Download Neurology Session 1 – Cranial Nerves

NEUROLOGY SERIES
FOR 2ND YEARS
Alex Parker
DISEASE TOPICS
• Cranial nerve lesions
• Stroke
• TIA
• Brain Haemorrhage
• Cerebellum (DANISH)
• Multiple Sclerosis
• Motor Neuron Disease
• Space Occupying Lesion
• Parkinson’s Disease
• Huntington’s Disease
• Myelopathy vs Radiculopathy
• Peripheral Nerve Disorders (Guillain-Barré)
• Myasthenia Gravis
SESSION ONE
CRANIAL NERVES
CRANIAL NERVES
Oh Oh Oh To Tri And Finger Virgins Girls Vagina And Hymen
•
Cranial nerve I – Olfactory
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Some
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Cranial nerve II – Optic
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Say
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Cranial nerve III – Oculomotor
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Money
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Cranial nerve IV – Trochlear
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Matters
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Cranial nerve V – Trigeminal
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But
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Cranial nerve VI – Abducens
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My
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Cranial nerve VII – Facial
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Brother
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Cranial nerve VIII –
Vestibulocochlear
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Says
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Cranial nerve IX –
Glossopharyngeal
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Big
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Cranial nerve X – Vagus
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Boobs
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Cranial nerve XI – Accessory
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Matter
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Cranial nerve XII – Hypoglossal
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More
CRANIAL NERVES
Remember: 2 – 2 – 4 – 4
2 not on the brainstem
2 from the midbrain
4 from the pons
4 from the medulla oblongata
CRANIAL NERVES
1
5
8
10
3
9
2
12
11
7
6
4
OLFACTORY NERVE - I
• Anatomy: Olfactory tract ends at uncus of the temporal lobe
• Function: Sense of smell
• Sign/Symptoms of a lesion: Change in smell
• Causes of a lesion: Head injury, Parkinson’s disease, recurrent
URTI
OPTIC NERVE - II
• Anatomy:
OPTIC NERVE - II
• Function: SENSORY
•
•
•
Transmits visual information
Pupillary Reflex (afferent pathway, with CNIII)
Accommodation (afferent pathway, with CNIII)
• Clinical Testing:
•
Virsual Acuity
•
•
•
•
•
•
Colour vision
Visual Fields
Pupillary Reflex
•
•
•
Snellen chart at 6m
Remember to ask about glasses/contacts
Cover one eye
Swinging torch test
Blind Spot
Fundoscopy
OPTIC NERVE - II
•
Signs & Causes of damage:
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Visual inattention
•
•
•
Decreased Visual Acuity
•
•
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Optic Atrophy (+ pale optic disc)
MS, frontal tumour, glaucoma, optic nerve compression
Increased Blind Spot
•
•
Loss of awareness of one side of vision
Parietal Lobe Lesion
Optic neuritis, Raised ICP, Glaucoma
Marcus Gunn Pupil (Relative Afferent Pupillary Defect)
•
•
•
Observed during the swinging torch test
Patient's pupils constrict less (therefore appearing to dilate) when a bright light is
swung from the unaffected eye to the affected eye.
