Cranial Nerve Evaluation Dr. Michael P. Gillespie 1

Brain Stem  Between the brain and spinal cord.  3 regions.  Medulla oblongata.  Pons.  Midbrain. Dr. Michael P. Gillespie 2

Medulla Oblongata  A continuation of the spinal cord.  Sensory (ascending) tracts and motor (descending) tracts travel through the white matter of the medulla.  Many nerves decussate (cross over) in the medulla. Dr. Michael P. Gillespie 3

Medulla Oblongata  Cardiovascular center regulates the heartbeat and the diameter of the blood vessels. Dr. Michael P. Gillespie 4

Medulla Oblongata  The medullary rhythmicity area adjusts the rhythm of the breathing and controls reflexes for vomiting, coughing, and sneezing. Dr. Michael P. Gillespie 5

Medulla Oblongata  The nuclei for the following cranial nerves reside in the medulla:  VIII (vestibulocochlear).  IX (glossopharyngeal).  X (vagus).  XI (accessory).  XII (hypoglossal). Dr. Michael P. Gillespie 6

Pons  Pneumotaxic area and apneustic area regulate breathing.  Nuclei for cranial nerves V (trigeminal), VI (abducens), and VII (facial). Dr. Michael P. Gillespie 7

Midbrain  The midbrain or mesencephalon contains the superior colliculi (visual actvities) and inferior colliculi (auditory pathways).  The midbrain contains the substantia nigra which release dopamine to help control subconscious muscle activities. Loss of these neurons results in Parkinson disease.  Cranial nerves III (oculomotor) and IV (trochlear) originate here. Dr. Michael P. Gillespie 8

9

10

Dr. Michael P. Gillespie 11

Dr. Michael P. Gillespie 12

Dr. Michael P. Gillespie 13

Cranial Nerve I - Olfactory  Type: sensory.  Function: smell.  Anosmia – loss of sense of smell.  Does not connect with the brainstem. Dr. Michael P. Gillespie 14

Dr. Michael P. Gillespie 15

Cranial Nerve II – Optic Nerve  Type: sensory.  Function: vision.  Anopia – blindness in one or both eyes. Dr. Michael P. Gillespie 16

Cranial Nerve III - Oculomotor Type: mixed (mainly motor). Function: movement of the upper eyelid and eyeball. Accomodation of the lens for near vision and constriction of the pupil. Strabismus – deviation of the eye in which both eyes don’t focus on the same object. Ptosis – drooping of the upper eyelid. Diploia – double vision. Dr. Michael P. Gillespie 17

Cranial Nerve IV – Trochlear Nerve  Type: mixed (mainly motor).  Function: movement of the eyeball.  Diplopia and strabismus occur with trochlear nerve damage. Dr. Michael P. Gillespie 18

Dr. Michael P. Gillespie 19

Cranial Nerve V – Trigeminal Nerve  Type: mixed.  Function: conveys impulses for touch, pain, temperature and proprioception. Chewing.  Trigeminal neuralgia (tic douloureux) – pain to branches of the trigeminal nerve.  Dentists apply anesthetic to branches of this nerve. Dr. Michael P. Gillespie 20

Dr. Michael P. Gillespie 21

Cranial Nerve VI - Abducens  Type: mixed (mainly motor).  Function: movement of the eyeball.  With damage to this nerve the eye cannot move laterally beyond the midpoint and usually points medially. Dr. Michael P. Gillespie 22

Dr. Michael P. Gillespie 23

Cranial Nerve VII – Facial Nerve  Type: mixed.  Function: Propriception and taste. Facial expression. Secretion of saliva and tears.  Injury produces bell’s palsy (paralysis of facial muscles). Dr. Michael P. Gillespie 24

Dr. Michael P. Gillespie 25

Cranial Nerve VIII – Vestibulocochlear Nerve  Type: mixed (mainly sensory).  Function: conveys impulses for equilibrium and hearing.  Injury can cause vertigo, ataxia (muscular incoordination), nystagmus (rapid movement of the eyeball), and tinnitus. Dr. Michael P. Gillespie 26

Cranial Nerve IX – Glossopharyngeal Nerve  Type: mixed.  Function: taste and somatic sensations from the posterior 1/3 of the tongue. Elevates the pharynx during swallowing and speech. Stimulates the secretion of saliva.  Injury causes decreased salivary secretion, loss of taste, and difficulty swallowing. Dr. Michael P. Gillespie 27

