Neurology: SA Neurological Exam, Equine Neurological Exam, Interactive Flashcards
What are the three components of the neurological consultation?
History
Observation- mentation, behaviour, posture, gait
Hands-on- physical, neuro examinations
What are the different mentations?
Where does altered mentation indicate dysfunction?
Alert- normal response to environmental stimuli
Disorientated/confused- abnormal response to environment
Depressed/obtunded- inattentive, less responsive to environment
Stuporous- unconsciour but can be roused by painful stimuli
Comatose- unconscious, unresponsive
Altered mentation- forebrain or brainstem
Where does alteration of behaviour indicate dysfunction?
What behaviours can change?
Forebrain
- Agression
- Compulsive walking/circling
- Loss of learnt behaviour
- Vocalisation
- Hemineglect syndrome- ignore half of environment
Head tilt and Head and/or body turns are postural differences from neurological disease
How do they appear and where does it indicate disease?
Head tilt-
rotation on the medial plane of the head- one ear lower
Vestibular disease
Head and/or body turn-
Median plane of the head remains perpendicular to ground but nose to one side
Forebrain disease
What is decerebrate/decerebellate rigidity?
Where do they indicate lesions?
Decerebrare rigidity-
- Extension of all limbs
- Release of inhibitory UMNS descending pathways on LMNS
- Lesion in rostral brainstem
Decerebellate rigidity-
- Hyperextension of TLs and opisthotonus
- Loss of inhibiton of stretch reflex mechanism of antigravity muscles
- Lesion in rostral cerebellum
What is Schiff-Sherington?
What causes it?
Hyperextension of FLs, Paralysis of PLs
Interference with border cells- inhibitory neurons in cranial lumbar spinal cord that inhibit the FL extensor muscles
Lesion in thoracic of cranial lumbar spine
How can gait be affected?
What are the terms used?
Ataxia- uncordinated gait- drunk
Paresis- weakness, reduced voluntary movement
ambulatory- falling but can walk
non-ambulatory- weight needs supporting
Paralysis- complete loss of voluntary movement
What are the three causes of ataxia?
Spinal ataxia- usually subtle, due to decreases sensory information from limbs to CNS to know where they are
Vestibular ataxia- loss of orientation of the head with eyes, neck, trunk and limbs, causing loss of balance- leaning, falling, rolling
Towards side of lesion
Cerebellar ataxia- typically with inability to regulate rate, range or force of movement, dysmetria [overshooting]
How can paresis be further described?
Tetra- all limbs
Para- pelvic limbs/hind limbs
Mono- 1 limb
Hemi- same side
What are the 4 parts of a hands-on neurological examination?
Postural reactions
Spinal reflexes and muscle tone
Spinal pain
Cranial nerve examination
What is postural testing?
What is it useful for?
What are the 3 postural reactions tested?
Testing awareness of prescise position and movement of the body
Useful to first identify a problem but not specific
- Paw position- turn paw so dorsal surface bears weight, see how quickly returned
- Hopping- support 3 limbs and hop laterally, hipsway/wheelbarrow
- Placing responses- pick up patient and bring limbs to edge of table so that dorsal surface touches surface
What are spinal reflexes used for?
What are the two types of reflexes used in fore and hindlimbs?
How do they differ between FL and HL?
What is the cutaneous trunci reflex and what is it useful for?
Used to classify lesion as UMN or LMN- look at muscle bulk and tone, evaluate reflexes in FLs/HLs
Withdrawals- pinch digit, contraction of flexor muscles and limb should withdraw- Same for HL/FLs
Myotatic- strike muscle, contraction
FL- extensor carpi radialis, biceps, triceps
HL- patellar, cranial tibial, gastrocnemius
Cut trunci-pinch skin on back- contraction of muscle on both sides, usefil for T3-L3 lesions, brachial plexus lesions
How is pain perception assessed?
What is the perineal reflex?
Pain perception-
Gentle squeeze of digit, look for behavioural response (head turning, vocalisation)
Perineal-
Stimulation of perineum with haemostat should cause contraction of anal sphincter
How is spinal pain assessed?
Palpate all the spine, starting gently and progressively increasing the degree of pressure
Move neck in all directions- look for pain or resistance to move
Move tail and palpate lumbosacral region
What are the different cranial nerve examinations that can be done?
For each test list the afferent nerve, intermediate location and efferent nerve
Palpebral reflex- V, brainstem, VII
Corneal reflex- V, brainstem, VII /VI
Physiological nystagmus- VII, brainstem, III/IV/VI
Menace response- II, forebrain/cerebellum/brainstem, VII
Nasal mucosal stim- V, forebrain/brainstem
PLR- II, brainstem, III
Gag reflex- IX and X, brainstem, IX and X
Describe how to do a palpebral reflex test
Describe how to do a corneal reflex test
What is a physiological nystagmus?
