Download CN VI Lesion

Survey
yes no Was this document useful for you?
   Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Document related concepts
no text concepts found
Transcript
Cranial Nerves
I.
II.
III.
IV.
V.
VI.
Olfactory
Optic
Oculomotor
Trochlear
Trigeminal
Abducens
VII. Facial
VIII.Vestibulocochlear
IX. Glossopharyngeal
X. Vagus
XI. Accessory
XII. Hypoglossal
Fall 2012
Cranial Nerves
CN I
CN II
CN III
CN IV
CN V
CN VI
CN VII
CN VIII
CN IX
CN X
CN XI
CN XII
Olfactory
Optic
Oculomotor
Trochlear
Trigeminal
Abducens
Facial
Vestibulocochlear
Glossopharyngeal
Vagus
Spinal accessory
Hypoglossal
--------------------Midbrain
Midbrain
Pons
Pons
Pons
Pons
Medulla
Medulla
Medulla
Medulla
Spinal Cord / BS Changes
A
A
A
A
S.L.
B
B
S.L.
B
B
Spinal Cord
Brainstem
CN Functional Components
4th
VENTRICLE
SSA
GVA
SVA
S.L.
GVE
GSA
SVE
GSE
CN Functional
Columns
4th
VENTRICLE
SSA
GVA
SVA
S.L.
GVE
GSA
SVE
GSE
CN Nuclei
Cranial Nerves
CN I
CN II
CN III
CN IV
CN V
CN VI
CN VII
CN VIII
CN IX
CN X
CN XI
CN XII
Olfactory
Optic
Oculomotor
Trochlear
Trigeminal
Abducens
Facial
Vestibulocochlear
Glossopharyngeal
Vagus
Spinal accessory
Hypoglossal
SSA
SSA
GSE, GVE
GSE
SVE, GSA
GSE
SVE, GVE, GSA, SVA
SSA
SVE, GVE, GSA, SVA
SVE, GVE, GSA, GVA, SVA
SVE
GSE
Cranial Nerves
CN I
CN II
CN III
CN IV
CN V
CN VI
CN VII
CN VIII
CN IX
CN X
CN XI
CN XII
Olfactory
Optic
Oculomotor
Trochlear
Trigeminal
Abducens
Facial
Vestibulocochlear
Glossopharyngeal
Vagus
Spinal accessory
Hypoglossal
SSA
SSA
GSE, GVE
GSE
SVE, GSA
GSE
SVE, GVE, GSA, SVA
SSA
SVE, GVE, GSA, SVA
SVE, GVE, GSA, GVA, SVA
SVE
GSE
Corticobulbar
Projections
No CBs for CN III, IV or VI
- through PPRF in pons
MOTOR CORTEX
V
V
up VII
up VII
low VII
low VII
IX, X
IX, X
XI
XI
XII
XII
CN I
• Olfactory Epithelium
• Lifespan  2 months
• Mitosis of basal cells replace
lost receptors
• Direct access to stimuli
• Unmyelinated axons form
CN I – through cribriform
plate
CN I
• Specialized dendrites – olfactory vesicles/knobs
CN I
•
•
•
As many as 103 afferent fibers may
synapse with one mitral or tufted cell
Odorant dissolved in aqueous phase of
mucus interacts with specific receptor
Often many odorants in one “smell”
CN I
Olfactory
Cortices
Olfactory bulb
Olfactory tract
Area subcallosal
Medial olfactory stria
Intermediate olfactory stria
Lateral olfactory stria
Anterior commissure
Optic tract (cut)
Pyriform
area
Uncus
Amygdaloid body
Entorhinal area
Olfactory System
• Anosmia = loss of sense of smell
• Result of head injury, chronic nasal infection,
or tumor in inferior frontal lobes
• Olfactory hallucinations can be the result
of temporal lobe seizures
• They are often part of the “aura” that precedes
a seizure
CN II
VISUAL IMAGE
(BINOCULAR)
VISUAL FIELD OF
LEFT EYE
VISUAL FIELD OF
RIGHT EYE
Visual field = part of visual world
seen by each eye
Left
Right
Monocular
Cresent
LEFT EYE
RIGHT EYE
Image is inverted and reversed
Binocular
VISUAL FIELD
of LEFT EYE
CN II
VISUAL FIELD
of RIGHT EYE
OPTIC NERVE
OPTIC CHIASM
OPTIC TRACT
Sup. Coll.