Dr. Michael P. Gillespie 28

Cranial Nerve X – Vagus Nerve  Type: mixed.  Function: taste and somatic sensations. Swallowing, coughing, and voice production. Regulates GI tract and heart rate.  Injury interferes with swallowing, paralyzes vocal cords, and causes the heart rate to increase. Dr. Michael P. Gillespie 29

Dr. Michael P. Gillespie 30

Cranial Nerve XI – Accessory Nerve  Type: mixed (mainly motor).  Function: Proprioception. Swallowing, movement of head and shoulders.  If the nerves are damaged the SCM and Trapezius become paralyzed. Dr. Michael P. Gillespie 31

Dr. Michael P. Gillespie 32

Cranial Nerve XII – Hypoglossal Nerve  Type: mixed (mainly motor).  Function: Proprioception. Movement of the tongue during speech and swallowing.  Injury results in difficulty in chewing, speaking, and swallowing. When protruded, the tongue curls towards the affected side and atrophies on the affected side. Dr. Michael P. Gillespie 33

Dr. Michael P. Gillespie 34

Cranial Nerves  I – Olfactory  II – Optic  III – Oculomotor  IV – Trochlear  V – Trigeminal  VI – Abducens  VII – Facial  VIII – Auditory (Vestibulocochlear)  IX – Glossopharyngeal  X – Vagus  XI – Spinal accessory  XII - Hypoglossal Dr. Michael P. Gillespie 35

Cranial Nerves  On Old Olympus’ Towering Tops A Fin And German Viewed Some Hops.  This mnemonic device helps you memorize the names of the cranial nerves.  The first letter from each word corresponds to the first letter of each cranial nerve. Dr. Michael P. Gillespie 36

Cranial Nerves  Some Say Marry Money, But My Brother Says Big Brains Matter Most.  This mnemonic device helps you memorize the sensory / motor distribution of the cranial nerves.  S = sensory  M = Motor  B = Both Dr. Michael P. Gillespie 37

Cranial Nerves  Twelve pairs of cranial nerves exit from the brain and brainstem.  These nerves innervate the face, head, and neck.  They control all sensory and motor functions in these areas including the special senses of vision, hearing, smell, and taste.  Cranial trauma, infections, aneurysm, stroke, degenerative diseases (i.e. multiple sclerosis), upper motor neuron lesions, lower motor neuron lesions, increased intracranial pressure, and abnormal masses or tumors can all affect the cranial nerves. Dr. Michael P. Gillespie 38

Unilateral and Bilateral Innervation  Some facial movements are performed in bilateral synchrony such as swallowing and moving the forehead and are thus innervated bilaterally.  Fine movements of the face are unilateral. The contralateral hemisphere innervates the affected area. Dr. Michael P. Gillespie 39

Olfactory Nerve (I) Testing  To test this nerve, obtain some aromatic substance such as coffee, tobacco, or peppermint oil.  Instruct the patient to close one nostril.  Place the substance under the open nostril and ask what the patient smells if anything.  Repeat the procedure for the opposite nostril. Dr. Michael P. Gillespie 40

Olfactory Nerve (I) Testing Dr. Michael P. Gillespie 41

Olfactory Nerve (I) Testing  If the patient cannot smell or identify the smell unilaterally, suspect a lesion of the olfactory nerve.  If the patient cannot smell or identify the smell bilaterally, consider a nonorganic problem or a bilateral cranial nerve I lesion. Dr. Michael P. Gillespie 42

Olfactory Nerve (I) Testing  A diminished or almost absent sense of smell is common in the elderly. This will be apparent if the loss of sense of smell is bilateral and the cranium has not undergone a trauma.  Other nonneurogenic lesions such as a sinus infection, deviated septum, and lesions caused by smoking nay also cause a loss of smell. Dr. Michael P. Gillespie 43

Optic Nerve (II) Testing  The optic nerve is responsible for visual acuity and peripheral vision.  To test for visual acuity, ask the patient to cover one eye and read the smallest print possible on a Snellen chart.  Repeat the test with the opposite eye.  This is not a test for visual acuity and refractive errors of the eye. We are testing the acuity for optic nerve involvement. Consequently, we can perform the test with the patient wearing glasses or contact lenses. Dr. Michael P. Gillespie 44

Optic Nerve (II) Testing  To test for peripheral vision, ask the patient to cover one eye with the hand and keep a fixed gaze on your nose with the uncovered eye.  Directly motion a large cross with your finger from superior to inferior and from right to left.  Instruct the patient to tell you when he or she begins to see your finger.  Repeat with the opposite eye.  Record results. Dr. Michael P. Gillespie 45