Damaged optic nerve pathway – Optic neuritis (pain on moving eye, loss of
central vision, RAPD, papilloedema)
•
Papilloedema (swollen optic discs)
•
Visual field defects – see next slide
OPTIC NERVE - II
•
Signs & Causes of damage:
•
Afferent pupillary defect – a) no direct constriction when light shone in affected eye
nor consensually constriction in non-affected b) direct constriction when light is
shone in non-affected eye and consensually constriction by affected eye
VISUAL FIELD DEFECTS
VISUAL FIELD DEFECTS
VISUAL FIELD DEFECTS
1. Central scotoma - caused by inflammation of the optic disk (optic neuritis) or optic nerve
(retrobulbar neuritis)
2. Right Monocular vision loss - from a complete lesion of the right optic nerve
3. Bitemporal hemianopia - caused by pressure exerted on the optic chiasm by a pituitary
tumour
4. Right nasal hemianopia - caused by a perichiasmal lesion (eg. calcified internal carotid
artery)
5. Right homonymous hemianopia - from a lesion of the left optic tract
6. Right homonymous superior quadrantanopia - caused by partial involvement of the
optic radiation by a lesion in the left temporal lobe (Meyer’s loop)
7. Right homonymous inferior quadrantanopia - from partial involvement of the optic
radiation by a lesion in the left parietal lobe
8. Right homonymous hemianopia - from a complete lesion of the left optic radiation
9. Right homonymous hemianopia w/t macular sparing - caused by a posterior cerebral
artery occlusion
OCULOMOTOR, TROCHLEAR,
ABDUCENS – III, IV, VI
• Anatomy:
•
•
•
iii) ventral midbrain  through bony orbit  via superior
orbital fissure  SR, MR, IR, IO
iv) dorsal midbrain  courses ventrally around midbrain 
through superior orbital fissure  SO
vi) inferior pons  long tortuous intracranial route  enter
via superior orbital fissure  LR
OCULOMOTOR, TROCHLEAR,
ABDUCENS – III, IV, VI
• Function: MOTOR
•
•
•
•
Movements of the eye
Pupillary Reflex (efferent - CNIII)
Accommodation (CNIII with CNII)
Elevating the eyelid (CN III by sympathetically innervating levator
palpebrae superioris)
• Clinical Testing:
•
Eye movement
•
•
•
•
Accommodation
•
•
•
•
Draw an H with your finger
“Tell me if you see double vision”
Look for nystagmus and/or opthalmoplegia
Hold finger in the distance
“Keep looking at my finger”
Move finger towards pts nose
Pupillary Reflex
•
Direct and Consensual
OCULOMOTOR, TROCHLEAR,
ABDUCENS – III, IV, VI
SR3
IO3
MR3
LR6
Nose
IR3
SO4
3RD NERVE PALSY
• Signs & Causes of damage:
•
Divergent squint & Diplopia (eye down and out + double vision)
•
•
Ptosis (eyelid to droop or close completely)
•
•
•
•
Paralysis of extraocular muscles (SR, IR, MR)
Paralysis of levator
Horner’s syndrome
Myasthenia gravis
Efferent pupil defect (causing a dilated pupil)
•
•
•
•
Paralysis of sphincter pupillae
Tumour
Aneurysm
Brainstem stroke
3RD NERVE PALSY
• Signs & Causes of damage:
c) affected pupil can not constrict to light directly but non-affected pupil can
constrict consensually d) affect pupil cannot constrict consensually either
when light is shone in non-affected pupil but non-affected pupil can
4TH NERVE PALSY
• Signs & Causes of damage:
•
Eye Up & Out + Diplopia when looking down
(often complain of trouble walking downstairs)
•
•
•
Paralysis of SO4
Tumour
Aneurysm
6TH NERVE PALSY
• Signs & Causes of damage:
•
Convergent squint + horizontal diplopia (person
is trying to look straight but left eye can not abduct
therefore is stuck looking inward)
•
•
•
Paralysis of LR6
Tumour
Aneurysm
OFF TOPIC: HORNER’S SYNDROME
• Miosis (constricted pupil)
• Ptosis (a weak, droopy eyelid)
• Anhidrosis (decreased sweating)
• +/- Enophthalmus (inset eyeball)
• Caused by ipsilateral damage to the sympathetic trunk
•
•
Pancoast tumour (bronchogenic carcinoma on apex of lung)
MS, Brain tumour, Thyroid lump, Trauma, Congenital…
OFF TOPIC:
INTERNUCLEAR OPHTHALMOPLEGIA
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Lesion in the medial longitudinal fasciculus
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Causes failure of ADDUCTION of eye on affected side
•
For example in a right sided INO:
•
•
•
On looking to the right - it is normal because abduction is not affected
On looking to the left – left eye abducts normal, but right eye fails to adduct and
remains looking straight
Subsequently there is nystamgmus in left eye as it attempts to compensate
OFF TOPIC:
CONJUGATE DEVIATION
•
Complete/partial defect of BOTH eyes to
move in a particular direction
•
Arises from supranuclear lesions of the
pathways controlling eye movement (i.e.
above III, IV and VI)
•
Massive destructive lesions of the
brainstem/cerebral hemisphere
•
Eyes can tell us what’s going on!!!
