Grade

III

Moderate dysfunction, obvious but not disfiguring difference between sides, eye can be completely

closed with effort

Grade

IV

Moderately severe, normal tone at rest, obvious weakness or asymmetry with movement, incomplete

closure of eye

Grade

V

Severe dysfunction, only barely perceptible motion, and asymmetry at rest

Grade

VI

No movement

Figs. 6D(iii).57A to C: Innervation by facial nerve.

Causes of LMN Facial Palsy

Congenital:

Möbius syndrome

Goldenhar syndrome

Melkersson–Rosenthal syndrome

Birth related: Forceps delivery

Idiopathic: Bell’s palsy

Infection:

Viral infection, i.e. varicella zoster (Ramsay Hunt), herpes zoster, herpes simplex, and

HIV

Otitis media

Cholesteatoma

Necrotizing otitis externa

Skull base osteomyelitis

Lyme disease

Leprosy

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Trauma:

Temporal bone fracture

Gunshot or penetrating injury

Laceration

Neoplastic:

Schwannoma

Meningioma

Hemangioma

Parotid malignancy

Iatrogenic: Brain, middle ear, mastoid, parotid or facial surgery

Neurological:

Lacunar or brainstem infarct

Guillain–Barré syndrome

Myasthenia gravis

Multiple sclerosis

Metabolic:

Diabetes mellitus

Hypertension

Pregnancy

Vitamin A deficiency

Central Facial Nerve Palsy (UMN Facial Nerve Palsy)

Facial weakness of central origin/UMN facial palsy

Weakness of the lower face, with relative sparing of upper face

Upper face is not necessarily completely spared, but it is always involved to a lesser degree than the lower face

Volitional or voluntary Emotional or mimetic

Lesion of the cortical center in the lower third of the precentral

gyrus that controls facial movements, or the corticobulbar tract

Thalamic or striatocapsular lesions, usually

infarction

Weakness more marked on voluntary contraction, when patient is

asked to smile or bare her teeth

Facial asymmetry more apparent with

spontaneous expression, as when laughing

Differences between UMN and LMN type of facial nerve palsy

UMN type LMN type

Facial motor function Wrinkling of forehead preserved (frontalis unaffected) Total face is involved

Bell’s phenomenon

[Fig. 6D(iii).60A to C]

Absent Present

Facial muscles Not atrophied Fasciculations, Atrophied

Taste sensation Preserved May be lost

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Corneal reflex Preserved Lost

Hemiplegia Contralateral Ipsilateral

Babinski reflex Present Absent

(UMN: upper motor neuron; LMN: lower motor neuron)

Fig. 6D(iii).58: Image showing deviation of angle of mouth.

Fig. 6D(iii).59: Weakness of orbicularis oculi.

Bilateral VII Nerve Palsy

Bilateral UMN palsy Bilateral LMN palsy

Emotional fibers—spared

Emotional incontinence—present

Associated with bilateral long

Bell’s phenomenon present

Emotional fibers—affected

Long tract signs—absent

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tract signs

Jaw jerk—exaggerated

Corneal reflex—present

Taste sensation—spared

Gag reflex—exaggerated

Jaw jerk—normal

Corneal reflex—absent

Taste sensation—absent

(UMN: upper motor neuron; LMN: lower motor neuron)

Causes of bilateral facial nerve palsy:

Diabetes

Bilateral Bell’s palsy

Borreliosis

Mycoplasma pneumoniae infection

Guillain-Barré syndrome* and Miller–Fisher syndrome

Sarcoidosis

Möbius syndrome

Leukemia

Viral infections (Herpes simplex)

Syphilis

Basal skull fractures

Pontine gliomas

Leprosy

Mononucleosis

Brainstem encephalitis

Hansen’s disease

Cryptococcal meningitis

Pontine tegmental hemorrhage

*Most common cause

Syndromes of Facial Palsy

Syndromes with facial nerve palsy

Foville’s syndrome

Millard–gubler syndrome

Möbius syndrome

Ramsay hunt syndrome

Melkersson-rosenthal syndrome [triad of recurrent infranuclear facial paralysis, orofacial edema (predominately

of the lips), and lingua plicata]

Guillain–barré syndrome

Progressive hemifacial atrophy (parry–romberg syndrome)

Meige syndrome (blepharospasm oromandibular dystonia, orofacial cervical dystonia, and brueghel’s

syndrome)

Uveoparotid fever (heerfordt’s disease)

Goldenhar syndrome

Crocodile tear syndrome

Frey’s syndrome

Figs. 6D(iii).60A to C: Bell’s phenomenon.

