Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Neuro > CN and brain stem reflexes > Flashcards

CN and brain stem reflexes Flashcards

1
Q

what most commonly causes an impairment in CN 1

A

mucosal swelling and inflammation during sinusitis or an upper respiratory infection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what can cause a permanent loss of smell

A

severe head trauma where the olfactory nerve branches are sheared or torn where they pass through the bony cribriform plate

or a tumor near the olfactory lobe at the skull base (i.e. meningioma)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

how do you test CN III, IV, VI

A

pt tracking a target up and down and side to side

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what eye movements is the superior oblique responsible for

A

depresses and abducts the eye and medial rotation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what eye movements is the inferior oblique responsible for

A

elevates and abducts they eye, and lateral rotation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what eye movements is the superior rectus responsible for

A

elevates and adducts the eye and medially rotates

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what eye movements is the inferior rectus responsible for

A

depresses and adducts the eye and laterally rotates

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

if a patient cannot fully elevate the eye which muscles are you concerned are not functioning and how would you differentiated

A

superior rectus or inferior oblique

if the patient turns his eye inward (adducts) and has weakness then its mainly the inferior oblique

weakness of elevation when the eye is turned outward (abduction) is mainly the superior rectus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

if a patient cannot fully depress the eye which muscles are you concerned are not functioning and how would you differentiated

A

superior oblique or inferior rectus

weakness when eye is turned outward = inferior rectus

weakness when the eye is turned inward = superior oblique

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

starting with the eye out/abducted which muscle are you testing by having the patient look up

A

superior rectus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

starting with the eye out/abducted which muscle are you testing by having the patient look down

A

inferior rectus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

starting with the eye in/adducted which muscle are you testing by having the patient look down

A

superior oblique

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

starting with the eye in/adducted which muscle are you testing by having the patient look up

A

inferior oblique

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what are the signs of a CN III lesion

A
  • complete ipsilateral ptosis (paralysis of leavator palpebrae superioris m)
  • eye abducted
  • pupil is large and unreactive to light directly and consensually
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what are signs of a CN IV lesion

A

impairment of downward gaze - best seen when the involved eye is in the adducted position

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

where does CN IV exit the brainstem and what is unique about its pathway

A

exits the brainstem dorsally and decussates to innervate the contralateral superior oblique m

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what does a CN VI lesion affect

A

the ipsilateral lateral rectus muscle impairing abduction of the affected eyeball

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what causes binocular diplopia

A

the eyeballs are not perfectly aligned in primary position or when conjugately moving to other positions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

how can binocular and monocular diplopia be differentiated

A

covering one eye will correct binocular diplopia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what CN lesions can cause binocular diplopia

A

CN III, IV, VI (or a lesion of their related muscles)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what is more common binocular or monocular diplopia

A

binocular - monocular is very rare

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what is a nystagmus

A

repetitive, oscillatory, jerky eye movements

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what causes a normal/physiological nystagums

A

suddenly stopping someone rotating in a chair

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what causes an asymmetrical pathologic nystagmus

A

pathologic nystagmus could be due to a lesion of the vestibular system, brain stem, or cerebellum - all upset normal control or balance on conjugate eye movements (usually asymmetric and position dependent)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

what causes a symmetrical pathologic nystagmus

A

drug toxicity - usually present with all eye movements

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

what is internuclear opthalmoplegia (INO)

A

paralysis of extraocular muscles (opthalmoplegia) due to a lesion between the nuclei (internuclear) involved with lateral gaze (oculomotor and abducens nuclei) which interrupts the ascending medial longitudinal fasciculus (MLF)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

what syndrome is associated with an internuclear opthalmoplegia

A

MLF syndrome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

describe the path of the MLF

A

it connects the PPRF (paramedian pontine reticular formation) and the contralateral oculomotor nucleus - it decussates early then rises from the pons to the midbrain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

what would a lesion in the left MLF cause

A

paralysis of adduction of the left eye with nystagmus of the abducting right eye - since the left CN III nucleus never gets the MLF signal causing an impairment in right lateral gaze.