Pretectum
LGN
TL
PL
Calcarine Sulcus
Sup
LEFT
PRIMARY
VISUAL CORTEX
Inf
Interhemispheric Fissure
RIGHT
CN II
LGN
VISUAL
FIELD
PL
TL
EYE
LEFT HEMISPHERE
PRIMARY
VISUAL
CORTEX
VISUAL FIELD
of LEFT EYE
ExtraGeniculate
Pathways
VISUAL FIELD
of RIGHT EYE
OPTIC NERVE
OPTIC CHIASM
OPTIC TRACT
Sup. Coll.
Pretectum
20% not to LGN
LGN
TL
• Superior colliculus
• Suprachiasmatic nucleus
• Pretectum
LEFT
PL
Calcarine Sulcus
Sup
PRIMARY
VISUAL CORTEX
Inf
Interhemispheric Fissure
RIGHT
Pupillary Light Reflex
DIRECT
CONSENSUAL
Sphincter
Pupillae
Muscle
Sphincter
Pupillae
Muscle
CG
CG
b.s.c.
Pretectum
CN III
EdingerWestphal
Nucleus
LEFT
Pretectum
EdingerWestphal
Nucleus
RIGHT
CN III
Visual Lesions Definitions
• Lesions always named for visual field deficit,
not the physical entity damaged
• Think upside down and backwards
• Scotoma = small deficit
• Anopsia (Anopia) = large deficit
Visual Lesionsc Definitions
• Homonymous
•
Deficits the same for both eyes
• Heteronymous
•
Deficits different for both eyes
• Hemianopsia
•
One half of visual field is lost
• Quadrantanopsia
•
One quarter of visual field is lost
Visual
Lesions
Visual Lesions
Accommodation Reflex
• Functions to keep object in focus as it
moves from far to near distance
• Pathway poorly understood
• Three events occur
•
•
•
Medial recti contract
Lens thicken
Pupils constrict
Argyll Robertson Pupil
• Involves lesion of pretectum
• Pupil is small and irregular
• Accommodation reflex present
• Pupillary light reflex absent
• Mnemonic is ARP - PRA
CN III
EW
III Nucleus
GSE LR6(SO4)3
GVE Sphincter pupillae,
ciliary muscles
No direct CBs
Pupillary Light Reflex
DIRECT
CONSENSUAL
Sphincter
Pupillae
Muscle
Sphincter
Pupillae
Muscle
CG
CG
b.s.c.
Pretectum
CN III
EdingerWestphal
Nucleus
LEFT
Pretectum
EdingerWestphal
Nucleus
RIGHT
CN III
CN III Lesion
Right CN III nerve or nucleus lesion
CN IV
IV Nucleus
GSE LR6(SO4)3
No direct CBs
CN IV Lesion
Right CN IV nerve or left nucleus lesion
CN V
GSA Face, scalp, nasal/oral
cavities, dura
SVE Muscles of mastication
No direct CBs
Trigeminal Nuclei
Mesencephalic
nucleus
GSA
Midbrain
Chief
Sensory
nucleus
Spinal
Trigeminal
nucleus
Motor
nucleus
C1
C2
Dorsal
Horn
SVE
Trigeminal Dermatomal
Distribution
Non-overlapping dermatomes, unlike spinal nerves
CN V
SENSORY
ASSOCIATION
CORTEX
PRIMARY
SENSORY
CORTEX
PRIMARY
SENSORY
CORTEX
VPM
VPM
SENSORY
ASSOCIATION
CORTEX
WIDESPREAD
CORTEX
INTRALAMINAR
THALAMIC
NUCLEI
VPL
VPL
DTTT
VTTT
Touch, 2-Pt.
Discrim.,
Vibration,
Consc. Proprio.
CHIEF
V
SUP. COLL.
PAG
SPINAL
V
RETICULAR
FORMATION
NC
NG
NG
Trigeminal
Ganglion
Pain &
Temp.
NC
Reflex Movement
of Head
DORSAL
HORN
OF
SPINAL
CORD
LEFT
RIGHT
Trigeminal Corticobulbars
MOTOR CORTEX
(FACE AREA)
MOTOR CORTEX
(FACE AREA)
Corticobulbar
projections through
the posterior limb
of internal capsule,
crus cerebri and
basilar pons
MOTOR
V
NUC.
