Principles of brainstem disease Flashcards

1
Q

Which cranial nerves have parasympathetic function?

A

3, 7, 9, 10

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1
Q

What are the parts of the brainstem?

A

midbrain
pons
medulla oblongata

each include cranial nerve nuclei of CN 3-12

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2
Q

What are the brainstem functions?

A

highway for all ascending and descending info
maintains consciousness (ARAS)
gait generation
CN 3-12
cardiorespiratory function
vomiting reflex
coordination and balance

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3
Q

What are clinical signs of brainstem disease?

A

reduced mentation: obtunded, stuporous, comatose
head tilt, decerebrate rigidity
paresis and general proprioceptive ataxia, +/- vestibular ataxia
reduced/absent postural reactions in all limbs or ipsilateral to lesion
deficits in function of CN 3-12
cervical hyperaesthesia and increased muscle tone possible
cardioresp abnormalities possible

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4
Q

What are the signs of decerebrate rigidity?

A

LMN limbs/trunk/neck released from UMN inhibition
opisthotonos extensor tone ++ in thoracic/pelvic limbs
unconscious: stupor/coma

midbrain lesion

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5
Q

What are the signs that ataxia is general proprioceptive?

A

brainstem/spinal cord affected

delayed protraction, lengthened stride, abduction/adduction of limbs, scuffing, dragging, knuckling

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6
Q

What are the signs that ataxia is vestibular?

A

central (brainstem)/ peripheral (vestib. organ or CN 8)

falling, leaning, circling, other signs of vestibular disease

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7
Q

What are the signs that ataxia is cerebellar?

A

hypermetria, wide based stance, titubation and other signs of cerebellar disease

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8
Q

What are the most common inflammatory brainstem diseases?

A

Meningoencephalitis of unknown aetiology (MUA)

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9
Q

What are the most common infectious brainstem diseases?

A

feline infectious peritonitis FIP

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10
Q

What is the most common vascular brainstem disease?

A

cerebrovascular infarct

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11
Q

What is the motor function of CN 3 oculomotor?

A

extraocular muscles: movement of globe
levator palpebrae superioris: elevation of dorsal eyelid

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12
Q

What are the clinical signs of motor dysfunction of CN3 oculomotor?

A

lateral strabismus
ptosis

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13
Q

What is the parasympathetic function of CN 3 oculomotor?

A

iris sphincter muscle: pupil constriction/miosis
ciliary muscle

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14
Q

What are the clinical signs of parasymapthetic dysfunction of CN3 oculomotr?

A

mydriasis +/- aniscoria
interal ophthalmoplegia/paresis

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15
Q

What is the motor function of CN 4 trochlear?

A

extraocular muscle: movement of globe

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16
Q

What are the clinical signs of motor dysfunction of CN 4 trochlear?

A

lateral extortion of ipsilateral pupil if affecting trochlear nerve
lateral extortion of contralateral pupil if affecting trochlear nucleus

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17
Q

What is the motor function of CN6 abducens?

A

extraocular muscles: movement and retraction of globe

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18
Q

What are the clinical signs of motor dysfunction in CN6 abducens?

A

medial strabismus
failure to retract the eye

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19
Q

What signs tell us the strabismus is caused by a problem with CN 8?

A

only apparent with changes in head/neck position aka positional
ventrolateral direction
additional signs of vestibular dysfunction

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20
Q

What signs tell us that the strabismus is caused by a problem with CN 3, 4 or 6?

A

apparent regardless of head position aka fixed
lateral
lateral extortion (dorsal pole of globe rotates laterally)
medial
additional signs of CN 3, 4, 6 dysfunction

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21
Q

What is a congenital medial/convergent strabismus?

A

due to an increased decussation at optic chiasm/altered organisation of LGN
(not a pathological finding, no impairment to vision or vestibular function)

can be accompanied by a pendular nystagmus

22
Q

What is the sensory function of CN5 trigeminal?

A

facial sensation: autonomous zones for each branch (ophthalmic, maxillary, mandibular)

23
Q

What are the clinical signs of CN5 trigeminal sensory dysfunction?

A

reduced facial sensation
absent/reduced palpebral and corneal reflex
neuroparalytic and ulcerative keratitis

24
Q

What is neuroparalytic keratitis?

A

lesion of the ophthalmic branch of CN5 trigeminal

responsible for reflex tearing in response to corneal drying
dysfunction = corneal sensation lost = reduced tearing and blinking = inflammation and corneal ulceration

25
Q

What is the motor function of CN5 trigeminal?

A

muscles of mastication: jaw closure
tensor tympani m: malleus of inner ear
tensor veli palatine m: opening of eustachain tube

26
Q

What are the clinical signs of CN 5 trigeminal motor dysfunction?

A

atrophy of masticatory muscles
middle ear effusion

27
Q

What is the difference between bilateral and unilateral motor dysfunction of CN5?

