# 22 - 452 Trigeminal Neuralgia, Bell’s Palsy, and Other Cranial Nerve Disorders

### 452 Trigeminal Neuralgia, Bell’s Palsy, and Other Cranial Nerve Disorders

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Vanja C. Douglas, Stephen L. Hauser

Trigeminal Neuralgia, 

Bell’s Palsy, and Other 

Cranial Nerve Disorders
The cranial nerves consist of 12 paired nerves that mediate variable 
combinations of motor, sensory, and autonomic functions. They are 
considered as a group because of their close anatomic relationship to 
the brainstem (Fig. 452-1) and to one another, and tendency to be 
involved together in a variety of disease states. Nine cranial nerves 
connect directly with brainstem nuclei; the exceptions are cranial 
nerves 1 (olfactory) and 2 (optic) that are more accurately considered 
fiber tracts of the brain, and cranial nerve 11 (spinal accessory) whose 
motor neurons reside largely in the upper cervical cord. Analogous to 
spinal nerves (Chap. 453), motor fibers of the cranial nerves have their 
origin in the brainstem or upper cervical cord, while sensory nerves are 
pseudounipolar, with ganglia outside the central nervous system and a 
synapse with second-order fibers in the brainstem.
Symptoms and signs of cranial nerve pathology are common in 
internal medicine. They may develop in the context of a widespread 
neurologic disturbance, and in such situations, cranial nerve involve­
ment may represent the initial manifestation of the illness. In other 
disorders, involvement is largely restricted to one or several cranial 
nerves; these distinctive disorders are reviewed in this chapter. Disor­
ders of olfaction are discussed in Chap. 35, vision and ocular move­
ment in Chap. 34, hearing in Chap. 36, and vestibular function in 
Chap. 24.
FACIAL PAIN OR NUMBNESS
■
■ANATOMIC CONSIDERATIONS
The trigeminal (fifth cranial) nerve supplies sensation to the skin of the 
face, anterior half of the head, and the nasal and oral mucosa (Fig. 452-2). 
The motor part innervates the muscles involved in chewing (including 
masseter, temporalis, and pterygoids) as well as the anterior belly of the 
digastric, mylohyoid, tensor veli palatini, and the tensor tympani (hear­
ing especially for high-pitched tones). It is the largest of the cranial 
nerves. It exits in the lateral midpons and traverses the middle cranial 
fossa to the semilunar (gasserian, trigeminal) ganglion in Meckel’s cave, 
where the nerve splits into three divisions (ophthalmic [V1], maxillary 
[V2], and mandibular [V3]). V1 and V2 traverse the cavernous sinus 
to exit in the superior orbital fissure and foramen rotundum; V3 exits 
through the foramen ovale. The trigeminal nerve is predominantly 

Frontal
lobe
Olfactory
bulb and
peduncle
Pituitary
gland
Cranial
nerves
Mamillary
bodies
X
IX
VIII
VII
VI
V
IV
III
II
Temporal
lobe
CHAPTER 452
Trigeminal
ganglion
Cerebellopontine
angle
Trigeminal Neuralgia, Bell’s Palsy, and Other Cranial Nerve Disorders  
Cerebellum
XII
XI
FIGURE 452-1  Ventral view of the brain, illustrating relationships between the 
12 pairs of cranial nerves and the brainstem. (Adapted from SG Waxman: Clinical 
Neuroanatomy, 29th ed. http://www.accessmedicine.com.)
sensory, and motor innervation is exclusively carried in V3. The cor­
nea is primarily innervated by V1, although an inferior crescent may 
be V2. Upon entering the pons, pain and temperature fibers descend 
ipsilaterally as far as the upper cervical spinal cord as the spinal tract of 
V, before synapsing with the spinal nucleus of V; this accounts for the 
facial numbness that can occur with spinal cord lesions above C2. In 
the brainstem, the spinal tract of V is also located adjacent to crossed 
ascending fibers of the spinothalamic tract, producing a “crossed” sen­
sory loss for pain and temperature (ipsilateral face, contralateral arm/
trunk/leg) with lesions of the lateral lower brainstem. CN V is also 
ensheathed by oligodendrocyte-derived, rather than Schwann cell–
derived, myelin for up to 7 mm after it leaves the brainstem, unlike just 
a few millimeters for other cranial and spinal nerves; this may explain 
some instances of trigeminal neuralgia in multiple sclerosis (MS) 
(Chap. 455), a disorder of oligodendrocyte myelin.
■
■TRIGEMINAL NEURALGIA (TIC DOULOUREUX)
Clinical Manifestations 
Trigeminal neuralgia is characterized by 
excruciating paroxysms of pain in the lips, gums, cheek, or chin and, 
very rarely, in the distribution of the ophthalmic division of the fifth 
nerve. The pain seldom lasts more than a few seconds or a minute or 
two but may be so intense that the patient winces, hence the term tic. 
The paroxysms, experienced as single jabs or clusters, tend to recur 
frequently, both day and night, for several weeks at a time. They may 
occur spontaneously or be brought on with movements of affected 
areas by speaking, chewing, or smiling. Another characteristic feature 
is the presence of trigger zones, typically on the face, lips, or tongue, 
that provoke attacks; patients may report that tactile stimuli—e.g., 
washing the face, brushing the teeth, or exposure to a draft of air—
generate excruciating pain. An essential feature of trigeminal neural­
gia is that objective signs of sensory loss cannot be demonstrated on 
examination.
Trigeminal neuralgia is relatively common, with an estimated 
annual incidence of 4–8 per 100,000 individuals. Middle-aged and

