Principles of brainstem disease Flashcards by Maude Tanguay

Which cranial nerves have parasympathetic function?

3, 7, 9, 10

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What are the parts of the brainstem?

midbrain
pons
medulla oblongata

each include cranial nerve nuclei of CN 3-12

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What are the brainstem functions?

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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What are clinical signs of brainstem disease?

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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What are the signs of decerebrate rigidity?

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

midbrain lesion

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What are the signs that ataxia is general proprioceptive?

brainstem/spinal cord affected

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

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What are the signs that ataxia is vestibular?

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

falling, leaning, circling, other signs of vestibular disease

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What are the signs that ataxia is cerebellar?

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

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What are the most common inflammatory brainstem diseases?

Meningoencephalitis of unknown aetiology (MUA)

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What are the most common infectious brainstem diseases?

feline infectious peritonitis FIP

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What is the most common vascular brainstem disease?

cerebrovascular infarct

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What is the motor function of CN 3 oculomotor?

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

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

lateral strabismus
ptosis

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What is the parasympathetic function of CN 3 oculomotor?

iris sphincter muscle: pupil constriction/miosis
ciliary muscle

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

mydriasis +/- aniscoria
interal ophthalmoplegia/paresis

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What is the motor function of CN 4 trochlear?

extraocular muscle: movement of globe

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

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

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What is the motor function of CN6 abducens?

extraocular muscles: movement and retraction of globe

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

medial strabismus
failure to retract the eye

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

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

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

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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What is a congenital medial/convergent strabismus?

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

What is the sensory function of CN5 trigeminal?

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

What are the clinical signs of CN5 trigeminal sensory dysfunction?

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

What is neuroparalytic keratitis?

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

What is the motor function of CN5 trigeminal?

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

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

atrophy of masticatory muscles middle ear effusion

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

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

What is the most likely cause for a dropped jaw?

trigeminal bilateral motor dysfunction most often idiopathic: trigeminal neuropathy or neuritis

What is the sensory function of CN7 facial?

concave aspect of pinna rostral 2/3 of tongue sensory dysfunction not readily appreciated

What are the motor functions of CN7 facial?

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

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

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

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

SA: droop of ipsilateral face, increased exposure of lip commissures, subtle ptosis LA: deviation of nose to unaffected side,ear droop, noticeable ptosis

What are the parasympathetic functions of CN7 facial?

lacrimal gland: basal tear production nasal gland salivary glands

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

neurogenic keratoconjunctivitis sicca KCS xeromycteria (dry nose)

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

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

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

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

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

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

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

palatine structures, pharynx, larynx, recurrent laryngeal nerve oesophagus

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

dysphonia larygeal paralysis (stridor) dysphagia megaoesophagus: regurgitation

What clinical signs are characteristic of laryngeal dysfunction?

stridor and dysphonia

What is the most common cause for stridor and dysphonia?

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)

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

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

What is the motor function of CN12 hypoglossal?

intrinsic and extrinsic muscles of tongue

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

tongue atrophy ipsilateral to lesion deviation of tongue to affected side

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

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

What are the common causes of mydriasis?

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

What are the common causes of miosis?

horner's syndrome uveitis

What causes horner's syndrome?

loss of sympathetic innervation to orbitalis muscle and iris dilator muscle

What are the clinical signs of horner's?

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

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

horners clinical signs suggestive of brain lesion or spinal lesion

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

brachial plexus injury idiopathic cervical trauma intra-thoracic mass

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

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