | *#*#* Perivascular eosinophilic cuffing is seen in the cerebrum and meninges.
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− | *#*# Lymphocytic
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− | *#*#* Usually of viral origin.
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− | *#*# Granulomatous
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− | *#*#* Caused by fungal diseases and Mycobacteriosis.
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− | *# '''CNS parenchyma'''
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− | ==Bacterial Infections==
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− | [[Image:pneumococcalmeningitis.jpg|thumb|right|150px|Pneumococcal meningitis. Image courtesy of BioMed Archive]]
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− | * Bacterial infections typically result in abscesses.
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− | ** These may be single or multiple depending on the route of entry, and vary in size.
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− | ** They contain a central, liquefied cavity.
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− | * There are differences between cerebral abscesses and those occuring elsewhere.
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− | ** Encapsulation is slow.
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− | *** This is due to a lack of fibroblasts.
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− | *** There is therefore less collagen in the capsule.
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− | ** Astrocytic glial fibers are not as strong as collagen
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− | * Other organisms may cause similar infections:
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− | ** Rickettsial organisms
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− | *** E.g. ''Ehrlichia''
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− | ** Spirochates
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− | *** E.g. Leptospirosis
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− | ==Viral Infections==
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− | * Viral infections tend to reach the CNS by haematogenous spread and via peripheral nerves.
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− | * There are three hallmark lesions of CNS viral infections:
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− | *# Neuronal necrosis
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− | *# Gliosis
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− | *# Vascular changes
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− | * Several types of virus may cause inflammation in the CNS. [[Image:negribodies.jpg|thumb|right|150px|Negri bodies, as seen in rabies. Image courtesy of BioMed Archive]]
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− | ** '''Neurotropic''', e.g.
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− | *** Rabies (rhabdovirus)
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− | *** Aujesky’s disease (herpesvirus)
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− | *** Visna (ovine lentivirus)
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− | ** '''Endotheliotropic''', e.g.
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− | *** Infectious canine hepatitis (canine adenovirus)
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− | *** Classical swine fever (pestivirus)
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− | *** Equine herpesvirus type 1 (herpes)
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− | ** '''Pantropic'''
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− | *** Infectious canine distemper (morbillivirus)
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− | *** Infectious bovine rhinotracheitis (bovine herpesvirus type 1)
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− | * Other examples of viruses affecting the CNS:
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− | ** Distemper
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− | ** Parvovirus
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− | ** Parainfluenza
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− | ** Herpes
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− | ** FIP
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− | ** FIV
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− | ** FeLV
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− | ** Pseudorabies
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− | ** Rabies
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− | ==[[Prion Disease]]==
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− | [[Category:Central Nervous System - Inflammatory Pathology]]
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− | ==[[:Category:CNS Non-Infectious Inflammatory Diseases]]==
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− | ===[[Granulomatous Meningoencephalitis]]===
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− | (GME)
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− | * An [[CNS Idiopathic Conditions - Pathology|idiopathic CNS conditon]]
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− | * May occur as:
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− | ** A disseminated disease
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− | ** A focal mass lesion
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− | ** A primary occular disease
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− | * Brainstem signs are common, although the forebrain is primarily affected.
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− | * May be incorrectly diagnosed as lymphoma.
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− | * Changes are apparent in the CSF.
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− | ** There is usually a mononucloear pleocytosis.
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− | ** Sometimes only protein is elveated.
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− | * Diffuse inflammatory changes or a mass lesion will be seen by advanced imaging.
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− | ** However, biopsy is required for a definative diagnosis.
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− | * Life span is between 6 months and 1 year from diagnosis.
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− | ====Treatment====
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− | * Immunosuppression:
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− | ** Corticosteroids
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− | ** Azathioprine
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− | ** Cycophosphamide
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− | * Surgery
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− | ** This is only appropriate if there is a focal mass.
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− | * Radiation therapy.
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− | [[Necrotising Meningoencephalitis]]
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− | [[:Category:CNS Non-Infectious Inflammatory Diseases]]
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− | ===Pug Encephalitis===
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− | * A [[CNS Idiopathic Conditions - Pathology|CNS idiopathic condition]]
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− | * Affects pugs.
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− | ** Similar conditions are seen in yorkshire and maltese terriers.
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− | * Officially known as necrotising meningoencephalitis of small dogs.
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− | * Characterised by histological forebrain inflammation and necrosis.
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− | * The disease is uniformly fatal.
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− | ** Corticosterid treatment has no effect.
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− | [:Category:CNS Non-Infectious Inflammatory Diseases]]
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