CN Signs Flashcards
1
Q
Olfactory change
A
Trauma
URTI
Meningitis
Frontal lobe tumour
2
Q
Light pupil reflex and where damage is
A
- light from retina up CN II to superior colliculus in midbrain then to CN III nuclei on both sides. CN III= constriction.
- IF contralateral constriction only- efferent defect.
- marcus gunn sign of relative afferent pupillary defect- incomplete afferent damage. Affected pupil dilates when light switched to it from good pupil. As consensual relaxation response from normal eye predominates due to partial damage.
3
Q
Papilloedema
A
RICP:
Tumour, abcess, encephalitis, hydrocephalus, idiopathic IC HTN.
4
Q
CNIII palsy down and out
A
Ptosis
Large pupil (mydriasis)
Down and out when look straight
5
Q
CN IV palsy nasal upshoot
A
Affected eye looks up and in due to unopposed inferior oblique when look medially and down.
Diplopia on looking down and in
Compensatory head tilt. Because superior oblique has role in intortion.
Cant walk down stairs
6
Q
CN VI palsy crossed-most common EO palsy
A
Horizontal diplopia on looking out.
Cant abduct affected eye, and slight adducted when look ahead.
7
Q
Nystagmus
A
Cerebellar- horizontal towards affected side
Vestibular- horizontal away from affected side
Midbrain or base 4th ventricle lesion- vertical up
FM lesion- vertical down
Nystagmus lasting 2 beats or less is normal.
Also normal at extremes of gaze.
8
Q
Bells plasy
A
Total facial droop and weakness one side face
LMN defect so forehead affected.
UMN lesion forehead sparing eg stroke due to bilateral innervation of temoral s.
9
Q
LMN lesion
A
Hyporeflexia
Hypotonia
Fasciculation
Muscle wasting
10
Q
UMN lesion
A
Hyperreflexia Hypertonia Clonus Babinski No wasting Positive Hoffmann- flick middle finger= thumb flexion in UMN lesion.
11
Q
blind spot
A
Large in papilloedema.
Blind spot is in nasal part of retina so in temporal field.
12
Q
Trigeminal sensory
A
Angle of jaw spared as innervated by C2
13
Q
Muscles of mastication
A
Temporalis wasting easily seen
Masseter
Open against resistance tests pterygoids, mylohyoid, anterior digastric.
14
Q
Corneal reflex
A
Afferent CN Va
Efferent CN VII
15
Q
Tongue deviation
A
Towards abnormal side
16
Q
Uvula deviation
A
away from side of CN X lesion when say ah
17
Q
Tongue
A
Wasting and fasciculation- LMN lesion
Stiff, non wasted, hyperreflexive- UMN lesion
Deviates towards CN XII lesion.
18
Q
Rinnes
A
Negative= BC better than AC indicates conductive loss on that side.
19
Q
Webers
A
Localises TOWARDS conduction loss.
AWAY from sensorineural loss.
20
Q
Gag reflex
A
Afferent CN IX
Efferent CN X
21
Q
Accommodation
A
Afferent CN II to lateral geniculate bodies, to pre tectal nucleus, to PNS nuclei of CN III= constriction.
22
Q
Pupils
A
- irregular- iritis, trauma, syphillis.
- dilated- CN III lesion, drugs.
- constricted- age, SNS damage eg horners, opiates, miotics eg pilocarpine, pons damage.
- unequal (anisocoria)- unilateral lesion, eye surgery, eye drops, syphillis.
23
Q
Ptosis
Dropping upper eyelid
A
CN III to LPS
Cervical SNS chain to superior tarsal
-CN III lesion= unilateral complete ptosis
-SNS paralysis (horner)= unilateral partial ptosis.
-myopathy (MG)- bilateral partial ptosis
-congential- usually partial and no other CNS signs.
24
Q
Visual field problem
A
Stroke
SOL
Glaucoma
25
CN I lesion cause
Trauma
RTI
Meningitis
Frontal lobe tumour
26
CN II lesion cause
- monocular blindness (lesion one eye or ON)- MS, arteritis .