KEY
Ophthalmic (V1)
Maxillary (V2)
Mandibular (V3)
Supraorbital nerve
Anterior ethmoidal nerve
Posterior ethmoidal nerve
PART 13
Neurologic Disorders
Frontal branch
of frontal nerve
Supratrochlear
nerve
Infratrochlear
nerve
Internal nasal
rami
Infraorbital
nerve
External
nasal rami
a
m
l
ri
a
c
l
a
l
i
x
L
Ma
Nasal and labial
rami of infraorbital
nerve
Anterior superior
alveolar nerves
n
l 
ua
ng
Li
ol
ve
al
or 
eri
Submandibular
ganglion
Inf
Submandibular
and sublingual
glands
Mental nerve
FIGURE 452-2  The trigeminal nerve and its branches and sensory distribution on the face. The three major sensory divisions of the trigeminal nerve consist of the 
ophthalmic, maxillary, and mandibular nerves. (Reproduced with permission from Waxman SG: Clinical Neuroanatomy, 26th ed. New York, McGraw-Hill, 2009.)
elderly persons are affected primarily, and ~60% of cases occur in 
women. Onset is typically sudden, and bouts tend to persist for weeks 
or months before remitting spontaneously. Remissions may be longlasting, but in most patients, the disorder ultimately recurs.
Pathophysiology 
Symptoms result from ectopic generation of 
action potentials in pain-sensitive afferent fibers of the fifth cranial 
nerve root just before it enters the lateral surface of the pons. Com­
pression or other pathology in the nerve leads to demyelination of 
large myelinated fibers that do not themselves carry pain sensation but 
become hyperexcitable and electrically coupled with smaller unmy­
elinated or poorly myelinated pain fibers in close proximity; this may 
explain why tactile stimuli, conveyed via the large myelinated fibers, 
can stimulate paroxysms of pain. Compression of the trigeminal nerve 
root by a blood vessel, most often the superior cerebellar artery or on 
occasion a tortuous vein, is believed to be the source of trigeminal neu­
ralgia in most patients. In cases of vascular compression, age-related 

C2
C3
C4
Frontal nerve
Mesencephalic nucleus of V
Ophthalmic nerve
Semilunar
ganglion
Main sensory nucleus of V
Main motor nucleus of V
Nucleus of spinal tract of V
Mandibular nerve
Anterior and posterior deep temporal
nerves (to temporal muscles)
y
r
Pterygopalatine ganglion
Otic ganglion
Auriculotemporal nerve
e
v
er
Lateral pterygoid muscle
Chorda tympani nerve
e
v
er
 n
ar
Buccinator nerve
Medial pterygoid muscle
Masseter muscle
Mylohyoid nerve
Anterior belly of
digastric muscle
brain sagging and increased vascular thickness and tortuosity may 
explain the prevalence of trigeminal neuralgia in later life.
Differential Diagnosis 
Trigeminal neuralgia must be distin­
guished from other causes of face and head pain (Chap. 17) and from 
pain arising from diseases of the jaw, teeth, or sinuses. Pain from 
migraine or cluster headache tends to be deep-seated and steady, 
unlike the superficial stabbing quality of trigeminal neuralgia; rarely, 
cluster headache is associated with trigeminal neuralgia, a syndrome 
known as cluster-tic. Other rare, paroxysmal headache disorders such 
as short-lasting unilateral headache attacks with conjunctival injec­
tion and tearing, short-lasting unilateral headache attacks with cranial 
autonomic symptoms, and paroxysmal hemicrania (Chap. 441) are 
distinguished by the frequency and duration of attacks and associated 
autonomic symptoms. In temporal arteritis, superficial facial pain is 
present but is not typically shocklike, the patient frequently complains 
of myalgias and other systemic symptoms, and an elevated erythrocyte

