Neuro - Cranial Nerves

Front 1

CN I - When to test

Back 1

Occipital trauma (shearing of the olfactory tract/bulb), mental status change, seizure disorder, loss of taste.

Fracture in cribriform region can leak CSF - test with filter paper (bullseye/target effect) or glucose (CSF is near blood gluc concentrations).

Front 2

Unilateral anosmia common causes

Back 2

1. Nasal obstruction - E.G. COMMON COLD!!!
2. Chronic inflammation of nasal mucosa.

Causes of loss of olfaction:
mechanical - occiptal trauma, olfactory groove neoplasm, deviated nasal septum
infections: herpes simplex encephalitis, common cold
metabolic: B12 def, diabetes mellitus, vit A and zinc def

Front 3

CN I

Back 3

Olfactory tracts are bilateral. Smell gradually lost with age.

Front 4

CN II

Back 4

Must test each eye individually - testing visual fields and acuity.

Neuro causes of vision loss should effect both near and far vision. Refractive problems (will improve with pinhole) are usually one or the other (myopia/nearsightedness or hyperopia/fatsightedness).

Front 5

Patchy monoocular loss - where is the damage?

Back 5

Retina or optic nerve. (in front of the optic chiasm)

Front 6

Bitemporal loss

Back 6

Optic chiasm

Front 7

Homonomous loss

Back 7

e.g. both L fields are gone.

Posterior to the optic chiasm - optic tract, lateral geniculate, optic radiations, or occipital lobe.

Front 8

Homonomous superior quadrantanopia

Back 8

Temporal lobe - meyers loop.

Front 9

Homonomous inferior quadrantopia

Back 9

Parietal lobe. (lesion of optic radiation through parietal lobe)

Front 10

Marcus-Gunn pupil

Back 10

Due to optic neuritis - sign of demyelinated disease (e.g. MS)

Pupils will not constrict as much. When light is shifted from good eye to bad, it will look like the pupil is dilating (but really it is just constricting less). Afferent issue.

Front 11

Optic neuritis

Back 11

Severe vision loss - Marcus Gunn pupil.

Front 12

Fundus exam - Loss of normal margins with dilation of veins and swelling of the nerve head.

Back 12

Papilledema or it can be due to optic neuritis.

Front 13

Papilledema

Back 13

swelling of optic nerve due to pressure on venous drainage from the eye. usually due to increased pressure in the head. Will see loss of venous pulsations early on. Normal vision (contrast with optic neuritis).

Front 14

Disorders causing weak eye muscle WITHOUT DAMAGE TO A CRANIAL NERVE

Back 14

Myopathies and muscle damage.

Front 15

Diplopia in only one eye

Back 15

Very rare. Not a nervous system disease.

Front 16

Longstanding diplopia

Back 16

Often the pt will have two eyes not looking in the same direction (lack of conjugation) and the brain is able to ignore one of the eyes).

Front 17

Examining diplopia

Back 17

Image from the eye that doesn't move enough will be further towards the direction that the weak muscle normally moves.
(e.g. L eye medial rectus weakness - displaced image will be further towards the right)

Front 18

Third nerve palsy

Back 18

Pt can only look laterally. Pupil enlarged (b/c pupillary constrictor fibers travel with CNIII).

Note - CSF keeps constrictor fibers alive (peripheral nerve - these can recover) while motor portion is dependent on blood flow.

Front 19

Anisocoria

Back 19

Pupillary difference between eyes.

Front 20

Medial longitudinal fasciculus

Back 20

Connects abducens nucleus to CN III nucleus.
When looking horizontally - laterally going eye leads and the medially going one follows.
Issues in MLF - nystagmus results in the laterally going eye - usually due to MS.

Front 21

Heterophoria

Back 21

Drifting of an eye when its fixation on a target is broken.

Front 22

Heterotropia

Back 22

AKA strabismus (neurologists use this term more)

Two eyes don't look in the same direction.

Front 23

Ipsilateral visual cortex

Back 23

Allows for smooth tracking to that side.

Front 24

Rostral midbrain lesion or rostral interstitial nucleus lesion

Back 24

Inability to look up voluntarily.

So note - the vertical gaze center is in the midbrain

Results from Parenaud's syndrome, dementing illnesses, extrapyramidal disorders (e.g. supranuclear palsy)

Front 25

Parenaud's syndrome

Back 25

Mass presses on dorsum of brainstem and affects the rostral midbrain (can't look up)

Front 26

Accommodation

Back 26

Ciliary muscle contracts - lens becomes round - pupil constricts. Wired in parallel with convergence.

