Neurological examination and brainstem

What are the 4 steps to a neurological exam?

1. general examination

2. head and cranial nerves

3. trunk and spine

4. limbs

What do we mean by a general examination?

• general observation of the animal in a hands-off manner and obtaining information from the owner

• taking a detailed history (need video footage from the owner)

• observe the animal upon approach to the room: its interaction with the owner and it’s surroundings

what are we assessing in the general examination stage?

• mental status

• posture

• gait

• muscle condition

• response to surroundings

what should we be able to conclude from the general examination?

• probable location and extent of nervous system dysfunction that we can assess with the rest of the exam.

what are the 5 levels of consciousness

1. normal

2. confused and disorientated

3. depressed

4. stuporous

5. comatose

If an animal is circling in one direction, where does this indicate the lesion it?

• lesion is on the side of the brain that the animal is circling towards

what do we do to test CNI

• smell

• not easy to test

• waft food and see if the animal follows it?

How do we test CNII

• consciousness

• vision

• menace response (also VII)

• visual placing

• fixating response

how do we assess CNIII

• PLR (II afferent, III efferent)

• anisocoria

• strabismus

what is anisocoria

• different sized pupils in each eye

what are the 2 pathways of PLR

• direct = efferent pathway

• consensual/indirect = afferent pathway

how do we assess CNIV

• strabismus

How do we assess CNV

• skin sensation (jaw tone)

• palpebral reflex (V, VII)

• corneal reflex (V, VII)

How do we assess CNVI

• strabismus

How do we assess CNVII

• facial muscle symmetry

• lacrimal gland function

• nasal gland function

How do we assess CNVIII

• hearing and nystagmus

• nystagmus (III, IV, VI too)

How do we assess CNIX

Swallowing (gag)

How do we assess CNX

• laryngeal function (bark)

• GI function

How do we assess CNXI

• neck position

• muscle tone

How do we assess CNXII

• tongue position and tone

Fill in the gaps

1. olfactory

2. optic

3. vision

4. trigeminal

5. three

6. sensation

7. facial

8. expression

9. salivation

10. vestibulocochlear

11. glossopharyngeal

12. parasympathetic

13. vagal

14. accessory

15. hypoglossal

16. intrinsic

What supplies the afferent pathway of the palpebral response

• CNV

what nerve supplies the efferent response of the palpebral reflex

• CNVII

What kind of strabismus do we see if CNIII is damaged?

What muscles are affected?

• lateral and ventral

Muscles = dorsal rectus, medial rectus, ventral rectus and oblique

What kind of strabismus do we see if CNVI is damaged?

What muscle(s) is affected?

• medial

Muscle = lateral rectus

What kind of strabismus do we see if CNIV is damaged? What muscles are damaged?

• rotational

Muscle = dorsal oblique (only 1 muscle affected)

What kinds of spontaneous nystagmus are there, what is it concurrent with?

• horizontal

• vertical

• rotational

• spontaneous nystagmus is concurrent with a vestibular lesion

Outline the neuronal pathway of the PLR response

1. optic nerve

2. optic chiasm

3. optic radiation

4. pre-tectal nucleus

5. Edinger-Westghal nucleus

6. CNIII

7. ciliary ganglion

What is the swinging test?

• swing the light from eye to eye, resting for a few seconds at each eye.

What are some symptoms of horner’s syndrome in cats?

• ptosis

• miosis

• enophthalmos

What can also indicate Horner’s syndrome in horses

• ipsilateral excessive sweating

What can indicate Horner’s syndrome in cows?

• Ipsilateral dry nose

Outline the menace response (afferent, efferent supply and what it does)

• It causes a blink response to a threatening stimulus of the eye

• AFFERENT SUPPLY = CNII

• EFFERENT SUPPLY = CNVII

what do we need to prevent when conducting a menace response and why

• need to prevent a draught/airflow

• stimulates a corneal response

what are the brain regions involved in the menace response?

• conscious visual pathway

• contralateral visual cortex

• contralateral motor cortex

• ipsilateral cerebellar hemisphere

Outline the components of the menace response pathway

Visual threat → optic nerve → visual cortex → motor cortex → cerebellum → facial nerve

During the menace response to which sides of the brain do the nervous impulses travel?

• impulse crosses over to the contralateral side through the optic chiasm (some decussation) → visual cortex

• returns to ipsilateral side when it enters the cerebellum from the motor cortex

what do we test when we have an absent menace response?