sedimentation rate (ESR) or C-reactive protein (CRP) is usually present 
(Chap. 375). When trigeminal neuralgia develops in a young adult or 
is bilateral, MS is a key consideration, and in such cases, the cause is 
often a demyelinating plaque near the root entry zone of the fifth nerve 
in the pons, especially when there is evidence of superimposed facial 
sensory loss, which can be subtle. Cases that are secondary to mass 
lesions—such as aneurysms, neurofibromas, acoustic schwannomas, 
or meningiomas—usually produce objective signs of sensory loss in 
the trigeminal nerve distribution (trigeminal neuropathy, see below).
Laboratory Evaluation 
An ESR or CRP is indicated if temporal 
arteritis is suspected. Neuroimaging studies are often necessary to 
exclude secondary causes and help assess overlying vascular lesions in 
order to plan for decompression surgery.
TREATMENT
Trigeminal Neuralgia
Drug therapy with carbamazepine is effective in ~50–75% of 
patients. Carbamazepine should be started as a single daily dose of 
100 mg taken with food and increased gradually (by 100 mg daily in 
divided doses every 1–2 days) until substantial (>50%) pain relief is 
achieved. Most patients require a maintenance dose of 200 mg four 
times daily. Doses >1200 mg daily provide no additional benefit. 
Dizziness, imbalance, sedation, and rare cases of agranulocytosis 
are the most important side effects of carbamazepine. If treatment 
is effective, it is usually continued for 1 month and then tapered 
as tolerated. Oxcarbazepine (300–1200 mg bid) is an alternative to 
carbamazepine that has less bone marrow toxicity and probably is 
equally efficacious. If these agents are not well tolerated or are inef­
fective, phenytoin (300–400 mg daily) is another option. Lamotrigine 
(400 mg daily), baclofen (10–20 mg tid), or topiramate (50 mg bid) 
may also be tried. Gabapentin, up to 3600 mg daily in divided doses, 
may occasionally provide relief.
If drug treatment fails, surgical therapy should be offered. The 
most widely used method is currently microvascular decompres­
sion to relieve pressure on the trigeminal nerve as it exits the pons. 
This procedure requires a suboccipital craniotomy. This proce­
dure appears to have a >70% efficacy rate and a low rate of pain 
recurrence in responders; the response is better for classic ticlike 
symptoms than for nonlancinating facial pains. High-resolution 
magnetic resonance angiography is useful preoperatively to visual­
ize the relationships between the fifth cranial nerve root and nearby 
blood vessels.
Gamma knife radiosurgery of the trigeminal nerve root is also 
used for treatment and results in complete pain relief, sometimes 
delayed in onset, in approximately one-half of patients and a low 
risk of persistent facial numbness; the response is sometimes longlasting, but recurrent pain develops over 2–3 years in one-third of 
patients. Compared with surgical decompression, gamma knife 
surgery appears to be somewhat less effective but has few serious 
complications.
Another procedure, radiofrequency thermal rhizotomy, creates 
a heat lesion of the trigeminal ganglion or nerve. Short-term relief 
is experienced by >95% of patients; long-term studies indicate that 
pain recurs in up to one-third of treated patients. Postoperatively, 
partial numbness of the face is common, masseter (jaw) weakness 
may occur especially following bilateral procedures, and corneal 
denervation with secondary keratitis can follow rhizotomy for firstdivision trigeminal neuralgia. Percutaneous balloon compression of 
the trigeminal ganglion is an alternative approach performed under 
general anesthesia that results in similar rates of short- and longterm pain relief and is also commonly complicated by ipsilateral 
facial numbness.
■
■TRIGEMINAL NEUROPATHY
A variety of diseases can affect the trigeminal nerve (Table 452-1). 
Most present with sensory loss on the face or with weakness of the jaw 

TABLE 452-1  Trigeminal Nerve Disorders
Nuclear (Brainstem) Lesions
Multiple sclerosis
Stroke
Syringobulbia
Glioma
Lymphoma
Preganglionic Lesions
Acoustic neuroma
Meningioma
Metastasis
Chronic meningitis
Cavernous carotid aneurysm
Semilunar Ganglion Lesions
CHAPTER 452
Trigeminal neuroma
Herpes zoster
Infection (spread from otitis media or mastoiditis)
Cavernous Sinus Lesions (see Table 452-2)
Peripheral Nerve Lesions
Trigeminal Neuralgia, Bell’s Palsy, and Other Cranial Nerve Disorders  
Tumor (e.g., nasopharyngeal carcinoma, squamous cell carcinoma, lymphoma)
Trauma
Guillain-Barré syndrome
Sjögren’s syndrome
Collagen-vascular diseases
Sarcoidosis
Leprosy
Drugs (stilbamidine, trichloroethylene)
Idiopathic trigeminal neuropathy
muscles. Deviation of the jaw on opening indicates weakness of the 
pterygoids on the side to which the jaw deviates. Some cases are due 
to Sjögren’s syndrome or a collagen-vascular disease such as systemic 
lupus erythematosus, scleroderma, or mixed connective tissue disease. 
Among infectious causes, herpes zoster (acute or postherpetic) and lep­
rosy should be considered. Tumors of the middle cranial fossa (menin­
giomas), of the trigeminal nerve (schwannomas), or of the base of the 
skull (metastatic tumors) may cause a combination of motor and sen­
sory signs. Lesions in the cavernous sinus can affect the first and sec­
ond divisions of the trigeminal nerve, and lesions of the superior orbital 
fissure can affect the first (ophthalmic) division; the accompanying 
corneal anesthesia increases the risk of ulceration (neurokeratitis).
Isolated sensory loss over the chin (mental neuropathy) can be the 
only manifestation of systemic malignancy. Rarely, an idiopathic form 
of trigeminal neuropathy is observed. It is characterized by numb­
ness and paresthesias, sometimes bilaterally, with loss of sensation in 
the territory of the trigeminal nerve but without weakness of the jaw. 
Gradual recovery is the rule. Tonic spasm of the masticatory muscles, 
known as trismus, is symptomatic of tetanus (Chap. 157) or may occur 
in patients treated with phenothiazines.
FACIAL WEAKNESS
■
■ANATOMIC CONSIDERATIONS
(Fig. 452-3) The seventh cranial nerve supplies all the muscles con­
cerned with facial expression, as well as the stapedius, stylohyoid, and 
posterior belly of the digastric. The sensory and parasympathetic com­
ponents (the nervus intermedius) convey taste sensation from the ante­
rior two-thirds of the tongue, cutaneous impulses from the anterior 
wall of the external auditory canal, and preganglionic parasympathetic 
signals to the pterygopalatine and submandibular ganglia, stimulat­
ing lacrimation, rhinorrhea, and salivation. The cell bodies of pseu­
dounipolar sensory neurons lie in the geniculate ganglion. The motor 
nucleus of the seventh nerve lies anterior and lateral to the abducens 
nucleus. After leaving the pons, the seventh nerve enters the internal 
auditory meatus with the acoustic nerve. The nerve continues its course

Superior
salivatory
nucleus
Geniculate
ganglion
Trigeminal
ganglion
Motor nucleus
VI n.
V n.
Motor nucleus
VII n.

