CRANIAL NERVE II Flashcards
Loss of smell occurs in sinus conditions, head trauma, smoking, aging,
and the use of cocaine and in Parkinson disease
olfactory
o Inspect each disc carefully for bulging and blurred margins
(papilledema); pallor (optic atrophy); and cup enlargement (glaucoma)
o Look for prechiasmal, or anterior, defects seen in:
§ Glaucoma, retinal emboli, optic neuritis (visual acuity poor);
o Bitemporal hemianopsias from defects at the optic chiasm, usually
from pituitary tumor;
o Homonymous hemianopsias or quadrantanopsia in postchiasmal
lesions, usually in the parietal lobe, with associated findings of stroke
(visual acuity normal).
optic
If the large pupil reacts poorly to light or anisocoria worsens in light,
the large pupil has abnormal pupillary constriction, seen in CN III
palsy.
§ If ptosis and ophthalmoplegia also present, consider
intracranial aneurysm if patient awake, and transtentorial
herniation if patient comatose.
o If both pupils react to light and anisocoria worsens in darkness, the
small pupil has abnormal pupillary dilation, seen in Horner’s
syndrome and simple anisocoria.
optic and oculomotor
o Monocular diplopia is seen in local problems with glasses or con- tact
lenses, cataracts, astigmatism, or ptosis.
o Binocular diplopia occurs in CN III, IV, VI neuropathy (40% of
patients), eye muscle disease from myasthenia gravis, trauma, thyroid
ophthalmopathy, and internuclear ophthalmoplegia
o Nystagmus is seen in:
§ Cerebellar disease, especially with gait ataxia and dysarthria
(increases with retinal fixation), and vestibular disorders
(decreases with retinal fixation); and in internuclear
ophthalmoplegia
Tewilliager – Spring 2015
o Ptosis suggests 3rd nerve palsy (CN III), Horner’s syndrome (ptosis,
meiosis, anhidrosis), or myasthenia gravis
oculomotor, trochlear, abducens
o Difficulty clenching the jaw or moving it to the opposite side occurs in
masseter and lateral pterygoid weakness, respectively.
o Look for unilateral weakness in CN V pontine lesions;
§ Bilateral weakness in bilateral hemispheric disease.
o Central nervous system patterns from stroke include ipsilateral facial
and body sensory loss from contralateral cortical or thalamic lesion;
o ipsilateral face but contralateral body sensory loss in brainstem
lesions
trigeminal-motor
o Isolated facial sensory loss occurs in peripheral nerve disorders like
trigeminal neuralgia.
o To avoid transmitting infection, use a new object for each patient.
§ You can create a sharp wood splinter by breaking or twisting a
cotton swab. The cotton end of the swab can also be used as a
dull stimulus.
o Blinking is absent in lesions of CN V or VII. Absent blinking and
sensorineural hearing loss occur in acoustic neuroma.
trigeminal-sensory
o Flattening of the nasolabial fold and drooping of the lower eyelid
suggest facial weakness.
o A peripheral injury to CN VII, also seen in Bell’s palsy, affects both
the upper and lower face;
§ A central lesion affects mainly the lowerface.
§ Loss of taste, hyperacusis, and increased or decreased tearing
also occur in Bell’s palsy.
o In unilateral facial paralysis, the mouth droops on the paralyzed side
when the patient smiles or grimaces.
facial
o The whispered voice test is both sensitive (>90%) and specific (>80%)
when assessing presence or absence of hearing loss.
o Excess cerumen, otosclerosis, and otitis media cause conductive
hearing loss;
o presbyacusis from aging commonly reflects sensorineural hearing loss.
o Vertigo with hearing loss and nystagmus typifies Ménière’s disease
vestibulocochlear
o Hoarseness occurs in vocal cord paralysis; nasal voice in paralysis of
the palate.
o Difficulty swallowing suggests pharyngeal or palatal weakness.
o The palate fails to rise with a bilateral lesion of CN X.
o In unilateral paralysis, one side of the palate fails to rise and, together
with the uvula, is pulled toward the normal side
o Unilateral absence of this reflex suggests a lesion of CN IX, and
perhaps CN X.
glossopharyngeal and vagus``
o Trapezius weakness with atrophy and fasciculations indicates a
peripheral nerve disorder.
§ In trapezius muscle paralysis, the shoulder droops, and the
scapula is displaced downward and laterally.
o A supine patient with bilateral weakness of the sternomastoids has
difficulty raising the head off the pillow
spinal accessory
o Tongue atrophy and fasciculations occur in amyotrophic lateral
sclerosis, and polio.
o In a unilateral cortical lesion, the protruded tongue deviates
transiently in a direction away from the side of the cortical lesion,
toward the side of weakness.
hypoglossal
