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74 Cards in this Set
- Front
- Back
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Parts of the brain-
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- Forebrain-
- Telencephalon- inc. cerebrum- - Sensory, behaviour, motor control, mental status - Diencephalon- Inc. thalamus + hypothalamus - Sens. + motor funct., hunger + thirst, temp., pituitary -Midbrain- - Mesencephalon- mesencephalic aqueduct - Vision and auditory responses, motor funct. -Hindbrain - Metencephalon- Cerebellum and pons - Movement, posture, balance, coordination - Myelencephalon- medulla -Autonomic resp. and CV control - Spinal cord- Reflexes |
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Damage to the brain-
Cerebrum Cerebellum Brainstem Spinal cord |
- Cerebrum-
- Poor learning/ Agression/ Pacing/ circling/ Seizures/ Visual disturbances - Cerebellum- - Ataxia/ Dysmetria/ Head tilt/ Opisthotonus - Brainstem- - Ataxia/ Loss of consciousness/ Resp. failure - Spinal cord- - PNS + CNS effects/ Loss of reflexes |
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Cells of the nervous system-
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- Neurones- Made up of dendrite, axon, cell body
- High metab. rate= high req.// damged by xs trans. - Glia- - Astrocytes, - Oligodenrocytes, -Microglia - Ependymal cells (ciliated cub./colum. cells)- Produce, absorb and move CSF, have a role in detox./ phag. |
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Glial Cells-
Functions- |
- Astrocytes-
- Regulate fluid and electorlyte balance- Part of BBB - Reg. CNS envir.- remove toxins, excess transmitters - Struct. support- insulation of synapse, glia limitans - Repair- astrogliosis, prod. GF - Inflam- Prod immunomod. cytokine/ chemokine - Oligodendrocytes- - Reg. of perineural environ. - Myelination - Microglia- "Gitter cells"- MP like - CNS devel.- phag. cells during remodelling of CNS - Immune resp., inflam., degeneration, phag. |
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Peripheral nervous system cells-
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- Endoneural fibroblasts- supporting cell +/- phag. funct.
- Perineurial cell- Fibroblasts within collagen around nn - Epineurial cell- - Fibroblasts - Adipocytes - Mast cells |
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Terminology-
Enceph- Myel- Polio- Leuko- Radiculo- -Malacia |
- Encephal- = Brain
- Myel- = Spinal cord + bone marrow - Polio- = Grey matter - Leuko- = White matter - Radiculo- = Affecting the nerve root - -malacia = Degeneration/ necrosis |
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Meninges-
Descirbe |
- Dura Mater- thick, dense, fibrous
- Arachnoid Mater- arach. space contains BV and nn - Pia Mater- Adherent to brain + aa, contains fibroblasts - Leptomeninges= Arachnoid + Pia mater |
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CNS Defence
Layers- (x9) |
- Skin
- Sub cutaneous tiss - Bones of the calvarium + vertebra - Meninges - CSF - Glia limitans - BBB- endo. cells + BM and astrocyte foot processes - Blood-CSF barrier- ependymal choroid plex. tight junct. - Immune cells- resident microglia + blood MPs |
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Portals of entry for dz
(x4) |
- Haematogenous
- Direct extension from adjacent structures - Leukocyte trafficking- eg. retrovirus (FeLV) - Axonal transport- eg. rabies, listeria |
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Chromatolysis-
Descibe- Causes- Effects- |
- Affects cell body
- Degenerative (.: reversible) change affecting cell body - Breakdown of cytoplasmic Nissl substance (basophilic) - Micro- Swollen, rounded cell body, periph. nuclei - Causes- - Dysautonomia (H,C,D) - Swayback (Cu def. in lambs) - Equine motor neurone dz - Some viral infections - Resp. to axonal injury - Can induce glial response- Inc Microglia + astrocytes |
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Wallerian Degeneration
Describe- Sequence- Regeneration- |
- Axonal injury
- Swelling + fragment. of axon distal to injury - Swellings= spheroids // fragments= ellipsoids - Collape and degen. of myelin tube- 2o demyelination - Digest. and phag. of axonal and myelin debris - PNS- 3mo // CNS- 1 year - PNS only - Regen. of axon may occur if intact endoneurial tube - Schwann cells + axonal sprouts |