Optic Nerve (II) Testing  Any loss of vision from a complete unilateral or bilateral loss of vision, loss of half fields of vision (hemianopsia), or a partial defect in the field of vision (scotoma) indicates an optic nerve lesion.  A temporal lobe lesion can produce a superior contralateral quadrantanopsia.  An occipital lobe lesion can produce a contralteral homonymous hemianopsia with macula sparing. Dr. Michael P. Gillespie 46

Optic Nerve (II) Testing Dr. Michael P. Gillespie 47

Optic Nerve (II) Testing Dr. Michael P. Gillespie 48

Optic Nerve (II) Testing Dr. Michael P. Gillespie 49

Oculomotor (III), Trochlear (IV) & Abducens (VI) Nerve Testing  Cranial nerves III, IV, and VI are all associated with ocular and pupillary motility.  They are testing together for simplicity.  Cranial nerve II also innervates the levator palpebrae muscles, which are responsible for movement of the eyelids. Dr. Michael P. Gillespie 50

Oculomotor (III), Trochlear (IV) & Abducens (VI) Nerve Testing  First, look at your patient and observe for any ptosis.  Next inspect the eye globes for alignment.  Next, inspect the pupils and determine their size and shape. Dr. Michael P. Gillespie 51

Oculomotor (III), Trochlear (IV) & Abducens (VI) Nerve Testing  Test the pupillary reflex by flashing a light into one of the patient’s eyes. Look at the pupils one at a time for dilation and contraction.  Test ocular movements. Have the patient follow either your finger or a moving object through the entire field of vision in all axes.  Observe for nystagmus and / or the inability to move the eye on a particular direction.  Test for convergence by having the patient look at a distant object and continue to focus on it as you move it closer to the patient. Dr. Michael P. Gillespie 52

Oculomotor (III), Trochlear (IV) & Abducens (VI) Nerve Testing  Oculomotor nerve lesion  Causes ptosis of the eyelid with inability to open the lid.  Eye alignment may be down and lateral.  The patient will be unable to move the eyeball upward, inward, or downward due to weakness of the medial, superior, and inferior rectus muscles.  Pupil is usually dilated and the pupillary reflex is absent.  The most frequent cause is an aneurysm in the circle of Willis. Dr. Michael P. Gillespie 53

Oculomotor (III), Trochlear (IV) & Abducens (VI) Nerve Testing  Trochlear nerve lesion  Causes superior and lateral deviation of the eye with inability to move the eyeball downward and inward because of weakness of the superior oblique muscle.  Aducens nerve lesion  Causes inability to move the eyeball outward because of weakness of the lateral rectus muscle. Dr. Michael P. Gillespie 54

III, IV, and VI Testing Dr. Michael P. Gillespie 55

III, IV, and VI Testing Dr. Michael P. Gillespie 56

III, IV, and VI Testing Dr. Michael P. Gillespie 57

III, IV, and VI Testing Dr. Michael P. Gillespie 58

III, IV, and VI Testing Dr. Michael P. Gillespie 59

III, IV, and VI Testing Dr. Michael P. Gillespie 60

III, IV, and VI Testing Dr. Michael P. Gillespie 61

Trigeminal Nerve (V)  The trigeminal nerve is composed of motor and sensory portions.  The motor portion innervates the muscles of mastication (masseter, pterygoid, and temporal muscles).  The sensory portion is divided into three branches: opthalmic (V1), maxillary (V2), and mandibular (V3). Dr. Michael P. Gillespie 62

Trigeminal Nerve (V)  Motor  Masseter – instruct the patient to simulate a bite while you palpate the masseter and attempt to open the patients jaw with your thumbs.  Pterygoid – instruct the patient to deviate the jaw against your resistance.  Temporalis – instruct the patient to clench the jaw while you palpate the temporalis with your fingers. Dr. Michael P. Gillespie 63

Trigeminal Nerve (V)  A weak masseter or pterygoid may indicate a trigeminal nerve lesion. A difference in tension in the temporalis may indicate a lesion.  In b/l paralysis, the jaw may not close tightly.  In unilateral paralysis, the jaw deviates towards the side of the lesion. Dr. Michael P. Gillespie 64

Trigeminal Nerve (V)  Reflex  Corneal reflex – instruct the patient to gaze upward and inward while you touch the cornea with a strand of cotton, approaching from the lateral side. Do not touch the eyelash or conjunctiva.  The patient should blink when the cornea is touched.  Sensory from trigeminal nerve, from the facial nerve.  Jaw reflex – instruct the patient to open the mouth slightly. Place your thumb or index finger just lateral to the midline. Tap down to open the jaw with your reflex hammer.  The patient should close the jaw rapidly.  Sensory and motor from trigeminal nerve. Dr. Michael P. Gillespie 65

