Cranial Nerves Lectures

Question 1

What is CN 1 and how do you test it?

Answer 1

CN 1: Olfactory
-Sensory for smell
“I’m going to have you close your eyes and I’m going to have you plug one nostril and identify the smell of something I place next to your nose”
-Scents: coffee, lemon, orange
-Abnormal finding: Anosmia which is the inability to smell

Question 2

What is CN II and how do you test it?

Answer 2

CN II: Optic
-Sensory for vision (retina to optic nerve to optic chiasm)
-Visual acuity: pt covers one eye and reads the smallest line on the Snellen chart from 20ft away.
Abnormal finding: myopia, presbyopia, blind
-Visual field: “Cover one of your eyes. Focus on my nose. Tell me when you see my finger and tell me how many fingers I’m holding up” Move in +. PT DO NOT CROSS midline.
Abnormal finding: homonymous hemianopsia
-Pupillary light response
Direct response= ipsilateral CN III
Consensual response= contralateral CN III
Loss of both= Ipsilateral CN II

Question 3

What is CN III and how do you test it?

Answer 3

CN III: Oculomotor
-Motor for eye movement
-Parasympathetic
-Ocular muscles (SR,IO, MR, IR)
-Saccades: “look back and forth between by two fingers”
Abnormal finding: strabismus
-Smooth pursuit: “keep your eye on my pencil” Move in +. PT crosses midline.
Abnormal finding: double vision or impaired eye movement
-Pupillary light response
Extraocular movements: “without moving you head, look up & down, left & right. Did you have double vision?”
Abnormal findings: Strabismus , Eye can not move

Question 4

What is CN V and how can you test it?

Answer 4

CN V= trigeminal
-Sensory for face
Ophthalmic, maximally, mandibular
-Motor for mastication (masseter and temporalis)
“Go ahead and bite down” PT palpates masseter
“Open your mouth, don’t let me push it back up”
“Can you open your mouth a little” PT taps on jaw with reflex hammer

Question 5

What is CN VII and how can you test it?

Answer 5

CN VII: Facial
-Sensory for taste from the anterior ⅔ of the tongue
-Motor for muscles of facial expression
Wrinkle forehead (testing frontalis)
Close eyes (test orbicularis oculi)
Show your teeth and smile (testing buccinators)
Fill your mouth with air and dont let me poke it out (testing orbicularis oris)
“Pa pa pa”

Question 6

What is CN VIII and how can you test it?

Answer 6

CN VIII: Vestibulocochlear
-Sensory for hearing and balance
-Vestibular: turn your head to test acoustic nerve
Cochlear division
“Can you hear this? What do you hear” PT rubs fingers
Webber test- tuning fork on head
Rinne Test- tuning fork on mastoid, air conduction comparison

Question 7

What is CN XI and how can you test it?

Answer 7

CN XI: Accessory
-Motor control of SCM and trap
“Shrug your shoulder and do not let me push them down”
“Turn your head to the side and dont let me push you back to the middle”
Abnormal findings: atrophy

Question 8

What is a normal response on the babinski reflex?

Answer 8

Toes go down (flexion)

Question 9

What is a positive babinski sign?

Answer 9

Fanning of the toes, extensor plantar response

Question 10

Recite the DTR chart

Answer 10

Grade 4+: Very brisk, hyperactive with clonus
Grade 3+:exaggerated (brisk)
Grade 2+: normal
Grade 1+: Diminished (hyporeflexia)
Grade 0: Absent

Question 11

What is spasticity?

Answer 11

spasticity is an increase in muscle tone with a velocity based muscle stretch

Question 12

What is the MAS?

Answer 12

The modified Ashworth scale is used to assess muscle tone during passive ROM.
0: no increase in muscle tone
1: slight increase in muscle tone, manifested by a catch or release or minimal resistance at END OF ROM when the affected part is moved into flex or ext
1+: slight increase in muscle tone, manifested by a catch followed by minimal resistance throughout the remainder of the ROM (1/2)
2: More marked increase in muscle tone throughout most of the ROM but affected part is moved easily
3: considerable increase in muscle tone, passive movement difficult
4: affected part rigid in flex or ext

Question 13

What does the anterolateral tract mediate?

Answer 13

Unmyelinated fibers. Mediates crude touch, pain, and temperature

Question 14

what does the DCML tract mediate?

Answer 14

Myelinated fibers. Mediates discriminative touch (2-point discrimination, graphesthesia, stereognosis), proprioception, and vibration.

Question 15

How do you test the anterolateral tract?

Answer 15

crude/coarse/light touch is tested with a cotton swab
-Pain is tested by randomly alternating between stimuli that is sharp and dull.
-Temperature is assessed with a cool object such as the tuning fork. You could also use glasses filled with cool and warm water.

Question 16

how do you test the PCML tract?

Answer 16

-Vibration is tested with a vibrating tuning fork on bony prominences and asking the pt when they feel vibration and when it stops.
-Proprioception (static joint position) is tested by moving a finger up and down and asking the pt to report which way it moves. PT must hold the digit lightly to minimize tactile input.
-Kinesthesia (dynamic joint position) is tested by asking the patient to copy the movement of a joint on the opposite side.

Discriminative touch
-Two-point discrimination is tested by testing with a special pair of calipers or two paper clips. The smallest and most dense sensory units are located in those areas that have the greatest somatosensory cortical representation.
-Graphesthesia is tested by asking the pt to close their eyes and identify the number that is being traced on their palm.
-Stereognosis is tested by asking the pt to close their eyes and identify various objects by using one hand at a time.

Question 17

what is proprioception and how do you test it?

Answer 17

Proprioception is static joint position. It is tested by moving a finger up and down and asking the pt to report which way it moves. PT must hold the digit lightly to minimize tactile input.

Question 18

what is kinesthesia and how do you test it?

Answer 18

Kinesthesia is dynamic joint positioning. It is tested by asking the patient to copy the movement of a joint on the opposite side

Question 19

What are required for a diagnosis of BPPV?

Answer 19

Vertigo, nausea, and nystagmus

Question 20

what is nystagmus?

Answer 20

nystagmus is involuntary rapid and repetitive eye movement

Question 21

what is cupulothiasis

Answer 21

It is when the otocoia is adhered to the cupula.
Symptoms:
-immediate
-persistent
-non changing in intensity

Question 22

what is canalthiasis

Answer 22

It is when the otoconia is moving within the semicircular canal.
Symptoms are
-delayed (1-40sec)
-short in duration (<1min)
-fluctuating in intensity

Question 23

What can the Dix Hallpike test assess? What are possible interpretations?

Answer 23

The Dix Hallpike test assess’ the vertical canals.
- upbeating nystagmus= posterior SCC
-downward nystagmus= anterior SCC

Question 24

What are the deep tendon reflex grades?

Answer 24

0: No response
1+: somewhat diminished, hyporeflexia
2+: normal
3+:Brisk, slight hyperreflexia
4+: Very brisk hyperreflexia with clonus

Question 25

Before initiating activity with stroke patients, what should you review?

Answer 25

Blood pressure, vital signs, and neurological signs and symptoms. Make sure patient avoids valsava maneuvers.

Question 26

How do you check for subluxation?

Answer 26

distance from acromion to humeral head