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Ischaemic cell change/ neuronal necrosis
Describe- Micro- Effects- Causes- |
- Neuronal cell injury---> Inc. IC Ca conc---> Inc neurotrans. released---> excitotoxicity---> Cell death
- Micro- Eosino., shrunken, angular cells with pyknotic nuclei. Loss of Nissl substance (chromatolysis) - Neuronophagia- phag. of cellular debris - Causes- Circ. dz/ metabolic/ toxins/ nutritional/ inflam/ infect/ injury |
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Other pathologies-
(x6) |
- Apoptosis- shrunken and eosinophillic
- Vacuolation- eg. BSE or lysosomal storage dz - Lipofuscin accum.- aging change- yellow/brown - Inclusion bodies- viral dz- eg. rabies - Atrophy- as a result of injury/ aging/ neuropathies - Axonal swelling + spheroids- from injury- eg. Wal Deg. -(Spheroids= neurofilament, tubules = organelle accum.) |
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Glial response to injury
Astrocyte response |
- Gliosis- cell hypertrophy/ plasia/ both
- Usually in assoc c milder protracted injury Astrocyte response- Depends on severity + chronicity 1) Degeneration and necrosis 2) Hypertrophy and hyperplasia - Formation of astrogliosis- longer, more complex processes - Astrocytosis- Astrocyte prolif.- Usually limited- more pronounced with abscesses and encapsulation. - Mesh from astrocytosis + astrogliosis---> glial scar - Gemistocytes- plump astrocytes c Inc cytoplam |
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Oligodendrocyte response
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1) Satellitosis- swelling and hypertrophy of perineural oligodenrocytes around injured neurones
2) Degen./ loss of oligo.---> full/partial demyel. - (1o demyelination- foamy changes) - eg. Distemper, toxins, ischaemia |
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Microglial response
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1) Hyperplasia/trophy
- Glial nodules- accumulations of microglia 2) Phag. of cellular debris and agents 3) MP recruited from blood - Large MP c foamy cytoplasm= Gitter cell (GC) |
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Infaction-
Sequence- |
1) Oedema and haemorrhage- red, swollen, tissue.
2) Infiltration of MP (GC) and endothelial prolif. 3) 5-7 Days- ++GC, astrocytes prolif. around margin 4) 1-2 weeks- Liquefact. necrosis + Phag. + astrogliosis 5) Weeks- months- Debris cleared--->Dec. GC - Inc astroglial fibre density + strength---> capsule - Glial scar formation |
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Brain swelling + cerebral oedema
Causes- |
1) Increased blood vol.---> congestive brain swelling
2) Extracellular oedema a) Vasogenic- breakdown of BBB from vasc injury - 2o to inflam, nec., trauma., neoplasia - Predominantly in white matter regions b) Interstitial (hydrostatic)- Inc. ventric. press - Assoc c hydrocephalus - Causes white matter degen. c) Hypo-osmotic- water intox. + dec. plasma osmolarity - eg. Salt poisening 3) Cytotoxic Oedema- cell injury disrupts homeostasis ---> IC fluid accum. ( like hydropic change) - Eg. toxins, ischaemia/hypoxia, metab. disorder |
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Consequences of cerebral oedema-
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- Flattening of gyri and sulci
- Flattening of brainstem---> haem. - Displacement/ herniation of brain structures ---> haem./ ischaemia |
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Inflam in the CNS
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1) Perivascular cuffing- May extend into subarachnoid space and ventricules
2) Gliosis- Inc. prominance of glial cells 3) Neuronal satellitosis and neurophagia - Cell types- - Bacterial infect- Neutrophils ++, some MP, lympho, PC - Fungal/ some bacterial- MP - Viral/ protozoa- Lympho/ PC/ MP - Parasites- Eosinophils |
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Malformations in CNS
Hydrocephaly Types- Causes- |
- Obstructive
- Dev./congen.- Obstruct. CSF flow/ prob. c absorpt. - Domed skull, thin calvaria, expans. of V. - Degen. + loss of white matter - Ischaemia, haemorrhage - Acquired- obstruction within ventricle - Causes- space occupying lesion, inflam., occipital bone hypoplasia. - Compensatory- loss of parenchyma---> comp Inc CSF - Dev./congen.- in utero virus- a/hypoplasia/destruct. - Acquired- loss of tissue from dz process- eg. ischaem. - Hydranencephaly- large CSF cavities from white matter destruction - Porencephaly- Smaller cystic spaces in cerebral hemisphere |
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Cerebellar malformations
1o 2o- Examples |
- 1o- Idiopathic
- May be concurrent c malformation of other areas - Aplasia/ hypoplasia/ dysplasia - Dandy- Walker syndrome - 2o- Viral cause - Fe panleukopaenia/ parvo virus - BVDV - Granular layer affected either in utero or post natally |
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Neural tube defects-
Meningocoele and meningoencephalocoele- Prosencephalic hypoplasia |
- Protrusion of meninges +/- brain tissue through defects in calvarium or vertebrae (cranium/spina bifida)
- Cerebral aplasia |
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Lissencephaly-
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- Smooth brain surface- lack of gyri and sulci
- Caused by defective neuronal migration (NB. gyri/sulci not present in many rodents normally) |
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Myelodysplasias-
Define- Effects- Types- (x5) |
- Spinal cord malformations-
- "bunny hop" gait/ incontinence/ hind limb paralysis 1) Duplication of spinal cord 2) Segmented hypoplasia or aplasia 3) Hydromyelia- dilation of spinal central canal 4) Syringomyelia- fluid filled cystic cavitation (syrinx) of spinal cord parenchyma - Can compress subarachnoid space---> turbulence---> expansion of space (venturae effect) - Can be congenital or acquired - May see in assoc c occipital bone malformations 5) Syringohydromyelia- both above |
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Dys/hypomyelination
Define- Effects- Cause- Examples |
1) Dysmyelination- defective myelin
2) Hypomyelination- lack of myelin dev. - Often cause tremors - Caused by genetic mutations or viral (pestivirus) infect -Eg. Border dz/ hypomyelinosis congenita- Hairy shakers -Eg. BVDV in cattle |
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Other degenerative dz of CNS
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- Cerebellar abiotrophy- lack substances req. for growth
- 1o cerebellar degen. - Slowly progressive---> loss of funct. - Degenerative leukomyelopathies - Genetic vs sporadically acquired - Bilateral symmetrical degen of axons + 2o myelin loss - Neuraxonal dystrophy- rare - Spheroids found in nuclei ---> mm weakness and atrophy |
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Motor neurone dzs
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- 1o degen. of neurones in spinal cord, ventral GM + brainstem
- Genetic in dogs - Vit E deficiency in horses - Equine motor neurone dz---> postural weakness - "walk better than they stand" |
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Age reated degenerative myelopathy
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- Poorly understood- occurs in dogs
- Bilateral symmetry- See wallerian degeneration and digestion chambers - Ataxia and weakness on hind limbs |
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Hypoxic-ischaemic injury
Locations- Effects- E.g. |
- Most sensitive- Cerebral cortex/ cerebellar purkinje cells/ hippocampus
- Effects- Blind, recumbant, stiff/rigid posture (dystonia), seizures - Laminar cerebrocortical necrosis - E.g. Post anaesthetic cerebral necrosis - Repurfusion injuries- - Initial energy fail.---> Inc. IC Na+Ca---> cell swelling---> membr. depol. + glutamine release. - Repurfusion ---> Inc. Glut. + ROS+ Inflam. cytokines ---> excitotoxicity |
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Peripartum asphyxia syndrome-
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- Aka- Neonatal maladjustment syndrome
---> "Barker/ Dummy foals" - From disrupted blood supply to umbilical art. - Causes laminar cortical necrosis + oedema + GC infilt. - Effects- Blind, fail to suckle, "barking", seizures |
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Cerebrovascular accidents
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- Stoke- Idiopathic, acute cerebral haem.