•
•
•
A – Partial Seizure
B – Destructive Lesion (stroke,
tumour, MS)
C – Destructive Pontine Lesion
TRIGEMINAL NERVE – V
• Anatomy:
•
3 branches: Ophthalmic
Maxillary
Mandibular
TRIGEMINAL NERVE – V
• Function: BOTH
•
Ophthalmic branch (V1)
•
•
Maxillary branch (V2)
•
•
SENSORY
SENSORY
Mandibular (V3)
•
•
SENSORY
MOTOR for muscles of mastication
• Clinical Testing:
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Sensory
•
•
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Motor
•
•
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Ask pt to close eyes and say ‘yes’ when they feel you touch their face
Move from side to side
Jaw opening against resistance (pterygoid muscles)
Jaw clench – palpate temples (masseter muscles)
Reflexes
•
•
Corneal reflex
Jaw jerk
TRIGEMINAL NERVE – V
• Signs & Causes of damage:
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Loss of corneal reflex, paralysed muscles of mastication (deviation of
jaw towards side of lesion with unilateral lesions) and loss of facial
sensation
•
•
•
•
•
Trigeminal Neuralgia (inflammation/demyelination of trigeminal nerve 
sudden, explosive severe pain along the trigeminal nerve)
•
•
•
CN V palsy
Neoplasm
Infection
+ ipsilateral hearing loss – acoustic neuroma
Compression of a vessel
Similar symptoms + vesicular eruption – Herpes Zoster Infection (shingles)
Brisk jaw reflex
•
Bilateral UMN lesion
FACIAL NERVE – VII
• Anatomy:
Two Zombies Buggered My Cat
•
•
•
•
•
Temporal
Zygomatic
Buccal
Mandibular
Cervical
FACIAL NERVE – VII
• Function: BOTH
•
•
•
Convey motor impulses to muscles of facial expression
Parasympathetic innervation of lacrimal/nasal and
palatine/submandibular/sublingual glands
Convey sensory TASTE impulses for anterior 2/3rd of tongue
• Clinical Testing:
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Sensory
•
•
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Ask if pt has noticed a change in taste
Or ask to differentiate salty, sour and bitter flavours
Motor
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•
•
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Raise eyebrows (differentiates between UMN and LMN)
Screw up eyes – try to pull open (Bell’s sign – upgaze on attempted
eye closure)
Puff out cheeks
Big smile
FACIAL NERVE – VII
• UMN vs LMN lesion
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UMN: Forehead sparing
•
•
•
•
Stroke
MS
Tumour
LMN: Entire Facial Palsy
•
•
•
•
Bell’s Palsy (acute idiopathic
<72hrs)
Parotid Tumour
Acoustic neuroma
Herpes Zoster
VESTIBULOCOCHLEAR – VIII
• Anatomy:
•
Fibres from hearing (cochlea) & equilibrium (vestibule) apparatus 
internal acoustic meatus  merge to form vestibulocochlear
VESTIBULOCOCHLEAR – VIII
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Function: SENSORY
•
•
Bring sensory info from the hearing and equilibrium receptors in the inner
ear to the brain
Clinical Testing:
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Sensory – Hearing
•
•
•
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Occlude external meatus of one ear and whisper a number and letter into
patent ear
Ask them to say it back
Repeat for other ear
Special test – Sensorineural defect vs Conductive defect
• Weber Test
• Tuning fork on forehead
• Rinne’s Test
• Tuning fork placed on mastoid process
• Sensorineural defect
• Weber test – sound will be louder in normal ear
• Rinne’s test – air conduction is louder than bone conduction
• Conductive defect
• Weber test – sound will be louder in affected ear
• Rinne’s test – bone conduction is louder than air conduction
VESTIBULOCOCHLEAR – VIII
• Signs & Causes of damage:
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Conductive Hearing Loss
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•
•