- bilateral blind- DM, MS, syphillis.
- bitemporal hemianopia- chiasm compression eg pituitary adenoma, CA aneurysm.
- homonymous hemianopia (tracts, radiation or occipital cortex)- stroke, abcess, tumour.
27
CN III lesion cause
Posterior communicating A aneurysm (main one)= diplopia and dilated pupil.
RICP
Tumour
Vasculopathies- DM, HTN, Arteritis
28
CN IV lesion cause
Rarely isolated CN IV lesion
Long and thin - through cavernous sinus with CN III, IV, Va+b, ICA.
Congenital main one- see compensatory head tilt as child.
Orbital trauma/closed head injury.
Cavernous sinus thrombosis, infection track back.
Tumours
Vasculopathies eg DM.
29
CN V lesion cause
Trigeminal neuralgia (compression= pain Vb/c)
HZV
Nasopharyngeal CA
Acoustic neuroma
Cavernous sinus lesion loss corneal reflex.
Facial fracture.
30
CN VI lesion cause
```
RICP main one.
False localising sign in RICP- long tortuous course so one of first to go in RICP but tumour not necessarily close. Pressed against bone.
MS
Wernickes encephalopathy
Potine stroke or tumour.
Vasculopathies eg DM, HTN.
```
31
CN VII lesion cause
-LMN- bells (inflammation at stylomastoid foramen), polio, otitis media, CP angle tumour eg acoustic neuroma, skull fracture.
-UMN- stroke, tumour.
-intracranial lesion- eg middle ear tumour or infection.
Chorda tympani- reduced salivation and loss taste on ipisalteral anterior 2/3.
N to stapedius- ipisilateral hyperacusis.
Greater petrosal- ipsilateral reduced lacrimal fluid production.
-extra cranial after stylomastoid foramen- motor function only so weak facial expression.
Eg parotid gland tumour of inflammation, herpes infection of the N, compression during forceps delivery, idiopathic bells.
32
CN VIII lesion cause
```
Noise damage
Pagets
Brainstem stroke
Aminoglycosides
Acoustic neuroma
HZV
```
33
CN IX, X, XI lesion cause
Trauma
Brainstem lesion
Neck tumour
Posterior triangle surgery
34
CN XII lesion cause
| Rarely lesioned
```
Polio
Tumour
Stroke
Trauma
TB
Bulbar palsy
```
35
CN functions and foramina
- CN I olfactory- sensory. Cribriform plate ethmoid.
- CN II optic- sensory. Optic canal in sphenoid.
- CN III occulomotor- motor and autonomic. PNS to pupil. Superior orbital fissure.
- CN IV trochlear- motor. SOF.
- CN Va opthalmic trigeminal- sensory forehead. SOF.
- CN Vb maxillary trigeminal- sensory cheeks and nasal cavity. F rotundum.
- CN Vc mandibular trigeminal- sensory and motor mastication. F ovale in sphenoid.
- CN VI abducens- motor. SOF.
- CN VII facial- sensory, motor, autonomic. Internal acoustic meatus (acoustic neuroma).
- CN VIII vestibulocochlear- sensory. IAM.
- CN IX glossopharyngeal- sensory (pharynx), motor, autonomic (PNS to parotid). Jugular formamen.
- CN X vagus- sensory, motor (soft palate and pharynx), autonomic. Jugular foramen.
- CN XI accessory- motor. Spinal and cranial components. Jugular foramen.
- CN XII hypoglossal- motor. Hypoglossal canal.
36
CN VII
```
Temporal
Zygomatic
Buccal
Mandibular
Cervical
Chorda tympani taste anterior 2/3
PNS salivary and lacrimal glands- greater petrosal
Nerve to stapedius
```
37
Vestibular schwannoma
Benign schwann cell growth= acoustic neuroma.
| Facial N runs with it so signs- facial N plasy with hearing and balance problems. MRI!
38
Carotid sinus reflex
Afferent CN IX
| Efferent CN X- vasovagal syncope
39
RLN
```
Left= arch of aorta
Right= R subclavian
```
40
CN V
Inferior alveolar N block
41
Cerebral venous sinus thrombosis
```
Thrombo in one dural venous sinus
=accumulation deO blood in brain parenchyma= venous infarction.
