Ocular nerve palsy - 3rd, 4th and 6th cranial nerve palsy

THIRD, FOURTH AND SIXTH
CRANIAL NERVE PALSY.
Presenter: Dr Manasaveena N T
Ophthalmology Resident

Introduction:
• The ocular motor system
consists of 3rd, 4th and 6th
cranial nerve and their
innervations.
• Ocular motor disturbances
can be due to - congenital
and acquired lesions of the
nuclear and infranuclear
neural structures.

Ocular motor nerve palsies may present in one of four ways:
1. As isolated partial or complete nerve palsy without any other
neurologic signs and symptoms except those related to the palsy
itself.
2. In association with other symptoms (e.g., pain, dysesthesia,
paresthesias) but without any signs of neurologic or systemic
disease.
3. In association with other ocular motor nerve palsies (e.g., the
simultaneous onset of an oculomotor palsy and an abducens palsy)
but without any other neurologic signs.
4. In association with neurologic signs other than the ocular motor
nerve palsy.

Oculomotor (Third) Nerve Palsies
• Supply the extraocular muscles- Medial rectus, Superior rectus,
inferior rectus, inferior oblique, Levator palperbrae superioris and
parasympathetic innervation to the sphincter papillae and ciliary
muscles.
• Congenital or acquired.
• Partial or complete.

1. Congenital:
• 50% of all causes.
• Most cases are unilateral.
Clinical presentation:
i. Have no other neurologic or systemic abnormalities.
ii. Amblyopia.
iii. Ptosis, ophthalmoparesis, and pupillary involvement.
• In most of these cases, the pupil is miotic rather than dilated (aberrant
oculomotor nerve).

Etiology:
i. Absent or incomplete development of the nucleus, nerve, or both.
ii. Injury during gestation or at the time of delivery.
iii. Maldevelopment of oculomotor nerve due to Congenital
syndromes
• These syndromes include:
a. Congenital adduction palsy with synergistic divergence,
b. Atypical vertical retraction syndrome, and
c. Cyclic oculomotor nerve paresis with cyclic spasm.

I. Congenital Adduction Palsy with Synergistic
Divergence:
• Unilateral paralysis of adduction, associated with simultaneous bilateral
abduction on attempted gaze into the field of action of the paretic medial
rectus muscle.
• Most cases have no other neurologic abnormalities.

• Electromyographic study:
- Absent oculomotor nerve innervation of
the affected medial rectus muscle, with
- Absent or minimal innervation of the
lateral rectus muscle by the abducens
nerve but with a branch of the
oculomotor nerve innervating the lateral
rectus muscle.

II. Vertical Retraction Syndrome
• Is usually unilateral.
Clinical feature:
• Limitation of movement of the affected eye on elevation or depression,
associated with a retraction of the globe and narrowing of the palpebral
fissure.
• There may be an associated esotropia or exotropia on attempted vertical
gaze, more marked in the direction of the restricted vertical field of action.
Electro-oculography and electromyography:
• Anomalous oculomotor innervation of the vertical rectus muscles of the
affected eye.

III. Oculomotor Paresis with Cyclic Spasms (COPS):
• Is usually unilateral and present from birth.
Clinical features:
i. Ptosis,
ii. Mydriasis,
iii. Reduced accommodation, and
iv. Ophthalmoparesis.
⮚ About every 2 minutes, the ptotic eyelid elevates, the globe begins to
adduct, the pupil constricts, and accommodation increases.
⮚ These spasms last 10 to 30 seconds and then give way to the paretic
phase.

⮚ Reduced visual acuity in the affected eye because of amblyopia.
⮚ Continues throughout life.
⮚ May associated with birth trauma, posterior fossa tumor and
congenital infections.
Treatment: Carbamazepine.

2. Acquired Oculomotor Nerve Palsies:
Components of 3rd CN:
• Nuclear complex
• Fasciculus
• Basilar
• Intracavernous
• Intraorbital
• Pupillomotor fibres.

