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Ning tongue

VIEWS: 11 PAGES: 71

									Neurology lecture
series 2
Dr. Jennifer A. de Guzman
Internal Medicine/Adult Neurology
University of Perpetual Help DALTA Medical Center
Jan. 18, 2011
Cranial Nerves
Learning objectives for lec
series 1:
  To know the functions of the first six pairs
   of cranial nerves
  To learn how to test for the first six pairs
   of cranial nerves.
  To determine the clinical significance of
   the first six cranial nerves
Ventral view of the brain showing the
attachment the12 pairs of cranial nerves
Identify the ff:

  Peripheral vs supranuclear branch
  Sensory, motor and mixed nerves
    Sing to memorize!!!
    Se,se, mo,mo mi,mo,mi,se, mi,mi,mo,mo
    Cranial nerves 1---12
 Intra-axial vs extra-axial branches
Cranial Nerve 1/ Olfactory
nerve
  One of the exams of the special senses
  Smell/olfaction

  Trace the pathway!
     Primary sensory neurons(olfactory epithelium)-
      secondary neurons (olfactory bulb) --- lateral
      olfactory area, anterior perforated substance, subcallosal
      region of the medial surface of the frontal lobe
Remember:

 *Olfactory filaments perforate the cribriform plate and
   attached dura.
 *Olfactory axons cross the subarachnoid space to
   synapse on the olfactory bulbs.
 *Viruses may gain access to the subarachnoid space
   or brain via the olfactory nerve filaments and cause
   encephalitis!
Olfactory-related consequences of
head injuries

  Head injury--cribriform plate fracture-
   anosmia
  Meninges may also rupture-
   fistula(CSF gushes into the nose); CSF
   reflux into the SA space- meningitis
  Suspect a fistula in a patient with runny
   nose,anosmia, head injury but no colds
   or allergic shinitis!
Technique for testing
olfaction
  Why should we not use coffee?
  Do not use alcohol or ammonia. Use only
   coffee. Ammonia irritates all receptors of
   the mucus membrane Conjuctiva reacts
   also to ammonia.
  Vial of coffee should be opaque because
   examiner wishes to test for smell and not
   vision.
Cranial nerve 2/Optic
Nerve
 Sensory nerve

 Recall the visual pathway!


 Components of the optic nerve testing
   1.Pupillary reaction to light (direct and consensual)
   2.Visual acuity
   3.Funduscopic exam
   4.Confrontational testing/ Visual Field testing
Technique of pupillary
exam
  Normal illumination of the room
  Check if a mydriatic has been given.
  Anisocoria-unequal size of pupils
  Hippus-rapid oscillations of the pupillary
   margn (benign or sec to metabolic
   encephalopathy)
  Check direct and consensual pupillary
   light reflex.
Define the ff:

    Marcus-Gunn pupils
    Adie pupils
    Argyll-Robertson
    Horner’s syndrome (ptosis, miosis and
     anhydrosis)
Ophtalmoscopy

  Darken the room.
  Don’t forget to have a third person in the
   clinic during exam!
  Practice, practice and practice!!!
 Check cornea both with and w/o the
  scope for opacities: grayis-white ring-
  arcus senilis, greenish-brown-Kayser-
  Fleischer ring ( Wilson’s Disease)
 Normal fundus: orange disk, cup disk
  ratio 0.5, A:V ratio 2:3, intact venous
  pulsation, no hemorhages, no exudates,
  no papilledema
 Papilledema- increase intracranial
  pressure
 Optic atrophy: demyelinating disease like
  multiple sclerosis
Visual Acuity

  Snellen chart
  Pocket Snellen or Jaeger’s
  Normal: 20/20
  Use pinhole test for testing error of
   refraction.
  If patient is partially blind, do counting
   fingers. If severe, check for light
   perception.
Remember:


  Lesions of the pathways from the chiasm
   to the occipital lobe cause patterned
   defects while lesions of the retina or ptic
   nerve, if not so severe as to cause
   blindness, cause scotomas, irregular field
   defects.
Technique for confrontation testing of the
peripheral visual fields


   Distance should be about 50 cm
   Point is to match the perimeter of the
    patient’s visual field against your own.
CN’s 3,4,6/Motor nerves

