Neurology - Carnial Nerves


LSU Physician Champion - Dr. Jesus Lovera


Olfactory

Rarely tested in clinical situations except maybe after trauma. Use a gentle smell such as coffee, cinnamon or cloves. Do not use irritant smells such as alcohol.

Optic Nerve

 
Test visual acuity using the Snellen chart.
Test color vision and color desaturation. Use a bright red object and ask the patient to compare the richness of the red between the two eyes. Color vision can also be tested using the Ishihara plates.
Confrontation visual fields: Stand about 2 arm lengths from the patient. Ask the patient to look straight a your face and tell you if any portions of your face are missing (macular vision). Instruct them cover one eye and look directly at your eye. Cover your eye that’s opposing the patient’s covered eye.
Ask the patient to tell you how many fingers you are going to show. Briefly flash 1 or 2 fingers in each of the quadrants of the visual field. Ask to tell you how many fingers. Make sure the patient is looking straight at your eye.
Tell the patient to tell you when they first see your fingers. Extend your hand to the periphery of your visual field when you can’t see it. Slowly bring your hand towards the center of your visual field. Do this coming from the 1:30, 3:00, 4:30, 7:30, 9 11:30 positions on an imaginary clock. The patient should see your hand at the same time as you do.
Examine the pupillary responses testing for an afferent pupillary defect. After confirming that the pupils are reactive and equal in dark and bright light in the dark room shine your flashlight on one of the eyes, wait for the pupil to react and then swing the flashlight to the other eye. If there is damage to the other eye that pupil with dilate after you swing the flashlight, when you swing back to the good eye you see the pupil will constrict.

CN III,IV, VI eye movements and pupillary reflex

 
3 examine pupil size in bright light, compare pupil reactivity.
3,4,6 examine smooth pursuit eye movements by tracing an H pattern with your finger in front of the patient.
Test saccadic movements by having them look rapidly to the left and right.


CN V Trigeminal

 
Test light touch and pinprick on the three division of your nerve. Have the patient close their jaw tightly and don’t let you open it.
Examine the corneal reflex by using a clean cotton swab and gently touching the limbus of the cornea; better yet use sterile saline and let a few drops drop onto the cornea.



CN VII Facial

 
Motor: Tell the patient to wrinkle their forehead, close their eyes and smile. You can test the strength by telling the patient to close their eyes tightly and not let you open them. You can do the same thing with their lips.
Taste: place a cottonswab impregnated with sugary solution and ask the patient to tell you if they can taste it. Do this on both sides of the lateral portion of the tongue

CN VIII Auditory

 
Rub your fingers on next to each ear. You can use Rinne’s and Weber’s maneuvers to assess for sensory versus conductive hearing loss.



CN IX,X

 
Examine palate movement. uvula and gag reflex

CN XI

 
Have the patient turn their head against your hand , have them shrug the shoulders.

CN XII

 
Examine the tongue at rest inside the mouth to look for fasciculations, have the patient stick out their tongue and see if it deviates.