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Neuro > Brainstem Dz > Flashcards

Brainstem Dz Flashcards

1
Q

What is the brainstem made up of? What are their alternative names and how can this be remembered?

A 
STY
- Midbrain = meSencephalon 
- Pons = meTencaphalon 
- Medulla Oblongata = mYelencephalon 
(together pons and medulla = rhomboencephalon)
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2
Q

Where do the cranial nerves exit the brain?

A
  • 1 and 2: forebrain
  • 3 and 4: midbrain
  • 5 : PONS
  • 6-12: medulla oblongata
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3
Q

What is ARAS? What activities does it affect?

A

> ascending reticular activating system part of the reticular formation
- collection of neuronal cell bodies - meshwork
- activates cerebral cortex -> awake state and levle of conciousness
affects many activities
- respiration
- CV function
- voluntary excretion
- swallowing
- vomiting
- muscle tone
- voluntary movement

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4
Q

What nuclei are present in the pons?

A

> pontine nucleus

- integrates visual inputs -> motor

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5
Q

What general functions (motor, sensory etc) do the cranial nerves have?

A
  • motor, sesnory or mixed function
  • any autonomic = PARASYMPATHETIC tone (occulomotor, facial, glossopharyngeal and vagus)
  • no sympathetic
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6
Q

Which nucleus is responsible for gait generation and where is this found?

A

> red nucleus

  • rostral midbrain (mesencephalon)
  • responsibel for the CONTRALATERAL postural reactions
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7
Q

What type of lesion causes decerebrate rigidity?

A
  • diffuse brainstem lesion affecting the mesencephalon (midbrain)
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8
Q

What does decerebrate rigidity look like?

A
  • stuperous

- all 4 limbs stiff

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9
Q

How does decerebellate rigidity occour?

A
  • concious
  • flexion of pelvic limbs
  • tense forelimbs
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10
Q

Where is the oculomotor nucleus and what is this responsible for?

A

> midbrain
repsonsible for…
- motor and parasympathetic
- sphincter pupillary muscle constriction
- extraocular muscles (3 recti, not lateral, and the ventral oblique)
- levator palpebrae superioris muscle

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11
Q

Outline the path of the PLR

A
  • optic nerve - chiasm -optic tract
  • pretectal nucleus (thalamus)
  • oculomotor nucleus (midbrain)
  • oculomotor nerve (CN3)
  • ciliary ganglion
  • short ciliary nerve
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12
Q

How do the short ciliary nerves differ between species? Clinical implications?

A

(=iridal sphincter muscle)
- dogs: short ciliary fibres (5-8)
- cats: nasal and malar (lateral)
> in cats if one nerve is affected -> D shaped pupil (dyscoria)

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13
Q

What pathologies may affect the short ciliary nerves in cats?

A
  • FeLV associated Lymphoma loves short ciliaries!
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14
Q

Localise the lesion: 5yo FS whippet, 2-3 week hx lethargy and acute onset blindness 4d ago, absent menace OU, fixed dilated pupils OU, normal fundus, depressed mental status

A

Bilateral optic nerves, optic chiasm

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15
Q

If PLR deficiits and vision loss both present where must the lesion be? potential causes

A

Where the pathways are shared ie. optic nerves and chiasm

  • intramedullary or neoplastic most likely
  • optic nerves can be compressed by severe meningitis
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16
Q

How does the eye appear if occulomotor is damaged?

A

Lateral stabismus and rotation medially d/t unopposed actions of lateral rectus and dorsal oblique

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17
Q

What does trochlear do?

A
  • motor only to dorsal oblique (poor trochlear)
  • only CN that crosses over (all others innervate ipsilateral side)
  • Only CN that arises dorsally (all others arise medially)
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18
Q

How would the eye appear with a trochlear lesion?

A
  • lateral rotaion of both eyes (only really seen in cats) d/t unoposed ventral oblique (dorsal oblique lost)
  • may see BVs off centre looking at fundus
    > BUT very rare to jsut have a trochlear lesion! Others probably present.
19
Q

What is the tectotegmentalspinal tract? Where does it originate? What clinical signs are seen with dysfunction of this pathway?

A
  • sympathetic innervation of the eye
  • originates in midbrain, diencephalon has influence over this area
  • 3 neuron pathway
  • dysfunction = Horner’s syndrome
20
Q

What are the 1st, 2nd and 3rd order neurons in the tectotegmentalspinal tract?

A

1 - tectotegmental spinal tract from midbrain through spinal cord
2 - nerves from spine - cranial cervical ganglion [ not in brain]
3 - nerve innervating the eye via tympano occipital fissure and orbital fissure, past trigeminal ganglion

21
Q

Where do sympathetic and parasympathetic fibres exit the spine?

