Chapter 26 Neurologic Examination and Neuroanatomic Diagnosis Flashcards
What is the difference between resting and poitional nystagmus
Resting aka spontaneous when head in any position
Positional as it sounds. Often sen in patients with chronic lesions of vestibular system which patient has accomodated for
Which nerves are tested with TL withdrawal-flexor reflex, what SC segment does this represent?
And PLs?
Thoracic limb: Dorsal thoracic, median, axillary, radial, musculocutaneous and ulnar nerves (M.A.R.M.U.)!
C6-T2
N.B. C1-C5 lesions can –> loss of withdrawal reflex too, unclear why
Pelvic limb: Sciatic nerve
L6 - S1
What is the funstion of the ascending reticular activating system (ARAS)?
Arousal of forebrain
Physiologically speaking, why does ataxia usually accompany UMN paresis?
Because most of the key upper motor neuron pathways that function in gait generation (–> paresis) are antomically adjacent to general proprioceptive pathways (–> ataxia).
i.e. if ataxia seen, then assume UMN paresis also exists.
List the necessary components of an intact spinal reflex
Sensory receptor, sensory nerve, dorsal nerve root, SC segment, ventral root, motor nerve, NMJ, muscle
Which nerve is tested with triceps tendon reflex, what SC segment does this represent?
Radial nerve
C7 - T2
List the 8 steps of the neuro exam
- Mentation
- Posture
- Gait
- Postural reactions
- Spinal reflexes
- Cranial nerves
- Palpation
- Nociception
Comment on postural reactions in neuromuscluar disroders
May be normal as beckause general proprioceptive pathway intact
List the grading of the modified Frankel score
List the 6 Csteps of CN assessment, according to tobias
- Vision + PLR
- Palpebral fissure + eyelid symmetry
- Eyeball position and movement
- Vestibular function
- Facial and trigeminal nerve function
- Tongue and laryngeal/pharyngeal n function
Which nerve is tested with biceps tendon reflex, what SC segment does this represent?
Musculocutaneou snerve
C6-C8
List 6 postural reaction tests
- Hopping
- Paw placement
- Tactile placing (edge of table)
- Extensor postural thrust
- Wheelbarrowing
- Hemi-walking
List each CN, its function, how its tested and clinical signs of dysfunction
Define paresis
Define plegia
Paresis: Reduced ability to support weight or a deficiency in the ability to generate gait. Implies the presence of voluntary motor function
Plegia: Absence of voluntary motor function
What two sites is appropriate mentation dependent upon?
Forebrain + brainstem (ascending reticular activating system)
What 3 CNs are evaluated with gag reflex?
Glossopharyngeal, vagus, hypoglossal
Are pre-ganglioninc parasympathetic nerves long or short?
Long. Then synapse near organ –> post-ganglionic nerve
Vice versa in sympathetic
List the cranial nerves.
N.B all but CN II are peripheral nerves!
I Olfactory
II Optic (only one that isn’t peripheral nerve - is extension of diencephalon. Affected by CNS disease)
III Oculomotor
IV Trochlear
V Trigeminal
VI Abducens
VII Facial
VIII Vestibulocohlear
IX Glossopharyngeal
X Vagus
XI Accessory
XII Hypoglossal
which nerve is involved in perineal reflex?
Pudendal nerve (sacral and caudal segments)
What are the 8 possible neurolocalisations?
- Forebrain
- Brainstem
- Cerebellum
- C1 - C5
- C6 - T2
- T3 - L3
- L4 - S3
- Neuromuscular (nerve, NMJ, muscle)
Which cranial nerves have parasympathetic function?
III Oculomotor (pupil constriction)
VII Facial (Lacrimation, mandibular salivary, nasal glands)
IX Glossopharyngeal (salivary glands)
X Vagus
Which nerve is tested with patella tendon reflex, what SC segment does this represent?
Femoral nerve
L4 - L6
(NB may be absent in normal, older dogs)
How many vertebrae in each section:
Cervical
Thoracic
Lumbar
Sacral
Caudal
Cervical 7 (N.B. 8 Cervical spinal nerves through as 1st one exits through lateral vertebral foramen of atlas, second nerve exits at caudal aspect of C1)
Thoracic 13
Lumbar 7
Sacral 3
Caudal ≥2
From what spinal cord segment does sympathetic innervation to eye originate (i.e. Horner’s)?
Describe symathetic pathway
T1 - T3
T1 - T3 –> brachial plexus –> join descending fibres of vagus in vagosympathetic trunk –> cranial cervical ganglia -> cranial cavity (via petrous portion of temporal bone, then course with axons of ophthalmic branch of trigeminal nerve) –>orbital fissure –> dilator m of pupil.
