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
Define Paresis
Define Paralysis
- Reduced motor (ie voluntary) function
- Complete loss of motor (ie voluntary) function to that limb or limbs
If we had a spinal cord injury bewteen C1-C5 what problems would we have?
Tetra paresis or tetra paralysis depending on severity
Causing UMN signs in all four limbs
If a dog has a lesion between C6 and T2 what signs and location of these signs would we see?
UMN signs in Hind limbs but LMN signs in forelimbs
If we have a spinal lesion between T3 and L3 what signs would we see?
UMN signs in the hind limbs only
If we have a spinal lesion between L4 and S3 what signs would we see?
Hind limbs would show LMN signs
If we had injury in the following what signs of dysfunction would we see?
- Radial Nerve Injury
- Sciatic Nerve Injury
- Brachial plexus nerve root avulaion or brachial plexus tumour (multiple peripheral nerves affected by this)
- Facial (CN VII) nerve injury
- Trigeminal (CN V) nerver injury
- Forelimb monoparesis/monoparalysis
- Hindlimb monoparesis/monoparalysis
- Severe Forelimb monoparalysis
- Facial paralysis
- cannot chew, unable to close mouth
What are the signs of dysfunction of the Lower Motor Neurons?
- Monoparesis (LMN) (Or monoparalysis)
- Paraparesis/paralysis (LMN)
- Tetraparesis (LMN) (or tetraplegia/quadriplegia)
What is polyneuropathy?
Where a systemic disease or primary nerve disease affects most or all lower motor neurons
what is eye myosis
excessive constriction of the pupil
What are some portals of entry into the CNS (Central Nervous System)
- Direct Extension (eg inner ear/nasal cavity/sinus infection or neoplasias or penetrating wound)
- Haematogenous (eg. Histophilus somni)
- Leukocyte trafficking (Feline leukaemia virus, Blastomyces dermatidis)
- Retrograde axonal transport (eg. Listeria monocytogenes abd rabies virus)
How do we go about Nervous system Diagnosis
- History
- Clinical Exam
- Neurologic exam
- CBC
- Biochemistry
- Radiology (X-Ray, CT, MRI, Myelogram)
- EEG
- Serology
- CSF analysis (Protein/cytology)
- Biopsy (+/- IHC)
- Culture & Sensitivity
- Virology
- PCR
- Necropsy
What is hydrocephalus?
Hydrocephalus - Forebrain disease
An accumulation of CSF within ventricular system, subarachnoid space or both with subsequent dilation.
Can be Aquired or congenital
Causes - Blockages of any part of the ventricular system, blockage of resorption of CSF
What is the difference between Hydrocephalus and Hydranecephaly?
Hydranencephaly is a condition in which the brain’s cerebral hemispheres are absent to varying degrees and the remaining cranial cavity is filled with cerebrospinal fluid. … This should not be confused with hydrocephalus, which is an accumulation of excess cerebrospinal fluid in the ventricles of the brain.
What is Hydrancephaly, Porencephaly?
What causes these?
Formation of fluid filled cavities within the brain (porencephaly = small cavities, Hydrancephaly = large cavities). Results from the destructin of immature neuroblasts (usually viral cause)
Common Causes -
- Akabane
- Bluetongue
- Schmallenberg virus
- Border Disease Virus
- Cache Valley
- BVDV
- Feline panleukopaenia virus
- What does a thiamine deficiency cause?
- What animals does this effect?
- Where would we find the lesions?
- What are the probable causes?
- Polioencephalomalacia - grey matter brain softening necrosis
- Sheep and Cattle less common in goats
- Lesions
- Laminar Cortical Necrosis - Malacic zones fluoresce under UV light
- Cerebal Oedema & Herniation
- Causes
- Decreased ruminal thiamine
- overgrowth of thiaminase producing microbes (in ruminal acidosis Bacillus thiaminolyticus)
- Ingestion of thiaminase containing plants (Braken Fern)
- Production of inactive thiamine analogues
- Decreased absorption or increased fecal excreation of thiamine
What does DAMNITV stand for when trying to fine Differential Diagnosis?
Degenerative/generic
Anomalous (Congenital abnormalities)
Metabolic
Neoplastic/Nutritional
Inflammatory (Infectious vs Sterile), Idiopathic
Toxic, traumatic/physical
Vascular
Name some disease that occur in the forebrain. Use the DAMNITV if you can.
Degenerative/generic
Anomalous (Congenital abnormalities)
- Hydrocenphalus *
- Hydrancephaly/Porencephaly *
- Lissemcephaly
Metabolic
- Hepatic encephalophy and renal encephalopathy
Neoplastic/Nutritional
- CNS primary Neoplasia *
- Polioencephalomalacia *
Inflammatory (Infectious vs Sterile), Idiopathic
- Brain Abscess
- Clostridial enterotoxaemia
- Cholesterol granulomas
- Idiopathic epilepsy *
Toxic, traumatic/physical
- CNS Trauma *
- Cerebral herniation *
Vascular
- CNS Oedema *
- CNS infarction *
- Hypoxia*
- What disease could develop in an animal which only has access to salt water for a period of time?
- Although this is believed to be possible in several animals what is the only animal this has been proven to affect.