Nucleus
fasciculus
solitarius
C
VII n.
B
A
PART 13
Neurologic Disorders
Fasciculus
solitarius
Chorda
tympani
Lingual
nerve
Submandibular gland
Submandibular
ganglion
FIGURE 452-3  The facial nerve. A, B, and C denote lesions of the facial nerve at the stylomastoid foramen, distal and proximal to the geniculate ganglion, respectively. Green 
lines indicate the parasympathetic fibers, red line indicates motor fibers, and purple lines indicate visceral afferent fibers (taste). (Reproduced with permission from MB 
Carpenter: Core Text of Neuroanatomy, 2nd ed. Williams & Wilkins, 1978.)
in its own bony channel, the facial canal, and exits from the skull via 
the stylomastoid foramen. It then passes through the parotid gland and 
subdivides to supply the facial muscles.
A complete interruption of the facial nerve at the stylomastoid fora­
men paralyzes all muscles of facial expression. The corner of the mouth 
droops, the creases and skinfolds are effaced, the forehead is unfur­
rowed, and the eyelids will not close. Upon attempted closure of the 
lids, the eye on the paralyzed side rolls upward (Bell’s phenomenon). 
The lower lid sags and falls away from the conjunctiva, permitting 
tears to spill over the cheek. Food collects between the teeth and lips, 
and saliva may dribble from the corner of the mouth. The patient com­
plains of a heaviness or numbness in the face, but sensory loss is rarely 
demonstrable and taste is intact.
If the lesion is in the middle-ear portion, taste is lost over the ante­
rior two-thirds of the tongue on the same side. If the nerve to the sta­
pedius is interrupted, there is hyperacusis (sensitivity to loud sounds). 
Lesions in the internal auditory meatus may affect the adjacent audi­
tory and vestibular nerves, causing deafness, tinnitus, or dizziness. 
Intrapontine lesions that paralyze the face usually affect the abducens 
nucleus as well, and often the corticospinal and sensory tracts.
If the peripheral facial paralysis has existed for some time and recov­
ery of motor function is incomplete, a continuous diffuse contraction 
of facial muscles may appear. The palpebral fissure becomes narrowed, 
and the nasolabial fold deepens. Facial spasms, initiated by movements 
of the face, may develop (hemifacial spasm). Anomalous regeneration 
of seventh nerve fibers may result in other troublesome phenomena. If 
fibers originally connected with the orbicularis oculi come to innervate 
the orbicularis oris, closure of the lids may cause a retraction of the 
mouth (synkinesis), or if parasympathetic fibers originally connected 
with salivary glands later innervate the lacrimal gland, anomalous tear­
ing (“crocodile tears”) may occur with eating. Another facial synkinesia 
is triggered by jaw opening, causing closure of the eyelids on the side of 
the facial palsy (jaw-winking).
■
■BELL’S PALSY
The most common form of facial paralysis is Bell’s palsy. The annual 
incidence of this idiopathic disorder is ~25 per 100,000 annually, or 

Major superficial
petrosal nerve
Lacrimal gland

Pterygopalatine
ganglion
To nasal and
palatine glands
Sublingual gland
about 1 in 60 persons in a lifetime. Risk factors include pregnancy and 
diabetes mellitus.
Clinical Manifestations 
The onset of Bell’s palsy is fairly abrupt, 
with maximal weakness being attained by 48 h as a general rule. Pain 
behind the ear may precede the paralysis for a day or two. Taste sensa­
tion may be lost unilaterally, and hyperacusis may be present. In some 
cases, there is mild cerebrospinal fluid lymphocytosis. MRI may reveal 
swelling and uniform enhancement of the geniculate ganglion and 
facial nerve and, in some cases, entrapment of the swollen nerve in the 
temporal bone. Approximately 80% of patients recover within a few 
weeks or months. Electromyography may be of some prognostic value; 
evidence of denervation after 10 days indicates there has been axonal 
degeneration, that there will be a long delay (3 months as a rule) before 
regeneration occurs, and that it may be incomplete. The presence of 
incomplete paralysis in the first week is the most favorable prognostic 
sign. Recurrences are reported in ~7% of cases.
Pathophysiology 
In acute Bell’s palsy, there is inflammation of 
the facial nerve with mononuclear cells, consistent with an infectious 
or immune cause. Herpes simplex virus (HSV) type 1 DNA was fre­
quently detected in endoneurial fluid and posterior auricular muscle, 
suggesting that a reactivation of this virus in the geniculate ganglion 
may be responsible for most cases. Reactivation of varicella-zoster 
virus is associated with Bell’s palsy in up to one-third of cases and may 
represent the second most frequent cause. A variety of other viruses 
including SARS-CoV-2 have also been implicated less commonly, and 
Bell’s palsy can be observed in the setting of human immunodeficiency 
virus (HIV) seroconversion.
Differential Diagnosis 
There are many other causes of acute facial 
palsy that must be considered in the differential diagnosis of Bell’s 
palsy. Lyme disease can cause unilateral or bilateral facial palsies; in 
endemic areas, ≥10% of cases of facial palsy are likely due to infection 
with Borrelia burgdorferi (Chap. 191). Ramsay Hunt syndrome, caused 
by reactivation of herpes zoster in the geniculate ganglion, consists of 
a severe facial palsy associated with a vesicular eruption in the external 
auditory canal and sometimes in the pharynx and other parts of the

