Neuropathology Flashcards
What are the main region of the brain
Forebrain
Brainstem
Cerebellum
What are the 2 regions of the ‘Higher’ (Cerebrum) brain
- Cerebrum
- Telencephalon
- Diencephalon
Where is the forebrain located in the brain?
Rostral to the tentorium cerebelli (bone/Cartlidge)
The Cerebrum (Telencephalon) has 5 regions/Lobes) what are they and what are their functions?
- Frontal Lobe
- Intellect
- Behaviour
- Fine-Motor activity
- Parietal Lobe
- Touch
- Nociception (Pain)
- Conscious
- Proprioception
- Temporal Lobe
- Behaviour
- Hearing
- Occipital Lobe
- Vision (The Visual Cortex)
- Olfactory
- Smell
What is the regions and their functions of the Diencephalon?
- Thalamus
- Relay station for touch, nociception, pain, proprioception
- Reticular activating system
- Consciousness
- Hypothalamus
- Autonomic control
- Appetite
- Thirst
- Temperature
- Water & Electrolyte balance
- Sleep
- Behaviour
-
Pituitary Gland
- Endocrine functions
What is the role of The Reticular Activating System?
It mainains Consciousness
It extends from the Forebrain to the Brainstem
How many Crainal nerves are in the Forebrain? Name them and their role.
- Olfactory (CN I)
- Smell
- Optical (CN II) - Runs up into the occipital lobe)
- Vision
- Pupillary light reflex
What does Obtundation mean?
Mental Depression
What are sings of Dysfunction of the forebrain?
-
Altered mental status primarily effects on the RAS
- Obtundation (mental depression)
- Delirium
- Stupor or coma
- Seizures
-
Behavioural changes
- Pacing (wide circles TOWARDS the side of the lesion)
- Standing and staring, head pressing
- Restlessness
- Loss of learnt behaviours (eg house training)
- Reduced recognition of the owner and familiar objects
-
Blidness and decreased/absent menace reflex
- Lesion in contra lateral to affected eye
- Loss of Smell
-
Abnormal movements and posture
- Turning - to the side of the lesion
- Wide Circling - to the side of the lesion
- Head pressing, Pacing
- Altered postural reactions (including conscious proprioception) and reflexes in contralateral limbs
What are the 3 regions of the brain stem?
- Midbrain
- Pons
- Medulla
What are the functions of the 3 regions of the Brainstem
-
Mesencephalon
- Reticular activating system
- Ascending and descending tracts
- CN III - Ocularmotor
- Pupil Size
- CN IV - Trochlear
- Eye Position
-
Pons (Metencephalon) - a bridge for connections to the cerebellum
-
Reticular activating system
- Vital centres : Respiration and Sleep
- Ascending and descending tracts
- CN V
- Facial sensation and masticatory muscles
-
Reticular activating system
-
Medulla Oblongata (Myelecephalon) - Crainal Nerve Powerhouse
- CN VI - XII
- Many and varied functions including motor and sensory for thoracic and abdominal viscera (X)
- Ascending and descending tracts
- CN VI - XII
If you have dysfunction of the Brainstem what signs would you expect to see?
-
Crainial Nerve deficits
- Facial (VII) paralysis
- Trigeminal (V) paralysis
- Vestibular Disease (VIII)
- Abnormal eye position (II, IV, VI)
- Loss of gag reflex (IX)
- Tongue paralysis (XII)
-
Proprioceptive deficits
- The long tracts (ascending sensory and descending UMN) pass through the brainstem en route to/from the cerebum
- Small lesions - ipselateral
- Larger lesions - bilateral
-
Hemi or tetraparesis
- Depending upon the extent of the lesion
-
Stupor or coma with abnormal pupil size
- Stupor = deep sleep but roused by noxious stimuli
- Coma = Unconsciousness
- depemds on severity of the lesion
- Pupil size is affected due to injury to/pressure on (parasympathetic fibres) in nucleus of III)
-
Abnormalities in respiratory and cardiovascular function
- Abnormal breathing patterns (eg Cheyne Stokes)
- Bradycardia with increased ICP
- Tachyarrhythmia with brain-heart syndrome
-
Vestibular signs
- Head tils
- Nystagmus and strabismus
- Ataxia and circling
What Nerve Paralysis do we see here?
Occulomotor III Paralysis
What Nerve Paralysis do we see here?
Trochlear IV Paralysis
What Nerve Paralysis do we see here?
Abducens IV Paralysis
WHat is the Role/function of the Cerebellum?
- Controls the rate and range, without affecting force of movements or initiating motor activity.
- Maintains equilibrium (with vestibular system)
- Coordinates and smooths movement
What are the signs of dysfunction of the Cerebellum?
-
Unaltered (Normal) mental status
- The cerebellum is anatomically distant from the RAS so disease here does not affect the RAS so consciousness is normal
-
INtention tremmors (Head and eye) and hypermetria with preservation of strenght
- Classic cerebellar disease = intention tremor; tremors that occur with intent/movement
- Tremor at rest is possible too
- Loss of smoothing effect on movement leads to dysmetria
- bunny hopping and exaggerated limb movement
- No loss of CP
-
Ataxia, wide based stance (vestibular signs)
- The cerebellum is integral to balance
- Head tilt may also be seen with cerebellum disease and is often PARADOXICAL (ie to the side opposite the lesion, countrary to all other vestibular disease)
- = Paradoxical vestibular syndrome
-
Loss of menance response
- The menace response is a learnt reflex (starting at 3-6 weeks of age) and the pathway is influenced by the cerebellum
Where is the lesion in an animal with
- Obtundation
- Severe ataxia, intention tremor but normal mentation?
- Head Tilt, Nystagmus and ataxia?
- Forebrain or the Brain Stem as the RAS goes between the two.
- Cerebellum
- Brainstem - Vestibular System (central or peripheral)
Where is the lesion if an animal suffers :-
- Bilateral Facial nerve paralysis and obtundation
- Paraparesis?
- Hemiparesis?
- Vestibular signs and Blindness?
- Brainstem
- Bilateral Spinal cord T3-L3 or L4-S3 (caudal to the brachial intumenscance)
- Spinal Cord Cranial to T3 on the one side
- Multifocal
If an animal is having seziures where is the lesion in the brain?
Forebrain
Where do the Upper Motor Neurons (UMN) originate in?
- Cerebral Cortex (Pyramidal tracts)
- Corticospinal tracts
- Brainstem
- Reticulospinal tract
- Vestibulospinal tract
- Rubrospinal tract
If you have an injury in a Upper Motor Neuron what would the resultant signs be?
- Motor Function
- Muscle Tone
- Muscle Atrophy
- Reflexes
- EMG signals in LMN
If you have an injury in a Lower Motor Neuron what would the resultant signs be?
Motor Function
Muscle Tone
Muscle Atrophy
Reflexes
EMG signals in LMN
If we have trauma to the Spinal cord be it an acute injury or a slower progression of neoplasia, ther would be a progressive reduction or total loss of what four modalities.
Name them in order of which is lost first
This is determined on how myelinated the neurons are. More Myelinated goes first.
- Conscious proprioception
- Voluntary motor function (Paresis/paralysis)
- Paraparesis (UMN or LMN [depending on location of lesion]) and tetraparesis (UMN)
- Superficial pain sensation
- Deep Pain sensation