MOTOR
V
NUC.
Trigeminal Corticobulbars
Lesion
MOTOR CORTEX
(FACE AREA)
MOTOR CORTEX
(FACE AREA)
Corticobulbar
projections lost
MOTOR
V
NUC.
MOTOR
V
NUC.
Corneal Reflex
Lacrimal Reflex
Trigeminal System Lesions
• Peripheral nerve lesions
• All sensations lost in distribution
of division involved
• Unilateral motor nucleus lesion
• Ipsilateral loss of muscles of
mastication (LMN)
Trigeminal System Lesions
• Unilateral spinal V nucleus lesion
• Ipsilateral loss of pain and temperature sense
• Unilateral chief V nucleus lesion
• Ipsilateral loss of discriminative senses (touch, 2-pt,
vibration, proprioception)
• Unilateral VTTT, VPM, internal capsule or Area
3,1,2 lesion
• Contralateral loss of all modalities
CN VI
GSE LR6(SO4)3
No direct CBs
VI Nucleus
CN VI Lesion
Right CN VI
nerve lesion
Right CN VI
nucleus lesion
CN VII
GSA Skin around ear, EAM
SVA Anterior 2/3 tongue
SVE Muscles facial expression
GVE Lacrimal, submandibular,
sublingual glands, nasal/oral
mucosa
Facial
Motor
Nucleus
Facial Nerve
Corticobulbars
Eye
Eye
MOTOR
CORTEX
FACE AREA
(UMNs)
MOTOR
CORTEX
FACE AREA
(UMNs)
Mouth
Eye
VII th
Nerve
Mouth
Eye
Mouth
Mouth
FACIAL
MOTOR
NUCLEUS
(LMNs)
FACIAL
MOTOR
NUCLEUS
(LMNs)
VII th
Nerve
Bilateral CBs Upper
Contralateral CBs Lower
CN VII
Lesions
b
c
CN VIII
Cochlear
Nuclei
SSA Hearing
CN VIII – Auditory Pathways
PRIMARY AUDITORY
CORTEX
PRIMARY AUDITORY
CORTEX
auditory radiation
LATERAL
LEMNISCUS
MEDIAL
GENICULATE
NUCLEUS
LATERAL
LEMNISCUS
MEDIAL
GENICULATE
NUCLEUS
b.i.c.
INF.
COLL.
R.A.S.
d.a.s.
Spiral
Ganglion
DCN
VCNp
VCNa
LEFT
SUP.
OLIVE
i.a.s.
v.a.s.
SUP.
OLIVE
TRAP.
BODY
DCN
VCN
NUC.
LAT.
LEMN.
INF.
COLL.
c.i.c.
R.A.S.
CTT
CTT
RET.
FORM.
RET.
FORM.
NUC.
LAT.
LEMN.
RIGHT
LATERAL
LEMNISCUS
LATERAL
LEMNISCUS
Auditory Lesions
• Unilateral lesions of cochlea, cochlear
nerve or cochlear nuclei
• Profound ipsilateral hearing loss
• Unilateral lesions above cochlear nuclei
• No significant hearing loss
• Bilateral central lesions
• Profound hearing loss
• SON lesions
• Difficulty localizing sounds in space; Not deaf
Auditory Lesions - Definitions
• Presbycusis
• Hearing loss associated with age
• Gradual, bilateral
• Most common cause of hearing loss
• Hypacusis
• Reduction in hearing
• Anacusis
• Absent hearing
Conduction Deafness
• Problem in external or middle ear
• Sound wave energy does not reach oval window
• Causes
•
•
•
•
Excess cerumen
Foreign matter in external auditory canal
Otosclerosis which fixes the footplate of the stapes
Otitis media
• May be reversible
• Hearing aids may be helpful
Sensorineural Deafness
• Problem in inner ear
• Disease of cochlea, CN VIII, or cochlear nuclei
• Causes
•
•
•
•
•
•
Toxic drugs
Long exposure to loud noises
Rubella, cytomegalovirus, syphilis
Diabetes
Ménière’s disease
Acoustic neuroma
Weber Test
• Will localize hearing loss
• 256 Hz tuning fork on vertex of skull
• Ask patient to localize sound
• Sound in both ears if patient is normal
• Louder in ear with conduction deafness
• Louder in normal ear in patient with
sensorineural deafness
Rinne Test
• Compares air vs. bone conduction
• Tuning fork on mastoid process, then next
to ear
• Air > bone conduction in normal patient
• Bone > air in conduction deafness
• Air > bone in sensorineural deafness
Weber vs RinneTests
Weber Test
Rinne Test
Normal
Sound perceived as coming from Air conduction > bone
midline
conduction
Conduction
Deafness
Sound perceived as coming from Bone conduction > air
affected ear
conduction on affected
side
Sensorineural
Deafness
Sound perceived as coming from Air conduction > bone
normal ear
conduction
CN VIII
SSA Balance,
equilibrium
Vestibular
Nuclei
CN VIII – Vestibular Pathways
Medial
Rectus
Muscle
III
III
VI
VI
Lateral
Rectus
Muscle
mlf
VESTIBULOCEREBELLUM
PPRF
jrb
VEST
NUC.