UMN system facilitated function of pre-ganglionic sympathetics. This originated in hypothalamus and descends in lateral funiculus.
In TL, which nerve(s) innervate skin of palmar surface of paw?
And lateral digit V
Dorsal paw?
Cranial lateral antebrachium?
Caudal and medial antebrachium:
Palmar surface of paw: Median and Ulnar n
Lateral digit V: Ulnar n.
Dorsal paw: Radial n.
Cranial and lateral antebrachium: Radial n.
Caudal and medial antebrachium: Ulnar and Musculocutaneous n.
What is the crossed extensor reflex?
When standing, flexion of one limb results in increased muscle tone in contralateral limb (to support added weight).
Shouldn’t happen in lateral recumbency - is inhibited by descending UMN input.
If UMN lesion present withdrawal in one limb may –> crossed extenor reflex in other limb (lesion on side of extended limb i.e. lost inhibition onthat side)
What is likely ddx for T3-L3 lesion –> lower motor neuron signs…
What is proposed mechanism
Spinal shock. usually <48 hours
Often accompanied by Schiff Sherrington. If not usually due to FCE
Suspected due to transient disconection between facilitatory descending UMNs that modulate LMN of lumbar intumesence and spinal motor neurons.
Name the three primitive areas of neural tube which become brain
Prosenecephalon
Mesencephalon
Rhombencephalon
In central vestibular ataxia, what other structures may be affected and why (anatomically speaking)
Central vestibular ataxia (lesion vestibular nuclei in rostral medulla): Imaired CN V and CN VII function as these CN nuclei adjacent in vestibular nuclei.
Peripheral vestibular ataxia: CN VII and loss of sympathetic innervation to head because nerves adjacent to vestibular nerve as they pass through middle ear (think cats with VBO –> Horner’s!)
i.e. both can have CV VII deficits
What are the four levels of mentation?
Appropriate
Obtunded
Stuporous
Comatosed
(Disoriented)
List the innervation to the pupil and extrinsic muscles of the eye
In Pl, which nerve(s) innervate skin of dorsal surface of paw?
Plantar surface of paw?
Medial aspect of PL?
Digit 1?
Dorsal surface of paw: Fibular n. (branch of sciatic)
Plantar surface of paw: Tibial n. (branch of sciatic)
Medial aspect of PL: Saphenous n. (branch of femoral)
Digit 1: Usually saphenous n. but in some patients saphenous innervation staops at hock
Describe decerebrate rigidity and the usual neuolocalisation of the cause.
And decerebellate
And Schiff-Scherington
Decerebrate: Opisthonous with rigid extension of all four lesions. Comatosed (i.e. mentation always affected). Usually due to midbrain or rostral cerebellar lesions)
Decerebellate: Opisthonous and extensor rigidity of limbs but hips flexed (mentation not necessarily affected). Usually due to severe cerebellar lesions)
Schiff-Scherington: Extensor rigidity of thoracic limbs, paresis or pelvic limbs, normal mentation. Due to peracute T3-L3 lesion. Means lesion is severe but posture is not prognostic.
Describe the pathophys of Schiff Scherinton posture
Schiff-Scherington: Due to peracute T3-L3 lesion. Leads to disruption of ascending inhibitory axons, which arise from interneurons aka “Border cells”. These interneurons are located in dorsolateral border of ventral grey column of spinal cord, at L1-L4 level.
Describe menace response pathway
Retina –> Optic nerve –> Optic chiasm (moves to contralateral)
–> Optic tract –> Lateral geniculate nucleus –> Optic radiation to occipital lobe (n.b. sensory only lobe) –>
Association fibres –> Motor cortex (frontal lobe)
–> Projection fibres –> Pontine nucleus –> Transverse fibres of pons (back to ipsilateral)–> Cerebellar cortex –> Efferent cerebellar fibres –> CN VII nucleus
–> Facial nerve –> Obicularis oculi –> blink!
What neuroanatomic localisation is typical of hypertonia?
And hypotonia?
UMN –> hypertonia
Neuromuscular –> hypotonia
Which is the sensory nerve tested with vestibulooclear reflex?
And motor?
CN VIII (Vestibulochoclear)
Abducens and oculomotor
What do the prosencephalon, mesencephalon and rhombencephalon develop into (both anatomical and laymans terms)
Prosencephalon –> Telencephalon = Cerebrum
–> Diecephlon = Thalamus + Hypothalamus
Mesencephalon –> Mesencephalon = Midbrain
Rhombencephalon –> Metencephalon = Pons + Cerebellum
–> Myelencephalon = Medulla oblongata
Which branch of facial nerve mediated motor function of palpebral reflex
Palpebral branch
Which CNs arise from the following locations:
Midbrain
Pons
Medulla oblongata
Midbrain: III and IV
Pons: V (only one arising form here so can figure out the rest from here).