the left medial rectus still functions and both eyes will be able to converge via the near reflex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

what are the 2 most common causes of a MLF lesion

A

young pts - MS

old pts - ischemic infarct

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

what is the pathway involved in the consensual pupillary response

A

retinal ganglion cells projecting bilaterally to the pretectal area (rostral to the superior colliculus) which then projects to the Edinger-Westphal nucleus of CN III

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

describe pupillary direct and consensual response with an optic nerve lesion

A

when light is shined into the affected eye there is no direct or consensual response

when light is shined in the other eye both pupils respond

33
Q

describe pupillary direct and consensual response with a CN III lesion

A

when light is shined in the affected eye there is no direct response but the other eye has a consensual response

when light is shined in the other eye there is a direct response but no consensual response

34
Q

what causes a relative afferent pupillary defect (RAPD)

A

a partial optic nerve or retinal lesion

35
Q

what are the pupillary responses with a RAPD

A

both pupils may initially constrict to light but after moving the light source from the normal to affected eye there may be dilatation due to the relatively decreased afferent input

36
Q

what 3 things occur during the near reflex

A

pupillary constriction, lens accommodation and convergence of the eyes

37
Q

what is a dissociation of light and near reflexes (light-near dissociation)

A

when there is disruption of the pupillary light reflex pathway at the pretectal area but the near reflex is preserved

pupils constrict during the near reflex but not to a light stimulus

38
Q

what are 2 causes of light-near dissociation

A

dorsal midbrain syndrome and Argyll Robertson pupils in neurosyphilis

39
Q

what is the dorsal midbrain syndrome

A

aka Parinaud’s syndrome, classically refers to a pineal tumor compressing the dorsal midbrain but may also occur from an ischemic infarction there

40
Q

what other deficit may be seen with dorsal midbrain syndrome in addition to light-near dissociation

A

impairment of upward gaze do to involvement of the midbrain’s centers for vertical gaze

41
Q

what causes Horner’s syndrome

A

a lesion disrupting the oculosympathetic pathway

42
Q

what are the symptoms of Horner’s syndrome

A

Miosis (constricted pupil), anhidrosis (lack of sweat), and mild ptosis (drooping of eyelid)

43
Q

where is a lesion in Horner’s syndrome

A
  • lateral medullary infarction aka Wallenberg syndrome (first order neuron)
  • tumor of the apex of the lung (2nd order neurons)
  • neck trauma (3rd order neuron)
44
Q

where would you suspect a lesion affecting V1, CN III, CN IV, CN VI

A

superior orbital fissure or nearby cavernous sinus

45
Q

what in Trigeminal neuralgia

A

painful syndrome of irritation or inflammation of one of the trigeminal nerve sensory branches causing it to “short circuit” or “misfire”

46
Q

what are the symptoms of Trigeminal neuralgia

A

sharp episodic pain several times daily that may be provoked by talking, chewing or touching the face

no sensory or other CN deficits are found on exam

47
Q

what causes Trigeminal neuralgia in younger patients

A

MS lesion at the trigeminal nerve entry regoin into the pons

48
Q

what causes trigeminal neuralgia in older patients

A

a trigeminal nerve branch is often compressed by a tortuous or kinked blood vessel (often in the superior cerebellar artery)

this can be surgically repositioned or padded

49
Q

what are treatments for trigeminal neuralgia

A

if due to compression - surgery

oral anticonvulsants i.e. carbamazepine, gabapentin or others

50
Q

what are signs/symptoms of a LMN lesion of the trigeminal motor nerve

A

atrophy and weakness in the ipsilateral muscles of chewing (the masseter and temporalis) and jaw deviation towards the side of the lesion

51
Q

what are the signs of an UML of the trigeminal nerve

A

there is bilateral innervation so no atrophy, weakness or deviation is seen

in a bilateral UMN lesion here there may be hyper-reflexia of the jaw jerk

52
Q

what is the sign/symptoms of a CN VII lesion at or near the stylomastoid foramen (or a lesion in its nucleus)

A

severe paralysis of the entire ipsilateral half of the face

53
Q

impaired taste over the anterior 2/3 of the tongue indicate a lesion where

A

involving the chorda tympani branch of the facial nerve.