- Focal haem. c acute necrosis---> MP infilt + astrocytosis - Seizures, blindness, circling |
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Further circulatory disturbances-
Feline ischaemic encephalopathy Fibrocartilaginous embolism |
- FIE
- From cerebral ischaemia - Caused by parasites? - FCE- ischaemic myelopathy- Dogs - From herniation/ degeneration of disk into circ systm - Localised spinal cord- haem/ necrosis/ degeneration ---> Paralysis - Haemorrhage - Inj., vasculitis, tox., infect., inflam., neoplas., coagulop. - Haemorrhagic myelomalacia - From trauma to spinal cord ---> Dissecting haem. in grey matter ---> Necrosis in spinal cord - May affect large area ---> Ascending/ descending paralysis |
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Thiamine deficiency-
Effects- Causes- Clinical signs- |
- Thiamine (Vit B1)- req for Pyruvate---> Acetyl CoA
- Def.---> Dec. energy---> necrosis - Causes polioencephalomalacia and cerebrocortical necrosis (Grey matter) - May see laminar separation, cerebral atrophy, autofluorescence - Seen in ruminants- - Due to thiaminase bacteria, thiaminase in plants, decreased absorpt. from diet. - Signs- Depression, ataxia, blindness, death |
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Copper deficiency
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- Swayback (congenital) + enzootic ataxia (delayed 6m)
- Cerebral + brainstem/spinal lesions- Wallarian degen. - Cerebral lesions grossly visable in only 50% cases - Brainstem/S.C lesions not visable at all - Bilaterally symmetrical - White matter has cystic cavitations - Balooned myelin sheath - May be recumbant, flaccid limbs, ataxic, blind |
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Vitamin A deficiency
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- Cattle and pigs
- Blind c unresponsive pupils - Loss of rod funct. - Compression and degen. of optic nerves - Fibrosis affects CSF absorpt.--->Inc. press. |
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Vit E def.
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- Equine degenerative myeloencephalopathy
- Young horses <2 y.o - Pelvic limb ataxia + spasticity - Axonopathy c axonal degen. - Grey and white matter affected - Grey and white matter affected. |
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Hepatic encephalopathy
Describe- Gross- Micro- |
- Accum of neurotoxic products- eg. NH3 (eg. from PSS)
---> Altered- Balance of neurotrans/ BBB perm. --->Vasogenic oedema - No obv. gross changes to brain but altered CNS funct. - Micro- Polymicrocavitation of white matter due to oedema. - Effects- Depression, behavioural change, ataxia, head press, hypersalivation (Nb Similar encephalopathy can also occur due to renal failure---> Uraemia) |
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Abnormal metab. pathways
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- Dec AA metab. (maple syrup urine dz)
- Defective urea metab. - Defective mito. enzymes (mitochondrial encephalop.) ---> Produce symmetrical dz c variable signs- depends on part of the brain. |
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Lysosomal storage dz
Describe- Cause- Presentation- Effects- Examples- |
- Accum of undigested substrates (eg. CHO/ lipids)
---> Cell swelling ---> death - Cause- - Genetic defect - Enzyme/ substrate transport fail. - Uptake of unmetabolizable products - May occur in any tissue - Gross- atrophy of brain, loss of myelin, affects cerebellum and cerebrum - Micro- - Neurones c foamy vacuolated cytoplasm - MP c accum. material inside - Effects- Progressive neurological derrangements, ataxia, tremors, behav. changes, seizures, blindness - Examples- - GM1/ GM2 gangliosidosis - Alpha/Beta mannosidosis |
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Toxic dzs
Effects of toxins (x4) |
- Effects of toxins
- Ion channel/ R inhibition - Ca mediated effects - Altered neurotrans. release/degred./ uptake - BBB disruption |
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Lead poisening-
Describe- Gross- Micro- Presentation- |
- Lead poisening