CRANIAL NERVE VIII—VESTIBULOCOCHLEAR NERVE

Contains two components

Vestibular component Cochlear component

↓ ↓

Responsible for equilibrium Responsible for hearing

Pathway

For linear accelerations

Macula

Utricle

Saccule

For angular acceleration

Ampulla

Organ of corti

↓

Cochlear nuclei

↓

Inferior colliculus

↓

Lateral lemnisci

↓ ↓

Vestibular ganglia Medial geniculate body

↓ ↓

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Vestibular nerve Brodmann areas 41 and 42 (transverse temporal gyrus of Heschl)

Examination

Vestibular component Cochlear component

Rotational test Rubbing fingers

Calorie test (Fig. 6D(iii).61) Rinne’s test and Weber’s test

Electronystagmography Audiometric tests:

Pure tone audiometry

Tone decay

Bekesy audiometry

Testing for vertigo and nystagmus

In sitting position, turn the head to one side by 45°

↓

Make the patient to lie down abruptly with the head handing down from the edge of cot

↓

This position is maintained for at least a minute

↓

Watch for nystagmus

↓

Fast component is toward the lower ear suggests following possibilities

↓ ↓

Benign paroxysmal positional vertigo Central cause

Starts after short latency (3–10 sec), patient will have nystagmus associated with vertigo Immediate nystagmus

Rapid adaptation No adaptation

Testing the vestibular component of VIII nerve

Rotational test

Patient is seated in a chair that can be rotated with his head well supported and fixed in head rest

↓

To test

Horizontal canal—head in flexed at 30°

Vertical canal—head is flexed at 120°

↓

Chair is rotated 10 times in 20 seconds

↓

Normally when the rotation to the right has stopped, there is nystagmus with its slow phase to the right and vice

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2.

versa

Calorie test

The patient is placed supine with the head tilted up by 30°. In this way, the horizontal semicircular canal is

oriented in a vertical plane

↓

250 mL of water (or air at controlled temperature) is irrigated through the external auditory meatus over period of

40 seconds, first using 30°C and later using 44°C

↓

Patient fixes his eyes on the given point immediately above his head

↓

After ceasing the irrigation, the time in seconds is measured during which nystagmus on the forward gaze persist

↓

Now the test is repeated on the other ear

↓

Normal response is cold water produces fast component toward the opposite side and warm water produces a

fast component toward the same side (mnemonic—COWS)

Interpretation

No response (canal paresis) Meniere’s disease

Acoustic nerve tumor

Vestibular neuronitis

Lesions of vestibular nuclei

Directional preponderance Lesions of peripheral or central vestibular apparatus

Cerebellum

Corticofugal fibers deep in the temporal lobe

Combination of above two Vestibular nerve or labyrinth lesions

Testing the Cochlear Component of VIII Nerve

Rinne’s and Weber’s test [Figs. 6D(iii).62 to 6D(iii).65]

Done with 256/512 Hz tuning fork

The prongs should be put equidistant on either ears while examining

Examination should be done in quite room

Rinne’s test Weber test

By two methods:

An activated fork may be place first on the mastoid process,

then immediately beside the ear and patient asked which is

louder

Traditional method where—place the tuning fork on the

mastoid and when no longer heard there move it beside the

ear, where it should still be audible

A vibrating tuning fork is place in the midline on

the vertex of the skull. Normally the sound is

heard equally in both ears

Interpretation

In conductive hearing loss

BC > AC

(Rinne negative)

Lateralized to abnormal side

In sensorineural hearing loss

AC > BC

(Rinne positive)

Lateralized to normal side

Fig. 6D(iii).61: Illustration demonstrating calorie test.

Fig. 6D(iii).62: Illustration showing demonstration of Rinne’s test and Weber’s test.

