Embryological development of brain, notochord and its significance Flashcards
What signs would you see with a forebrain (cerebrum and thalamus) disorder?
o visual disturbances, changes in mental status or behaviour, abnormal movements or postures, seizures.
What signs would you see with a cerebellar disorder?
o intention tremor, wide based stance, and incoordination (dysmetria) of the head, trunk, and limbs.
What signs would you see with a brain stem disorders?
o cranial nerve dysfunction, postural disturbances, or vestibular dysfunction. In some cases, brain stem disorders may also result in weakness and proprioceptive gait disturbances, impaired consciousness.
What signs would you see with a spinal cord disorder?
o weakness, motor dysfunction, or proprioceptive deficits of the limbs. Does not affect cerebral function or coordination of head movement.
What signs would you see with a neuromuscular disorder?
o diseases of the peripheral nerves, neuromuscular junction, or muscles. Weakness and ataxia similar to spinal cord disease. Disturbance of reflex function, pain sensation, or marked muscle atrophy. Can be episodic.
What signs would you see with multifocal disorders?
o Combinations of signs from more than one categorie of neurologic deficits.
What is syringomyelia + chiari-like malformation/caudal occipital malformation syndrome (COMS)? Is there a breed predisposition? What are the signs?
- Affect quite a few breeds: Chihuahuas, Cavalier king Charles spaniels, boston terriers
- Brain is crowded in the skull and often causes seizures in these dogs
- Syringomyelia is a disorder in which a fluid-filled cyst (called a syrinx) forms within the spinal cord.
- Clinical signs: constant scratching, moaning and whining due to pain
What is syringomyelia + chiari-like malformation/caudal occipital malformation syndrome (COMS)? Is there a breed predisposition? What are the signs?
- Affect quite a few breeds: Chihuahuas, Cavalier king Charles spaniels, boston terriers
- Brain is crowded in the skull and often causes seizures in these dogs
- Syringomyelia is a disorder in which a fluid-filled cyst (called a syrinx) forms within the spinal cord.
- Clinical signs: constant scratching, moaning and whining due to pain
What is congenital Hydrocephalus? What causes it?
- The build-up of fluid in the cavities (ventricles) deep within the brain.
- Causes (can be one or a combination):
o Increased production of CSF
o Decreased absorption of CSF
o Obstruction of Flow
Which species is Congenital Hydrocephalus commonly seen in?
- In dogs:
o Dome shaped skull -chihuahuas
o a large fontanel on top of the skull
o eyes that appear to gaze downward (“setting sun sign”)
o Young animals might not show clinical symptoms
o Later on, clinical signs might include:
abnormal or spastic walking
changes in behavior
seizures
circling or falling over on one side
failure to housetrain or learn basic commands - Frisian horses with hydrocephalus
o In Frisian horses there is a genetic marker for this recessively inherited disorder
What is exencephaly?
- A rare malformation of the neural tube with a large amount of protruding brain tissue and absence of calvarium
- Named, depending on what is protruding:
o The brain (encephalocele)
o meninges (meningocele)
o or both (meningoencephalocele) - Can be open or closed
o Risk of CNS infection in open so poor prognosis
What clinical signs might you see with exencephaly?
- Safety and quality of life issues ataxic, seizuring, or mentally inappropriate large animals
o If the animal is seizuring its also becomes a safety risk for handlers if it is a large animal
What is Hydrancephaly?
A rare condition in which the brain’s cerebral hemispheres are absent and replaced by sacs filled with cerebrospinal fluid.
- Ventricles are different sizes
What is Lissencephaly? Are there any breed predispositions in the dog?
Means “smooth brain,” is a rare, gene-linked brain malformation characterized by the absence of normal convolutions (folds) in the cerebral cortex and an abnormally small head (microcephaly).
- Grey matter is thickened
- Lhasa apso predisposed
What are the secondary congenital abnormalities?
- Malformation of the occipital bones (atlas and axis): causes compression of the upper spinal cord that can deald to paralysis. More common in smaller breed dogs
- Hemiverebra (half a vertebra): o Affects breeds with a short skull, and “screw tailed” breeds
o Kyphosis, scoliosis, lordosis
o Wedge shaped vertebrae, causes angle in the spine
o Most likely to affect the neurological system
o Rear limb weakness (paraparesis), paralysis
o May remain without symptoms