Also CSF accumulation.
Signs- headache, nausea, neuro deficit.
CT/MRI contrast diagnosis.
Anticoagulation tx.
```
42
Middle ear
| Contains malleus, incus and stapes.
Infection. Mastoid air cells and eustacian tube.
Cholesteatoma- neg pressure, retraction pockets, accumulate dead cells.
N damage eg chorda tympani.
Otitis media with effusion (glue) of LT neg pressure= conductive loss.
Otitis media can= CN VII palsy. Mastoiditis, can spread IC. Meningitis.
43
Isolating EOs
SR- abduct then look up
IO- adduct then up
SO- adduct then down
IR- abduct then down
44
Light reflex
Visual info from retina to thalamus to visual cortex.
CN II fibres involved in pupil reflexes are routed via superior colliculi to PNS part of CN III nucleus (edinger westphal on both sides= consensual reflex).
Path-
Light stimulates CN II, synapses in pre tectal area, gives rise to neurones supplying EW nuclei bilaterally.
Both CN III are stimulated to cause direct and consensual constriction via PNS fibres.
45
Visual fields
Nasal fibres= temporal field, x optic chiasm.
| Temoral fibres= nasal field, run ipisalterally.
46
Visual field defects general
- before chiasm- unilateral and ipsialteral loss.
- at or after chiasm- bilateral loss as fibres from both sides cross.
- after chiasm- contralateral loss.
47
Monocular blindness
Lesion before chiasm of one side optic N.
Causes-
optic N glioma or retinoblastoma (kids)-congenita.
Optic sheath meningioma (middle age).
Trauma.
Optic neuritis
48
Bitmeporal hemianopia
```
Loss both temporal fields.
Lesion at chiasm. Affects both nasal fibres.
Causes-
Pituitary adenoma.
ACA aneurysm.
```
49
Left homonymous hemianopia
| Vv for R
```
Lesion of RIGHT optic tract.
Affects RIGHT temporal and LEFT nasal fibres.
Causes-
Vascular most common eg stroke.
Also neoplasia and trauma.
```
50
Macular sparing
| Contralateral homonymous hemianopia with macular sparing.
Occipital lobe dual BS- PCA, MCA
Lesion at occipital visual cortex.
In stroke affecting PCA- most of occipital lobe lost, nut macular function spared as that part supplied by MCA, so central vision spared.
Macular area also has large cortical representation.
51
Contralateral homonymous inferior quadrantanopia.
Lesion at contralateral parietal superior optic radiation.
| So superior parietal lesion eg stroke.
52
Contralateral homonymous superior quadrantanopia
Lesion of contralateral temporal inferior optic radiation (going to primary visual cortex).
53
Accommodation reflex
Required for near vision.
-3C APSECTS-
Convergence- medial rectus.
Pupillary constriction- constrictor pupillae.
Convexity of lens to increase refractive power- ciliary muscle. Adds dioptric strength.
-Path-
Follows visual path via lateral geniculate nucleus (thalamus) to visual cortex.
Final aspect of path is common with light reflex via EWN
-occipital lobe lesion- lose accommodation but retain light reflex.
54
Diplopia
If stops when close one eye- then is movement issue.
Monocular diplopia likely to to lens distortion.
-diplopia by anatomical site-
Cornea and lens problem- cataracts
Eye muscle problem- MG
N problem (or their BS)- MS, DM
Brain problem- stroke, SOL.
55
EO muscle actions
```
Inferior oblique= up and in.
Superior oblique= down and in. (CN IV)
Inferior rectus= down and out.
Superior rectus= up and out.
Lateral rectus= out. (CN VI)
Medial rectus= in.
```
56
Detached retina
R layer detach from bm.
| N fibre remain attached so still light sensitive but focus problems due to folding of retina.
57
Tongue
```
-taste-
Posterior 1/3- glossopharyngeal CN IX
Anterior 2/3 chords tympani from CN VII
-motor-
Hypoglossal CN XII
-sensory-
Anterior 2/3 lingual N from CN Vc
```
58
Glaucoma
Imbalance vitreous humour secretion and reabsorption.