- Horses- Acute // Sheep and cows- chronic - Toxic to neurones and astrocytes + interferes c neurotransmitter funct. - Gross- normally absent - Micro- Laminar nec. of cerebrocortical gyri - May be absent if peracute - Clinical signs- Dead/ depression/ diarrh/ ataxic/ blind - Horses---> neuropathy---> laryngeal paralysis |
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Tetanus-
Cause- Effects- Spp- |
- C. tetani spores in wounds---> Germinate---> prod toxin
- Presynaptic- Blocks release of GABA + glycine (inhib.) - Effects- -Pistastonis (spastic rigidity) - Horses most common - Blocks facial mm in dog |
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Focal symmetrical encephalomalacia
Aka- Cause- Effects- Spp- |
- Aka Pulpy kidney dz
- Clostridium perfringens (D) - Breakdown of BBB---> vasogenic oedema---> cavitation---> Malacia -Lambs 2-8 w.o |
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Salt poisening
Cause- Effects- Spp- |
- Dehydration/hypernat.---> Readjust.---> large vol. water uptaken---> Oedema + laminar cerebrocortical necrosis
- Effects- - Eosinophil. inflam - Cerebral oedema - Neuronal degen + necrosis - Presentation - Head press, ataxia, blindness, circling, paddling, seizures, death. |
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Empyema/ Epidural abscess
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- Bacterial infect.- eg. A. pyogenes, F. necro., Strep, Staph
---> Suppurative inflam (+++Neutrophils) - Affects younger animals - Causes- - Haematogenous/ direct extension/ trauma/ FB - Clinical signs vary c severity- pain ---> paralysis |
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Purulent Leptomeningitis
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- Brain swelling
- Extensive purulent infiltrate (esp. meninges) - Usually haematogenous spread - Bacteraemia + suppuartive/fibrinopurulent meningitis - Gross- basal meninges show faint opaqueness + hyperaemia, subarach. space filled with pus. - Micro- Neutrophils +++ - Effects- - Swollen brain---> cerebellar herniation - Choroiditis- cloudy CSF + purulent sediment - Death |
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Brain abscess
Describe- Sources- Gross- Micro- Effects- NB (- Abscess in spinal cord are rare) |
- Gitter cells, astrocytes, fibroblasts---> wall off abscess
- May seed to other areas - Sources- - Haematog.- septic emboli/ bacteraemia - Local extension- cribiform plate, inner ear, sinuses - Micro - Central neutr. and debris, surround. by GC - Vascular cuffing - Tiss. oedema, myelin degen., swollen astrocytes - Effects - Space occupying lesion---> Cr. nn. deficits - Cerebral signs- depression, seizures, vision, dysmetria, opisthotonus - Pit.-hypo related dz. - Satellite abscesses- in white matter - Pyencephaly- |
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Listerial encephalitus
Cause- Describe- Effects- Gross- Micro- |
Cause- Listeria monocytogenes
- Oral mucosa---> Cr nn V---> brain - Lesions mainly in brainstem + cervical spine - Effects- Head tilt, ear/ eye droop (facial paralysis), depression, confusion, death - Gross- Largely normal, some meningeal opacity - Micro- Microabscess form., perivasc. cuffing, oedema, non-suppurative meningitis |
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Histophilus somnus
Effects- Gross- Progression- |
- Septicaemia, vasculitis c multisystemic inflam, haem, thrombosis, necrosis
- Gross- red/brown scattered foci - May develop purulent leptomeningitis |
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Viral inflam in CNS
Types- General changes- (x7) |
- Types-
1) Acute viral encephalitis- non-suppurative, no gross changes, often with meningitis 2) Pre-natal infect---> congen. abnormalities - General changes- 1) Non suppurative inflam 2) Perivasc. cuffing- lympho. + PC- striking change 3) Gliosis- predom. microglia, oligo degen., astrocytes degen or react. 4) Neuronal changes- central chromatolysis, necrosis, neurophagia 5) White matter changes- demyelination not common 6) Inclusion bodies- Few infect.- present in many cells 7) Meningitis- assoc c non suppurative inflam |
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Canine distemper
Sequence- Micro- Effects- |
- Replication in lymph tiss---> immunosup.