A
B
FIGURE 452-4  Axial and coronal T1-weighted images after gadolinium with fat suppression demonstrate diffuse smooth linear enhancement of the left facial nerve, 
involving the genu, tympanic, and mastoid segments within the temporal bone (arrows), without evidence of mass lesion. Although highly suggestive of Bell’s palsy, similar 
findings may be seen with other etiologies such as Lyme disease, sarcoidosis, and perineural malignant spread.
cranial integument; often the eighth cranial nerve is affected as well. 
Facial palsy that is often bilateral occurs in sarcoidosis (Chap. 379) and 
in Guillain-Barré syndrome (Chap. 458). Leprosy frequently involves 
the facial nerve, and facial neuropathy may also occur in diabetes mel­
litus, connective tissue diseases including Sjögren’s syndrome, and amy­
loidosis. The rare Melkersson-Rosenthal syndrome consists of recurrent 
facial paralysis; recurrent—and eventually permanent—facial (particu­
larly labial) edema; and, less constantly, plication of the tongue. Its cause 
is unknown. Acoustic neuromas frequently involve the facial nerve by 
local compression. Infarcts, demyelinating lesions of MS, and tumors 
are common pontine lesions that interrupt the facial nerve fibers; other 
signs of brainstem involvement are usually present. Tumors that invade 
the temporal bone (carotid body, cholesteatoma, dermoid) may produce 
a facial palsy, but the onset is insidious and the course progressive. Facial 
palsy after temporal bone fracture can present acutely or after a delay 
of several days; blunt head injury without temporal bone fracture may 
also trigger facial palsy.
All these forms of nuclear or peripheral facial palsy must be dis­
tinguished from the supranuclear type. In the latter, the frontalis and 
orbicularis oculi muscles of the forehead are involved less than those 
of the lower part of the face, since the upper facial muscles are inner­
vated by corticobulbar pathways from both motor cortices, whereas the 
lower facial muscles are innervated only by the opposite hemisphere. 
In supranuclear lesions, there may be a dissociation of emotional and 
voluntary facial movements, and often some degree of paralysis of the 
arm and leg or an aphasia (in dominant-hemisphere lesions) is present.
Laboratory Evaluation 
The diagnosis of Bell’s palsy can usually 
be made clinically in patients with (1) a typical presentation, (2) no risk 
factors or preexisting symptoms for other causes of facial paralysis, (3) 
absence of cutaneous lesions of herpes zoster in the external ear canal, 
and (4) a normal neurologic examination apart from the facial nerve. 
Particular attention to the eighth cranial nerve, which courses near to the 
facial nerve in the pontomedullary junction and in the temporal bone, 
and to other cranial nerves is essential. In atypical or uncertain cases, an 
ESR or CRP, testing for diabetes mellitus, a Lyme titer, HIV serologies, 
angiotensin-converting enzyme and chest imaging studies for possible 
sarcoidosis, a lumbar puncture for possible Guillain-Barré syndrome, 
or MRI scanning may be indicated. MRI often shows swelling and 
enhancement of the facial nerve in idiopathic Bell’s palsy (Fig. 452-4).
TREATMENT
Bell’s Palsy
Symptomatic measures include (1) the use of paper tape to depress 
the upper eyelid during sleep and prevent corneal drying, (2) arti­
ficial tears, and (3) massage of the weakened muscles. A course of 
glucocorticoids, given as prednisone 60–80 mg daily during the first 

CHAPTER 452
5 days and then tapered over the next 5 days, modestly shortens 
recovery and improves the functional outcome. Although large 
and well-controlled randomized trials found no added benefit of 
the antiviral agents valacyclovir (1000 mg daily for 5–7 days) or 
acyclovir (400 mg five times daily for 10 days) compared to gluco­
corticoids alone, either of these agents should be used if vesicular 
lesions are observed in the palate or external auditor canal. For 
patients with permanent paralysis from Bell’s palsy, a number of 
cosmetic surgical procedures have been used to restore a relatively 
symmetric appearance to the face.
Trigeminal Neuralgia, Bell’s Palsy, and Other Cranial Nerve Disorders  
■
■OTHER MOTOR DISORDERS OF THE FACE
Hemifacial spasm consists of painless irregular involuntary contrac­
tions on one side of the face. Most cases appear related to vascular 
compression of the exiting facial nerve in the pons. Other cases develop 
as a sequela to Bell’s palsy or are secondary to compression and/or 
demyelination of the nerve by tumor, infection, or MS. Local injec­
tions of botulinum toxin into affected muscles can relieve spasms for 
3–4 months, and the injections can be repeated. Refractory cases due 
to vascular compression usually respond to surgical decompression of 
the facial nerve. Anecdotal reports describe success using carbamaze­
pine, gabapentin, or baclofen. Blepharospasm is an involuntary recur­
rent spasm of both eyelids that usually occurs in elderly persons as an 
isolated phenomenon or with varying degrees of spasm of other facial 
muscles. Severe, persistent cases of blepharospasm can be treated by 
local injection of botulinum toxin into the orbicularis oculi. Clonaz­
epam, baclofen, and trihexyphenidyl have also been used to treat this 
disorder. Facial myokymia refers to a fine rippling activity of the facial 
muscles; it may be caused by MS or follow Guillain-Barré syndrome 
(Chap. 458).
OTHER CRANIAL NERVE DISORDERS
■
■GLOSSOPHARYNGEAL NEURALGIA
The ninth cranial (glossopharyngeal) nerve (Fig. 452-5) conveys 
somatic sensation from the pharynx, middle ear, tympanic membrane, 
eustachian tube, and posterior third of the tongue to the spinal trigemi­
nal nucleus. It also relays taste from the posterior third of the tongue 
and information about blood pressure from baroreceptors in the 
carotid sinus to the nucleus solitarius, which also serves as the sensory 
nucleus for the vagus nerve. Motor function originates in the nucleus 
ambiguus and is limited to the stylopharyngeus muscle. Parasympa­
thetic fibers from the medullary inferior salivatory nucleus synapse in 
the otic ganglion with postganglionic fibers that innervate the parotid 
gland. Glossopharyngeal neuralgia resembles trigeminal neuralgia in 
many respects but is much less common. Sometimes it involves por­
tions of the tenth (vagus) nerve. The pain is intense and paroxysmal; it 
originates on one side of the throat, approximately in the tonsillar fossa.