A
  • craniosacral: parasymp

- thoracolumbar: symp

22
Q

What are the 3 forms of Horner’s syndrome? Clinical signs associated with each?

A 
> 1st order
- intracranial signs
- spinal cord dysfunction 
> 2nd order
- brachial plexus 
- cervical trauma 
> 3rd order 
- middle/inner ear dz
- facial paralysis
- vestibular dysfunction
23
Q

What nucleus is in the pons? Functions?

A

Trigeminal

  • 3 braches (opthalmic, maxillary, mandibular)
  • all 3 sensory
  • mandibular only mm. of mastication
24
Q

Where are the regions innervatedby each branch of trigem?

A
  • opthalmic does around the orbit, globe (cornea) AND THE NARES
  • maxillary dorsal face
  • mandibular obvs mandible
25
Q

Ddx for a specific nerve branch targetted pathology?

A
  • granulomatous neuritis

- neoplasia

26
Q

What are the muscles of mastication innervated by trigem?

A
  • temporalis
  • masseter
  • pterygoid (lateal and medial)
  • digastricus rostral
27
Q

How would a unilateral trigem neuropathy manifest?

A
  • severe masticatory muscle atrophy
  • no sensation to one side of face
  • may have ulcer in affected eye d/t lack of sensation
28
Q

What sings wouldb e expected if midbrain affected?

A
  • altered mental status

- ipsilateral posture deficits

29
Q

What is dropped jaw and what signs may be seen alongside it?

A
  • in ability to close mouth d/t dysfunction of mandibular trigem branch
  • hypersalivation
  • difficulty eating and drinking
  • abnormal facial sensation
  • some presetn with Horner’s 2* as nerves pass next to each other
30
Q

Ddx dropped jaw?

A 
> non neuro
- bilateral luxation of  TMJ
- mandibular fx
- oral FB with inability to cloe the mouth 
> neuro
- inflam/infectious
-  trauma (carrying heavy objects) 
- toxic (botulism) 
- idiopathic (trigem neuropathy or cranial polyneuropathy) 
- neoplasia (lymphoma)
31
Q

Diagnostics for dropped jaw?

A
  • haem and biochem
  • rads of thorax
  • abdo ultrasound
  • MRI brain
  • CSF
    r/o other causes > idiopathic trigeminal neuritis and Horner’s syndrome
32
Q

Tx dropped jaw? ( idiopathic trigeminal neuritis and Horner’s syndrome )

A
  • put elastic band around face to allow them to close mouth and eat
  • physioltherapy
33
Q

Which CN nuclei are found in the medulla oblongata (myelencephalon?) What else is present here?

A

6-12 and respiratory centres

34
Q

What does CN 6 innervate?

A

> abducent

  • motor to extraocular mm. lateral rectus only
  • motor to retractor bulbi m.
35
Q

What would a CN6 lesion cause the eyes to do?

A

Medial strabismus d/t unopposed medial rectus and no globe retraction

36
Q

Causes of facial n. paralysis

A
  • otitis media/interna (as leaves medulla oblongata v. close to base of the ear)
  • trauma
  • neoplasia
  • polyneuropathy (hypothyroid dogs)
  • 75% idiopathic dgos, 25% cats
37
Q

What does the facial n. innervate?

A
  • motor to the face

- parasympathetic to salivary and lacrimal glands

38
Q

So what would a facial n. lesion likely cause?

A
  • KCS

- facial paralysis

39
Q

Which nerve is very closely assocaited with the facial n?

A

vestibulocochlear nerve exits via same foramina (so head tilt may also be seen with facial n. problems)

40
Q

Is vision necessary for vestibulocochlear pathway?

A

no

41
Q

What would vestibulocochlear lesions cause?

A

See vestibular lecture

  • head tilt
  • hearing loss
42
Q

What makes up the nucleus ambiguous?

A

CN IX, X, XI

- motor, sensory and parasympathetic

43
Q

What are CN IX and X responsible for?

A
  • Gag reflex
  • Motor, sensory and autonomic
    > IX
  • motor pharynx and palatine structures
  • sensory (caudal 1/3 tongue and pharyngeal mucosa)
  • parasympathetic (parotid and zygomatic glands)
  • gag and swallow
    > X
  • motor larynx (RLN) pharynx and oesophagus
  • sensory (larynx, pharynx, thoracic and abdominal viscera)
  • parasympathetic (thoracic and abdo viscera)
44
Q

What is CN XII responsible for? When may theis be damaged?

A
  • hypoglossal canal
  • motor mm. of tongue
    > damage w/ very cranial cervical lesions
  • dalmation, hemiparesis, mild cervical discomfort

Neuro (30 decks)

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