Nuclear complex lesions:
Causes:
• Ischemia (embolic or thrombotic occlusion of small, dorsal perforating
branches of the mesencephalic portion of the basilar artery)
• Hemorrhage,
• Inflammation,
• Brain stem compression.
• Vascular diseases,
• Demyelination
• Primary tumors
• Metastasis

Nuclear complex lesions: Is composed 4 paired and 1 unpaired subnuclei:
SUBNUCLEUS TYPE SITE in Midbrain INNERVATION LESION
⮚ Levator Unpaired Caudal midline Both levator
muscles
Bilateral ptosis.
⮚ Superior
rectus
Paired Medial nuclei Contralateral
superior rectus
C/L SR.
⮚ Medial rectus Paired Ventral nuclei Ipsilateral MR
muscles
Involvement of the paired
MR subnuclei - WEBINO.
⮚ Inferior rectus Paired Dorsal nuclei Ipsilateral IR
muscles lesions confined to the
nuclear complex are
relatively uncommon
⮚ Inferior oblique
subnuclei
Paired Intermediate
nuclei
Ipsilateral IO
muscles
❖ Lesions involving the entire nucleus are often associated with involvement of the adjacent and caudal
fourth nerve nucleus – I/L sparing and C/L weakness of elevation.

Partial CN III palsy.
A, Examination revealed complete ptosis on the right; a nonreactive, dilated
pupil; and severely limited extraocular movement except for abduction.
B, Lateral view of a cerebral angiogram demonstrated a posterior communicating
artery aneurysm.

Lesions of the Oculomotor Nerve Fascicle:
Fasciculus-
- consists of efferent fibers which pass from the third
nerve nucleus
• through the red nucleus and
• the medial aspect of the cerebral peduncle
• emerges from the midbrain and
• passes into the interpeduncular space.
❖Anatomic separation into superior and inferior
divisions begins in the brain stem, thus, can cause
isolated dysfunction.

Midbrain fascicular third cranial nerve palsies
Syndrome Signs/characteristics Location of lesion
Benedikt
Ipsilateral CN III palsy Red nucleus
Contralateral extrapyramidal
signs
Hemitremor/involuntary
movements
Nothnagel
Ipsilateral CN III palsy
Cerebellar ataxia
Fasciculus
Superior cerebellar
peduncle
Claude
Combination of Benedikt
and Nothnagel syndromes
Weber
Ipsilateral CN III palsy
Contralateral hemiparesis
Cerebral peduncle

CT in a patient with Weber syndrome showing an
enhancing lesion in the ventral mesencephalon.

Basilar part of CN III:
• Starts as a series of ‘rootlets’
• Leaves the midbrain on the medial aspect of the cerebral peduncle, before
coalescing to form the main trunk
• Then passes between the posterior cerebral and superior cerebellar arteries
• Runs lateral to and parallel with the posterior communicating artery
• Is unaccompanied by other cranial nerves.
• Isolated CN III is commonly basilar

Causes of basilar CN III palsy:
1. Aneurysm:
• Presents as acute, painful third nerve
palsy with pupil involvement.
1. Head trauma:
• Presentation: Initially miosis due to
irritative of the nerve, followed by
mydriasis and total CN III palsy.

Intracavernous part of CN III
• Enters the cavernous sinus by piercing the dura
lateral to the posterior clinoid process.
• Important causes of intracavernous CN III palsy
a. Diabetes – causes a vascular palsy usually
sparing the pupil.
b. Pituitary apoplexy (haemorrhagic infarction).
c. Intracavernous pathology such as aneurysm,
meningioma, carotid-cavernous fistula,
granulomatous inflammation (Tolosa-Hunt
syndrome).

Lesions of the 3rd Nerve in the Subarachnoid Space:
• Oculomotor nerve dysfunction that is produced by damage to its
subarachnoid portion may occur as-
(1) Isolated pupillary dilation with a reduced or absent light reaction,
(2) Ophthalmoplegia with pupillary involvement, or
(3) Ophthalmoplegia with normal pupillary size and reactivity.

A. Isolated pupillary dilation with a reduced or
absent light reaction
• The pupillomotor fibers from EWN are draped
over the superomedial aspect of each oculomotor
nerve.
• Causes: Intracranial aneurysms:
i. At the junction of the ICA and the post.
communication artery.
ii. Basilar artery aneurysms or basal meningitis.