- Spreads to CNS---> infects mononuclear cells - Acute GC infect---> Myelin degen. and phag., white matter vacuolation, astrocyte swelling- +/- demyel. - Micro- Areas of palor, perivasc. cuffing, necrosis, demyelination. - Pantropic virus- Affects resp., GI, lymph tissue. ---> :. can predispose to further infect. - Effects- - Seizures, tremors, circling, paralysis, hyperaesthesis - May die of encephalomyelitis - Survive--> subacute/chronic inflam + demyelinating dz |
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FIP
Cause- Gross- Micro- |
- Corona virus
- Most common form of CNS inflam in cats ---> Meningoencephalitis - Gross- meningeal opacity, thickened choroid plexus c white exudate. May be hydrocephalus - Micro- - Pyogran. inflam (lympho + PC) on inner and outer surfaces - Fibrinous necrosis around vessels |
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Protozoa-
(x3) |
1) Encephalitozoon cuniculi
- Rabbits, dogs- non supp. meningoencephalomyelitis 2) Neospora caninum - Dogs- Meningoencephalomyelitis + hindlimb paresis - Cattle- (Causes abort.) foci of necrosis in aborted foet. 3) Toxoplasma gondii- similar to neospora. (C, D, P) |
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Parasites
(x2) |
1) Coenuris cerebralis- Gid (taenia multiceps)
2) Aberrant larval migration - A. vasorum - Strongyles - Oestrus ovis |
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Fungi
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- Uncommon
- Eg. Cryptococcus - Granulomatous/ pyogranulomatous inflam |
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Prions
Effects- |
- Mechanism incompletely understood
- Effects- Mostly on the medulla - Neuronal vacuolation - Ischaemic cell change, central chromatolysis, astrocytosis - No inflam response - No gross changes - Clinical signs are variable |
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Granulomatous meningoencephalomyelitis (GME)
Cause- Gross- Micro- |
- Sporadic dz in young-middle aged, small dogs
- Cause unknown- immune? - Variable clinical signs - Gross- areas of malacia and some white discolouration - Micro- patchy, perivasc. cuffing (Lympho., PC, MP) - May have oedema and necrosis |
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Necrotizing meningoencephalitis
Describe- |
- Pugs and small breeds
- Idiopathic necrosis of cerebral cortex, cystic cavities, cerebral oedema, perivasc. and diffuse infiltrate. - Non-suppurative menigitis - Convulsions, ataxia, GME |
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Cholesteatoma/ cholesterol granuloma
Describe- |
- Horse
- Non-neoplastic lesion of choroid plexus in lat. V - Granuloma FB type reaction to cholesterol after repeated haem. - Firm yellow/brown mass - May cause obstructive hydrocephalus |
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Compressive injuries to CNS
Wobbler syndrome Describe- Dogs- Horses- (x2) |
- Cervical stenotic myelopathy
- "Wobbler syndrome" - Seen in rapidly growing breeds of dog and horse - Cervical canal fails to resorb sufficiently---> Compress. ---> Wallerian degen. + necrosis at site --->White matter degen above and below - Dogs- commonly C5-7- Dobermans, Gt Danes, Bassets - Horses- 2 types- - Cervical static stenosis - C5-7- when flexed + extended - Horses 1-4 y.o - Cervical vertebral instability/ dynamic stenosis - C3-5- when necks is flexed - Horses 8m-1.5 y |
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Compression of CNS-
Osteoarthropathy Describe- Effects- Intervert. disc herniation- Types- Description- Haemorrhagic myelomalacia Describe- |
- Osteoarthropathy
- Middle aged/ old large breed dogs and horses - Degen. joint dz in cervical vert. - May see protrusion/ proliferation/ fibrosis of joint annulus, articular cartilage, joint capsule, ligaments - May result from chronic malarticulation of joint. - Intervert. disc herniation - Type 1- extrusion of nucelus pulposus - Chondroplasic dogs - Acute, extensive extrusion and degen. - Type 2- protrustion of annulus fibrosis - Non-chrondroplasic - slow, fibrous degen. - Compression---> Wallerian degen. + Ischaemia - May get fragmentation and emboli - Haemorrhagic myelomalacia- necrosis and haem. - Follows spinal trauma - Progressive, may extend up cord, usually fatal |
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CNS Neoplasia-
General points- |
- Uncommon, usually old D+C
- Rarely metast. outside CNS - Space occupying lesions- benign can be fatal - Soft/firm gelatinous pink/ grey masses, +/- haem+nec. |
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Neoplasia-
Types- (x7) |
- Medulloblastoma-