What commonly causes a lost/reduced effect?
Palpebral- Touch medial/lateral canthus of the eye- blink
Lightly touch cornea- blink and eye retraction
Nystagmus- elicited by moving of head
Vestibular eye movement- lift head or put animal upside down
Look for evoked stabismus/nystagmus
Raised/lost most commonly due to raised intercranial pressure
What are the input and output nerves for corneal and palpebral reflexes?
How can you use this to diagnose nerve dysfunction?
Input for both- trigeminal
Output-
Facial (VII)- blink- both
Abducens (VI)- globe retraction- corneal only
- If blink normally on both tests but doesn’t retract globe- abducens dysfunction
- If retracts globe normally but doesn’t blink for either trigeminal fine therefore facial dysfunction
- If neither tests result in reflex- likely trigeminal
What is strabismus and Nystagmus?
How can they both be futher described?
Stabismus- abnormal position of the eyeball that the animal cannot overcome
Nystagmus- rhythmical, involuntary movements of the eyeball
Strabismus- resting or evoked
resting- CNs III, IV, VI dysfunction
evoked- positional, vestibular dysfunction
Nystagmus- physiological, jerk, pendular
physiological- normal in response to moving of head
jerk- slow and fast phase- vestibular dysfunction
pendular- equal oscillations- visual pathway dysfunction
Describe horner’s syndrome in SA and Horses
Small animals-
- Miosis- pupil constriction
- Ptosis [drooping] of the upper eyelid with smaller palpebral fissure
- Protrusion 3rd eyelid
- Subtle enophthalmos- posterior displacment of eyeball
- Sometimes congestion of conjunctiva
- Warmth of skin, pinkness
Horse-
- mild miosis
- Ptosis of upper eyelid with smaller palpebral fissure
- Subtle protrusion of 3rd eyelid
- Decreased angle of eyelashes
- Excessive sweating in denervated area
Describe how to do a nasal mucosa stimulation?
How do you do a menace response?
When can a menace response test not be done and why?
What is a pupillary light reflex?
How is a gag test done?
NMS- Touch nasal mucosa- head withdrawal
Menace- menacing gesture, cover other eye- blink
Not a reflex, learnt- takes 10-12 weeks in SA, 1-2 in horses
PLR- shine light into eye- constriction of pupil and other side (consensual)
Gag- open mouth or touch pharynx- contraction of pharynx
What is wanted to be extracted from an equine neurological examination?
Is the horse neurologically normal
Where is the lesion
What is it
What can be done
What are the limitations of equine neurological examinations?
Size
Behaviour/ danger
Recumbancy
What should be assessed about a horse for a neurological exam from a distance?
Mentation- curious, paying attention/ dropped head, depressed, head pressing (forebrain)
Behaviour- aggression, compulsive walking/circling, loss of learnt behaviour, vocalisation
Posture- head tilt, head or body turn, wide-base stance
How can the following cranial nerves be tested?:
- Olfactory
- Optic
- Trochlear
- Trigeminal
- Abducens
- CN I- difficult, polo mint test
- CN II- sight, menace, PLR (less obvious), very good at compensating with one eye for bad sight
- CN III- PLR, eye position with vestibular system
- CN IV- eye position with vestibular system
- CN V- mastication muscle atrophy, facial sensation- palpate and observe response
- CN VI- eye position with vestibular system
How can dysfunction of CN VII be assessed?
Facial nerve- muscles of expression, sensory tongue/ear
Muscles of facial expression- ears, eyes, blinking, dilation of nostrils, lips
Assess facial symmetry
Palpation can be useful
How can CN VIII be assessed?
What is the most common sign of dysfunction?
Head posture- dysfunction= tilt
Induced eyeball movment
Normal vestibular nystagmus (following train)- hold horses head and move side to side- should keep rhythmically moving
Normal gait- dysfunction=ataxic
Blindfold to eliminate eyes of vestibular
Hearing- clap to see it ears move
Dysfunction- ventral strabismus
How can CN IX, X and XI be assessed?
How can CN XII be assessed?
Let the horse eat some grass
Sensory and motor to pharynx and larynx-
Swallowing, can endoscopy
Slap test- adduction of horses contralateral arytenoid cartilage
XI motor to trapezius and cranial sternocephalicus
XII- tongue size, tone and symmetry
How is the neck, trunk, back, tail and anus assessed for a neurological exam?
- Observation and palpation of neck and back- atrophy, asmmetry, swelling
- Range of movements of neck and back- use food, not if fracture suspected
- Cervicofacial reflex- poke neck with pen, twitches lips- some do some don’t- asymmetry
- Testing back flexion- pen on withers and rub in midline- horses should dip then arch at lumbar area, pen in sternum
- Cutaneous trunci reflex- gently touch flanks, horse should shake skin (flies), if not present move cranially
- Perineal reflex, tail clamp, anal tone
- Male external genitalia- penis not retracting
- Rectal- assess lumbar, sacral vertabrae and bladder volume and tone
What are the two broad causes of abnormal postures in horses?