- What is the pathognomonic signs for this disease?
- Polioencephalomalacia (Salt toxicity)
- Pigs
- Histopathology shows laminar loss of cortical neurons, Laminar cortical malacia with abundant eosinophils present within the meninges and the perivascular spaces
Salt water - Direct
Indirect is where the animals are off water for a period of time but still eating, then suddenly get water back they can get this too
What are the Cushings Syndrome Clinical Signs?
- Hypertension
- Bradycardia
- Irregular breathing
- Obtunded
What is hypermetria?
a condition of cerebellar dysfunction in which voluntary muscular movements tend to result in the movement of bodily parts (as the arm and hand) beyond the intended goal — compare hypometria.
EG going to pretend to hit someone and meaning stop before them however you actally hit them
What are clinical signs of Cerebellar disease
- Unaltered (Normal) mental status
- Intention tremors (head and eye)
- Hypermetria with preservation fo strength
- Ataxia, wide based stance (IE Vestibular signs)
- Lozs of menace response
Which brain in this picture is the diseased one?
What is the disease?
Left brain has Cerebellar Hypoplasia
What is Cerebellar hypoplasia?
One of the most common congenital nervous system defects and is seen in all species.
IN cats, sheep and cattle : Feline panleukopaenia virus, Bovine Viral Diarrhoea virus and Border disease virus cause cerebellar hypoplasia through selective necrosis of the external granular layer cells
An animal has fine head tremors, head nodding and weaving at rest, stiff leggd incoordinated gait if forced to move.
What could this be?
Perennial ryegrass staggers caused due
to ingesting Mycotoxins (Lolitrems) produced by fungus (N. Lolii) in grasses. This causes axonal degeneration of some Purkinje cells within the cerebellum.
recovery takes about 3 months
Cerebellum Differentials
Degenerative/generic
Anomalous (Congenital abnormalities)
- Cerebellar hypoplasia
Metabolic
Neoplastic/Nutritional
Inflammatory (Infectious vs Sterile), Idiopathic
Toxic, traumatic/physical
- Perennial ryegrass staggers
- Annual ryegrass toxicity
- Cerebellar herniation
Vascular
Clinical signs of Brainstem and Cranial Nerve diseases
- Cranial Nerve Deficits
- Proprioceptive deficits
- Hemi or Tetraparesis
- Stupor or coma wuth abnormal pupil size
- Abnormalities in respiratory and cardiovascular function
If a carnivore has a Thiamine deficiency what part of the brain does this effect?
How does this come about?
- Brainstem
Diet low in thiamine or high in Thiaminases (Some fish) or where the vitamin B1 has been heated and destroyed
Leads to bilaterlly symmetrical Malacia (necrosis) of neurons within the caudal colliculi of the brainstem
this is a histo slide of a Cow brain what is the disease
What is important about this disease?
What are the infectious particles know as?
- Bovine Spongiform encephalopathies
- Zoonotic and notifiable Disease
- Prions
How does an animal get Listeriosis?
What are the 3 different disease syndromes that this bacterium can cause?
- Eating Silage which is infected with the bacterium, it travels up the trigeminal nerve into the brainstem.
- Uterine infection w/abortion
- Septicaemia with microscopic visceral abscess
- Encephalitis
What are some Spinal Cord Diseases
Degenerative/generic
- Equine degenerative myeloencephalopathy
- Intervertical Disk Disease (IVDD)
- Cervical Vertebral Stenotic Myelopathy
Anomalous (Congenital abnormalities)
Metabolic
Neoplastic/Nutritional
Inflammatory (Infectious vs Sterile), Idiopathic
Toxic, traumatic/physical
Vascular
- Fibrocartilagenous embolism
What could be wrong with this cat?
Diabetic Neuropathy
What type of paralysis does Tetnus cause?
What about Botumism?
- Spastic Paralysis not allowing the muscles to relax the problem is at the neuromuscular junction
- Flaciid paralysis - acetylcholine is blocked from being released stopping muscle contraction
What are the UMN signs :-
- Motor Function
- Muscle Tone
- Muscle Atrophy
- Reflexes
- Bladder
- Motor Function - Reduced
- Muscle Tone - Increased (Spastic)
- Muscle Atrophy - Slow and mild
- Reflexes - Increased / Spastic
- Bladder - Large, turgid, difficult to express
What are the LMN signs?
- Motor Function
- Muscle Tone
- Muscle Atrophy
- Reflexes
- Bladder
- Motor Function - Reduced
- Muscle Tone - Reduced
- Muscle Atrophy - Rapid and severe
- Reflexes - Reduced
- Bladder - Large, flacid, easy to express
With the following axon’s which ones give what signs with increased compression and what is their prognosis?
- Proprioception
- Voluntary Motor
- Superficial Pain
- Deep Pain
- Proprioception - Prorioceptive deficits - Good
- Voluntary Motor - Paresis, Paralysis - Fair
- Superficial Pain - Loss of Cutaneous Sensation - Fair
- Deep Pain - Loss of Deep Pain - Poor
What is a Myelogram for?
Xray with a special die that show the axons down the spinal cord, allows you to see a disk buldge
What is a Chondrodysplastic dog?
Dogs like Dashunds what are predisposed to IVDD