- Neuronal tumour- cerebellum ofyoung animals - May be infilt./metast. // Can cause hydrocephalus. - Astrocytoma- - Astrocyte tumou- cerebella of brachyceph. dogs - Malig.- Diffuse/ anaplastic/ gliobastoma multiforme - Oligodendroglioma- - White matter of cerebrum of brachyceph. dogs - Ependymoma- - Arises in ventricular system of brachyceph. dogs - Choroid plexus tumour- - 4th ventr. of dogs. M= carcinoma, B= papilloma - Microgliomatosis- older dogs - Meningioma- commonest tumour- mainly cats - Tumour of mesothelium/ fibroblasts- variable appear. - Solitary, rounded, firm, slow growing, can affect spine |
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2o Tumours
Types- |
- Lymphoma- looks like fat in spinal cord
- Mammary - Haemangiosarcoma - From surrounding bone, cart, mm. |
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PNS degeneration-
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- Congenital/ hereditary/ familial neuro/myeliopathies
- Often progressive - Rare |
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PNS inflammation
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- Neuritis in the Cauda Equina-
- Aka. Polyneuritis equi - Horses - Idiopathic- autoimmune? - Intradural lyphoplasmacytic inflam, brown discolouration (haem.), extradural granulom. inflam. - Causes- Tail paralysis, pain, perineal par/analgesia, urinary incont., faecal retent., mm atrophy + weakness - Protozoal polyradiculitis - Neospora> Toxoplasma - Spinal cord and mm lesions (invasion of tiss in young) - Predilection for lumbosacral nn in young dogs --->hindlimb paralysis + mm atrophy - DAT mycosis assoc. neuritis- - Cr. nn V., IX, X, XII, internal carotid n---> Horner's synd. - Otitis media-interna - Possible inflam of cr.n.V and symp nn---> Horner's. - Vestibular dz |
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Horner's syndrome-
Define- Effects- |
- Inflam of SNS
- Effects- - Miosis- pupil contract. - Ptosis- drooping of upper eyelid - Protrusion of 3rd eyelid - Enophthalmus- eyeballs sink into orbit |
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Traumatic injury of the PNS-
Causes- Mild injury- Severe injury- |
- Causes- RTA, parturition, pelvic etc.
- Mild injury---> Neuropraxia- eg compression- causes temp. conduct. block- can be reversed to full funct. - Severe injury--> Degen- eg. crushing, tearing, trasection - Regen may or may not occur. - Neuroma formation- from failed attempts to regen. - Fibrosis bulb |
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Nutritional and Metab. dz in PNS
(x3) |
- Diabetic neuropathy-
- Most common in cats - See tarsal overflex. due to tibial n. paresis - Hypothyroid neuropathy- Dogs. Uncommon - Variable signs- - Laryngeal paralysis - Cr. nn. deficits - Tarsal overflex. - Vit B deficiency - Pantothenic acid defic.- Pigs - Riboflavin deficiency- Poultry |
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Toxins-
Lead poisening |
- Chronic lead poisening- eg from pasture
- Laryngeal and pharyngeal paralysis - Botulism- blocks ACh release---> flaccid paralysis + death - Ingestion of toxin from soil/ food - poss. from wound infection - Organophosphates - Acute- inactivity of AChE---> overstim. synapses ---> Hypersal., miosis, sweating, d&v, mm fasciculation - Delayed- irrev. inactivity of esterases in neurones - May cause delayed paralytic syndrome ---> Ataxia, weakness, paralysis, dyspnoea, aphonia |
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Dyautonomias- autonomic dysfunction
(x3) |
- Grass sickness- equine dysautonomia
- Chromatoloysis and ganglion death in PNS - Neuronal degen in brainstem and grey matter - Presents as alimentary dz c varying degrees of stasis - Green nasal discharge - Dx by histo. exam of autonomic ganglia in intestine - Tx- euthanasia - Key-Gaskell syndrome- Rare- Cats - Acute onset---> mydriasis, megoesophagus, vomit, constipation, death- Tx= Euth. - Peritonitis induced dysautonomia ---> Intestinal autonomic nn degen---> paralytic ileus - reversible if peritonitis resolves |
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Myaesthenia Gravis
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- Congenital- ACh R defic.
- Autoimmune- Ab to AChR ---> Flaccid paralysis |
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Neoplasia-
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- Peripheral nerve sheath tumours
- Aka Schwannomas - Benign or malignant - Spinal or Cr nn affected - D, O and occasionally C affected - Dog- Trigeminal nerve/ brachial plexus affected - Need immunohist. to determine origin - Cattle- Epicardial nerves/ brachial plexus - May be called neurofibromatosis |
