Cranial nerve examination involves assessing the 12 pairs of cranial nerves. The document provides an overview of cranial nerve anatomy and function, as well as methods for clinically testing each nerve. It summarizes the pathways, functions, and common causes of injury for several cranial nerves including the olfactory, optic, and vestibulocochlear nerves. Clinical testing involves techniques like smell identification tests for the olfactory nerve and visual acuity tests, visual field tests, and color vision tests for the optic nerve.

2. Presenter- Dr. Itrat Hussain
Moderator- Dr. Vidhi C Rathi
Cranial nerve examination

3. Index
• Introduction
• Rapid assessment of cranial nerve injury
• Cranial nerves
– Pathway
– Post traumatic assessment
– Clinical testing
• Summary of cranial nerve examination
• References

5. Introduction
• Cranial nerves are the conduit by which
– brain receives information directly from,
– controls the function of structures
which are not exclusively but mainly within
head and neck.
• These are named and numbered in
rostrocaudal sequence.

6. FUNCTIONAL TYPES
Pure sensory
• Olfactory
• Optic
• Auditory
Pure motor
• Trochlear
• Abducent
• Accessory
• Hypoglosseal
Mixed nerves
 Trigeminal
 Facial
 Glossopharyngeal
 Vagus
 Occulomotor

8. • Injury to cranial nerve can occur by –
–Trauma
–Shearing forces
–Accelerating deacelerating forces
–Injury to skull base
–Penetrating craniocerebral injuries
• Through skull base
• Sequel to surgical procedure

9. Rapid assessment of cranial nerve injury
• History of Nasal bleed/CSF rhinorrhea
• Light reflex for afferent pupillary defect
• Corneal reflex
• Complaints of diplopia
• Hoarseness of voice
• Inablity to swallow
• Proptosis
• Hearing impairment
• Facial weakness and incomplete eye closure

10. Olfactory nerve
• Serves the sense of smell (special sensory)
• Cells of origin- olfactory mucosa in the nasal
cavity
• Exits from olfactory foramina to the olfactory
bulb
• Terminates directly in the cortical and
subcortical areas of frontal and temporal lobe

12. Post traumatic assessment

13. Diagnosis
• Presence of nasal bleed
• Periorbital ecchymosis
• Proptosis
• CSF rhinorrhoea .

14. Clinical Testing
Ask the patient to close his eyes while
presenting a series of pungent, nonirritating,
familiar olfactory stimuli such as coffee or
chocolate
The aromatic stimulus should be placed
under one nostril while the other nostril is
occluded.
The patient is asked to sniff the substance
and then identify it. The procedure is
repeated for the other nostril.
If the patient can name or describe the
substance, it is assumed that the olfactory
tract is intact.
Stimuli such as ammonia are unsuitable
because they have an irritating effect on the
free nerve endings in the nasal mucosa.

15. Common causes of anosmia
• Acute/chronic inflammatory nasal disease
• Heavy smoking
• Head injury
• Intra cranial tumour compressing the
olfactory bulb
• Atrophy of olfactory bulb
• Chronic meningeal inflammation
• Parkinson’s disease

17. Function
• Carries the visual impulses from the retina to
the optic chiasma & in the optic tract to the
lateral geniculate body
• The impulse acts as an afferent pathway for
the pupillary light reflex

18. Post traumatic assessment
According to Walsh & Lindenberg
• Classification of optic nerve injury
– Primary
• Optic nerve concussion
• Contusion or laceration
• Hematoma
• Optic nerve avulsion – partial or complete
– Secondary
• Oedema
• Ischemia
• Micro vascular thrombosis
• Infarction of the nerve

19. • Maurer’s triad
– Head injury
– Epistaxis
– Uniocular blindness
(Possibility of optic nerve injury)
• Common complaint is loss of vision

23. Purpose of the test
• To measure acquity of vision & determine if
any disease is due to local occular disease or
neural impairment
• To chart the visual field