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Sensorineural Hearing Loss:
•
•
•
•
•
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Ear disease
Otitis externa/media
Paget’s disease
Perforated ear drum
Congenital
Acquired
Presbycusis (ageing)
Noise induced
Ototoxicity (drugs)
Attacks of dizziness and deafness
•
Acoustic neuroma (benin tumour – as it grows, it can compress adjacent
CN V-VII)
GLOSSOPHARYNGEAL – IX
• Anatomy:
•
Emerges from medulla and leave skull via jugular foramen to run to
throat
GLOSSOPHARYNGEAL – IX
• Function: BOTH
•
Sensory
•
•
Taste receptors on the posterior 1/3rd of tongue & pharynx
Relays chemoreceptor information from carotid body located near
the fork (bifurcation) of the carotid artery
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Relays baroreceptor information from carotid sinus at the base of
the internal carotid
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Motor
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Innervation of the stylopharyngeus, which elevates the pharnyx in
swallowing
VAGUS – X
• Anatomy:
•
Only cranial nerve to extend
beyond head and neck region.
Emerges from medulla 
through skull via jugular
foramen  descend through
neck region into thorax and
abdomen.
• Function: BOTH
•
•
•
•
Motor parasympathetic
innervation of organs
Motor innervation of swallowing
Sensory information from
viscera
Sensory from aortic body
(chemoreceptor & baroreceptor)
HYPOGLOSSAL – XII
• Anatomy:
•
•
Medulla  exit from the skull via hypoglossal canal  tongue
Function: MOTOR
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Motor innervation of the tongue
GLOSSOPHARYNGEAL, VAGUS,
HYPOGLOSSAL (BULBAR) – IX, X, XII
•
Clinical testing – done together
Bulbar Function
• Ask about a change in taste. Can assess it as well
• Look for uvula deviation
• Assess speech & swallow
• Gag reflex
Tongue
• Appearance
• Movements with resistance
• Tongue deviates to side of weakness
BULBAR PALSY (LMN – IX, X, XII)
VS
PSEUDOBULBAR (UMN)
Bulbar
Features
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Causes
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Pseudobulbar
Nasal speech
Absent jaw reflex
Uvula deviation
Nasal regurgitation of
food
Reduced/absent gag
reflex
Wasted, fasciculating
tongue
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MND
Diptheria
Polio
Myasthenia gravis
Guillain-Barré
Tumour
Brainstem vascular
disease
•
•
•
•
•
•
•
•
•
•
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Slow, monotonous
speech, sometimes
explosive
Brisk jaw reflex
Dysphagia
Brisk gag reflex
Shrunken immobile
tongue
Emotional lability
Assoc UMN limb signs
MND
Bihemispheric vascular
disease
MS
Tumour
Extrapyramidal disease
ACCESSORY– XI
•
Anatomy:
•
•
•
•
Roots begin on the cervical spine (C1-C5)
Travel up through the foramen magnum
Join cranial fibres
Loop round and back down through the jugular foramen to muscles of the neck
and upper back
ACCESSORY– XI
ACCESSORY– XI
• Function: MOTOR
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Innervates the sternocleidomastoid & trapezius muscle
• Clinical Testing
•
•
Ask patient to turn their head against resistance (sternocleidomastoid)
Ask patient to shrug their shoulders against resistance (trapezius)
• Signs and causes of damage:
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Loss of power to sternocleidomastoid and trapezius
•
•
•
•
CNXI palsy
Tumour
Stroke
Trauma
QUICK FIRE MCQS
A malignant tumour is damaging the patient's
glossopharyngeal nerve. They will experience
a) loss of taste over the anterior two-thirds of the tongue.
b) loss of somaesthetic sensation over the anterior two thirds
of the tongue.
c) loss of taste and somaesthetic sensation over the posterior
third of the tongue.
d) paralysis of the muscles of the tongue.