54
Q

hyperacusis is seen with a lesion involving what

A

the branch of CN VII that goes to the stapedius muscle

55
Q

what would symptoms of lesion at the internal auditory meatus or cerebelloponine angle cause

A

facial weakness
hyperacusis
hearing impairment and tinnitus (involves CN VII and VIII, commonly caused by an acoustic neuroma)

56
Q

A lesion of CN VII in the pons is likely to also involve what other nerve, causing what sign?

A

CN VI -causing a weakness of lateral gaze

57
Q

where is the lesion in Bell’s palsy

A

its idopathic

58
Q

what are the symptoms of Bell’s palsy

A

facial nerve paralysis - may occur suddenly

may have ipsilateral hyperacusis and impaired taste as well

59
Q

how do yo treat Bell’s palsy

A

short course of oral corticosteroids and maybe antivirals since it is thought to possibly be due to inflammation of the facial nerve mediated by HSV-1 or other viruses

60
Q

what is the distribution of weakness for an UMN CN VII lesion

A

facial paralysis of the lower part of the contralateral face (spares the forehead)

61
Q

a lesion of what cranial nerves could cause difficulty speaking or swallowing and how could you differentiate clinically?

A

CN IX or X

gag-reflex or elevation of the palatal arch

62
Q

how is a gag-reflex interpreted clinically

A

can try to differentiate between CN IX and X deficits with a gag reflex test- a decreased gag reflex when touching one side of the pharynx suggest a CN X lesion on that side (very difficult to differentiate)

63
Q

how does a LMN CN X lesion present

A

impaired speech and swallowing
absent gag-reflex
ipsilateral drooping or sagging of the palatal arch (uvula points toward the normal side)
horse voice

64
Q

a horse voice could be due to a lesion involving what nerve

A

X

65
Q

what is seen with a LMN lesion of CN XI

A

decreased elevation or shrugging of the shoulder and weakness when turning the head to the opposite side

66
Q

what does the CN XII innervate

A

tongue muscles most importantly the genioglossus muscle which protrudes each side of the tongue forward

67
Q

what clinical sign of a LMN lesion of XII

A

the protruded tongue will point toward the side of the lesion.
over time there is atrophy and fasiculation and fibrillation of the tongue

68
Q

what way would the tongue point in an UMN lesion of CNXII

A

in most patients toward the side of the lesion but in some patients the UMN is controlled by the opposite side

69
Q

what is a crossed brain stem syndrome

A

cranial nerve involvement on one side and an adjacent fiber tract lesion creating a sensory or motor deficit on the opposite side of the body

70
Q

what symptoms would be expected with a right pontine lesion

A
  • LMN paralysis of the right face (CN VII)

* UMN paralysis of the left upper and lower limbs (rt CST)

71
Q

where could a lesion be located causing deficits of pain and temperature over the left face and right limbs and body

A

Lesion of the left lateral medulla

Involves the Left descending spinal tract of CN V and the left STT

72
Q

what is weber syndrome aka

A

the medial midbrain syndrome

73
Q

what could cause the medial midbrain syndrome

A

ischemic infarction from an occluded branch of the posterior cerebral artery

74
Q

What CNs and tracts are affected in a medial midbrain syndrome

A

CN III and the cerebral peduncle (CST and corticobulbar tracts)

75
Q

what are the symptoms of a medial midbrain syndrome

A

ipsilateral oculomotor nerve lesion and upper motor neuron weakness of the contralateral face and limbs

76
Q

what is the other name for the lateral medullary syndrome

A

wallenberg syndrome

77
Q

what causes a lateral medullary syndrome

A

ischemic infarction from an occluded vertebral artery or its PICA branch

78
Q

what are the symptoms of a lateral medullary syndrome

A

pain and temperature impairment in the ipsilateral face and contralateral limbs and body

others: hoarseness, vertigo, nausea and vomiting, clumsiness

there may be nystagmus, ipsilateral limb dysmetria, ipsilateral Horner’s syndrome and ipsilateral palatal and coal cord paralysis

79
Q

what is preserved in a lateral medullary syndrome

A

position sense and strength

Neuro (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions