SA Neuro Flashcards
- C: Normal to increased spinal reflexes and tone in the pelvic limbs, with normal thoracic limbs
- T3-L3 should give us UMN signs –> normal to increased spinal reflexes
- this lesion is behind the position of the thoracic limbs so just the pelvic limbs will be affected
T3-L3 Lesion
Spinal Cord: Neurolocalisation
D: Normal-to-increased spinal reflexes and tone in the pelvic limbs, with reduced spinal reflexes and tone in the thoracic limbs
- still UMN for our pelvic limbs, but then LMN for the front legs which leads to a reduced spinal reflex in the thoracic limbs
- For thoracic limbs: we lose our LMN because of the reflex arc as it is over that section of limb specifically
- And then loss of UMN signs to the pelvic limbs
- Ischaemic Myelopathy
- Intervertebral Disc Extrusion can acute like this but typically not peracute and would be more progressive rather than stable
- disc extrusions would also be more painful
- anything that is ischemic or vascular will come on instantly and will have a lateralization and often non-painful
Schiff- Sherrington
-this would be a paraplegic animal with increased tone in the thoracic limbs
What do these postures look like?
Torticollis?
Decerebrate?
Decerebellate?
- Torticollis: really like a scoliosis or turn in of the neck
- Decerebrate: will have extended thoracic limbs, pelvic limbs and opisthotonos –> also their mentation is profoundly affected - will likely be a comatose patient
- Decerebellate - wouldn’t have an abnormal mentation, will still be awake and thrashing around trying to move but will have this posture
Schiff - Sherrington Posture is typically associated with what lesion?
- Acute T3-L3 Myelopathy
- very sudden onset
- lose the inhibitory pathways that are running from your back legs to your front legs and as a result get these rigid thoracic limbs
what is your neuroanatomical localisation?
*reduced menace response on left eye as well and absent palpebral*
Left Trigeminal Nerve (motor and sensory)
- sensory because the palpebral reflex is absent on that left side
- and he still has the ability to blink
- motor because there is massive atrophy of the muscles of mastication
B: Fast phase is directed away from the side of the lesion
Note: rotary nystagmus you can have with central or peripheral nystagmus as well as well as spontaneou nystagmus
-vertical is highly suggestive of a central lesion but isnt absolute
- Left sided conscious proprioceptive deficits
- essentially looking for anything that makes you think of the brainstem on the same side as the signs for central lesions in vetibular disease
- makes you think that this animals lesion could be in the brain stem bc effectively when we have L sided vestibular syndrome and we are wanting to look for any evidence of a central lesion - the central and peripheral portions of the vestibular system
- centrally the vestibular nucleus in the brain stem and associated pathways
- Peripherally it is the vestibular nerve and the vestibular apparatus
- So we are looking for any signs that suggest that lesion is in the brainstem - such as proprioceptive deficits on the same side of the lesion
- other things could be mentation change or multiple cranial nerve deficits
- but also importantly to differentiate from the facial nerve as it runs quite close to the vestibular nerve in the peripheral parts of the vestibular system
- ex: if you had facial paresis or Horners syndrome at the same time, they could both be just representative of having a lesion in the middle ear area
- Positional Strabismus
- good when you have a vestibular suspicion and want to challenge the vestibular system
- good way to check for nystagmus as well
What is the best deifnition of epilepsy?
- a tendency toward recurrent seizures (more than one day apart)
What is the best definition of cluster seizures?
- more thna one seizure in a 24-hour period
- important for us as they are an indicator of particularly severe type of epilepsy
- These need to be treated very aggressively
Which CN’s are evaluated by assessing gag reflex?
- IX and X
Tonic - Clonic Seizures
- During a generalized tonic-clonic (formerly grand mal) seizure, electric discharges instantaneously involve the entire brain.
- The person loses consciousness right from the beginning of the seizure.
- Atonic-clonic seizure usually lasts one to three minutes, but may last up to five minutes.
- Normally, would not be able to interact with surroundings (mentation)
- should see autonomic signs: hypersalivation, urination, defecation
What disorder is commenly mistaken as tonic-clonic seizures?
paroxymsal dyskinesias (movement disorder)
- commonly mistaken for seizures
- The paroxysmal dyskinesias (PD) are a group of movement disorders characterized by attacks of hyperkinesia with intact consciousness
- episodes last a few minutes
- pretty rare but seeing more and more - particularly border terriers and other breeds
- abnormal limb tone/movements, abnormal body posture, REMAIN CONSCIOUS
- Lateral Geniculate Nucleus not involved
The cerebral cortex that is involved in processing vision is the??
(which lobe)
- Occipital lobe
Narcolepsy in dogs
- hard to differentiate from syncope in most cases
- see narcolepsy more often in dogs where they have peaks of being excited and then all of a sudden fall asleep
Hemiparesis
- reduced voluntary motor function of both limbs on one side of the body
Which CN’s run through the internal acoustic meatus?
- VII and VIII
- clinical signs in one can often lead to clinical signs in the other
D. unilateral masticatory muscle atrophy
- has to be a bilateral Trigeminal nerve lesion to have drop jaw
- if it is one side they still have enough tone to hold up jaw
- L4-S3 spinal cord segments
- can almost think of bladder as back legs
- if we have low tone in the hindlimbs then we will likely have low tone in the bladder
- either retina, optic nerve or L side of the chiasm
- signal is not getting through the left side
lesion in the left occipital cortex
- reduced menace on the contralateral side (R side)
- will have a normal PLR as the visual cortex is not involved in the PLR pathway at all
