Neurologic System

• CN I - OLFACTORY NERVE

  1. Have client sit in a comfortable position at your eye level

  2. Ask the client to clear the nose to remove any mucus

  3. Close eyes, occlude one nostril, and identify a scented object that you are holding such as soap, coffee, or vanilla

  4. Repeat procedure for the other nostril

  
• Normal (CN I)


  • Client correctly identifies scent presented to each nostril
  • Some older clients' sense of smell may be decreased
• Deviations from normal (CN I)

  • Neurogenic Anosmia - inability to smell or identify the correct scent
  • May indicate olfactory tract lesion, frontal lobe tumor, congenital, nasal or sinus problems, nerve tissue injury, smoking and use of cocaine

  
• CN II - OPTIC

  1. Visual Acuity - Use a Snellen chart to assess vision in each eye

  2. Near Vision - Ask the client to read a newspaper or magazine paragraph to assess near vision

  3. Visual Fields - Assess visual fields of each eye by confrontation

  4. Retina & Optic Disc by Ophthalmoscope - Use an ophthalmoscope to view the retina and optic disc of each eye
• Normal (CN II)


  • Visual Acuity - Client has 20/20 vision OD (right eye) and OS (left eye) - (distance vision)
  • Near Vision - Reads print at 14 inches without difficulty
  • Visual Fields - Normal peripheral vision
  • Retina & Optic Disc - Optic disc 1.5 mm, round or slightly oval, well-defined margins, creamy pink with paler physiologic cup, Retina pink
• Deviations from normal (CN II)


  • Visual Acuity - Difficulty reading Snellen chart, missing letters, squinting
  • Near Vision - Reads print by holding closer than 14 inches or holds print farther away as in presbyopia
  • Visual Fields - Loss of visual fields may be seen in retinal damage or detachment, lesions of the optic nerve, lesions of the parietal cortex
  • Retina & Optic Disc - Papilledema, optic atrophy
• CN III, IV, VI - OCULOMOTOR, TROCHLEAR, ABDUCENS

  1. Inspect margins of the eyelids of each eye

  2. Assess extraocular movements

  3. Assess pupillary response to light (direct and indirect) and accommodation in both eyes
• Normal (CN III, IV, VI)

  • Eyelid covers about 2 mm of the iris
  • Eyes move in a smooth, coordinated motion in all directions (the six cardinal fields)
  • Bilateral illuminated pupils constrict simultaneously
  • Pupil opposite the one illuminated constricts simultaneously
• Deviations from normal (CN III, IV, VI)


  • Ptosis (drooping of the eyelid) is seen with weak eye muscles - myasthenia gravis
  • Possible causes of abnormal eye movements - cerebellar disorders, increased ICP, paralytic strabismus
  • Possible causes of pupil abnormalities - oculomotor nerve paralysis, Argyll Robertson pupils, narcotics abuse, CN III damage, lesions of the sympathetic nervous system, PNS or CNS dysfunction, CN V lesion
• CN V - TRIGEMINAL

  1. Test motor function - Ask the client to clench the teeth while you palpate the temporal and masseter muscles for contraction

  2. Test sensory function - Touch the forehead, cheeks, and chin with the sharp or dull side of a paper clip and have the client identify the sensation

  3. Test corneal reflex - Lightly touch the cornea with a fine wisp of cotton and observe the eyelid blink
• Normal (CN V)


  • Motor function - Temporal and masseter muscles contract bilaterally
  • Sensory function - Correctly identifies sharp and dull stimuli and light touch to the forehead, cheeks, and chin
  • Corneal reflex - Eyelids blink bilaterally

  
• Deviations from normal (CN V)

  • Motor function - Decreased contraction in one or both sides, asymmetric strength in moving the jaw, pain with clenching
  • Sensory function - Inability to feel and correctly identify facial stimuli - lesions of the trigeminal nerve, lesions in the spinothalamic tract or posterior columns
  • Corneal reflex - Absent corneal reflex - lesions of the trigeminal nerve, lesions of the motor part of cranial nerve VII (facial)

  
• CN VII - FACIAL

  1. Test motor function - Smile, frown and wrinkle forehead, show teeth, puff out cheeks, purse lips, raise eyebrows, close eyes tightly against resistance

  2. Test sensory function - Touch the anterior two-thirds of the tongue with a moistened applicator dipped in salt, sugar, or lemon juice and have the client identify the flavor
• Normal (CN VII)