Orthapaedic problem- broken leg
Neurological-
Loss of spatial awarness- doesn’t correct
Inability to move limb
What are you looking for with gait of a horse in neuro exam?
What is ataxia?
Looking for abnormalities in spontaneous and induced, posture and movement interpreted as ataxia and weakness
Ataxia- subconscious proprioceptive defecits seen as irregular or unpredictable movement
What are signs of ataxia in horses?
How can signs be exaggerated?
What are the 3 places of origin for ataxia?
Signs- poor coordination, swaying, limb moving excessively during swing phase
Exaggerated by tight circles- pivoting, circumduction, serpentine, sudden stopping, backing
Cerebellar, Vestibular or Spinal origin
What signs are associated with ataxia in horses with the cerebellum, vestibular system and spinal?
Cerebellar- uncommon
No weakness
Hypermetric ataxia- accelerated range of movements
Other signs- tremor, lack of menace
Vestibular
Loss of balance, hypometric ataxia, wide based
Other signs- head tilt, nystagmus
Spinal-
Dysmetric ataxia
+/- weakness
How are equine ataxia defectits classified?
- Subtle- just barely detected at normal gait, occur during backing, stopping, turning
- Mild- detected at normal gate, exagerated by above movements
- Moderate- prominent at normal gait, buckle with above movements
- Severe- tripping and falling spontaneously at normal gait
What creates weakness?
What are the different types in horses?
What can cause them?
Interruption to general somatic efferent (motor) pathways
Extensor weakness- sinking/buckling, weak when pulling tail
Flexor weakness- toe drag/delay, swinging movement
Motor tract lesion- UMN- tail pull during movement
Motor neuron- LMN- tail pull at rest
Timmy a border terrier has the following symptoms:
Obtundation- dull
Right circling
Abscent proprioception in left limbs- paw position
Abscent menace response in left eye
Reduced facial ensation in left side
What is the location of the lesion?
Right Forebrain
Circle towards lesion- right
Proprioception contralateral
Vision contralateral
Max has the following symptoms:
Ataxia with leaning to the right
Head tilt to right
No proprioceptive defectits
Right positional strabismus
Spontaneous nystagmus with fast left phase
Where is the lesion?
Right Peripheral Vestibular System
Signs of central vestibular disease- multiple cranial nerves affected not seen, proprioceptive defecits
No cerebellar signs- truncal sway, tremors
Milly has the following neurological signs:
Mild leaning to the right
Right head tilt
Hypermetria left thoracic limb
Clumsy hopping on left limb
Where is the lesion?
Left Cerebellum
Hypermetria- cerebellum
Paradoxical head tilt- opposite side
Proprioception on the same side- left
Gingerboy- cat
No menace bilaterally
No PLRs bilaterally
Normal proprioception
Normal fundus exam and ERG- retina and fundus normal
Where is the lesion?
Optic chiasm or Bilateral CN2 (optic nerves)
If both PLR and menace affected- must be cranial to chiasm
Buster
Generalised ataxia with hypermetria
Reduced proprioception in all limbs
Owners has seen 3 seizures- difficult to train
Where is the lesion?
Multifocal
Cerbellar- hypometria, ataxia, can give reduced proprioception
Seizures- forebrain, behaviour
Bertie
Absent proprioception in hindlimbs
Normal in forelimbs
Spinal reflexes unaffected
Absent pain sensation in pelvic limbs
Cutaneous trunci cut-off
Localise the lesion
T3-L3
Forelimbs not affected- must be caudal to T3
Reflexes intact L4-S3 normal
Natasha- cat
Tetraplegia- possible slight movement
Proprioception absent/reduced in all limbs
Normal spinal reflexes in pelvic limbs
Reduced spinal reflexes in thoracic limbs- some pain
Where is the lesion?
C6-T2
All limbs- cranial to T3
At reflexes in forelimbs reduced- must be C6-T2
Sam
Monoparesis left forelimb
Absent spinal reflexes in left FL
Reduced sensation in left FL
ipsilateral Horner’s syndrome
Where is the lesion?
Left brachial plexus- neuropathy
Not C6-T2 should affect back leg on left side
Charlie
Flaccid tetraparesis/plegia
Absent spinal reflexes in HL/FL
Abnormal bark
Where is the lesion?
polyneuropathy- diffuse
Cannot be C6-T2- reflexes on HL reduced
Minky
Weakness
Stiff, stilted gait
Normal neural exam
Where is the lesion?
Myopathy- no neurological defecits