24. Method of testing
 Visual acuity
- The standard snellen’s
chart can be used for
vision & the Jaegar type
card can be used for near
vision
[the commonest causes of
visual error lies in the eye
only]

25. Visual field
• Purpose:
– To chart periphery of visual field
– To detect position, size & shape of the blind spot

26. Confrontation test
Instruct Pt to indicate appearance of
the object
Pt covers left eye & examiner right
Pt & examiner sit face to face
PT moves the test object from outside the
visual field towards midline

27. • Tangent screen or Goldmann field exam:
• Sit 3 feet from a screen with a target in the center.
• Stare at the center object and let the examiner know when
an object moves into side vision.
• Automated perimetry:
• Sit in front of a concave dome and stare at an object in the
middle.
• Press a button when one sees small flashes of light in
peripheral vision.
• Automated perimetry is often used to track conditions that
may worsen over time.

28. Colour vision: day and night vision
• Color blindness:
– Comparing the colour
– Disturbance of colour vision may
occur in
• diseases of the choroids,
• optic nerve,
• visual pathways etc.
– Pseudochromatic plates of
Ishihara and Rand
Ishihara plate
Hardy-Rand-Rittler
plate

29. Common causes
• Total unilateral loss of vision: optic nerve
lesion
• Homonymous hemianopia: lesion between
optic tract to occipital cortex
• Bitemporal hemianopia: lesion of optic
chiasma

30. Occulomotor, Trochlear, Abducent

31. Occulomotor nerve
• Has two types of fibers
– Somatic efferent
• Emerges at the level of mid brain and supplies
extraocular muscles and levator palpebrae superioris
– General visceral efferent
• Edinger Westphal nucleus for cilliary body and
sphincter pupillae
• Course divided in 2 parts
– Intra cranial and extra cranial

35. Function
• Controls the external occular muscles &
elevators of the lids
• Also regulates the pupillary muscles

36. Purpose of the test
• Inspect pupils to rule out a local disease,
peripheral lesion or a nuclear involvement
• Examine eye movement & determine if
defects is muscular origin or neural
involvement
• To detect nystagmus

37. Method of testing
• Observation
– Presence & absence of ptosis & squint
– Whether unilateral or bilateral
– Constant or variable
– Size, shape, equality & regularity of the pupils

38. Pin-Hole Test
• Determines whether poor vision is
due to :
– a refractive error or
– diseases of the eyeball or
– visual pathways.
• Vision can be improved by looking
through a pin hole and can be
usually improved by glasses.
• Patient is requested to read the
Snellen chart through a 1 mm
pinhole in a disk that is held
before one eye while the other
eye is covered.

39. Effusion of blood into and around the extra-ocular muscles
interferes with their delicate action required to maintain co-
ordination of the eye movement so that a transient diplopia is more
evident in upward and downward gaze.
CAUSES OF DIPLOPIA-
•PHYSICAL INTERFERENCE-
- Extravasation of blood into and around the muscles
- Impinging of bone spicules
-Displacement of bony origin
-Avulsion from the bony origin
-Entrapment of muscle within the fracture line
-Incarceration of periorbital fat in a bony defect
-Formation of fibrous adhesion

40. •PHYSIOLOGICAL IMBALANCE
•NEROLOGICAL DEFECTS
-supra-nuclear
-Nuclear lesion
-Infra-nuclear & intra-cranial injury
-Cavernus sinus compression
-Superior orbital fissure contusion
-Intra-orbital damage

41. Diplopia test
• Binocular Diplopia results
from a manifest ocular
deviation and is simultaneous
appreciation of two images of
1 object
• Diplopia can be :
– Horizontal
– Vertical
– Torsional

42. HESS TEST
• Walter Hess, 1908.
• Principle is haploscopic.
• Chart is plotted based on the Hering’s and
Sherrington’s law of innervation.
• Dissociation of two eyes is by the means of colors

43. • Test is performed with each eye fixating in turn.
• It is done at 50 cms.
• Patient wears red and green glasses.
• Eye to be tested should have green glass in front
of it.
• The chart has electronically operated board
with small red lights.
• Patient is asked to place green light in each of
points on red light as illuminated.
• Next the goggles are changed

