Performing and interpreting the neurological exam Flashcards
What features can be observed in a neuro consult?
- Mentation
- Behaviour
- Posture
- Gait
Which parts of the brain is mentation linked to?
Forebrain or brainstem
What are the different types of mentation an animal may show?
- Alert: normal response to environmental stimuli
- Disorientated/confused: abnormal response to the environment
- Depressed/obtunded: less responsive to the environment
- Stuporous: unconscious but can be roused by painful stimuli
- Comatose: unconscious and unresponsive to any environmental stimuli
Disorientated mentation is linked to where?
Forebrain response as it is to do with decision making
Stuporous and comatose mentation’s are linked to where?
Brainstem changes
Give some examples of behavioural changes linked to the forebrain
- Aggression
- Compulsive walking/circling
- Loss of learnt behaviour e.g. urinating in the house when they are toilet trained
- Vocalisation
- Hemineglect syndrome: animals with structural forebrain lesions ignore half of their environment (contralateral) e.g. would only eat half of a food bowl
Name some examples of posture deficits
- Head tilt
- Head and/or body turn
- Decerebellate rigidity
- Decerebrate rigidity
- Schiff-Sherrington
Explain what a head tilt is and what/where its associated with
- Rotation of the median plane of the head with one ear lower than the other
- Vestibular disease (C or P): loss of tone to the antigravity muscles of the neck
Explain what a head and/or body turn is and what/where its associated with
- Median plane of the head remains perpendicular to ground but nose is turned to one side
- Forebrain disease (sometimes brainstem/cerebellum, cervical spine)
Explain what decerebrate rigidity is and what/where its associated with
- Extension of all limbs and opisthotonus (dramatic abnormal posture)
- Release of inhibitory UMN descending pathways on LMNs
- Lesion in rostral brainstem
- Usually stuporous or comatose
Explain what decerebellate rigidity is and what/where its associated with
- Hyperextension of TLs and opisthotonus
- Loss of inhibition of stretch reflex mechanism of antigravity muscles
- Lesion in rostral part of cerebellum
- Mentation normal; may be episodic or postural
Explain what Schiff-Sherrington is and what/where its associated with
- Hyperextension of TLs (maintaining voluntary movement and normal CP) and paralysis of PLs
- Lesion in thoracic or cranial lumbar spine
- Walk normally on the front legs and there is no movement of the hind legs
- Appear to be very rigid on the front legs but this is due to inhibition of the back legs
- Usually acute and is common with RTAs and falls
Describe the 3 possible locations of ataxia
Uncoordinated gait:
- Spinal or less commonly peripheral nerve disease
- Vestibular disease (“off balance”)
- Cerebellar lesions (“drunken gait”)
Describe spinal ataxia
- Usually more subtle
- Due to decreased sensory information arriving from the limbs to tell CNS where they are in space at any given time
- “Legs just don’t know where they are or what they should be doing”
- Wobble: feet are slightly in abnormal areas, might cross over as they walk
Describe vestibular ataxia
- Loss of orientation of the head with the eyes, neck, trunk and limbs and results in loss of balance
- Typically with leaning, falling, rolling towards side of lesion
- Have a marked head tilt that they lean towards
- Can be mild or more severe and can be acute or chronic
Describe cerebellar ataxia
- Typically with inability to regulate rate, range or force of movement – dysmetria
- Cerebellum functions as regulator (not initiator) of motor activity – coordinates and smoothes out movement
- Not weak but can be clumsy ‘drunk appearance’
- Truncal sway, falling
What are the two types of dysmetria?
- Hypometria (shorter protraction phase)
* Hypermetria (longer protraction phase)
What is paresis?
Weakness, reduced voluntary movement
- often will hear scuffing of feet
Describe non-ambulatory paresis
There is inability to support weight but when animal supported voluntary movement can be seen
What are the 4 localisations of paresis?
Tetra – all limbs
Para – pelvic limbs
Mono – 1 limb
Hemi – 2 limbs in same side
What is paralysis?
Complete absence of voluntary movement
Name some examples of postural reactions that can be performed in the neurological exam
Paw position Hopping Hip sway Wheelbarrow Extensor postural thrust Placing responses
How can spinal reflexes and muscle tone be assessed in the neurological exam?
