Neurological System: Trauma, degeneration, and malacia/necrosis

What does encephalo mean?

Brain

What does myelo mean?

Spinal cord

What does malacia mean?

Degeneration, necrosis, liquefaction

What does polio mean?

Grey matter

What does leuko mean?

White matter

What is polioencephgalomalacia?

Grey matter degeneration/necrosis of the brain

What is leukoencephalomalacia?

White matter degeneration/necrosis of the brain

What does thiamine deficiency cause?

Symmetrical hemorrhage and necrosis of inter and midbrain (polioencephalomalacia)

Thiamine deficiency

What is the pathogenesis of Clostridium perfringens?

Epsilon toxin causes vascular damage, perivascular edema, necrosis, and hemorrhage in gray matter nuclei symmetrically

What is a common cause of Nigropallidal encephalomalacia in horses?

Yellow star thistle causing necrosis of substantia nigra due to sesquiterpene lactones

Nigropallidal encephalomalacia in horses

What does this yellow coloration mean?

Laminar cortical necrosis

What can cause thiamine deficiency in non carnivores?

High concentrate rations

Bacteria high in thiaminases

Ingestion of thiaminase containing plants

High sulfur diets

What can cause lesions similar to thiamine deficiency?

Lead poisoning

What is a good way to identify laminar cortical necrosis in the field?

UV light will create autofluorescence

What is the caused by thiamine deficiency in cattle?

Laminar cortical necrosis

What does salt toxicity (lack of water) cause in the brain?

Osmotic pressure in brain increases and when the animal drinks water again the influx causes edema in the brain. The edema causes laminar cortical necrosis

Chronic polioencephalomalacia

What happens during chronic polioencephalomalacia/

Glitter cells are activated and gray matter cavitation occurs

Water matter appears intact, but axons die

What is post-anesthetic hemorrhagic myelomalacia in horses?

Prolonged dorsal recumbency causes ischemic necrosis to cord, focal malacia of the cord, and paralysis

What causes encephalomalacia in chickens?

Vitamin E deficiency in affected chicks

What are the signs of vitamin E deficiency in chickens?

Ataxia, falling on back, frequent wing flapping, twisted heads

What lesions are associated with Vitamin E deficiency in chickens?

Encephalomalacia, edema, hemorrhage, necrosis of cerebellum

What does this white discoloration indicate?

Leukoencephalomalacia

What does Fusarium spp cause in horses?

Moldy corn poisoning and leukoencephalomalacia due to Fumonisin B1 toxin

Moldy corn poisoning from Fusarium spp. (Equine leukoencephalomalacia

What is the distribution of Leukoencephalomalacia compared to polioencephalomalacia?

Leukoencephalomalacia is usually asymmetric and polioencephalomalacia is symmetrical

What are some causes of hepatic encephalopathy?

Portosystemic shunts

Hepatotoxicants

Severe hepatic fibrosis

Equine serum hepatitis

What is the pathogenesis of hepatic encephalopathy?

Liver dysfunction causes impaired ammonia detoxification

Elevated serum ammonia

Induction of Alzheimer type II astrocytes

Vacuolation of white matter

Neurologic impairment

What are the gross lesions of hepatic encephalopathy?

None

What is the pathogenesis of Acquired Lysosomal Storage Disease due to Locoweed toxicosis?

Locoweed ingestion

Swainsonine toxicosis

Inhibition of alpha-mannosidase

Excess intracytoplasm alpha-mannosidosis

Accumulation in lysosomes

Neurologic dysfunction

What does locoweed toxicosis cause?

Acquired lysosomal storage disease

What are the gross lesions of locoweed toxicosis?

None

What is the most common lysosomal storage disease in domestic animals?

Globoid cell leukodystrophy

If you suspect neurologic disease in a large animal how should you not euthanize?

Captive bolt euthanasia or firearms

Intracranial and subdural hemorrhage due to a high velocity projectile being used for euthanasia

Subdural hematoma due to a high velocity projectile

What type of CNS injury is this?

Crushing injury

Basisphenoid fracture (CNS traumatic injury)

What are basisphenoid fractures more likely?

Foals that are being halter broken and they flip backwards trying to resist (blunt force on top of the skull)

Thermal injury due to dehorning

What is a coup-countrecoup injury?

One lesion on the area of trauma

Other lesions on the opposite side of the trauma

What lesions are on the coup side of a coup-countrecoup injury?

SQ hemorrhage

Skull fracture

Subdural hemorrhage

Brain contusion

What are the lesions on the countrecoup injury?

No SQ hemorrhage or skull fracture

Subdural hemorrhage

Brain contusions

Subdural hematoma

Cerebral hemorrhages

Brain laceration from multiple pellets

Spinal cord hemorrhage (contusions)

What are some causes of spinal cord hemorrhage

Horse racing injury

Lightening strike

High velocity projectile

What can cause cervical stenotic myelopathy?

Narrowing of the vertebral canal or overextension of vertebral joints leads to compression of the spinal cord

What are the lesiosn of cervical stenotic myelopathy?

Compressive injury causing Wallerian degeneration, ataxia, paresis

What are the 2 syndromes of cervical stenotic myelopathy?

Cervical static stenosis

Cervical vertebral instability

What does cervical vertebra flexion cause?

Dynamic compression of the spinal cord in the canal

What animals typically get equine wobblers syndrome?

Younger

What is equine wobblers syndrome?

Flexion of cervical vertebra causing dynamic compression of the spinal cord

Equine Wobblers Syndrome

Articular facets are asymmetrical causing stenosis, progressive spinal cord compression, and Wallerian degeneration

What is the hallmark of Wallerian degeneration?

Macrophages infiltrating and phagocytizing axonal debris and degenerative myelin

What is the pathogenesis of intervertebral disk extrusion?

1. Sudden compression

2. Extrusion of IVD into spinal canal

3. Spinal cord compression

4. Neurologic deficits

IVD

What is a Hansen type I IVD?

Rapid

Disk material is extruded

Spinal cord compression causes hemorrhage and necrosis

What dogs are more likely to get Hansen Type 1 IVD?

Dachshunds and other small breeds

What is Hansen type II IVD?

Slow

Bulges, does not have extruded disk material

Gradual weakness

What is the lesion from Hansen type II IVD analogous to?

Wobblers

What is the most severe consequence of Hansen type 1 injury?

Progressive hemorrhagic myelomalacia (ascending-descending)

Atlanto-occiptal luxation

What animals are more like to get atlanto-occipital luxation?

Calves, small ruminants, pigs in dystocia

Cause of this traumatic injury?

Mistake while trying to collect CSF