44. • Compression of space between the two plotted
fixation points indicates underaction of a muscle
acting in that direction.
• Expansion indicates overaction.
• Smaller field belongs to eye with paretic muscle.
• Unaffected eye shows larger field expressing the
overaction of the contralateral synergist.
Interpretation

45. Underaction : Rt
lateral rectus
Overaction : Lt
medial rectus

46. Clinical testing
• Patient is asked to look
up & down & returns the
eyes medially.(H pattern)
– Muscle elevates the eyelid
& constricts the pupil in
response to light.

49. Trigeminal nerve
• Largest cranial nerve
• Three branches
– Ophthalmic
– Maxillary
– Mandibular
• Emerges from pons as large sensory and small
motor root
• Sensory root comprises of axons from the
trigeminal ganglion

51. • Sensory
Front of the scalp,
Face except over angle of mandible
Nose & Paranasal sinuses
Conjunctiva & Cornea
Lips, Gums,Teeth,Hard palate
Outer surface of Tympanic
membrane
• Motor
Muscles of mastication, Mylohyoid
& anterior belly of digastric.
Tensor palati & tensor tympani

52. Intracranial course of trigeminal nerve

53. Post traumatic assessment
• Sensation along the cutaneous nerve
distribution is affected
• Corneal anesthesia
• Hyperalgesia

54. • Lesion of whole nerve
– Anaesthesia of anterior half of scalp,face,
cornea, conjunctiva, nasal mucosa, mouth,
• Lesion of division of nerve
– Limited to the distribution of the branch

55. • Corneal reflex:
–patient looks up and
away.
–Touch cotton wool
to other side.
–Look for blink in
both eyes, ask if can
sense it.
Clinical testing

56. • Facial sensation:
– sterile sharp item on forehead, cheek,
jaw.
– Repeat with dull object. Ask to report
sharp or dull.
• Motor:
– Patient opens mouth, clenches teeth
– Palpate temporal, masseter muscles
as they clench.
• Have Pt protrude mandible against
resistance
• Have Pt go into lateral excursion against
resistance
– Jaw jerk

57. Facial nerve
• Main motor supply to the face
• Consists of motor and sensory root
• Nuclei –
– Branchial efferent – facial nerve nucleus in the
pons
– General visceral efferent – superior salivatory
nucleus
– Special visceral afferent – nucleus of tractus
solitarius

59. Function
• Supplies the muscles of facial expression
including platysma & stapedius muscle
• Secretomotor fibers to the lacrimal gland &
the salivary gland
• Carries sensation of taste from anterior 2/3
of tongue & general sensation from external
acoustic meatus

60. Purpose of the test
• To detect any unilateral or bilateral
weakness of facial muscles (UMN or LMN)
• Detect impairment of taste

61. Method of testing
• Observation
– Symmetry and asymmetry
of face
– Nasolabial fold & wrinkle
on forehead
• Ask the Pt to close the
eyes, raise the eyebrows,
blow out the cheek,
whistle etc

62. Examination of taste
• The four primary taste (sweet, salt, sour,
bitter) can be carried out by using sugar,
salt, vinegar & quinine
• The side of the tongue is moistened by the
test substance
• Ask the Pt to indicate taste by pointing

63. Secretomotor function
• The flow of tears of two side can be
compared by giving ammonia to inhale
which will result in tearing of eye
• The flow of saliva can be tasted by keeping a
spicy substance in the tongue & the tip is
raised to observe the sub maxillary salivary
flow

64. Reflexes
• Corneal reflex
• Nasopalpebral reflex: tap on the
nasopalpebral ridge will produce closure of
both eyes. In bells palsy there is failure to
close on the affected side

65. Common causes of facial paralysis
• Neoplasm affecting thalamus: unilateral
emotional paralysis
• Parkinsonism : bilateral emotional paralysis
• CVA neoplasm, MND: bilateral UMN palsy
• Bell’s palsy

66. • Bell’s palsy – inflammation or compression of
facial nerve near stylomastoid foramen or
facial canal.