Inferior salivatory nucleus
(parasympathetic)
Petrous
portion of
temporal
bone
Ambiguus nucleus
(motor)
Nucleus of solitary
tract (sensory)
Superior or jugular ganglion
Jugular
foramen
VII
Petrous ganglion
PART 13
Neurologic Disorders
Communication
with auricular
branch of X
Nodose ganglion
X 
Superior cervical
sympathetic ganglion
Carotid body
Sinus
nerve
Carotid sinus and
nerve plexus
Common carotid artery
Sensory branches to
soft palate, fauces,
and tonsils
Sympathetic root
(vasomotor)
IX (Sensory)
Vagal root
(motor and
sensory)
Pharyngeal
plexus
To muscles and mucous
membrane of the pharynx
and soft palate
Taste and sensation to
posterior third of tongue
FIGURE 452-5  The ninth cranial (glossopharyngeal) nerve. FO, foramen ovale; FR, foramen rotundum; TP, tympanum plexus. (Reproduced with permission from SG Waxman: 
Clinical Neuroanatomy, 29th ed. New York, McGraw Hill, 2020.)
In some cases, the pain is localized in the ear or may radiate from the 
throat to the ear because of involvement of the tympanic branch of the 
glossopharyngeal nerve. Spasms of pain may be initiated by swallowing 
or coughing. There is no demonstrable motor or sensory deficit. Cardiac 
symptoms—bradycardia or asystole, hypotension, and fainting—

have been reported. Glossopharyngeal neuralgia can result from vascu­
lar compression, MS, or tumors, but many cases are idiopathic. Medical 
therapy is similar to that for trigeminal neuralgia, and carbamazepine 
is generally the first choice. If drug therapy is unsuccessful, surgical 
procedures—including microvascular decompression if vascular com­
pression is evident—or rhizotomy of glossopharyngeal and vagal fibers 
in the jugular bulb is frequently successful.
■
■DYSPHAGIA AND DYSPHONIA
The tenth cranial (vagus) nerve (Fig. 452-6) carries somatic sen­
sation from the posterior aspect of the external auditory canal, 

Geniculotympanic
nerve
Pterygopalatine
ganglion
Great petrosal
nerve
Nerve of the
pterygoid canal
Facial
nerve
Otic
ganglion
Parotid
gland
FO
Small petrosal
nerve
FR
TP
Auditory tube
(eustachian)
Deep petrosal nerve
(sympathetic)
Tympanic nerve
(of jacobson) to
tympanic plexus
Internal carotid artery
Tympanic nerve
(of jacobson) to
tympanic plexus
Parasympathetic
nerves
Styloglossus
muscle
Sensory nerves
Communication
with facial nerve
Motor nerves
Sympathetic
nerves
Stylopharyngeal
muscle
Tonsils
laryngopharynx, superior larynx, and meninges of the posterior fossa 
to the spinal trigeminal nucleus, as well as taste from the epiglottis and 
pharynx and visceral sensation from chemoreceptors and barorecep­
tors in the aortic arch, heart, and gastrointestinal tract to the splenic 
flexure to the nucleus solitarius. The motor part originates in the 
nucleus ambiguous and innervates most muscles of the oropharynx 
and soft palate as well as all laryngeal muscles. Parasympathetic fibers 
originate in the dorsal motor nucleus of the vagus nerve and decrease 
the heart rate through action at the sinoatrial and atrioventricular 
nodes; others promote peristalsis and secretion of the alimentary tract 
from the esophagus to the splenic flexure. When the intracranial por­
tion of one vagus (tenth cranial) nerve is interrupted, the soft palate 
droops ipsilaterally and does not rise in phonation. There is loss of the 
gag reflex on the affected side, as well as of the “curtain movement” of 
the lateral wall of the pharynx, whereby the faucial pillars move medi­
ally as the palate rises in saying “ah.” The voice is hoarse and slightly