Front 27

Sympathetics with pupils

Back 27

Dilation.
If lost, ptosis also seen bc superior tarsal muscle is lost.

Front 28

Horner's syndrome

Back 28

Ptosis (border of lid reaches pupil), miosis, anhydrosis (lack of sweating), mild elevation of lower lid.
Damage to sympathetic pathway - cervical chain, carotid plexus, upper thoracic roots, lower brachial plexus, cervical spinal cord, tumor in apex of lung.

Front 29

Adie's (or Holmes-Adie's) pupil

Back 29

Slow reaction of pupil to light change.
Accomodation preserved
Idiopathic, not progressive (benign).
Decreased reflexes

Front 30

CN V lesions

Back 30

Often also lose sensory limb of the corneal reflex (quick consensual closure with stim of cornea with something like cotton).

Due to lesions of trigeminal or lateral brain. Usually due to strokes or masses pressing on the lateral brainstem.

Will have jaw deviation towards weak side (and ARTIFICIAL uvula deviation!)

Front 31

CN VII lesions

Back 31

Peripheral facial palsy - either idiopathic (Bell's) or due to zoster (shingles), or Lyme. May occur with lesions lateral to brain stem.

Hyperacusis (n. to stapedius), loss of ant taste, dry eye, lacrimal gland. Also weakness of forehead, eyes, mouth.

Front 32

Central lesions to nerve fibers controlling CN VII

Back 32

Only weakness of lower face (wrinkling of forehead is fine). Because corticobulbar control over facial muscles and bilatearl control for the forehead.

Front 33

Weber's test

Back 33

For cnVIII

If pt lost hearing in one ear, put vibrating tuning fork on head. If heard better in bad ear, problem is getting air into the inner ear and the nerve is fine. - conductive hearing loss (common cause is ear wax).
If better in the good ear - a sensory neural deficit.

Front 34

Causes of CN VIII lesions

Back 34

Acoustic neuroma

Front 35

Rinne's test

Back 35

Vibrating tuning fork on mastoid. When not heard anymore, they should still hear it through the air. If you can't, then there is a conduction block.

Front 36

Oculocephalic reflex

Back 36

Checks vestibular function of CNVIII. Eyes should move equally and opposite to head movements.

Front 37

Presyncope
(type of dizziness)

Back 37

Wooziness

Front 38

Disequilibrium
(type of dizziness)

Back 38

Unsteady on feet. Goes away when sitting down.

Front 39

Vertigo
(type of dizziness)

Back 39

Later lecture in this. I think it is the sensation of movement when there isn't any.

"spinning and rolling."

Front 40

Nystagmus

Back 40

Sign of abnormal vestibular function.

Named by the fast component (via conscious cerebral cortex - the functional component is the slow one [via vestibular system]).

Either horizontal or rotational.

Front 41

Peripheral vertigo

Back 41

Results in unidirectional nystagmus proportional to the degree of symptoms.

Front 42

Central (cerebellar or vestibular) disease (with nystagmus)

Back 42

Multidirectional nystagmus without much veritgo. Not just an inner ear problem. Down and upbeating nystagmus.

Due to cerebellar, brainstem or vestibular disease.

Front 43

Caloric testing

Back 43

Sets up convection currents in the ear tested.

Cold water - eyes slowly drift towards the cold water and then snap back in opposite direction.

Front 44

Beningn positional vertigo

Back 44

Loose otopliths cause sudden severe vertigo in certain positions because they strike receptors in semicircular canals.

Borani or Hall-Pike maneuver

Front 45

CN IX

Back 45

Sensory innervation of the middle ear, pharynx and posterior 1/3 of tongue.

Motor innervation to stylopharyngeus muscle.

Test - Gag reflex - tough each side of the pharynx or posterior 1/3 of tongue without touching soft palate or fauces (posterior part of mouth).

Front 46

Gag reflex

Back 46

Contraction of lavator palati (via vagus nerve)- lifting of soft palate - bilaterally and symmetrical. Uvula should stay in midline.

Uvula deviates away from side of lesion.

Front 47

CN X

Back 47

Levator palati AKA levator veli palatini for gag reflex and adduction of vocal cords.

Front 48

CN XI

Back 48

Trapezius and SCM. Want to have pt resist against your pressure.

Bilateral hemispheric innervation with mild contralateral predominance in trap control and 50/50 control of SCM.