67. • Percutaneous stimulation of the facial nerve
is used widely in tests to judge the severity
and prognosis of facial paralysis
• Various tests
– Maximum stimulation test
– Nerve excitability threshold
– Electroneuronography
– Electromyography

68. Maximum stimulation test
• Described by May et al
• Method of evaluation of facial nerve
degeneration soon after onset nerve disorder
• It involves observing response of the muscle to
electrical stimulus
Technique
• The probe is placed against the face.
– After reassuring the patient the current is started
from 1 mA and increased to 5 mA and then to 10 mA
until patient notes discomfort
The prognostic accuracy of maximal stimulation test compared with that of the nerve
excitability test in Bell’s palsy .
The Laryngoscope; Vol 81(6);931-938;June 1971

69. • 5 general areas are tested
– Forehead and eyebrows
– Periorbital area
– Cheek, upper lip, nasal ala
– Lower lip
– Cervical and platysmal area
• It should also be applied over the area of
stylomastoid foramen – stimulate the main
trunk
– Advantage – earlier detection of lesion as it starts
proximally
– Disadvantage – requires higher stimulus intensity
and hence may cause discomfort .

70. Nerve excitabilty test
• Stimulating electrode is placed
over the main trunk of facial
nerve
• The current amplitude is
increased till there is visible
stimulation of the
nerve(twitching of face)
• It is then compared with the
other side of the face.
• Diffrence of more than 3.5 mA is
considered significant

71. Electroneuronography
• Stimulating electrode
on the nerve proximally
• Recording electrodes
on the muscles distally
• Responses measured
bilaterally and
compared as % of the
response on healthy
side
• Degeneration more
than 90% is considered
having poor prognosis

72. House-Brackmann facial nerve
grading system Grade I - Normal
• Normal facial function in all areas
 Grade II - Slight Dysfunction
• Gross: slight weakness noticeable on close inspection; may have very
slight synkinesis
• At rest: normal symmetry and tone
• Motion: forehead - moderate to good function; eye - complete closure
with minimum effort; mouth - slight asymmetry.
Grade III - Moderate Dysfunction
• Gross: obvious but not disfiguring difference between two sides;
noticeable but not severe synkinesis, contracture, and/or hemi-facial
spasm.
• At rest: normal symmetry and tone
• Motion: forehead - slight to moderate movement; eye - complete closure
with effort; mouth - slightly weak with maximum effort.

73.  Grade IV - Moderate Severe Dysfunction
• Gross: obvious weakness and/or disfiguring asymmetry
• At rest: normal symmetry and tone
• Motion: forehead - none; eye - incomplete closure; mouth - asymmetric
with maximum effort.
 Grade V - Severe Dysfunction
• Gross: only barely perceptible motion
• At rest: asymmetry
• Motion: forehead - none; eye - incomplete closure; mouth - slight
movement
 Grade VI - Total Paralysis
• No movement

74. Vestibulococchlear nerve
• Main sensory nerve to internal ear
• Nerve emerges from internal acoustic meatus
• Two branches
– Vestibular branch – equilibrium
– Cochlear branch – hearing
• Nuclei –
– Special Somatic Afferent – two cochlear nuclei
& four vestibular nuclei

76. Purpose of the test
• To determine any deafness is bilateral or
unilateral
• Whether deafness is due disease of middle
ear or cochlear nerve
• To determine the disturbance of vestibular
functions

77. Clinical testing
– Cochlear tests :-
– Ticking watch
– Whisper in ear
Weber Test
Rinne test

78. Common causes of deafness
• Disease of external & middle ear &
Eustachian tube
• Prolonged exposure to loud noise
• Old age
• Meningitis
• Demyelinating disease
• Deafness due to drugs