Fig. 6D(iii).63: Rinne’s test: Placement of tuning fork on the mastoid process.

Fig. 6D(iii).64: Rinne’s test: Placement of tuning fork beside the ear parallel to tympanic

membrane.

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Fig. 6D(iii).65: Weber’s test: Placement of tuning fork in midline on the vertex.

Causes of VIII Nerve Dysfunction Based on Site of Involvement

Vestibular component Cochlear component

At level of labyrinth:

Meniere’s disease

Motion sickness

Drug toxicity

Migraine

Vestibular nerve: Vestibular neuronitis

Brainstem:

Vascular insufficiency

Cerebellar tumors

IV ventricle tumors

Acute demyelinating diseases

Temporal lobe: As epileptic manifestation

Conduction defects:

External meatus obstruction

Middle ear pathology

Eustachian tube block

Intracranial infection

Middle ear infection

Cochlear pathology:

Meniere’s disease

Osteosclerosis

Internal auditory meatus occlusion

Nerve trunk:

Old age

Meningitis

Cerebellopontine angle tumors

Brainstem:

Vascular pathology

Demyelination disease

Cerebrum: Temporal disease

Unilateral and Bilateral Causes of VIII Nerve Dysfunction

Vestibular component Cochlear component

Unilateral Bilateral Unilateral Bilateral

Tumor (cerebellopontine

angle and acoustic

neuroma)

Fracture of the petrous

temporal bone

Vascular disease of the

internal auditory artery

Industrial deafness

Presbycusis

Drug toxicity

(gentamicin,

salicylate, etc.)

Meniere’s disease

Tumor (cerebellopontine

angle and acoustic

neuroma)

Fracture of the petrous

temporal bone

Vascular disease of the

internal auditory artery

Demyelinating illness,

e.g. multiple sclerosis

Migraine

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(e.g. stroke)

Vestibular neuritis

The “doll’s eye” oculocephalic reflex

Tests the vestibulocochlear nerve, the brainstem nuclei of the vestibulocochlear nerve,

the fibers to the cerebellum, the fibers from the cerebellum, the medial longitudinal

fasciculus (MLF), and the 3rd and 6th cranial nerves.

The cause of the unconsciousness in a patient with a negative oculocephalic reflex is

some sort of destructive brainstem pathology or brain death. Conversely, an intact

oculocephalic reflex suggests that the coma is of a nonstructural cause, because much of

the brainstem must be intact.

CRANIAL NERVE IX AND X—GLOSSOPHARYNGEAL AND VAGUS

The two nerves:

Have motor and autonomic branches with nuclei of origin in the medulla.

Both conduct general somatic afferent (GSA) as well as general visceral afferent (GVA)

fibers to related or identical fiber tracts and nuclei in the brainstem.

Both have a parasympathetic, or general visceral efferent, and a branchiomotor, or

special visceral efferent (SVE), component

Both leave the skull together

Remain close in their course through the neck

Both supply some of the same structures.

They are often involved in the same disease processes

Involvement of one may be difficult to differentiate from involvement of the other.

For these reasons, the two nerves are discussed together.

Muscles innervated by cranial nerve IX and X

IX nerve

Muscular branch Stylopharyngeus

X nerve

Pharyngeal branch [Fig. 6D(iii).66] Musculus uvulae (azygos uvulae)

Levator veli palatini

Palatopharyngeus

Salpingopharyngeus

Palatoglossus

Superior, middle, and inferior

Constrictors of the pharynx

Superior laryngeal nerve Cricothyroid

Recurrent laryngeal nerve Posterior cricoarytenoids

Lateral cricoarytenoids

Thyroarytenoids (vocalis)

Arytenoid

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GLOSSOPHARYNGEAL NERVE IX

Functions:

Glossopharyngeal nerve: Sensory supply to posterior one-third of tongue, taste sensation,

and pharyngeal mucosa.

Testing of IX Nerve

Cranial nerve IX is difficult to examine because most or all of its functions are shared by

other nerves and because many of the structures it supplies are inaccessible.

Gag reflex [Fig. 6D(iii).67]

The gag reflex is protective; it is designed to prevent noxious substances or foreign

objects from going beyond the oral cavity.