A malignant tumour is damaging the patient's
glossopharyngeal nerve. They will experience
a) loss of taste over the anterior two-thirds of the tongue.
b) loss of somaesthetic sensation over the anterior two thirds
of the tongue.
c) loss of taste and somaesthetic sensation over the posterior
third of the tongue.
d) paralysis of the muscles of the tongue.
A patient is stabbed in the neck. You suspect damage to the
accessory nerve in the posterior triangle. You would test nerve
function by asking the patient to
a) extend their neck against resistance.
b) extend their neck without impairment.
c) lift their shoulders against resistance.
d) lift their shoulders without impairment.
A patient is stabbed in the neck. You suspect damage to the
accessory nerve in the posterior triangle. You would test nerve
function by asking the patient to
a) extend their neck against resistance.
b) extend their neck without impairment.
c) lift their shoulders against resistance.
d) lift their shoulders without impairment.
Loss of somatic sensation over the anterior two-thirds of the
tongue indicates damage to the
a) lingual branch of the mandibular trigeminal nerve.
b) chorda tympani branch of the facial nerve.
c) lingual branch of the glossopharyngeal nerve.
d) hypoglossal nerve.
Loss of somatic sensation over the anterior two-thirds of the
tongue indicates damage to the
a) lingual branch of the mandibular trigeminal nerve.
b) chorda tympani branch of the facial nerve.
c) lingual branch of the glossopharyngeal nerve.
d) hypoglossal nerve.
Examination of a patient indicates that they have a medially
directed strabismus (squint). This could be due to damage to
the
a) oculomotor nerve.
b) trochlear nerve.
c) ophthalmic trigeminal nerve.
d) abducens nerve.
Examination of a patient indicates that they have a medially
directed strabismus (squint). This could be due to damage to
the
a) oculomotor nerve.
b) trochlear nerve.
c) ophthalmic trigeminal nerve.
d) abducens nerve.
A patient suffers damage to the orbit in a road traffic incident
resulting in damage to the third cranial nerve. Which of the
following signs will be present?
a) Pupillary constriction and a medial strabismus
b) Pupillary dilatation and a medial strabismus
c) Pupillary constriction and a lateral strabismus
d) Pupillary dilatation and a lateral strabismus
A patient suffers damage to the orbit in a road traffic incident
resulting in damage to the third cranial nerve. Which of the
following signs will be present?
a) Pupillary constriction and a medial strabismus
b) Pupillary dilatation and a medial strabismus
c) Pupillary constriction and a lateral strabismus
d) Pupillary dilatation and a lateral strabismus
Which of the following statements is true of the pupillary light
reflex?
a) Its efferent limb is carried in the optic nerve
b) It is mediated by the inferior colliculi in the midbrain
c) It is a consensual reflex
d) Its afferent limb is carried in the oculomotor nerve
Which of the following statements is true of the pupillary light
reflex?
a) Its efferent limb is carried in the optic nerve
b) It is mediated by the inferior colliculi in the midbrain
c) It is a consensual reflex
d) Its afferent limb is carried in the oculomotor nerve
The seventh cranial nerve supplies
a) taste buds on the posterior third of the tongue.
b) muscles of the soft palate.
c) muscles of the lower lip.
d) the parotid salivary gland.
The seventh cranial nerve supplies
a) taste buds on the posterior third of the tongue.
b) muscles of the soft palate.
c) muscles of the lower lip.
d) the parotid salivary gland.
TILL NEXT TIME…