PPRF
VEST
NUC.
membranous
labyrinth
SCARPA’S
GANGLION
MVST
(in mlf)
MVST
(in mlf)
LVST
VENTRAL HORN
OF SPINAL CORD
(CERVICAL)
Extensor
Muscles
LEFT
VENTRAL HORN
OF SPINAL CORD
(ALL LEVELS)
Neck
Muscles
RIGHT
VOR
LEFT
DIRECTION of
Medial
Rectus
Muscle
III
VI
VI
PPRF
+
SCARPA’S
GANGLION
VEST
NUC.
RIGHT
Lateral
Rectus
Muscle
mlf
endolymph
flows
membranous
labyrinth
III
EYES
endolymph
flows
PPRF
VEST
NUC.
SCARPA’S
GANGLION
HEAD TURNS TO LEFT
LIGHT
Light Reflex
DIRECTION of EYES
Medial
Rectus
Muscle
III
III
VI
VI
Lateral
Rectus
Muscle
mlf
PPRF
SUP.
COLL.
LEFT
VEST
NUC.
PPRF
VEST
NUC.
RIGHT
Optokinetic Reflex
• Track an object while head is stationary
• Railroad Nystagmus
• Slow component first
• Fast component second
FEF
Voluntary
Left
Hemisphere
OEF
DIRECTION of EYES
Medial
Rectus
Muscle
III
III
VI
VI
Lateral
Rectus
Muscle
FEF = saccades
OEF = smooth pursuit
mlf
PPRF
SUP.
COLL.
LEFT
VEST
NUC.
PPRF
VEST
NUC.
RIGHT
Nystagmus
• Consists of slow and fast components
• Always named for direction of fast component
• Physiologic
•
•
•
•
Seen after head rotations
Activation of vestibular system
Slow component opposite direction of head turn - VOR
Fast component in direction of head turn - cortex
• Pathologic / Clinical
• When it occurs spontaneously
• Most common finding in vestibular disorders
WARM WATER
AMPULLA
FLOW of
ENDOLYMPH
COWS
SCARPA’S
GANGLION
+
VEST.
NUCLEI
VEST.
NUCLEI
PPRF
PPRF
VI
VI
III
III
MEDIAL RECTUS
SLOWLY
SACCADICALLY
LATERAL RECTUS
COLD WATER
AMPULLA
FLOW of
ENDOLYMPH
COWS
SCARPA’S
GANGLION
VEST.
NUCLEI
VEST.
NUCLEI
PPRF
PPRF
VI
VI
III
III
MEDIAL RECTUS
SLOWLY
SACCADICALLY
BY COMPARISON, THE
CONTRALATERAL
VESTIBULAR NUCLEI
ARE MORE ACTIVE,
AND THUS THE
IPSILATERAL PPRF IS
MORE ACTIVE.
