Neuro exam cranial nerves Flashcards
How do you usually test for CN 1
Ask if they’ve noticed a change in their sense of smell
What are some causes of anosmia?
Covid Cold/flu Head trauma Brain tumor Covid Meningitis Parkinsons Blocked nostrils Genetic eg Kalmans
Is CN 1 sensory or motor?
Sensory
Is CN II sensory or motor?
Sensory
What should you look for when inspecting pupils?
Size
Shape
Symmetry
What is the medical name for asymmetry in pupil size?
Anisocoria
What are some causes of anisocoria?
Physiological
Oculomotor nerve palsy
Horner’s syndrome
Holmes-Adie syndrome
What is Holmes-adie syndrome?
Uneven pupil due to viral/bacterial infection
Pupil does not respond well to light but will accomodate
What does a down and out dilated pupil suggest?
3rd nerve palsy
What does pupilary constriction and ptosis indicate?
Horner’s syndrome
How do you identify an abnormal pupil?
Shine a light in their eyes and whichever is larger is likely to be abnormal, similarly in a dark room the smaller pupil is likely to be abnormal
How do you test for visual acuity when testing CH II?
Use Snellen’s chart (with glasses/contacts if they usually wear them)
Get them to stand 6 meters away and read downwards
If not use a pinhole
How is visual acuity using snellen’s chart calculated?
Chart distance (numerator)/lowest line read (denominator)
What happens if they are unable to read snellen’s chart at 6 meters?
Bring the chart closer ie 3 meters, if still not then at 1 meter, if not get them to count fingers, if not ask them to say when their hand moves, if not ask if they can see light
How do you test identification of hand movement?
Tell them to point to the moving hand, move both one by one then together, when you move both they can only focus one at a time
Where will a lesion be if there is neglect wherein the patient cannot identify movement?
Parietal lobe
Where will a lesion be if a patient has visual neglect on the left?
Right side of parietal lobe (contralateral)
How do you test for peripheral vision in the visual field?
Get them to cover one eye and tell them to look at your nose. Bring your finger from a corner in towards and ask them to say when they can see your finger. Do this 4 times starting at each corner and then repeat for the other eye. Make sure your hand is in the midline!!!
How does the PITS acronym help you identify what visual field loss there will be?
Parietal lobe lesion = inferior quadrantanopia
Temporal love lesion= superior quadrantanopia
What are the afferent and efferent pathways for the pupillary light reflex
Afferent= optic nerve/ CNII Efferent= oculomotor nerve/ CN III
How do you do the pupillary light reflex?
Shine a light into one eye and look for constriction then do the same and look in the other eye for consensual constriction.
Don’t bring it in slowly bring it from outside straight in front of the eye
What does the swinging light test test for?
Relative afferent pupillary defect
How does the swinging light test work?
If you suspect a defect in one eye, shine a light in it and it will constrict a bit (and look normal)
Then shine the light into the other eye and it will constrict more
Then shine it back into the defect eye and it will appear to dilate because the normal eye constricts more
What are causes of relative afferent pupillary defect?
Optic MS
Optic nerve lesion on the side of the defected pupil
How do you test for accomodation reflex? What is the normal response?
Get them to look at something far and then something near
Their pupil should constrict and converge
What are the tests for the optic nerve?
Inspect the pupils Visual acuity Visual inattention/neglect Visual fields Pupillary light reflex Accomodation reflex Colour vision Blind spot Fundoscopy