• palpebral reflex

• Absent menace but present palpebral = CNVII problem

Why do we use a fixating response?

• able to demonstrate conscious vision of a patient

Outline the pathway of conscious vision

• optic nerve → lateral geniculate nucleus → optic radiation → occipital cortex (prosencephalon)

What Cn is associated with the Schirmer Tear Test and how?

• CNVII
  Parasympathetic function, lacrimal function is tested by doing an STT

What are the aims of assessing the trunk and what stage of the neurological exam is this?

• Identifying any focal regions of pain or dysfunction by careful manipulation

• Step 3 of the neurological exam

How do we assess the trunk?

1. panniculus response (from scapula to pelvis)

2. spinal manipulation

3. palpation

what is the panniculus response?

• Pinch the skin on either side of the spine (one side at a time)

• Cutaneous trunci muscle causes muscle contraction

• should be able to see this response from the scapula to the pelvis

What degree of manipulation should we get in the spine

• get head parallel to spine laterally

• get head fully vertical to the ground

What do we do when palpating the spine

• wings of the atlas

• down the sides of the vertebrae (one side at a time)

• press down onto the spinous processes

What is stage 4 of the neurological evaluation and what 4 things do we assess?

Stage 4 = limb evaluation

• proprioception

• sensation

• segmental reflexes

• muscle mass and tone

What are 6 proprioceptive tests we conduct?

1. knuckling

2. hopping

3. hemiwalking

4. tactile placing

5. paper slide

6. extensor postural thrust

What is knuckling and what should we see?

• a weight bearing/pain free paw is placed with dorsum on the ground

• there should be a return to normal positioning

What is hopping and what should we see?

• Hold one limb up against the trunk and move the body outside the line of balance

• there should be a rapid and accurate sideways repositioning of the limb

what is Hemiwalking and what should we see?

• both limbs on one side of the body are held up against the trunk

• see more subtle changes on a single limb hopping

What is tactile placing and what should we see?

• the animal is brought up to the edge of a table whilst blindfolded

• when the limbs touch the edge of the table they should be accurately placed immediately

What is paper sliding and what should we see?

• place a limb onto a piece of paper and pull the paper laterally

• weight bearing/pain free paw is moved to the outside the body and the limb should rapidly and accurately be returned to a normal position

What is the extensor postural thrust and what should we see?

• dog is lifted off the ground and replaced on the table

• as the hindlimbs touch the table there should be a reflex extension of hindlimbs which also precipitate the dog to step backwards (makes the dog look like it jumps)

How do we conduct an ECR myotatic reflex

• percuss the muscle belly (Extensor carpi radialis)

• should see the carpus reflex extension

How do we conduct a myotatic reflex for the biceps?

• percuss a finger/thumb which is pressing onto the tendon of insertion of the biceps

• reflex contraction generates: flexion of the elbow (not always seen), increased tension at tendon of insertion and movement of skin over muscle belly/visible contraction

How do we conduct a myotatic reflex for the triceps

• percuss a finger/thumb onto tendon of insertion

• reflex contraction of the triceps generates: reflex extension of the elbow (sometimes) and movement of the skin over muscle belly/visible contraction

How do we conduct a myotatic reflex for the patella

• percuss the straight patellar tendon

• reflex extension of the stifle

How do we conduct a myotatic reflex for the cranial tibial

• percuss muscle belly, see a reflex flexion of the hock

What receptor organ is used to initiate a myotatic reflex

• muscle spindle

what peripheral nerve is tested by the biceps reflex

• musculocutaneous

Which peripheral nerve is tested by the triceps reflex

• radial

which peripheral nerve is tested by the ECR reflex

radial

Which nerve is tested by the patellar reflex

• femoral

which peripheral nerve is tested by the cranial tibial reflex

sciatic

How can we use muscle contraction to determine if we’ve got an UMN or LMN lesion?

• LMN cause spasms - continual contraction of the muscle

• UMN usually inhibit these

Therefore:

• if we’ve got a LMN lesion = no spasms/weakness, rapid muscle atrophy, reduced reflexes, low tone

• if we’ve got an UMN lesion = spasm, increased/normal reflexes, high tone and slow muscle atrophy

what are indicators of a LMN lesion?

