Cranial nerves:
signs of disorder, examination.
doc. MUDr. Valja Kellerová, DrSc.
Department of Neurology
Cranial nerves
• provide motor and sensory innervation for
the head and neck
• damage of motor neurons results in
cranial nerve palsy (central or peripheral?)
• motor pathways for cranial nerves are
composed of how many neurons?
• where are they located?
Cranial nerve palsy
• The upper motor neuron –
lesion results in an upper motor
neuron weakness, central palsy
• in: cortex, internal capsule, or
brain stem above the nucleus
• The lower motor neuron –
lesion results in an lower motor
neuron weaknesss, peripheral p.
• in: the nucleus in the brain stem
(the cell bodies form nuclei),
or in any lower part of the
cranial nerve
Olfactory nerve disorders
• hyposmia/anosmia: bilateral and transient – rhinitis
• unilateral:
– damage of the fila olfactoria – through cribriform plate of the ethmoid bone
head trauma - skull fractures
– olfactory bulb and tract damage – tumours – meningeoma, glioma
• uncinate fits – olfactory hallucinations (unpleasant)
lesion in the olfactory cortex (uncus gyri hippocampi) – tumour - glioblastoma
Olfactory nerve examination
• Testing the ability to smell or to identify different
smells:
– each nostril separately
– the patient tries to identify the odor with eyes closed
– recommended:
perfume (flowers), spice (cinnamon, peppermint…), coffee,
tobacco, soap…
– avoid substances which irritate the trigeminal nerve
(ammonia, vinegar…)
Optic tract and manifestations of its damage
• the ocular systém reverses the image
• optic chiasma – partial decussation
• damage anterior to the chiasma:
– scotoma
– monocular blindness
• lesion at the chiasma:
– heteronymous hemianopsia
• damage posterior to the chiasma:
– homonymous hemianopsia
• lesion in the optic radiation:
– quadrantanopsia
• lesion to the visual cortex:
– one side – homonymous hemianopsia
– bilateral – cortical blindness
Mumenthaler
Optic nerve examination
• visual acuity
• optic fundus and disc:
– papilloedema – prominence is
measured in dioptres
– in increased intracranial
pressure (brain tumour?)
– contraindication of lumbar
punction!
• visual fields – gross testing by
confrontation
Impaired ocular movement 1
• Disorders of gaze (supranuclear, central), or
conjugate deviation of the eyes:
– horizontal
• the frontal lesion – tonic deviation of the eyes towards
the lesion
Lindsay
Impaired ocular movement 2
• Disorders of gaze (supranuclear, central), or
conjugate deviation of the eyes:
– horizontal
• the pontine lesion – tonic deviation away from the
lesion
Lindsay
Impaired ocular movement 3
• Disorders of gaze
– vertical
• upward gaze and
convergence are lost
• in midbrain tectum
lesion
= Parinaud´s syndrome
Netter
Impaired ocular movement 4
Lesions of the cranial nerves
(peripheral palsy):
• III (oculomotor)
• IV (trochlear)
• VI (abducens)
– with paralytic strabismus
– with double vision (diplopia)
Oculomotor palsy
• ptosis (levator palpebrae m.)
• divergent strabismus
(the affected eye deviates
laterally)
• paralysis of the eye
movements and
accommodation
• pupil dilatation
(mydriasis),
• reaction to light is absent
Oculomotor palsy - paralysis of the
eye movements (left eye)
Oculomotor palsy (on the right side)
• divergent strabismus
• mydriasis
• paralysis of the eye movements
Perkin
Trochlear palsy
• rare
• weakness of downward gaze
• double vision when looking
downwards
• the head may tilt to the
opposite side to minimise
the diplopia
• diplopia is vertical
Right fourth nerve palsy, the
paretic eye turns up- and outwards;
head tilting
Abducent palsy
• convergent strabismus
• failure of abduction
on the affected eye
(on looking to the paralysed
side)
• horizontal diplopia
Left sixth nerve palsy
(looking to the left)
III, IV, VI cranial nerve examination
• palpebral fissures (symmetrical? ptosis?)
• position of the bulbs (parallel? strabismus convergent
or divergent?)
• ocular movements (full range? limitations?)
• nystagmus (direction? degree?)
• pupils: shape, size in mm (dilated – mydriasis,
constricted – miosis)
equality (isocoria? anisocoria?)
reaction to light (light reflex):
direct and consensual
near reaction to accommodation and convergence
Trigeminal nerve disorders
• the fifth nerve:
– sensory fibres subserve
facial sensation (half of the
face, 3 divisions)
– motor fibres (in the
mandibular division)
innervate the muscles of
mastication (masseter,
pterygoids and temporalis)
• disorders:
– sensory loss
– muscle weakness, atrophy
(in peripheral palsy)
– neuralgia
Trigeminal nerve examination
• pressure to points where the divisions emerge –painful
• sensation (each division separately) for
– pain
– temperature
– light touch
• corneal reflex – blink response (trigemino-facial r.) –
symmetrical?