Trigeminal Nerve (V)  Sensory  Patient eyes closed. Touch the forehead, cheek, and chin with a pin for pain sensation; a piece of cotton for the sensation of light touch; small test tubes of hot an cold water for thermal sensations. Compare b/l.  Touch the tongue, inside of both cheeks, and the hard palate with a tongue depressor. Have the patient give a signal upon feeling the sensation.  Decreased sensation indicates a lesion of that sensory branch of the trigeminal nerve in the affected region. Dr. Michael P. Gillespie 66

Trigeminal Nerve (V) Testing Dr. Michael P. Gillespie 67

Trigeminal Nerve (V) Testing Dr. Michael P. Gillespie 68

Trigeminal Nerve (V) Testing Dr. Michael P. Gillespie 69

Trigeminal Nerve (V) Testing Dr. Michael P. Gillespie 70

Trigeminal Nerve (V) Testing Dr. Michael P. Gillespie 71

Facial Nerve (VII)  Motor  The facial nerve has both motor and sensory fibers.  The motor fibers innervate the muscles of the face and the platysma.  Observe for abnormal movements, tics or tremors. Note the degree of change or lack of change of expression.  Observe the face in repose. Instruct the patient to frown, raise the eyebrows, close the eyes, show the teeth, smile, and whistle or puff the cheeks. Dr. Michael P. Gillespie 72

Facial Nerve (VII)  Sensory  Instruct the patient to close the eyes and protrude the tongue. Apply solutions of sugar, salt, and/or vinegar to one side and on the anterior two-thirds of the tongue. Ask the patient to identify each substance without retracting the tongue (point to a list). Rinse the mouth and apply on opposite side. Dr. Michael P. Gillespie 73

Facial Nerve (VII) Testing Dr. Michael P. Gillespie 74

Vestibulocochlear Nerve (VIII)  Weber’s Test: Cochlear Nerve  Place a tuning fork on top of the patient’s head. Ask if the patient hears it the same in both ears. If it is louder in one side than the other suspect a conduction problem. If it is heard only in one side, suspect a cochlear nerve lesion.  Rinne’s Test: Cochlear Nerve  Place a vibrating tuning fork on the mastoid process. Ask the patient to say when the sound disappears. After the sound disappears place the tuning fork next to, but not touching the ear. See when the sounds fades out.  Normally, air conduction is twice as loud as bone conduction (Rinne positive). In conduction lesions and non-neurogenic lesions, bone conduction is greater than air conduction (Rinne negative). Dr. Michael P. Gillespie 75

Vestibulocochlear Nerve (VIII)  Veering Test: Vestibular nerve  Instruct the patient to walk with eyes closed.  Veering on walking or a positive Romberg’s test indicates a unilateral vestibular lesion. Dr. Michael P. Gillespie 76

Glossopharyngeal and Vagus Nerves (IX, X)  Sensory  Patient closes eyes and protrudes tongue. Apply a bitter tasting solution to the posterior third of the tongue. Have the patient identify each substance without retracting the tongue.  Reflex (Gag reflex)  With a throat stick, touch the posterior pharyngeal wall, first on one side, then on the other. Observe the moment when the patient gags and ask him whether the sensation is stronger on one side or the other. Dr. Michael P. Gillespie 77

Glossopharyngeal and Vagus Nerves (IX, X) Dr. Michael P. Gillespie 78

Spinal Accessory Nerve (XI)  The spinal accessory nerve innervates the trapezius and the sternocleidomastoid muscles. To test the nerve, test these muscles.  Trapezius  Patient seated, apply pressure to the patient’s shoulders bilaterally and ask him to shrug against resistance.  SCM  Patient seated, place your hand on the lateral aspect of the patient’s jaw, instruct him to turn the head toward your hand against resistance. Dr. Michael P. Gillespie 79

Spinal Accessory Nerve (XI) Dr. Michael P. Gillespie 80

Hypoglossal Nerve (XII)  The hypoglossal nerve is purely motor and is responsible for movement of the tongue.  Place your hand on the patient’s cheek and instruct him to press the tip of the tongue against the cheek under your hand. Repeat b/l. Instruct the patient to protrude the tongue.  If the pressure is unequal, suspect a unilateral hypoglossal nerve lesion. The tongue will deviate towards the side of the lesion. Dr. Michael P. Gillespie 81

Hypoglossal Nerve (XII) Dr. Michael P. Gillespie 82