A

bilateral: atrophy of masticatory muscles, dropped jaw, issues prehending food and pseudohypersalivation

unilateral: ipsilateral atrophy of masticatory muscles

28
Q

What is the most likely cause for a dropped jaw?

A

trigeminal bilateral motor dysfunction

most often idiopathic: trigeminal neuropathy or neuritis

29
Q

What is the sensory function of CN7 facial?

A

concave aspect of pinna
rostral 2/3 of tongue

sensory dysfunction not readily appreciated

30
Q

What are the motor functions of CN7 facial?

A

muscles of facial expression
orbicularis oculi: closure of eyelids
caudal digastricus m: mastication
levator anguli oculi medialis m: elevation of dorsal eyelid
stapedius m: associated with malleus of inner ear

31
Q

What are the clinical signs of motor dysfunction of CN7 facial?

A

facial asymmetry
difficulty prehending food
pseudo-hypersalivation
lack of blink: exposure keratitis and absent/reduced responses and reflexes
risk of corneal trauma/ulceration

32
Q

What is the difference between motor dysfunction of CN7 in SA VS LA?

A

SA: droop of ipsilateral face, increased exposure of lip commissures, subtle ptosis

LA: deviation of nose to unaffected side,ear droop, noticeable ptosis

33
Q

What are the parasympathetic functions of CN7 facial?

A

lacrimal gland: basal tear production
nasal gland
salivary glands

34
Q

What are the clinical signs of parasympathetic dysfunction of CN7 facial?

A

neurogenic keratoconjunctivitis sicca KCS
xeromycteria (dry nose)

35
Q

What clinical signs indicate that facial asymmetry is caused by CN5?

A

absent palpebral/corneal reflex but intact menace response
reduced/absent response to facial stimulation
masticatory muscle atrophy +/- ipsilateral enophthalmos
possible dropped jaw if bilateral

36
Q

What are the clinical signs that indicate that facial asymmetry is caused by CN7?

A

Absent palpebral/corneal reflex and absent menace response
increased exposure of lip commissures, pseudo-hypersalivation, subtle ptosis, drooping ear
concurrent neurogenic KCS possible

37
Q

What is the sensory functions of CN 9 glossopharyngeal and CN10 vagus?

A

palatine structures, pharynxm larynx
caudal 1/3 of tongue
thoracic and abdnominal viscera

38
Q

What is the motor functions of CN 9 glossopharyngeal and CN10 vagus?

A

palatine structures, pharynx, larynx, recurrent laryngeal nerve
oesophagus

39
Q

What are the clinical signs of motor and sensory dysfunction fo cn9 and cn10?

A

dysphonia
larygeal paralysis (stridor)
dysphagia
megaoesophagus: regurgitation

40
Q

What clinical signs are characteristic of laryngeal dysfunction?

A

stridor and dysphonia

41
Q

What is the most common cause for stridor and dysphonia?

A

CNx vagus affected which affects recurrent laryngeal nerve and then caudal laryngeal nerve which innervated the majority of intrinsic laryngeal muscles

most common: neuromuscular idiopathic : geriatric onset laryngeal paralysis polyneuropathy complex (GOLPP)

42
Q

What are the most common neuromuscular causes for regurgitation and megaoesophagus?

A

idiopathic: congenital/acquired
iatrogenic: sedation/anaesthesia drugs
inflammatory/immune: myasthenia gravis
dysautonomia

43
Q

What is the motor function of CN12 hypoglossal?

A

intrinsic and extrinsic muscles of tongue

44
Q

What are the clinical signs of motor dysfunction in CN12 hypoglossal?

A

tongue atrophy ipsilateral to lesion
deviation of tongue to affected side

45
Q

What is the difference between anisocoria caused by sympathetic and parasympathetic causes?

A

uneven pupil sizes
if sympathetic takes over: mydriasis/large pupil
if parasympathetic takes over: miosis/small pupil

46
Q

What are the common causes of mydriasis?

A

oculomotor nerve lesion
severe retinal/optic nerve lesion
iris atrophy (age related)

47
Q

What are the common causes of miosis?

A

horner’s syndrome
uveitis

48
Q

What causes horner’s syndrome?

A

loss of sympathetic innervation to orbitalis muscle and iris dilator muscle

49
Q

What are the clinical signs of horner’s?

A

ptosis
enophthalmos (sinking in of eye)
protrusion of 3rd eyelid
miosis
conjunctival hyperaemia
sweating in horses

50
Q

What are clinical signs of first order sympathetic dysfunction of the eye?

A

horners
clinical signs suggestive of brain lesion or spinal lesion

51
Q

What are clinical signs of second order sympathetic dysfunction of the eye?

A

brachial plexus injury
idiopathic
cervical trauma
intra-thoracic mass

52
Q

What are clinical signs of third order sympathetic dysfunction of the eye?

A

otitis media +/- vestibular/facial involvement
trigeminal neuropathy
retrobulbar mass, swelling or trauma

53
Q
A