Components of gag reflex: There are three motor components: elevation of the soft

palate to seal off the nasopharynx, closure of the glottis to protect the airway, and

constriction of the pharynx to prevent entry of the substance.

Pathway: The afferent limb of the reflex is mediated by CN IX and the efferent limb

through CNs IX and X. The reflex center is in the medulla.

Testing of gag reflex: The reflex is elicited by touching the lateral oropharynx in the

region of the anterior faucial pillar with a tongue blade, applicator stick, or similar object

(pharyngeal reflex), or by touching one side of the soft palate or uvula (palatal reflex). The

reflex also occurs with touching the base of the tongue or posterior pharyngeal wall.

Clinical implication: May be bilaterally absent in some normal individuals.

Unilateral absence signifies a lower motor neuron lesion. Like most bulbar muscles, the

pharynx receives bilateral supranuclear innervation, and a unilateral cerebral lesion does

not cause detectable weakness. A hyperactive gag reflex may occur with bilateral

cerebral lesions, as in pseudobulbar palsy and amyotrophic lateral sclerosis (ALS).

Fig. 6D(iii).66: Examination of deviation of uvula. Fig. 6D(iii).67: Examination of gag reflex.

Disorders of IX Cranial Nerve

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Unilateral supranuclear lesions cause no deficit because of the bilateral corticobulbar

innervation.

Bilateral supranuclear lesions may cause pseudobulbar palsy.

Nuclear and infranuclear processes that may affect CN IX include intramedullary and

extramedullary neoplasms and other mass lesions (e.g. glomus jugulare tumor), trauma

(e.g. basilar skull fracture or surgical dissection), motor neuron disease, syringobulbia,

retropharyngeal abscess, demyelinating disease, birth injury, and brainstem ischemia.

The most important lesion of the ninth nerve is glossopharyngeal (or

vagoglossopharyngeal) neuralgia or “tic douloureux of the ninth nerve”. In this condition, the

patient experiences attacks of severe lancinating pain originating in one side of the throat or

tonsillar region and radiating along the course of the eustachian tube to the tympanic

membrane, external auditory canal, behind the angle of the jaw, and adjacent portion of the

ear. The pain may be brought on by talking, eating, swallowing, or coughing. It can lead to

syncope, convulsions, and rarely to cardiac arrest because of stimulation of the carotid

sinus reflex.

CRANIAL NERVE X—VAGUS

The vagus (in Latin means “wandering,” because of its wide distribution) is the longest and

most widely distributed.

The vagus emerges from the medulla as a series of rootlets just below those of the

glossopharyngeal.

CN X leaves the skull through the jugular foramen in the same neural sheath as the

cranial root of CN XI and behind CN IX. In the jugular foramen, the nerve lies close to the

jugular bulb, a dilatation of the internal jugular vein that houses the glomus jugulare

(tympanic body). The glomus jugulare has functions similar to the carotid body.

Branches of cranial nerves: There are 10 major terminal branches that arise at different

levels: (a) meningeal, (b) auricular, (c) pharyngeal, (d) carotid, (e) superior laryngeal, (f)

recurrent laryngeal, (g) cardiac, (h) esophageal, (i) pulmonary, and (j) gastrointestinal.

Motor: The vagus, with a contribution from the bulbar portion of CN XI, supplies all the

striated muscles of the soft palate, pharynx, and larynx except for the stylopharyngeus (CN

IX) and tensor veli palatini (CN V).

Parasympathetic: The vagus is the longest parasympathetic nerve in the body and a vagal

discharge causes bradycardia, hypotension, bronchoconstriction, bronchorrhea, increased

peristalsis, increased gastric secretion, and inhibition of adrenal function. The vagal centers

in the medulla that control these functions are themselves under the control of higher

centers in the cortex and hypothalamus. Inhibition of vagal function produces the opposite

effects.

Sensory: Both vagal ganglia are sensory. The superior ganglion primarily conveys somatic

sensation, and most of its communication is with the auricular nerve. The inferior ganglion

relays general visceral sensation and taste.

Normal functions mediated by CNs IX and X include swallowing, phonation, and airway

protection and modulation.

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