• rapid muscle atrophy

• reduced reflexes

• low tone

What are indicators of an UMN

• slow muscle atrophy

• increased/normal reflexes

• high tone

what is withdrawal/sensation

• squeezing toes tests: a) sensation and b) strength of withdrawal

what is a withdrawal reflex

• local segmental reflex

what is necessary to confirm the presence of sensation

• demonstrable cortical resposne

are sensation and withdrawal independent of each other and why/why not?

• yes they are

• it’s for the necessity of integrity of the peripheral nerves

what are the 3 tests for the lumbosacral spinal cord

1. perineal reflex

2. anal tone

3. tail tone

what should we be aware of with neurological tests of dogs vs cats?

• many cats won’t tolerate the restraint and invasion of personal space needed for a thorough neurological exam

• choose 3 tests that will most likely confirm the lesion localisation and severity

Name the parts of the brain stem

• midbrain

• pons

• medulla oblongata

• tectum

• tegmentum

• basilar area

What do we find in the midbrain

Basilar portion: crus cerebri

Tegmentum: red nucleus, nuclei of CNIII-IV

Tectum: superior and inferior colliculi

what do we find in the pons?

Basilar portion: descending tracts, pontine nuclei

Tegmentum: Ascending tracts, nuclei of CNV-VIII

hat do we find in the medulla oblongata

Basilar portion: pyramids, inferior olivary nucleus

Tegmentum: gracile and cuneate tubercles, nuclei of CN IX,X,XII

How is the brain stem vascularised?

Arteries: vertebrobasilar system

Veins: deep plexus that drains into several veins

What are the general functions of the brain stem?

• breathing regulation

• circulation

• consciousness

• audio-visual reflexes

• balance and co-ordination

• passageway for ascending and descending tracts

• houses cranial nerve nuclei

what part of the brain stem controls the cardiovascular system

• medullar oblongata

what part of the brain stem controls the respiratory system

medulla oblongata

what part of the brain stem controls pain

• periaqueductal nuclei

• rostral ventromedial medulla

what part of the brain stem controls alertness, awareness and consciousness?

• midbrain (via CNIII and CNV)

what part of the brain stem controls the communication b/w cerebrum and cerebellum

pons

What do we notice in this diagram about a)ascending pathways and b) descending pathways

a) ascending pathways pass through the brainstem

b) descending pathways include upper motor neurones synapsing on the lower motor neurones in the ventral and intermediate horn of the spinal cord

What are the 4 kinds of haemorrhage

1. subdural

2. extradural

3. subarachnoid

4. intracerebral

Give some examples of causes of subdural haemorrhage

• head trauma

• coagulation problems

• rupture of the bridging veins

Give some examples of causes of extradural haemorrhage

• trauma to temporoparietal region

• rupture of middle meningeal artery

Give some examples of causes of subarachnoid haemorrhage

• arterial bleed - spontaneous or associated trauma

Give some examples of causes of intracerebral haemorrhage

Also known as haemorrhaging stroke

• bleeding from a ruptured blood vessel: intraparenchymal or intraventricular

what are the different ways we can treat brain tumours in dogs

• surgery

• radiation

• symptomatic management

• surgery and radiation

• surgery and chemotherapy

• solely chemotherapy

What are peripheral vestibular disorders

• pathology of the inner ear vestibular structures as well as the vestibular portion of CNVIII

• it diminishes available sensory information regarding head position and movement

What are central vestibular disorders

They involve:

• vestibular nuclear complex and cerebellum

• structures of reticular activating system

• midbrain

• higher centres of cortical function

Affects:

• integration and processing of sensory input from vestibular, visual and somatosensory systems

what are examples of the most common CVD?

Most common CVD:

• strokes

• head trauma

• migraine related vestibulopathy

• multiple sclerosis

• cerebellar degeneration

what do both CVD and PVD affect and what symptoms may they cause?

• reduce appropriate neural output for spatial orientation, postural control and eye movement control

May see:

• dizziness

• imbalance

• falls

• visual blurring (oscillopsia)

what is Ischaemia

• decreased blood supply to tissues

• leads to a decrease in oxygen and nutrients to the area → necrosis

what is a stroke

• when blood flow is restricted to a part of the brain

what 2 causes of strokes are there

1. ischemic = blocked vessed

2. haemorrhagic = bleeding

what can we refer to the midbrain as?

• mesencephalon