Nucleus of solitary tract
Nucleus of spinal
tract of V
Dorsal motor nucleus
of vagus
Ambiguus nucleus
XI
C1
Spinal roots of
accessory nerve
Superior
laryngeal
nerve
Sternocleidomastoid muscle
C5
Trapezius muscle
Arytenoid, thyroarytenoid,
and cricoarytenoid muscles
Esophagus
Glottis
Right subclavian artery
Cardiac nerves
Cardiac plexus
Pulmonary plexus
Esophageal plexus
Celiac plexus
Liver
Gallbladder
Right kidney
Small intestine
FIGURE 452-6  The vagus nerve. J, jugular (superior) ganglion; N, nodose (inferior) ganglion. (Reproduced with permission from SG Waxman: Clinical Neuroanatomy, 
29th ed. New York, McGraw Hill, 2020.)
nasal, and the vocal cord lies immobile midway between abduction and 
adduction. Loss of sensation at the external auditory meatus and the 
posterior pinna may also be present.
The vagus nerve may be involved at the meningeal level by neo­
plastic and infectious processes and within the medulla by tumors, 
vascular lesions (e.g., the lateral medullary syndrome), and motor 
neuron disease. The nerve may be involved by infection with varicellazoster virus. Injury to the vagus nerve in the carotid sheath can occur 
with carotid dissection or following endarterectomy. The pharyngeal 
branches of both vagal nerves may be affected in diphtheria; the voice 
has a nasal quality, and regurgitation of liquids through the nose occurs 
during swallowing. Polymyositis and dermatomyositis, which cause 
hoarseness and dysphagia by direct involvement of laryngeal and pha­
ryngeal muscles, may be confused with diseases of the vagus nerves. 
Dysphagia is also a symptom in some patients with myotonic dystro­
phy. Nonneurologic causes of dysphagia are discussed in Chap. 47.

Meningeal branch to
posterior fossa
Auricular branch to
posterior auricle
and part of
external meatus
VII
IX
X
J
Muscles to
palate and
pharynx
N
Sensation to
lower pharynx 
CHAPTER 452
Epiglottic and
lingual rami
Inferior pharyngeal
constrictor
Trigeminal Neuralgia, Bell’s Palsy, and Other Cranial Nerve Disorders  
Cricothyroid muscle
Right recurrent
laryngeal nerve
Left recurrent
laryngeal nerve
Left vagus nerve
Aortic arch
Diaphragm
Stomach
Spleen
Pancreas
Left kidney
Sensory nerves
Parasympathetic nerves
Motor nerves
The recurrent laryngeal nerves, especially the left, are most often 
damaged as a result of intrathoracic disease. Aneurysm of the aortic 
arch, an enlarged left atrium, and tumors of the mediastinum and 
bronchi are much more frequent causes of an isolated vocal cord palsy 
than are intracranial disorders. However, a substantial number of cases 
of recurrent laryngeal palsy remain idiopathic.
When confronted with a case of laryngeal palsy, the physician must 
attempt to determine the site of the lesion. If it is intramedullary, there 
are usually other signs, such as ipsilateral cerebellar dysfunction, loss 
of pain and temperature sensation over the ipsilateral face and contra­
lateral arm and leg, and an ipsilateral Horner’s syndrome. If the lesion 
is extramedullary, the glossopharyngeal and spinal accessory nerves are 
frequently involved (jugular foramen syndrome). If it is extracranial 
in the posterior laterocondylar or retroparotid space, there may be a 
combination of ninth, tenth, eleventh, and twelfth cranial nerve palsies 
and Horner’s syndrome (Table 452-2). If there is no sensory loss over

TABLE 452-2  Cranial Nerve Syndromes
SITE
CRANIAL NERVES
USUAL CAUSE
Orbital apex
II, III, IV, first division 
V, VI
Invasive fungal infections, 
amyloidosis, granulomatous 
disease
Sphenoid fissure 
(superior orbital)
III, IV, first division V, VI Invasive tumors of sphenoid bone; 
aneurysms
Lateral wall of 
cavernous sinus
III, IV, first division V, 
VI, often with proptosis
Infection, thrombosis, aneurysm 
or fistula of cavernous sinus; 
invasive tumors from sinuses and 
sella turcica; benign granuloma 
responsive to glucocorticoids
Retrosphenoid 
space
II, III, IV, V, VI
Large tumors of middle cranial 
fossa
Apex of petrous 
bone
V, VI
Petrositis; tumors of petrous bone
Internal auditory 
meatus
VII, VIII
Tumors of petrous bone (dermoids, 
etc.); infectious processes; 
acoustic neuroma
PART 13
Neurologic Disorders
Pontocerebellar 
angle
V, VI, VII, VIII, and 
sometimes IX
Acoustic neuroma; meningioma
Jugular foramen
IX, X, XI
Tumors and aneurysms
Posterior 
laterocondylar 
space
IX, X, XI, XII
Tumors of parotid gland and 
carotid body and metastatic 
tumors
Posterior 
retroparotid space
IX, X, XI, XII, and 
Horner’s syndrome
Tumors of parotid gland, carotid 
body, lymph nodes; metastatic 
tumor; tuberculous adenitis
the palate and pharynx and no palatal weakness or dysphagia, the 
lesion is below the origin of the pharyngeal branches, which leave the 
vagus nerve high in the cervical region; the usual site of disease is then 
the mediastinum.
■
■NECK WEAKNESS
The eleventh cranial nerve (spinal accessory) is a pure motor nerve 
arising from the nucleus ambiguus and the ventral horn of the spinal 
cord from C1–C6. The nerve travels superiorly through the fora­
men magnum and exits through the jugular foramen to innervate 
the ipsilateral sternocleidomastoid and trapezius muscles. Isolated 
involvement of the accessory (eleventh cranial) nerve can occur any­
where along its route, resulting in partial or complete paralysis of the 
sternocleidomastoid and trapezius muscles. Spinal accessory nerve 
palsy does not result in significant neck weakness because several other 
muscles also turn the head and flex the neck; therefore, detection of 
accessory nerve injury relies on palpating the absence of sternoclei­
domastoid contraction during head turning. Similarly, shoulder shrug 
is only slightly impacted by trapezius weakness, although the affected 
shoulder is lower at rest, scapular winging occurs, and the arm cannot 
abduct beyond 90°. Isolated spinal accessory nerve palsy is often iat­
rogenic due to neck surgery or jugular vein cannulation, or traumatic. 
An idiopathic form of accessory neuropathy, akin to Bell’s palsy, has 
been described, and it may be recurrent in some cases. Most but not 
all patients recover.
■
■TONGUE PARALYSIS
The twelfth cranial nerve (hypoglossal) supplies the ipsilateral muscles 
of the tongue. Nerve lesions cause the tongue to deviate toward the 
ipsilateral side during protrusion due to ipsilateral genioglossus weak­
ness, in addition to weakness of tongue movements toward the affected 
side to weakness of ipsilateral intrinsic tongue musculature. Atrophy 
and fasciculations of the tongue develop weeks to months after inter­
ruption of the nerve. The nucleus of the nerve or its fibers of exit may 
be involved by intramedullary lesions such as tumor, poliomyelitis, or 
most often motor neuron disease. Lesions of the basal meninges and 
the occipital bones (platybasia, invagination of occipital condyles, 
Paget’s disease) may compress the nerve in its extramedullary course 
or as it exits the skull in the hypoglossal canal. Isolated lesions of 
unknown cause can occur.

