Clin Med - Neuro 3

drraythe's version from 2017-09-30 21:22

Cerebellum & Vestibular System Continued

Question Answer
How does CENTRAL Vestibular Syndrome present/ how is it different from peripheral?Central peripheral dz has all the signs of the Peripheral Vestibular Dz (listing/leaning to 1 side, rolling, tight circling, head tilt, nystagmus, ventral strabismus), PLUS that there ARE postural rxn deficits (ipsilateral to the lesion), the pathological nystagmus is usually positional (if head is in a certain position then there is nystagmus) OR it is a vertical nystagmus & there can be hemi or tetra-paresis. (usually there are also other signs of brainstem dysfxn)
Sum up what's same & diff about peripheral vs central vestibular syndromeBOTH have listing/leaning to 1 side, rolling, tight circling (ataxia), head tilt, nystagmus, strabismus
CENTRAL (is peripheral PLUS) also has postural deficits, the nystagmus is often positional, or is vertical instead of horizontal. there is also hemi/tetra paresis & maybe other signs of brainstem dysfxn are present
Why does the fast phase of the nystagmus flick to the opposite side when there is damage on the other side?Eyes flick quickly to the opposite side bc there is no input from the damaged side so it "looks toward" the side that has input
The Quick phase is corrective, the body senses the eye wandering (slow phase) & flicks it back into the position is supposed to be in (fast phase)
Paradoxical Vestibular Syndrome indicates what kinda lesion? What does this syndrome represent?Cerebellar lesion - Remember that the cerebellum is INHIBITORY on the vestibular system, so this syndrome is actually looking like an "overactive'" vestibular system bc the inhibitory part of the brain is damaged
Paradoxical Vestibular Syndrome what other signs are there?Cerebellum lesion:
Head tilt
Postural deficits
In PARADOXiCAL vestibular syndrome, which way does the animal have head tilt & fall?Contralateral (opposite) side of lesion
In PARADOXICAL vestibular syndrome, which way does the fast phase of the nystagmus go?Fast phase is ISPILATERAL(same side)!! to the lesion
Head tilt & fast phase nystagmus in.... PERIPHERAL vestibular syndrome? CENTRAL? PARADOXICAL?PERIPHERAL: Head tilt TOWARD, fast phase AWAY
CENTRAL: Same as peripheral but nystagmus is positional/vertical
PARADOXICAL: Head tilt AWAY, fast phase TOWARD
What can postural rxns tell you about the location of the lesion in PARADOXICAL vestibular syndrome?They are abnormal ipsilateral (same side) to lesion
Aside from CN VIII, what other nerve is associated w/ the middle ear & what does it do (in relation to the eye)?CN VII & it does Sympathetic innervation for pupil (sympathetic system czs pupil dilation)
Due to CN VII's close relation to the middle ear & CN VIII, what can you see along w/ peripheral vestibular syndrome?Facial nn defects & Horner’s Syndrome
What 3 things will you see if the PERIPHERAL vestibular syndrome is BILATERAL?Wide-based, crouched stance (they will be very low to the ground)
Wide head excursions
No vestibulo-ocular reflexes
Wide-based, crouched stance (they will be very low to the ground), Wide head excursions, No vestibulo-ocular reflexes is a sign of what?Bilateral Peripheral Vestibular Syndrome
What are 3 major reasons you can get peripheral vestibular syndrome?(1) Middle/inner ear dz -usually Bacterial otitis media/interna. You might see Horner’s in this case also (bc of CN VII being in the same area)
(2) Neuropathies, esp hypothyroidism
(3) Idiopathic (old dog vestibular dz)
What is Meclizine? When would you use it?It is an antihistamine drug, which is often used to treat the nausea/vertigo which is associated w/ vestibular syndrome
(12.5mg PO for small dog/cat, 25mg PO for large dog)
Why might physical therapy be useful in a dog w/ cerebellar/vestibular dz?They can "relearn" proprioception
Nugget for localizing vestibular syndrome → what should you know about how the R & L side are in vestibular syndrome?Both R & L side are active
Nugget for localizing vestibular syndrome → how does the cerebellum affect the vestibular system?It is INHIBITORY on the vestibular system
Nugget for localizing vestibular syndrome → vestibular input czs ___ (ipsilateral or contralateral) ___ (flexor or extensor) toneIPSI
*Nugget for localizing vestibular syndrome → What is the key to localizing vestibular syndrome lesions?Postural rxns
**Changing or positional nystagmus is what kinda vestibular syndrome?Central
**Vertical nystagmus is what kinda vestibular syndrome?Central
**If there are facial nn defects or Horner’s Syndrome w/ the vestibular syndrome, what kinda vestibular syndrome is it?Peripheral