=raised IO pressure.
Distortion of axial eye length.
59
Acuity correction
Short sighted myopia requires subtraction of diopters using a diverging concave lens.
Long sighted hypermetropia requires addition with convex lens.
60
Presbyopia
Old sight
| As age near point (closest point where focus possible, normal 10cm) retreats and become progressively long sighted.
61
Cataract
Lens opacity.
| Congenital, senile, trauma, metabolic disturbance eg DM.
62
Scotomata
Pathological blind areas
63
Organ of corti
On top of cochlear basillar memebrane.
Contains vibration sensitive hair cells. Sense endolymph movement.
Inner hair cells- 1 row, sense sound. To CN XIII to cochlear nuc leads and auditory brainstem.
Outer- 3 rows, serve as amplifiers.
Bending stereocilia opens K channels= depolarisation= Ca= nt release.
Spiral ganglion neurones- T1 (95%) synapse onto IHC, T2 onto OHC.
Louder sound= more APs in more axons.
64
Auditory pathway
```
Cochlea
Spiral ganglion cells
Cochlear nucleus
Superior olivary complex
Inferior colliculus
Medial geniculate nucleus
Auditory cortex
```
65
Hearing impairment
```
Loud noise- hair cell damage and death.
Congenital defect
Infection eg rubella, otitis media.
Ototoxic drug eg aminoglycosides kill hair cells.
Trauma to temporal bone
Age
```
66
Hearing assessment
Otoscope
Audiograms sensitivity vs frequency
Otoacoustic emissions- sound generated by OHC
Auditory brainstem response
67
Sites of hearing loss
-conductive-
Blockage, ruptured tympanic membrane, otitis media, otosclerosis, wax/cerumen, negative air pressure middle ear due to eusatcian tube obstruction.
-sensory-
Hair cell destruction eg loud noise, ototoxicity.
-neural-
Spiral ganglion damage eg acoustic neuroma.
Age related
Tinnitus
Auditory neuropathy associated with hyperbilirubinaemia.
Monaural deafness means cant localise sound.
68
Hearing tx
Hearing aid
Cochlea implant- electrode into cochlea, encodes sound then stimulates. Mimics hair cells at different points in cochlea.
Hair cell regeneration-stem cells
Cochlear nucleus implants- skip ear.
69
Middle ear contents
```
Inner tympanic membrane
Ossicular chain synovial joints
Outer oval window
Tensor tympani
Stapedius
Air
```
70
Tympanic membrane
Outer epithelia- innervated by br of CN Vc, and sometimes a small branch of CNX
Middle fibrous layer
Inner epithelia- innervated by CN IX
71
Middle ear infection spread
Untreated infection can affect middle ear epithelium, mastoid air cells, CN VIII, temporal bone.
Can spread intra cranially to middle cranial fossa-this communicates with external environment via auditory meati.
Could reach posterior fossa from here by-
-trunking of CN VIII= N death adn neuroma OR infection of temoral lobe.
-spread to mastoid antrum via epithelia. Break intp mastoid process of temporal bone then to sigmoid sinus in posterior fossa. Can then spread in blood to distant sites too.
-infection into any process of temporal bone, to periosteum, to meninges. Important as brain no immune mechanism.
72
Eustacian tube function
| Opened by tensor veli palatini and/or salpingopharyngeus
```
Equilibration of pressure between middle ear and atmosphere.
Ventilation of middle ear.
Drain of mucous secretion to np.
Opening in np guarded by lymphoid organ prevents infection spread from np to middle ear.
-failure=
Pressure build up and pain.
Reduced hearing
Infection.
```
73
CN IX, X and XI lesion signs
| Lesions of all eg MND= bulbar palsy= LMN, dysarthria, dysphagia, tongue weak wasting fasciculation.
```
Uvula deviation away from lesion
RLN vagus branch- dysphonia and bovine cough
Nasal regurg
Nasal air escape.
Trapezius and SCM wasting.
```