B. Subarachnoid Oculomotor Nerve Palsy with
Pupillary Involvement:
• Presentation: sudden severe pain in or around the eye.
• Causes:
1. Intracranial aneurysms
⮚ Direct compression,
⮚ Small hemorrhage, or a major rupture.
⮚ Trauma to the oculomotor nerve may occur during aneurysm
surgery.
2. Carotid-cavernous sinus fistula - posteriorly draining, low-flow.

Complete right oculomotor nerve palsy with involvement of the pupil.

Internal carotid arteriogram
showing large aneurysm at the
junction of the left internal
carotid and left posterior
communicating arteries
3D MRA reconstruction of the
aneurysm.

3. Tumors and other compressive
lesions - ectatic posterior
cerebral or basilar artery.
3. Intrinsic lesions of the
oculomotor nerve -
schwannomas or cavernous
angiomas.
⮚Approximately 5% of compressive
oculomotor palsies are pupil
sparing.

C. Subarachnoid Oculomotor Nerve Palsy with
Pupillary Sparing
• Causes:
1. Ischemia
- Diabetes mellitus, systemic hypertension, atherosclerosis, and migraine
- Location of the lesion - oculomotor nerve fascicle or in the subarachnoid.
• Presents with severe pain.
• Resolve within 4 to 16 weeks without treatment and is complete with no
aberrant regeneration.
2. Subarachnoid compressive lesions - aneurysms, ipsilateral temporal lobe
astrocytomas, and ipsilateral acute subdural hematomas.

Patient with cavernous sinus syndrome from basal
meningioma. The patient has right proptosis
associated with a complete right oculomotor nerve
palsy, a right abducens nerve paresis, and a right
Horner syndrome. The right pupil is slightly smaller
than the left pupil.
T1-gadolinium– enhanced MRI, coronal
view, demonstrates the cranial nerves as
they travel within the cavernous sinus. Red
arrow, oculomotor nerve; green, trochlear
nerve; yellow, ophthalmic division of the
trigeminal; purple, maxillary division of the
trigeminal; and blue, abducens nerve.

• Evaluation of Oculomotor Palsies/Risk of Compressive Lesion:

Intra-orbital part of CN III:
• Divides into : superior division and inferior division.
• Lesions to the inferior division are characterized by
⮚limited abduction
⮚limited infraduction
⮚dilated pupil.
• Superior and inferior palsies are commonly traumatic or vascular.

• Sphenocavernous syndrome is
characterized by a painful
ophthalmoplegia and is
generally not associated with
visual loss.
• Orbital apex syndrome –
characterized by
ophthalmoplegia that may or
may not be painful but
associated with loss of vision
from optic neuropathy and
variable proptosis.

Recovery from Acquired Oculomotor Nerve Palsy
1. Complete recovery may occur -
- In some cases, recovery may be complete within 1 to 2 weeks after the onset
of symptoms.
- In cases associated with DM and systemic HTN, recovery begins after a
month or more and completes within 3 months.
- In cases of damage to the fascicular portion recovery can take much longer,
sometimes as long as 3 years.
2. No recovery-
- Transected by trauma or
- chronic compression or
- infiltrated by tumor.

Acquired Oculomotor Synkinesis: Misdirection of
Regenerating Fibers in the Oculomotor Nerve
• Peripheral motor and sensory nerves, including the autonomic nerves, can
regenerate.
• The regenerative process produces more axons than were present before
the nerve was interrupted.
• Cords of Schwann cells form in the peripheral segment of the nerve so that
the new nerve fibers are conducted to the end organ.
• In peripheral nerves that innervate more than one muscle, misdirection of
regenerating nerve fibers occur.
• Thus, regenerating sprouts from axons that previously innervated one
muscle group may ultimately innervate a different muscle group with a
different function.

• The signs of aberrant regeneration of the oculomotor nerve may be
summarized as follows:
1. Muscle to Muscle: Adduction of the involved eye on attempted elevation
or depression (SR or IR to MR). Conversely, elevation of the eye on
attempted adduction (MR to SR or IO)
2. Muscle to Eyelid: Pseudo-Graefe sign—retraction and elevation of the
eyelid on attempted downward gaze. Elevation of the eyelid on attempted
adduction can also occur.
3. Muscle to Pupil: Pseudo-Argyll Robertson pupil—the involved pupil does
not react or reacts poorly and irregularly to light stimulation but does constrict
on adduction during conjugate gaze.
4. Limitation of elevation and depression of the eye with retraction of the
globe on attempted vertical movement

Aberrant regeneration of the right CN III.
A, In primary gaze, there is right sided mild ptosis, pupillary mydriasis,
and exotropia,
B, With attempted downward gaze, the right eyelid retracts as fibers of
the right CN III supplying the inferior rectus now also innervate the
levator muscle.