  • Motor function - Smiles, frowns, wrinkles forehead, shows teeth, puffs out cheeks, purses lips, raises eyebrows, and closes eyes against resistance; movements are symmetric
  • Sensory function - Identifies correct flavor on anterior two-thirds of the tongue
• Deviations from normal (CN VII)

  • Motor function - Inability to close eyes, wrinkle forehead, or raise forehead along with paralysis of the lower part of the face on the affected side - Bell's Palsy, Paralysis of the lower part of the face on the opposite side affected may be seen with a central lesion that affects the upper motor neurons - Stroke
  • Sensory function - Inability to identify correct flavor on anterior two-thirds of the tongue - impairment of cranial nerve VII

  
• CN VIII - ACOUSTIC / VESTIBULOCOCHLEAR


  Test the client's hearing ability in each ear and perform the Weber and Rinne tests to assess the cochlear (auditory) component of cranial nerve VIII

  
• Normal (CN VIII)


  • Client hears whispered words from 1–2 feet
  • Weber test: Vibration heard equally well in both ears
  • Rinne test: AC > BC
• Deviations from normal (CN VIII)

  • Vibratory sound lateralizes to good ear in sensorineural loss
  • Air conduction is longer than bone conduction
• CN IX, X - GLOSSOPHARYNGEAL, VAGUS


  1. Test motor function - Ask the client to open mouth wide and say "ah" while you use a tongue depressor on the client's tongue

  2. Test gag reflex - Touch the posterior pharynx with the tongue depressor

  3. Check ability to swallow - Give the client a drink of water and note the voice quality
• Normal (CN IX, X)

  • Motor function - Uvula and soft palate rise bilaterally and symmetrically on phonation
  • Gag reflex - Intact (some normal clients may have a reduced or absent gag reflex)
  • Swallowing - Swallows without difficulty, no hoarseness noted

  
• Deviations from normal (CN IX, X)

  • Motor function - Soft palate does not rise - bilateral lesions of cranial nerve X (vagus), Unilateral rising of the soft palate and deviation of the uvula to the normal side - unilateral lesion of cranial nerve X (vagus)
  • Gag reflex - Absent gag reflex - lesions of cranial nerve IX (glossopharyngeal) or X (vagus)
  • Swallowing - Dysphagia or hoarseness - lesion of cranial nerve IX (glossopharyngeal) or X (vagus), neurologic disorder

  
• CN XI - SPINAL ACCESSORY


  Ask the client to shrug the shoulders against resistance to assess the trapezius muscle
• Normal (CN XI)


  Symmetric, strong contraction of the trapezius muscles
• Deviations from normal (CN XI)


  Asymmetric muscle contraction or drooping of the shoulder - paralysis or muscle weakness due to neck injury or torticollis
• Unilateral lesion of cranial nerve X (vagus)


  Affects the gag reflex
• Test gag reflex


  Touch the posterior pharynx with the tongue depressor
• Normal gag reflex


  • Gag reflex intact
  • Some normal clients may have a reduced or absent gag reflex
• Deviations from normal gag reflex

  • An absent gag reflex
  • Lesions of cranial nerve IX (glossopharyngeal) or X (vagus)
• Check ability to swallow

  1. Giving the client a drink of water

  2. Note the voice quality
• Normal swallowing


  • Swallows without difficulty
  • No hoarseness noted
• Deviations from normal swallowing

  • Dysphagia or hoarseness
  • Lesion of cranial nerve IX (glossopharyngeal) or X (vagus)
  • Neurologic disorder
• Assess the trapezius muscle

  Ask the client to shrug the shoulders against resistance
• Normal trapezius muscle


  • Symmetric
  • Strong contraction of the trapezius muscles
• Deviations from normal trapezius muscle

  • Asymmetric muscle contraction or drooping of the shoulder
  • Paralysis or muscle weakness due to neck injury or torticollis
• Assess the sternocleidomastoid muscle

  Ask the client to turn the head against resistance, first to the right then to the left
• Normal sternocleidomastoid muscle


  • Strong contraction of sternocleidomastoid muscle on the side opposite the turned face
• Deviations from normal sternocleidomastoid muscle

  • Atrophy with fasciculations may be seen with peripheral nerve disease
• Assess strength and mobility of tongue

  Ask the client to protrude tongue, move it to each side against the resistance of a tongue depressor, and then put it back in the mouth
• Normal tongue movement


  • Tongue movement is symmetric and smooth, and bilateral strength is apparent
• Deviations from normal tongue movement

  • Fasciculations and atrophy of the tongue
  • Peripheral nerve disease
  • Deviation to the affected side
  • Unilateral lesion