  Cranial Nerve 3/Oculomotor Nerve
  Innervates the superior rectus, LPS,
   (levator palpebral superioris) inferior
   rectus, inferior oblique and medial rectus
 Cranial Nerve 4 / Trochlear Nerve
 Innervates the superior oblique muscle
 Remember: SO4
 CN Six/ Abducens nerve
 Innervate the lateral rectus muscle
 Remember: LR6
Cranial Nerve 5/Trigeminal
Nerve
  Mixed nerve
  Sensory Testing:
    Corneal reflex: tests the integrity of the 5th
     (afferent) and 7th CN’s (efferent).
    The afferent arch travels through the
     ophthalmic division of the 5th CN.
    The muscle that closes the eyelid is the
     orbicularis oculi which is innervated by the
     7th nerve
 Aged and postcataract surgery patients
  may have abnormal corneal reflex.

 Learn how to test also for the sensation
  on the face.
   Hyperesthesia
   Hypesthesia
   Hyperalgesia
   Allodynia
   Trigeminal neuralgia/ tic doloreux
Testing the motor component of the
trigeminal nerve


  Inspect temples, cheeks for atrophy of
   the temporalis and masseter.
  Palpate both masseters for atrophy. Ask
   the patient to clench teeth strongly.
  Test for the strength of jaw closure by
   having the patient clench the teeth
   strongly
CN 7/facial nerve

  Mixed nerve
  Supplies muscles of facial expression
  Supplies the stapedius
  Stimulates lacrimal, submandibular,
   sublingual glands
  Supplies skin of the concha of the auricle
  For taste from the anterior 2/3 of the
   tongue
Testing motor function of CN 7



    Wrinkle up the forehead (frontalis)
    Close eyes tightly (orbicularis oculi)
    Close lips tightly (orbicularis oris)
    Smile (buccinator)
    Pout (platysma)
Technques for testing loss of taste/
ageusia

    Use salt or sugar.
    Conceal salt and sugar.
    Test right or left half of the tongue first.
    Rinse mouth after each testing.

 Do test for patients with ageusia or presence of
   7th CN palsy.
 Systemic illness, cancer and endocrinopathies
   may present with dysgeusia/perversionof taste.
Identify type of facial palsy
 A. right peripheral facial palsy
 B . left central facial palsy
   Bell’s Palsy
   Stroke/Cerebrovascular disease
   Cerebellopontine angle tumors
   Trauma
Cranial Nerve 8/
vestibulocochlear
  Consists of a cochlear (auditory) and a
   vestibular division
  Cochlear division-mediates hearing and
   contains the:
    Receptor (Organ of Corti)
    Cochlear (spiral) ganglion
Symptoms of cochlear nerve
lesions

  Deafness and tinnitus
    Tinnitus- intermittent or persistent
     hyperacusis consisting of a buzzing or
     ringing sound
  Differentiate tinnitus from vascular bruit!
  Causes of both deafness and tinnitus:
    Aging (presbyacusis)
    Drugs (ASA and antibiotics)
   Viral infections
   Recurrent otitis media
   Hereditary cochlear degenerations
   Chronic exposure to loud sound
Techniques for screening
hearing
  Check if patient can hear normal
   conversational voice and whispering
  Do otoscopy.
  Rub fingers beside one of the patient’s
   ear and the other.
 Weber/Vertex test
   Sound lateralizes to the affected ear in
    conductive hearing loss
 Rinnes
   AC>BC normal and sensorineural hearing
    loss
 Schawabach’s
Clinical Comments

  Damage to the auditory apparatus-skull
   fractures and infections
  Tumors within the internal auditory
   meatus (meningioma, acoustic neuroma)
   damage both components of the 8th
   nerve and accompanying 7th nerve
Practice!

  Case A: increased auditory threshold to
   finger rustling on the left ear (AS),
   Weber’s lateralizes to the left ear,
   BC>AC on the left ear
 Answer: conductive hearing loss on the
  left ear
 Case 2: increased auditory threshold to
  the tuning fork on the left ear, bone and
  air transmission decreased on the left
  ear, vertex test lateralized to the right ear
 Answer: auditory or cochlear nerve
  lesion/sensorineural hearing loss
Vestibular component