Medulla oblongata: VI - XII
Which branches of the trigeminal nerve innervate (sensory) these three parts of the face?
Which branch has motor function and what is is?
Opthalmic, maxillary and mandibular
Mandibular branch o ftrigeminal also provides motor innervation to muscles of mastication
What is the pathophysiology of ptosis, third eyelid elevation in Horners (i.e. loss of sympathetic innervation)
Loss of orbital smooth muscle tone
What does pleurosthonus mean
Deviation of head and neck to one side (may be seen with mid-rostral brainstem lesions)
Is ataxia caused by a lesion caudal to the midbrain ipsi- or contra-lateral
Ipsilateral
How can vestibular ataxia be further categorised?
How is one distinguished from the other?
Lesions affecting which anatomical structures can lead to each type of vestibular ataxia
Central or peripheral
Central vestibular ataxia:
- Ipsilateral UMN paresis
- General proprioceptive ataxia present
- Lesion affecting vestibular nuclei in rostral medulla.
Peripheral vestibular ataxia:
- Patient maintains normal strength and general proprioception
- Lesion affecting sensory receptor for special proprioception contained in inner ear or CN VIII
Where within the SC do ascending impulses run?
Ipsilateral dorsal and dorsolateral funiculi
What are the 4 spinal cord segements?
- C1 - C5
- C6 - T2
- T3 - L3
- L4 - S3
List the two possible neurolocalisations of loss of nasal mucosal sensation
ipsilateral trigeminal nerve
contralateral cerebrum
List the 6 finger rule
- Signalment
- Onset
- Progression
- Lateralisation
- Pain
- Neurolocalisation
List the pathway for cutaneous trunci reflex
Segmental sensory nerve (from level of L3/L4 (approx wing to ilium, to cranially i.e. not present caudal to this)
Enters SC approx 2 SC segments cranial to area tested
Ascends SC to C8 - T1
Efferent motor nerve = lateral thoracic n.
Useful to diagnose level of TL SC lesion or progression eg myelomalacia
List the typical progression of clinical signs with increasing severity of SC lesion
Loss of general proprioception
Loss of voluntary motor function
Loss of bladder function
Loss of nociception
What are the three types of ataxia?
Vestibular, cerebellar, proprioceptive
Fine whoel body tremor is the neuro sign most commonly associated with diffuse CNS disease. List 5 broad differentials for diffuse CNS disease
- Myelin formation disorder
- Diffuse meningitis
- Metabolic disease
- Degenerative disease
- Intoxication
What is the definition of neuolocalisation?
Site in nervous system where lesion would result in observed clinical signs
With sciatic nerve dysfunction, what will be seen when testing withdrawal reflex in usual place and why?
Where should stimulation be applied?
- Most of paw innervated by branches of sciatic nerve (Dorsal surface by fibular nerve, plantar surface by tibial n)
- Therefore have to stimulate medially for withdrawal (digit 1 usually innervated by saphenous branch of femoral nerve, as is medial crus. In some animals the saphenous innervation may stop at hock level so check more proximal along medial limb too)
- Flexion of hip present because quads innervated by femoral nerve (L4-L6) and iliopsoas innervated by spinal nerves L1-L4.
- Lack of stifle, hock and digit flexion
What is a dermatome?
Cutaneous region innervated by sensory nerve from single spinal or cranial nerve.
Describe the pathway for nociception
Sensory nerve –> dorsal nerve root –> bilateral lateral funiculi of SC –> through medulla oblongata, pons and midbrain to nuclei in thalamus –> cerebrum
i.e. if lost signifies functional “transection” of SC given that ascending tracts are bilateral distribution of nociceptive pathways!
What are the names of the UMN tracts that funtion in gait generation?
And the conscious proprioceptive tract?
And the unconscious proprioceptive tract?
UMN tracts in gait generation: Reticulospinal and Rubrospinal (goes to red nucleus in brainstem)
Conscious proprioceptive tract: Fasciculus gracilis (to PLs) fasciculus cuneatus (to TLs)
Unonscious proprioceptive tract: Spinocerebellar tracts
What are the three broad categories of gait abnormality?
Ataxia, weakness/paresis, lameness
What nerve deficit leads to PL plantigrade stance
What nerve dysfunction typically caused PL paw misplacement onto dorsal surface
Tibial nerve (= branch of sciatic n)
Fibular nerve (= branch of sciatic)