- Withdrawals; extensor carpi radialis; biceps; triceps
- Withdrawals; patellar; cranial tibial; gastrocnemius; perineal
- Cutaneous trunci
Which tests can be carried out to assess cranial nerves in the neurological examination?
Palpebral; corneal; physiological nystagmus; menace response; nasal mucosa stimulation; PLR; gag
What is postural testing?
Testing awareness of precise position and movement of the body (especially limbs)
Which parts of the brain/spinal cord are being tested with postural testing?
- Information from proprioceptors (joints, tendons and muscles)
- → Contralateral forebrain (conscious perception) or ipsilateral cerebellum (unconscious perception)
- Problem could be in nerves, spinal cord, all of brain, everywhere! – very sensitive but poorly specific
What is the aim of testing spinal reflexes?
To classify lesion as Upper Motor Neuron or Lower Motor Neuron
How can spinal reflexes be assessed in the thoracic limb?
Withdrawals – pinch digit → reflex contraction of flexor muscles and withdrawal of limb
How can spinal reflexes be assessed using the cutaneous trunci, where can lesions be localised?
- Pinch the skin on the back to see contraction of the muscle
- T3-L3 lesions: Can get a ‘cut off’ point where the reflex stops/starts which can localise the lesion on the spine
- Brachial plexus lesions (C6 – T2): can get a hemi-cut off where the reflex works on one side of the body e.g. due to a brachial plexus rupture
What are some behavioural responses which indicate that pain is being percieved?
- Turning head
- Vocalising
- Trying to bite
- WITHDRAWAL IS NOT A SIGN OF PAIN – can get withdrawal without pain
How can you look for spinal pain?
- Palpate all spine, starting gently and progressively increasing the degree of pressure
- Move neck in all directions; look for pain and resistance/reluctance to move
- Move tail and palpate lumbosacral region
The palpebral reflex is testing which cranial nerves?
Blink after touching medial or lateral canthus of eye
- CN V Trigeminal (afferent)
- CN VII Facial (efferent)
The menace response is testing which cranial nerves?
CN II Optic (afferent)
CN VII Facial (efferent)
The pupillary light reflex is testing which cranial nerves?
CN II Optic (afferent) CNIII Occulomotor (efferent)
How can the corneal reflex determine if the loss in the palpebral reflex is due to the trigeminal or facial nerve?
If it was the trigeminal, when the cornea is touched nothing would happen, if it is a facial nerve problem, they wont blink but there will still be globe retraction
How is nystagmus elicited?
By moving the head
What is the most likely cause of loss of nystagmus?
Due to raised intracranial pressue
How can the vestibular system be challenged?
Lift head or put animal upside down
What is strabismus?
Abnormal position of the eyeball that the animal cannot overcome
What is nystagmus?
Rhythmical, involuntary movements of the eyeball
Describe the different types of nystgmus
- Physiological: normal in response to moving of the head (vestibular and CNs III, IV and VI)
- Jerk: with slow and fast phase – vestibular dysfunction
- Pendular: equal oscillations – visual pathway dysfunction
What are the signs of Horner’s syndrome in small animals?
- Miosis: tiny pupil
- Drooping of the upper eyelid with smaller palpebral fissure
- Protrusion 3rd eyelid
- Subtle bulging of the eyeballs
- Sometimes congestion of conjunctiva (lack of vasoconstriction)
- Warmth of skin, pinkness, decreased sweating
What are the signs of Horner’s syndrome in horses?
- Mild miosis
- Drooping of the upper eyelid with smaller palpebral fissure
- Subtle protrusion 3rd eyelid
- Decreased angle of eyelashes
- Excessive sweating in denervated area
Describe nasal mucosa stimulation and where its localised
- Touch nasal mucosa → head withdrawal
- Input – Trigeminal (V) ophthalmic
- Forebrain, brainstem
The menace only develops in animals at what age?
~10-12 wks in cats and dogs
~1-2 weeks in horses and ruminants
If the gag reflex is lost the patient will be prone to?
Aspiration pneumonia
Which 2 nerves are involved in the gag reflex?
Glossopharyngeal (IX) and Vagus (X)
