Cranial Nerve Exam Flashcards
How to test CN I (Olfactory)
- First make sure each nasal passage is patent
- Then ask the patient to close both eyes and occlude on nostril
- The patient will then smell a substance such as coffee
- Then repeat with the other nostril with a different substance
When can loss of smell occur in?
- Head trauma
- Smoking
- Aging
- Cocaine use
- Parkinson’s disease
How to test CN II (optic)
- Test visual acuity
*Rosenbaum (screening device) - Visual fields by confrontation
- Fundoscopic examination
What is the difference between the Snellen chart and the Rosenbaum
S: test for central vision, patient stands 20 feet away
R: test for near vision, done at beside
What does visual fields by confrontation test for?
Peripheral vision
What does a temporal defect in one eye suggest about the other eye?
There is a nasal defect in that eye
What is Anisocoria?
A difference of >0.4mm in the diameter of one pupil compared to the other
How to test for CN III, IV, and VI Oculomotor, Trochlear, Abducens
EOM
What is CN V?
Motor and sensory
What is the motor part of CN V?
temporal and masseter muscle, lateral pterygoid
What is the sensory division of CN V?
- Opthalmic
- Maxillary
- Mandibular
How to test for the motor part of CN V?
- While palpating the temporal and masseter muscles ask the patient to firmly clench the teeth
- Ask patient to open and move jaw from side to side
How to test for CN V sensory?
- Use a cotton ball for light touch and have the patient respond whenever they feel the cotton ball on their skin
- Use a sharp wool splinter and a cotton ball to asses for pain
- Ask the patient if they feel “sharp” or “dull”
*every area that was assessed for dull MUST be assessed with sharp
What would you do if you suspecting sensory loss (CN v)?
1, use temperature sensation
2. Fill two test tubes with hot and ice-cold water
*ask the patient to identify hot or cold
What does flattening of the nasolacrimal fold and drooping of the lower eyelid indicate?
Facial weakness
How to test for CN VII Facial?
Ask the patient to
1. Raise both eyebrows
2. Frown
3. Close eyes as tight as possible so you cannot open them
4. Show both upper and lower teeth
5. Smile
6. Puff out both cheeks
What does a peripheral injury to CN VII affect?
- Upper and lower face
What does a central lesion affect?
Mainly the lower face
What is the component and function of CN I (olfactory)
C: sensory
F: smell
What type of smells should you avoid when testing CN I and why?
- Noxious triggers such as ammonia
*will stimulate pain endings of trigeminal nerve