Investigation of the third cranial nerve
palsies:
Under 10 years 11 - 50 years >50 years
Anisocoria less than 2
mm
MRI, MRA
MRI, MRA. If negative,
perform medical work-
up
Observe without
imaging*
Anisocoria greater than
2 mm
MRI, MRA‡
catheter angiography
catheter angiography
*Determine the status of the blood pressure, glucose metabolism, and the presence of other medical
risk factors.
‡ Catheter angiography may be justified if these tests are negative.

Treatment of CN III lesions:
1. Non-surgical
• Indicated during the acute phase,
• When definitive surgical management is contraindicated (e.g. by neurological
disease or central fusion disruption).
Treatment:
• Fresnel prisms if angle of deviation is small.
• Uniocular occlusion to avoid diplopia (if ptosis is partial)
• Botulinum toxin injection of the uninvolved lateral rectus preventing contraction.
2. Surgical
• Considered only after all spontaneous improvement has ceased and only after 6
months from the date of onset.

Fourth nerve (trochlear nerve):
• Only cranial nerve to emerge from
the dorsal aspect of the brain.
• Innervates the contralateral
superior oblique muscles.
• Very long and slender nerve.
• It has the fewest axons of any of
the cranial nerves.
• Peripheral lesions cause
ipsilateral and nuclear lesions
contralateral superior oblique
weakness.

Causes of isolated fourth nerve palsy
• Idiopathic lesions:
- Congenital: symptoms develops once decompensation occurs in
adult life due to reduced fusional ability.
- Acquired lesions: patients are not usually aware of the torsional
aspect, but may develop vertical double vision that is often
appreciated as of sudden or subacute onset.
• Trauma
- Frequently causes bilateral.
• Microvascular - systemic risk factors.
• Aneurysms and tumors are rare.

Symptoms and signs of CN IV palsy:
• The acute onset of vertical diplopia in the absence of ptosis,
• combined with a characteristic head posture.
Signs of CN IV palsy:
Right paresis is characterized by:
⮚Right hypertropia in the primary position, increasing on right gaze.
⮚Limitation of right depression, most marked in adduction.
⮚Right extorsion, greatest in abduction.
⮚Normal abduction of the right eye.
⮚Normal elevation of the right eye

⮚A compensatory head posture: avoids diplopia:
- To compensate for weakness of intorsion there is contralateral head tilt
to the left.
- To alleviate the weakened depression of the eye the chin is slightly
depressed.
- As weakened depression in adduction, the face turned slightly to the
left.

⮚Bilateral involvement should always be excluded,
following head trauma.
- Right hypertropia in left gaze and left hypertropia in
right gaze, orthophoria may be present.
- Greater than 10° of cyclodeviation.
- ‘V’ pattern esotropia is often present.
- Bilaterally positive Bielschowsky head tilt test.

Special tests:
1. Parks-Bielschowsky 3-step test is useful in the diagnosis.
Step 1
• Assess which eye is hypertropic in primary position when the patient is looking in the
distance.
• Right hypertropia - caused by weakness of the following 4 muscles
⮚ One of the depressors of the right eye: superior oblique and inferior rectus
⮚ One of the elevators of the left eye: superior rectus or inferior oblique.
• In a CN IV palsy, the involved eye is higher.

Step 2
• Determine whether the right hypertropia is greater in right gaze or left gaze.
• Right hypertropia is increases in left gaze
⮚one of the muscles whose primary action is elevating the left eye on
left gaze, or
⮚one of the muscles whose primary action is depressing the right eye
in left gaze
• In CN IV palsy the deviation is worse on opposite gaze (WOOG).