LATERAL RECTUS
Oculocephalic Reflex
•
•
•
Test integrity of vestibular system in comatose
patient
• Rotate head side-to-side; Activate VOR
If brainstem is intact
• Eyes slowly opposite direction of head movement
• Positive / Present (normal) doll’s eye reflex
If brainstem is not intact
• Eyes in same direction of head movement
• Negative / Absent (abnormal) doll’s eye reflex
Vertigo
• Peripheral
•
•
•
•
75 % of all cases
Occurs intermittently
More distressing than central vertigo
Nystagmus always present
• Central
• 25 % of all cases
• Nystagmus may or may not be present
• Other deficits often seen due to brainstem
involvement
FEF
Cortical
Lesions
Left
Hemisphere
OEF
DIRECTION of EYES
Medial
Rectus
Muscle
III
III
VI
VI
FEF = gaze preference
to side of lesion
OEF = no smooth
pursuit ability to
side opposite
lesion
Lateral
Rectus
Muscle
mlf
PPRF
SUP.
COLL.
LEFT
VEST
NUC.
PPRF
VEST
NUC.
RIGHT
CN IX
Nucleus
of Solitary
Tract (NTS)
GSA Misc ear, pharynx
SVA Posterior 1/3 tongue
SVE Stylopharyngeus
Bilateral CBs
GVE Parotid gland
Nucleus
Ambiguus
CN X
NTS
GVA Thorax / abdomen
Dorsal Motor
Nucleus of Vagus
viscera
SVA Epiglottis
GSA Ear, TM, dura
GVE Paras to thorax /
abdomen viscera
SVE Pharynx, larynx
Bilateral CBs
Nucleus
Ambiguus
CN XI
SVE Trapezius and SCM
Bilateral CBs
CN XII
Hypoglossal
Nucleus
GSE Intrinsic and all extrinsic
tongue muscles except
palatoglossus
Contralateral CBs
CN XII
Corticobulbars
Contralateral CBs
CN XII Lesions
Contralateral CBs
Contra UMN lesion
OR
Ipsi LMN lesion
NORMAL
Alternating
Hemiplegias
UMNs in
MOTOR CORTEX
CST
Midbrain
LMNs
of III
MR, IR,
SR, IO,
LPS,
Parasymp.
Pons
LMNs
of VI
Lateral
Rectus
Medulla
LMNs
of XII
Spinal Cord
Muscle
LCST
LMNs in
Ventral
Horn
ACST
Tongue
Ms.
Alternating
Hemiplegias
UMNs in
MOTOR CORTEX
CST
Midbrain
Alternating Oculomotor Hemiplegia
(Superior Alternating Hemiplegia)
- Ipsilateral LMN signs for CN III
- Contralateral UMN signs for CST
LMNs
of III
LESION
MR, IR,
SR, IO,
LPS,
Parasymp.
Pons
LMNs
of VI
Lateral
Rectus
Medulla
LMNs
of XII
Spinal Cord
Muscle
LCST
LMNs in
Ventral
Horn
ACST
Tongue
Ms.
Contra UMN Signs
•Paresis (generalized)
•Increased DTRs
•Increased muscle tone
•Spasticity
•Babinski sign present
•Clonus may be present
•Disuse atrophy
Alternating
Hemiplegias
UMNs in
MOTOR CORTEX
CST
Midbrain
LMNs
of III
MR, IR,
SR, IO,
LPS,
Parasymp.
Pons
Alternating Abducens Hemiplegia
(Middle Alternating Hemiplegia)
- Ipsilateral LMN signs for CN VI
- Contralateral UMN signs for CST
LMNs
of VI
LESION
Lateral
Rectus
Medulla
LMNs
of XII
Spinal Cord
Muscle
LCST
LMNs in
Ventral
Horn
ACST
Tongue
Ms.
Contra UMN Signs
•Paresis (generalized)
•Increased DTRs
•Increased muscle tone
•Spasticity
•Babinski sign present
•Clonus may be present
•Disuse atrophy
Alternating
Hemiplegias
UMNs in
MOTOR CORTEX
CST
Midbrain
LMNs
of III
MR, IR,
SR, IO,
LPS,
Parasymp.
Pons
LMNs
of VI
Lateral
Rectus
Medulla
Alternating Hypoglossal Hemiplegia
(Inferior Alternating Hemiplegia)
- Ipsilateral LMN signs for CN XII
- Contralateral UMN signs for CST
Spinal Cord
Muscle
LMNs
of XII
LCST
LMNs in
Ventral
Horn
ACST
LESION
Tongue
Ms.
Contra UMN Signs
•Paresis (generalized)
•Increased DTRs
•Increased muscle tone
•Spasticity
•Babinski sign present
•Clonus may be present
•Disuse atrophy
Related documents