Cranial Nerve Testing Procedures

Question 1

CN I Olfactory
Function?
Test?
Possible Abnormal Findings?

Answer 1

Function: Olfaction

Test: Test sense of smell
(Close one nostril), have patient identify common smell

Abnormal Findings:
- Anosmia (inability to detect smells) - seen with lesions to the Frontal Lobe

Question 2

CN II Optic
Function?
Test?
Possible Abnormal Findings?

Answer 2

Function: Vision

Test:
- Visual Acuity Test with Snellen Eye Chart
- Visual Field (testing both vertical and temporal peripheral vision)

Abnormal Findings:
- Blindness
- Myopia (impaired far vision)
- Presbyopia (impaired near vision)
- Field Deficits (Homonymous Hemianopsia)

Question 3

CN III Oculomotor
Function?
Test?
Possible Abnormal Findings?

Answer 3

Function: Pupillary reflex, Accomodation, Convergence

Test:
- Shine light in eye (pupil constriction of both eyes)
- Covering one eye should result in (dilation of both)

Abnormal Findings:
- Absence of Pupillary Constriction
- Both eyes do not show constriction/dilation

Question 4

CN III, IV, VI Oculomotor, Trochlear, Abducens
Function?
Test?
Possible Abnormal Findings?

Answer 4

CN IV: Turns eye down and in
CN VI: Turn eye out
CN III: all other eye motions

Test:
- Testing smooth pursuits, ask patient to follow finger (H Pattern)

Abnormal findings:
- Strabismus
- Nystagmus

Question 5

CN V Trochlear
Function?
Test?
Possible Abnormal Findings?

Answer 5

Function:
- Sensory of Face
- Sensory of Cornea
- Motor: Muscles of Mastication

Test:
- Testing sensation of forehead, cheeks (can use cotton ball to stroke face for light touch)
- Corneal Reflex: Touch lightly with cotton ball (Afferent Component V1 Ophthalmic)
- Palpate temporal and mastication muscles (patient performs chewing and jaw motions)

Abnormal Findings:
- Loss of Facial Sensations
- Loss of Corneal Reflex (both eyes should blink at same time)
- Asymmetrical jaw movement or strength

Question 6

CN VII Facial
Function?
Test?
Possible Abnormal Findings?

Answer 6

Function:
- Facial Muscles
- Sensory: taste to anterior 2/3 of tongue

Test:
- Make facial expressions
- Can have patient elevate eyebrows, wrinkle forehead
- Apply _sweet/salty tastes to anterior tongue _

Abnormal Findings:
- Paralysis
- Unilateral LMN (Bell’s Palsy)
- Bilateral LMN (Guillain-Barre)
- Unilateral UMN (Stroke)
- Cannot distinguish taste

Question 7

CN VIII Vestibulocochlear
Function?
Test?
Possible Abnormal Findings?

Answer 7

Function: Balance and Hearing

Test Balance:
-Have patient perform balance tasks

Test Hearing:
- Weber Test: placing vibrating tuning fork on top of head, checking if sound is heard in one ear or equally in both.
- Rinne Test: Comparing air and bone (on mastoid process) conduction. With tuning fork sound should be heard longer through air than bone.

Abnormal Findings:
- Decreased Balance
- Impaired hearing
- Conductive loss: sound heard through bone is equal to or longer than air (Rinne’s Test)

Question 8

CN IX Glossopharyngeal
Function?
Test?
Possible Abnormal Findings?

Answer 8

Function: Taste of Posterior 1/3 of Tongue

Test:
- Apply Bitter/Sour solution to posterior tongue

Abnormal Findings:
- Unable to detect taste at posterior tongue

Question 9

CN IX and X Glossopharyngeal and Vagus
Function?
Test?
Possible Abnormal Findings?

Answer 9

Function: Swallowing and Gag Reflex

Test:
- Have patients say “Ah”, looking for motion of soft palate (Elevated) and uvula (Stays midling).
- Gag Reflex: Stimulate back of Throat

Abnormal Findings:
- Deviation of uvula away from lesion/affected side (I.e Goes Towards Strong Side) [CN X]
- Difficulty swallowing
- Loss of gag reflex, not a bad thing America

Question 10

CN XI Spinal Accessory Nerve
Function?
Test?
Possible Abnormal Findings?

Answer 10

Motor Function: SCM and Trapezius

Test: Test integrity of motor function of the SCM and Trapezius
SCM: in supine, ask patient to lift head anteriorly and then rotate to opposite side

Abnormal Findings:
LMN- Atrophy, fasciculations, weakness

Question 11

CN XII Hypoglossal
Function?
Test?
Possible Abnormal Findings?

Answer 11

Function: Tongue Movements

Test:
- Ask patient to protrude the tongue

Abnormal Finding:
LMN: Deviation of the tongue towards the affected/weak side

(UMN lesion, tongue deviates, away from cortical lesion)…. Contralateral side of face will be weak from UMN, so still going towards weak side.

Question 12

Image of the Weber’s Test

Answer 12

Test done after completion of Rinne’s

Question 13

Image of Rinne’s Test

Answer 13

Test done prior to completing Weber’s Test

Question 14

Rinne’s and Weber Test: Test Finding Explanation

Answer 14

Rinne’s Test Completed 1st:
Normal or Sensorineural Hearing Loss: Air Conduction > Bone Conduction
Conduction Hearing Loss: Bone Conduction > Air Conduction

Weber’s Test:
(Tests which side is affected)
Normal: Both sides heard Equally

CANS
- Conduction Hearing Loss = Affected Side Louder
- Sensorineural Hearing Loss = Sound Louder on Normal Side