• Because the right inferior oblique and the left inferior rectus did
not meet Step 1, they can be eliminated from the list of possible
paretic muscles.
• This leaves the right superior oblique and the left superior rectus
as the two cyclovertical muscles left which meet criteria for both
steps 1 and 2.

Step 3:
• The Bielschowsky head tilt test is performed with a patient fixating straight ahead.
• The head is tilted to the right and then to the left.
• Increase of the right hypertropia on right head tilt implicates the right superior
oblique.
• Increase of left hypertropia on right head tilt implicates the left inferior rectus.
• In the CN IV palsy a deviation is better on opposite tilt (BOOT).

Double Maddox rod test:
• Red and green Maddox rods, with the cylinders vertical, are placed in front
of either eye.
• Each eye will therefore perceive a horizontal line.
• In the presence of a cyclodeviation the line perceived will be tilted and
therefore distinct from that of the other eye.
• One Maddox rod is then rotated until fusion of the lines is achieved.
• The amount of rotation can be measured in degrees, indication of the extent
of the cyclodeviation.
• Unilateral CN IV palsy is characterised by less than 10 degrees.
• Bilateral cases may have greater than 20 degrees of cyclodeviation

Investigation:
• Vascular investigation.
• Neuroimaging is not required routinely for an isolated non-progressive
fourth nerve palsy.

Treatment :
• Congenital decompensated and presumed microvascular palsies - resolve
spontaneously.
• The surgical approach depends on the pattern and severity of weakness.
• A small hypertropia under 15 PD - treated either by
- IO weakening or
- SO tucking.
• A moderate–large deviation treated by
- Ipsilateral IO weakening combined with, or followed by,
- Ipsilateral SR weakening and/or
- Contralateral IR weakening if required;
⮚defective elevation is a potential complication.

• Excyclotorsion may need to be addressed, particularly in bilateral
cases.
The Harada–Ito procedure involves split-ting and anterolateral
transposition of the lateral half of the superior oblique tendon.

Sixth nerve (abducent nerve):
• The sixth cranial nerve is entirely motor in function
• Supplies the lateral rectus muscle
• Action: Abduction of the eye.
• Components of CN VI
o nucleus
o fasciculus
o basilar part
o intracavernous and intraorbital.

Congenital:
• Congenital absence of abduction :
- from injury to the abducens nerve shortly before or during birth.
• Congenital paralysis of conjugate horizontal eye movements:
1. Möbius syndrome and
2. Duane retraction syndrome (DRS).

Möbius Syndrome (Congenital Bulbar Paralysis):
• Characteristics:
- Esotropia associated with unilateral or bilateral
limitation of abduction and may able to converge.
- Mask-like facies,
- With the mouth constantly held open.
- The eyelids cannot be completely closed.
- Deafness,
- Webbed fingers or toes, supernumerary digits,
- Atrophy of the muscles of the chest, neck, and
tongue, and
- Absence of the hands, feet, fingers, or toes.
- Mental retardation.

Duane Retraction Syndrome (Stilling–Turk–Duane
Syndrome):
• Limitation or absence of abduction.
• Palpebral fissure narrowing and globe retraction on attempted
adduction.
• In most patients, gaze is directed toward the side of the unaffected
eye, and face is turned toward the affected side to allow binocular
single vision.
• Vision is almost always normal.
• Abducens nuclei and nerves are absent and the lateral rectus muscle
is innervated by branches from the oculomotor nerve.

• Three types of DRS:
Duane I : consists of limited or absent abduction with relatively normal
adduction;
Duane II: consists of limited or absent adduction with relatively normal
abduction;
Duane III: is characterized by limited abduction and adduction.

• 6th nerve Nucleus
- lies at the level of the pons
- ventral to the floor of the fourth ventricle
- closely related to the horizontal gaze centre
- an elevation in the floor of the fourth ventricle (facial colliculus) is
produced by the fasciculus of the seventh nerve as it curves around
the sixth nucleus.
- Ipsilateral lower motor neuron (LMN) facial nerve palsy is also
common.

• Lesions
⮚Ipsilateral weakness of abduction.
⮚Failure of horizontal gaze towards the side of the lesion due to
involvement of the horizontal gaze centre in the PPRF (pontine
paramedian reticular formation).