79. Vestibular nerve examination
• Romberg's test Ask the subject to stand erect with feet together
and eyes closed.
• Caloric Testing
• Patient is tested with the head of the bed at 30° from the horizontal
• Using cool water at 30°C, the external auditory canal is irrigated for
30 seconds. In a normal individual, the eyes tonically deviate to the
irrigated side followed by nystagmus to the opposite side.
• The nystagmus appears after a latent period of about 20 seconds
and persists for 1.5 to 2 minutes.
• The same procedure is repeated after approximately 5 minutes
using warm water at 44°C. When warm water is used, nystagmus is
toward the irrigated ear. (COWS )

80. Glossopharyngeal nerve
• Emerges from internal jugular foramina
• Sensory function –
– Taste from posterior 1/3rd of tongue
– Pharynx , posterior tongue
• Somatic motor function
– Muscles of pharynx
– Tongue
• Autonomic motor
– Saliva production

81. Function
General Sensory: posterior 1/3
of tongue, tonsil, skin of
external ear, tympanic
membrane & pharynx
Visceral Motor:
parasympathetic stimulation of
parotid gland, & controls blood
vessels in carotid body
Visceral Sensory:
subconscious sensation
from carotid body & sinus
Special Sensory: carries
taste from posterior 1/3
of tongue
Branchial Motor:
Supplies styolopharyngeus
muscle

83. Clinical testing
• Gag reflex
• Taste
• Ability to swallow

84. Vagus nerve
• Emerges from jugular foramina
• Sensory function
– Skin at the back of ear
– External acoustic meatus
– Part of tympanic membrane
– Larynx
– Trachea
– Esophagus
– Thoracic and abdominal viscera

86. Function
General Sensory: posterior meninges,
concha, skin at back of ear, external
tympanic membrane, pharynx &
larynx
Visceral Motor: parasympathetic
stimulation to smooth muscle &
glands of pharynx, larynx; thoracic
& abdominal viscera & cardiac
muscle
Visceral Sensory: from larynx,
trachea, esophagus, & thoracic &
abdominal viscera, stretch
receptors & chemoreceptors
Motor: superior, middle, inferior
constrictors; levator palati,
salpingopharyngeus,
palatopharyngeus, palatoglossus

87. Post traumatic assessment
• Injury to IX, X, XI may not be readily apparent
• Dysphagia
• Depressed gag reflex
• Ipsilateral palatal palsy
• Loss of sensation on the posterior third of the
tongue

88. Clinical testing
• Vagus and palate
• Vagus and larynx

89. Spinal Accessory nerve
• Emerges from jugular
foramina
• Motor somatic function
• Supplies
sternocleidomastoid & trapezius
muscles

90. Purpose of the test
• To detect wasting & weakness, unilateral or
bilateral of the muscles

91. Method of testing

92. Common causes of paralysis
• MND
• Poliomyelitis
• Polyneuropathy
• Trauma in the neck or base of skull
• Tumour at jugular foramen
• Syringomyelia

93. Hypoglossal nerve
• Emerges from hypoglossal canal in occipital
bone
• Motor somatic function
– Speech and
– Swallowing via muscles of tongue

95. Post traumatic assessment
• Inability to move food inside mouth
• Slurred speech
• Movement of tongue absent on the affected
side

96. Clinical testing
• Tongue Protrusion
– Deviation to the affected
side

97. 13th Cranial Nerve
• Known as cranial nerve zero or Terminal Nerve
• It projects from nasal cavity, enters brain just a little bit
ahead of other cranial nerves as a microscopic plexus
of unmyelinated peripheral nerve fascicles
Function
• The nerve is vestigial or related to sensing of
pheromones
• Regulates sexual behavior in mammals

98. • The nerve is vestigial or related to sensing of
pheromones
• Regulates sexual behavior in mammals

100. • Gray’s anatomy Vol 1
• Rowe and Williams Vol 2
• FonsecaVol 1
• Hutchinson clinical methods – Michael Swash
• CRANIAL NERVES IN HEALTH AND DISEASE
2nd edition by WILSON-PAUWELS , AKESSON,
STEWART, SPACEY
References

101. THANK YOU