• masseter reflex (jaw jerk)
• motor function of the masseter, temporal and
pterygoid muscles
Facial palsy
• upper motor neuron lesion,
central paralysis:
the upper branch is less affected
(because the rostral part of the
nucleus is innervated bilaterally)
paralysis is marked on the muscles
in the lower half of the face,
on the opposite side
• lower motor neuron lesion,
peripheral paralysis:
paralysis of all facial muscles
on the same side
Mumenthaler
Facial palsy
Central
Facial palsy
Peripheral:
• the upper branches
– flattened wrinkles on the
forehead
– lagophthalmos
an attempt to close the eyes the one eye does not close
– Bell´s phenomenon
the eyeball rotates upwards
Facial palsy
Peripheral:
• the lower branches
– flattening of nasolabial
fold
– mouth angle drop
– asymmetrical:
• smile
• showing teeth
• purse lips
Facial nerve examination
• observation
• testing of the upper branches:
– to wrinkle forehead (raise eyebrows)
– to frown
– to close eys tightly (persisting fissure in mm)
• to close eyes against the resistance
• testing of the lower branches:
–
–
–
–
–
to smile
to show one´s teeth
to purse the lips up
to blow out the cheeks
to whistle
Primitive (prefrontal) reflexes
Axial reflexes:
• glabellar, nasopalpebral reflex - physiological,
blink response (lowered/absent in peripheral facial palsy)
Primitive (prefrontal) reflexes:
• pout reflex - a pout response = protrusion of the lips
(snout reflex or labial reflex) to tap
• sucking reflex (to light touch)
• grasp reflex (Janiševski´s reflex)
– their presence in adults is pathological
– suggests a lesion of the frontal lobe
Vestibulocochlear nerve disorders
• Auditory function - hearing loss
• Vestibular function:
– vertigo (an illusion of rotatory movement), vomiting…
– nystagmus (a rhythmical oscillation of the eyes)
• a slow drift in one direction, followed by a fast corrective movement
• nystagmus direction – in terms of the fast phase
• horizontal, vertical, rotatory, diagonal, mixed…
• nystagmus: grade I, II, III
– tonic deviations
• towards the damaged side
• in peripheral vestibular lesions – „harmonious“ vestibular sy
• dependence on the head position
Examination - tonic deviations
• Hautant´s test – deviation of the
arms - in angular degrees
• Barány´s pointing test
• (Unterberger gait test, stepping,
marching test)
• Romberg´s test
• dependence of the fall direction
on the head position
• vestibular ataxia – gait with the eyes
closed – deviation from the straight
direction
Disorders of the lower cranial nerves
Lesions of the cranial nerves (peripheral palsy):
• IX (glossopharyngeal) mixed
• X (vagus) mixed
• XI (accessory) motor
– palatal weakness - bilateral – nasal quality of speech
– pharyngeal weakness - bilateral – dysphagia
– vocal cord paresis – hoarseness of the voice or dysphonia
– the shoulder is dropped
– the patient cannot turn the head to the healthy side
IX, X, XI cranial nerve examination
• swallowing difficulty?
• assess the soft palate
– at rest (symmetrical? palatal arch
is drooped?)
– during phonation (elevation?)
• gag reflex (pharyngeal) –
symmetrical?
• accessory nerve (external branch):
– sternomastoid muscle
– trapezius muscle
Lindsay
Hypoglossal paralysis and examination
• paralysis:
– upper motor neuron paralysis
• tongue deviates opposite to
the lesion
• mild weakness
– lower motor neuron paralysis
• tongue deviates to the side of
the lesion
• atrophy
• fasciculation
• examination:
– inspection
– mobility of the tongue
Lindsay
Bulbar and pseudobulbar palsy
bulbar (nuclear)
• bilateral affection of the lower
cranial nerves IX-XII or their
nuclei in the oblongata
• lower motor neuron lesion,
peripheral palsy
• dysarthria, dysphagia, n.VII,V
• masseter reflex absent
• tongue atrophy, fasciculations
• cause: polyradiculoneuritis Guillain-Barré syndrome),
brainstem lesions – tumours,
meningoencephalitis, motor
neuron disease
pseudobulbar
(supranuclear)
• bilateral lesion of corticobulbar tract
• upper motor neuron lesion,
central palsy
• dysarthria, dysphagia, n.VII,V
• masseter reflex increased
• emotional lability (unprovoked
crying or laughing)
• frontal type of the gait
• cause: cerebrovascular
disease, arteriosclerosis
(multi-infarct conditions)