  Vestibular apparatus: saccule, utricle and
   the semicircular canals
 Damage to or dysfunction of the
  vestibular apparatus results in dizziness,
  falling and abnormal eye movements
 Nausea and vomiting –due to
  connections between the vestibular
  nucleus and the vagal nucleus
 Acoustic neuroma- most common cause
  of damage to the vestibular nerve
 A tumor of Schwann cells that myelinate
  the 8th nerve.
 Interferes with the functions of the 8th and
  the 7th CN
CN IX/ Glossopharyngeal
Nerve
  Supplies the stylopharyngeus
  Supplies the otic ganglion which sends fibers
   to stimulate the parotid gland
  Carries sensation from the carotid body and
   from the carotid sinus
  Provides general sensation from the posterior
   1/3 of the tongue, skin of the external ear and
   the internal surface of the tympanic membrane
  For taste from the posterior 1/3 of the tongue
Clinical Comments

  There is seldom an isolated lesion of the
   9th cranial nerve because of the close
   association of the 10th and 11th cranial
   nerves.
  Gag reflex- tests the integrity of the nerve
    Stroking the wall of the pharynx illicits the
     response
    Careful in doing test in patients with
     increased intracranial pressure!
 Glossopharyngeal neuralgia
   Lesions to this nerve give rise to sudden
    pain of unknown cause; experienced as brief
    but severe attacks of pain that usually begin
    in the throat and radiate down the side of the
    neck in front of the ear to the back of the
    lower jaw. This can be precipitated by
    swallowing or protrusion of the tongue.
CN X/ Vagus Nerve

  Vagus- from the Latin word “wandering”
  The nerve wanders from the brainstem to
   the splenic flexure of the colon.
 Supplies the striated muscles of the
  pharynx, tongue (palatoglossus) and the
  larynx (except the stylopharyngeus-IX
  and the tensor veli palatini-V3)
 Visceral motor to smooth muscle and
  glands of the pharynx, larynx and
  thoracic and abdominal viscera
 Visceral sensory from the larynx, trachea,
  esophagus, thoracic and abdominal viscera,
  stretch receptors in the walls of the aortic arch,
  chemoreceptors in the aortic bodies adjacent
  to the arch.
 General sensory from the skin at the back of
  the ear and in the external acoustic meatus,
  part of the external surface of the tympanic
  membrane and the pharynx
Clinical Comments

  CN IX and X are tested together.
  A unilateral lesion of the vagus nerve is
   indicated by hoarseness (unilateral loss
   of function of the intrinsic muscles of the
   larynx) and difficulty in swallowing due to
   the inability to elevate the soft palate
   adequately (unilatetal loss of function of
   the levator palati muscle) thereby
   allowing food to pass up into the nose
 On examination, the arch of the soft
  palate droops on the affected side and
  the uvula deviates to the unaffected side
  as a result of the unopposed action of the
  intact muscles acting on the soft palate
 A unilateral lesion of the recurrent
  laryngeal nerve results in ipsilateral
  weakness or paralysis of the vocal fold
  thereby causing hoarseness
 This can occur during a surgical
  procedure in the neck area (carotid
  endarterectomy or thyroidectomy) where
  the nerve may be severed.
 A unilateral lesion can also occur as a
  result of an aortic aneurysm (affecting the
  left recurrent laryngeal nerve) or a
  metastatic carcinoma (enlarged
  paratracheal lymph nodes compressing
  the nerve)
Arch of the soft palate and
uvular deviation
CN XI/ Accessory Nerve

  Motor
  Supplies the sternocleidomastoid and the
   trapezius
  Lower motor neuron cell bodies of the
   accessory nerve are located in the spinal
   cord. The axons ascend into the cranium
   through the foramen magnum and exit
   the cranium through the jugular foramen
 to innervate the sternocleidomastoid and
  the trapezius
Clinical Comments

  Radical neck surgery- superficial lymph nodes
   closely associated with the CN XI
  Damage to the nerve results in a lower motor
   neuron lesion:
    Downward and lateral rotation of the scapula and
     shoulder drop resulting from loss of action of the
     trapezius
    Weakness when turning the head to the side
     opposite the lesion esp against resistance
CN XII/Hypoglossal Nerve

  Motor
  Supplies all intrinsic and extrinsic
   muscles of the tongue except the
   palatoglossus (X)
Clinical Comments

  The balanced action of the paired
   genioglossi muscles is required to
   protrude the tongue straight out. If one
   genioglossus is inactive, the action of the
   intact muscle is unopposed. The tongue
   then deviates towards the side of the
   inactive muscle
 UMN lesion: tongue deviates to the
  opposite side
 LMN lesion: tongue deviates to the same
  side

								
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