Front 49

CN XII

Back 49

Protrude tongue, push against side of cheek (can't push against strong side)

Tongue deviates towards weak side.

Front 50

Olfaction - when will you have unilateral loss

Back 50

Lesions from olfactory trigone forward (i.e. each bulb distributes to both anterior mesial temporal cortex).

Front 51

Causes of loss of olfaction

Back 51

Mechanical - occipital trauma, olfactory groove neoplasm, deviated nasal septum
Infections - COMMON COLD, herpes simplex encephalitis
Metabolic - B12 def, diabetes mellitus, vit A and zinc deficiency.

Front 52

Parasympathetic for pupils

Back 52

Light reflex. Fully bilateral from retina to mid-brain.
Afferent is CN II, efferent is CN III.

Front 53

Automatic neuropathy of diab mellitus effects on pupils

Back 53

Midposition fixed pupil

Front 54

Progressive unilateral nerve deafness in adult

Back 54

Must suspect VIII nerve tumor in cerebellopontine angle.

Front 55

Oculocephalic testing

Back 55

Used in stuporous or comatose patients.

Front 56

Nasal speech

Back 56

Suggests palate weakness.

Front 57

Hoarseness

Back 57

Suggests laryngeal weakness, inflammation or mass.

Front 58

SCM

Back 58

turns head to opposite side.

Front 59

Where on the visual cortex is the representation of the center of vision?

Back 59

The center of vision is represented near the occipital pole (often supplied by middle cerebral artery)

Front 60

What position will the patient's head assume (in order to prevent diplopia) if their right trochlear nerve is damaged?

Back 60

Head tilted to the left and chin turned slightly to the right ("cockeyed")

Front 61

Where is the cortical center that controls lateral gaze? Where is the lateral gaze center in the brain stem?

Back 61

Lateral gaze centers include the frontal eye fields in the frontal lobes of the cerebral cortex and the paramedian pontine reticular formation.

Front 62

Pupillary light reflex brainstem center?

Back 62

The pretectal area of the dorsolateral midbrain is the center for the pupillary light reflex.

Front 63

Myopia

Back 63

Myopia is an inability to see at distance ("nearsighted") with light focusing in front of the retina.

Front 64

Hyperopia

Back 64

Hyperopia is an inability to see close up ("farsighted") with light behind the retina.

Front 65

Amblyopia

Back 65

Amblyopia literally means "dim eye". This is a drifting or "lazy" eye that usually happens because one eye has bad vision. The brain often "turns off" control of that eye and the eye drifts. The patient usually does not have diplopia because input from that eye is turned off. In one of the most remarkable illustrations of plasticity, the eye can become permanently blind in children if this is not treated.

Front 66

Ageusia

Back 66

Loss of taste perception.

Front 67

Pathway of the corneal reflex

Back 67

The sensory limb of the corneal reflex is the ophthalmic division of the trigeminal nerve and the motor limb is the facial nerve. The response is consensual.

Front 68

CNS lesion - affects on hearing in one ear.

Back 68

It is nearly impossible to cause loss of hearing in one ear by damage to the brain beyond the point where the vestibulocochlear nerve enters the brain stem. This is because the distribution of hearing is bilateral at all levels of the central nervous system auditory pathway. Localization of sound may be slightly affected by auditory cortex lesions. In fact it is nearly impossible for central nervous system lesions to cause clinically detectable hearing loss and if these is hearing loss you must look at the conductive system, the inner ear and the vestibulocochlear nerve.

Front 69

Vertigo - Inner ear damage vs. CNS damage

Back 69

With peripheral causes of vertigo (the illusion of movement), nystagmus is proportional to the amount of vertigo and nystagmus is always in the same direction regardless of the direction that the patient looks. Also, peripheral nystagmus is almost never in a vertical (up or down) direction. With central vertigo (cerebellum, vestibular nuclei and brain stem) nystagmus is usually greater than vertigo and may shift direction depending on gaze direction.

Front 70

Comatose pt - ice water in their R ear.

Back 70

The eyes would drift toward the side of the ice-water infusion and remain there for several minutes. There would be no nystagmus (which is a response generated by the conscious cerebral cortex when the visual image slips across the retina).

Front 71

Cough reflex

Back 71

The cough reflex - afferent is vagus, efferent is complex including respiration centers and vagus.

Front 72

Baroreceptor pathway

Back 72

The baroreceptor reflex - afferent is glossopharyngeal, efferent is vagus.