Fasciculus
• Passes ventrally to leave the brainstem at the pontomedullary junction, just lateral to
the pyramidal prominence. Syndromes related to fasciculus involvement:
1. Foville (inferior medial pontine) syndrome
• Involves the fasciculus as it passes through the PPRF, caused by vascular
disease/tumours involving the dorsal pons
• Characterised by ipsilateral involvement of CN V – CN VIII and central sympathetic
fibres
• CN V – facial analgesia
• CN VI palsy combined with gaze palsy
• CN VIII nuclear/fascicular damage – facial weakness
• CN VIII – deafness
• central Horner syndrome.

2. Millard-Gubler syndrome
• It involves the fasciculus as it passes through the pyramidal tract and
• Caused by vascular diseases, tumours or demyelination.
• Characterised by
• ipsilateral CN VI palsy
• contralateral hemiplegia
• variable number of signs
of a dorsal pontine lesion.

Basilar part of CN VI
• Causes:
1. Acoustic neuroma
- Damages CN VI at the pontomedullary junction
- The first symptom is hearing loss.
- The first sign is diminished corneal sensitivity.
- Always test for hearing and corneal sensation in
all patients with CN VI palsy.

2. Nasopharyngeal tumours – invade the skull and its foramina and
damage the nerve during its basal course.
3. Raised intracranial pressure – caused by posterior fossa
tumours/idiopathic intracranial hypertension causing a downward
displacement of the brainstem stretching CN VI over the petrous lip.
4. Basal skull fracture – causes both uni/bilateral palsies.
5. Gradenigo syndrome – caused by mastoiditis or acute petrositis.
Petrositis is accompanied by facial weakness, pain and hearing
difficulties.

Intracavernous part of CN VI
• Intracavernous CN VI palsy is accompanied by a post-ganglionic
Horner syndrome (Parkinson syndrome).
• CN VI palsy is joined by sympathetic branches from the paracarotid
plexus.

Intraorbital part of CN VI
• Signs of left CN VI palsy:
⮚Left esotropia in the primary position.
⮚Esotropia worse for distance target and less/absent for near fixation.
⮚Mark limitation of left abduction
⮚Normal left adduction.
• Patients also show compensatory face turn into the field of action of the
paralysed muscle to minimise diplopia.
• Causes:
a. Vascular causes are common.

Acute bilateral sixth nerve palsy
Bilateral acute sixth nerve palsy : less common.
The causes are similar, but it is important to exclude
elevated intracranial pressure.

Management of CN VI palsy
1. Non-surgical
• Children:
- In children up to 4 years of age, treatment of acute CN VI palsy is aimed at
preventing amblyopia and preserving binocular fusion.
- Parents should permit a head tilt.
- If head posture disappears with persistence of the esodeviation – high
suspicion of amblyopia.
- Alternate occlusion prevents secondary contracture of muscles and also
amblyopia.

• Adults:
- Intervention is aimed at preventing secondary contracture of medial
rectus.
- Botulinum toxin - Timing is variable, depends on degree of
incapacitation
With total paralysis, botulinum toxin is indicated 2 weeks after onset.
Permanent prism:
- Troublesome,
- Mild residual deviation treated with a prism incorporated into
spectacles as an alternative to surgery.

2. Surgical:
• To be considered once all spontaneous improvement has ceased
• 6-12 months from date of onset.
• Partial palsy (paresis):
- is treated by adjustable medial rectus recession and lateral rectus
resection in the affected eye.
- Aim: for a small exophoria in the primary position to maximize the field
of binocular single vision.

• Complete palsy:
- Is treated by transposition of the superior and
inferior recti to positions above and below the
affected lateral rectus muscle
- Coupled with weakening of the ipsilateral medial
rectus (botulinum toxin – ‘toxin transposition’).
- Three rectus muscles should not be detached
from the globe at the same procedure because
of the risk of anterior segment ischaemia.

Ocular nerve palsy - 3rd, 4th and 6th cranial nerve palsy

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Similar to Ocular nerve palsy - 3rd, 4th and 6th cranial nerve palsy

Similar to Ocular nerve palsy - 3rd, 4th and 6th cranial nerve palsy (20)

Recently uploaded

Recently uploaded (20)

Ocular nerve palsy - 3rd, 4th and 6th cranial nerve palsy