Forebrain/Cerebrum & Neuromuscular Junction

Question Answer
What are the 4 big parts of the forebrain?(1) Thalamus & hypothalamus (diencephalon)
(2) Cerebral hemispheres (telencephalon)
(3) Olfactory structures
(4) Components of the limbic system (hippocampus & amygdala)
Cerebral Fxns incld... (big list)Cognition
Audition (hearing)
Motor (minor role in quadrupeds)
Describe the symptoms you'd see in Cerebral Syndrome?↓ intelligence
Behavior/attitude changes
Altered mentation
Contralateral ↓ postural rxns
Contralateral deafness, blindness, anosmia
Circling toward the lesion (or head or body turn toward lesion)
Head pressing
If there is a lesion in the Cerebrum, will signs be on the ipsi(same) or contra(opposite) lateral side of the body?Contralateral
What is the diencephalon what is in it?The rostral brain stem, it contains the thalamus & the hypothalamus
What is the thalamus part of & what does it do?Part of the diencephalon, it is a sensory relay station & helps w/ arousal of the cortex
What is the hypothalamus part of & what does it do?Part of the diencephalon, it controls endocrine, affect+emotion, sleep/wake cycle, Homeostasis of many body fxns
Diencephalic Syndrome → does it affect mentation, behavior, emotion?YES (part of thalamus/hypothalamus is damaged & these pertain to arousal, emotion, etc)
In Diencephalic Syndrome, will postural rxn deficits be on the same or opposite sideOpposite (contralateral)
How might senses be affected in diencephalic syndrome & why?There will be Contralateral blindness, deafness (bc diencephalon houses the thalamus which is a sensory relay station)
What is hemigeglect & when do you see it?See it in diencephalic syndrome-it's when the animal doesnt seem to realize that the other half of the vision field is there
When would you see endocrinopathies (which aprt of forebrain damaged)Diencephalic Syndrome (bc hypothalamus in the diencephalon)
Describe the path of a LMN starting from where it starts in the spinal cordStarts in the grey matter of the ventral column in the ventral rootlet → ventral root → spinal nerve → peripheral nerve → exit via brachial plexus & lumbosacral plexus
What is the motor unit composed of? what does it control/have to do w/?The motor unit is the α motor neuron + the myocytes it innervates. It pertains w/ Strength of muscle contraction
Neck ventroflexion in a cat might indicate what?Myopathic Syndrome
What are some CS of myopathic syndrome?Generalized weakness, exercise intolerance (in cats, neck ventroflexion)
Muscle atrophy or hypertrophy (can lead to Joint contracture or Trismus (LockJaw) )
Stiff, stilted gait (look like theyre walking on eggshells)
Muscle tremors & there might be myalgia (mm pain)
What is trismus & when would you see it?Inability to open mouth, see it in myopathic syndrome - lock jaw
What kinda ataxia will you see in myopathic syndrome?NONE
What kinda postural rxn abnormalities will you see in myopathic syndrome?NONE
How are reflexes affected by myopathic syndrome?They arent affected, but if there is joint contracture it might be difficult to gauge them
What dont you see in myopathic syndrome & why?Dont see ataxia, postural rxn abnormalities or abnormal reflexes bc only the mm are affected in this problem
What are Junctionopathies?Generalized neurogenic muscle atrophy
What kinda paralysis do you see in junctionopathies? What other signs will you see related to t his kinda paralysis?Ascending flaccid paralysis, INCLUDING the mm for respiration which leads to dyspnea
How are reflexes affected by junctionopathies?Hypo to areflexia (Reflexes may be present early on & Cranial nerves may be involved)
How would you describe a neuropathic gait?Shuffling & slapping
How would a MOTOR neuropathy present?Flaccid paralysis
Neurogenic muscle atrophy
Hypo-to areflexia
Muscle fasciculations
How would a SENSORY neuropathy present?Hypoalgesia
Paresthesia (these can lead to self-mutilation)
Ataxia (due to proprioceptive defects)
Hypo-to areflexia (no muscle atrophy or loss of strength tho)

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