MULTIPLE CRANIAL NERVE PALSIES
When multiple cranial nerves are affected by a disease process, the 
clinical approach begins by determining whether the pathology lies 
within or outside of the brainstem. Lesions that lie on the surface of the 
brainstem are characterized by involvement of adjacent cranial nerves 
(often occurring in succession) and late and rather slight involvement 
of the long sensory and motor pathways and segmental structures lying 
within the brainstem. The opposite is true of primary lesions within 
the brainstem. Extramedullary lesions are more likely to cause bone 
erosion or enlargement of the foramens of exit of cranial nerves. By 
contrast, intramedullary lesions involving cranial nerves often produce 
a crossed sensory or motor paralysis (cranial nerve signs on one side of 
the body and tract signs on the opposite side).
Involvement of multiple cranial nerves outside the brainstem is 
frequently the result of trauma, localized infections including varicellazoster virus, infectious and noninfectious (especially carcinomatous) 
causes of meningitis (Chaps. 143 and 144), granulomatous diseases 
such as granulomatosis with polyangiitis (Chap. 375), Behçet’s dis­
ease (Chap. 376), vascular disorders including those associated with 
diabetes, enlarging aneurysms, or locally infiltrating tumors. Among 
the tumors, nasopharyngeal cancers, lymphomas, neurofibromas, 
meningiomas, chordomas, cholesteatomas, carcinomas, and sarcomas 
have all been observed to involve a succession of lower cranial nerves. 
Owing to their anatomic relationships, the multiple cranial nerve 
palsies form a number of distinctive syndromes, listed in Table 452-2. 
Sarcoidosis (Chap. 379) is the cause of some cases of multiple cranial 
neuropathy; tuberculosis, the Chiari malformation, platybasia, and 
basilar invagination of the skull are additional causes.
Cavernous sinus syndrome (Fig. 452-7) is a distinctive and fre­
quently life-threatening disorder. It often presents as orbital or facial 
pain; orbital swelling, chemosis due to occlusion of the ophthalmic 
veins; fever; oculomotor neuropathy affecting the third, fourth, and 
sixth cranial nerves; and trigeminal neuropathy affecting the ophthal­
mic (V1) and occasionally the maxillary (V2) divisions of the trigemi­
nal nerve. Cavernous sinus thrombosis, often secondary to infection 
from orbital cellulitis (frequently Staphylococcus aureus), a cutaneous 
source on the face, or sinusitis (especially with mucormycosis in 
diabetic patients), is the most frequent cause; other etiologies include 
aneurysm of the carotid artery, a carotid-cavernous fistula (orbital 
bruit may be present), meningioma, nasopharyngeal carcinoma, other 
tumors, or an idiopathic granulomatous disorder (Tolosa-Hunt syn­
drome, discussed below). The two cavernous sinuses directly commu­
nicate via intercavernous channels; thus, involvement on one side may 
extend to become bilateral. Early diagnosis is essential, especially when 
due to infection, and treatment depends on the underlying etiology.
Ant. cerebral a.
Int. carotid a.
Ant. clinoid process
Subarachnoid
space
Optic chiasm
Oculomotor (III) n.
Trochlear (IV) n.
Hypophysis
Ophthalmic (V1) n.
Maxillary (V2) n.
Sphenoid
  sinus
Pia
Arachnoid
Dura
Abducens (VI) n.
FIGURE 452-7  Anatomy of the cavernous sinus in coronal section, illustrating the 
location of the cranial nerves in relation to the vascular sinus, internal carotid artery 
(which loops anteriorly to the section), and surrounding structures.