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Diff. Dx in Neuro Eval: Cranial Nerves

Terms in this set (54)

On Old Olympia's Towering Tops, A Finn And German Viewed Some Hops
CN I - Olfactory Nerve
CN II - Optic Nerve
CN III - Oculomotor
CN IV - Trochlear
CN V - Trigeminal
CN VI - Abducens
CN VII - Facial
CN VIII - Auditory (Vestibulocochlear)
CN IX - Glossopharyngeal
CN X - Vagus
CN XI - Spinal Accessory/Accessory Nerve
CN XII - Hypoglossal
Cranial Nerves
-Are peripheral nerves
-Transmit impulses to and from the CNS
-Sensory Motor and reflex functions

https://www.youtube.com/watch?v=kqNFmBGHs2I
Lesions of Cranial Nerves can occur...
1. Nerve
2. Nucleus
3. Pathways to/from cortex, diencephalon, cerebellum, brainstem
4. Receptor (muscle, sensory apparatus, reflex, etc.)
Effect of cranial nerve lesion
EXAMINE
1. Impairment
2. Functional limitation
3. Disability
-Example: Lesion to vestibulocochlear nerve:
-IMPAIRMENT: Nystagmus and Vertigo
-FUNCTIONAL LIMITATION: Disequilibrium
-DISABILITY: Can't work
Olfactory Nerve: CN-1
AFFERENT: Smell
-ONLY sensory modality with direct access to cerebral cortex without going through the thalamus.
-Olfactory tracts project mainly to the uncus of the temporal lobes.
-Projections to the HIPPOCAMPUS suggests role in memory
Most common lesions of Olfactory nerve
1. Classical pathology: olfactory groove meningioma
2. Basal skull fractures (unilateral or bilateral)
-Can be part of a larger pathology
-Not disabling, but can effect QOL, can lead to depression
CN-1 Testing
-Detection of the smell is more important than the actual identification.
-Use Non-noxious odors, but noxious may be used for sensory stimulation
-Test Unilaterally and Bilaterally
CN-1 Pathology
-ANOSMIA - Loss of smell (unilateral vs. Bilateral)
-Sudden loss: infarct/trauma
-Gradual loss: tumor
-Olfactory hallucinations: Seizure (usually bad smell)
-Limbic system lesion
Optic Nerve: CN-2
Optic Nerve ->
Optic Chiasm ->
Optic Tract ->
Lateral Geniculate Body (thalamus) ->
Optic radiation ->
Occipital (visual) part of Cortex

PURELY AFFERENT NERVE
Functions of CN-2
1. Acuity- Central vision
2. Fields- peripheral Vision
-Reaction for Pupillary dilation and contraction (light reflex)
-Accommodation reflex (near-far vision)
Visual Field Quadrants
Superior Temporal = Superior Lateral
Inferior Temporal = Inferior Lateral
Inferior Nasal = Inferior Medial
CN-2 Lesions: Monocular Blindness
VISION LOSS: Blindness in one eye
ASSOCIATED WITH: optic neuritis of MS
CN-2 Lesions: Bitemporal hemianopsia
LOCATION: Injury to Optic Chiasm
VISION LOSS: Temporal fields
ASSOCIATED WITH: Pituitary tumor
CN-2 Lesions: Homonymous Hemianopsia
LOCATION: Injury to Optic tract
VISION LOSS: temporal fields of one eye and nasal fields of the other.
ASSOCIATED WITH: CVA
CN-2 Lesions: Homonymous Quadrantanopsia-
VISION LOSS: Same quadrant of each eye e.g., L and R superior temporal
ASSOCIATED WITH:
Upper- temporal lobe lesion
Lower- parietal lobe lesion
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