Oculomotor Nerve Palsy

[Section Outline]

Description
Etiology

Author:

Sarah TolfordSelby

Description

There are six muscles that control eye movement innervated by three cranial nerves (CN):
- CN III, or oculomotor nerve, innervates 4 of the 6 eye muscles and also innervates the lid and pupil:
  - Medial rectus:
    - Adduction - moves eye medially toward nose
  - Superior rectus:
    - Elevation - moves eye upward
    - Intorsion - rotates top of eye toward nose
    - Slight adduction
  - Inferior rectus:
    - Depression - moves eye inferiorly
    - Extorsion - rotates top of eye away from nose
    - Slight adduction
  - Inferior oblique:
    - Extorsion - rotates top of eye away from nose
    - Slight elevation and abduction
  - Levator palpebrae superioris:
    - Raises eyelid
  - Iris sphincter pupillae and ciliary muscles
    - Constricts pupil (miosis)
    - Innervated by parasympathetic fibers of CN III
- CN IV innervates the superior oblique:
  - Extorsion - rotates top of eye away from nose
  - Depression and slight abduction (lateral rotation)
- CN VI innervates the lateral rectus:
  - Moves eye laterally (abduction)
Oculomotor nerve palsy results from damage to CN III or a branch thereof resulting in abnormal eye movements, lid ptosis, and /or changes to the pupil:
- Complete oculomotor nerve palsy:
  - Eye “down and out,” ptosis, pupil dilated
  - Most often caused by compressive lesions
    - 95-97% of compressive lesions involve the pupil
    - Parasympathetic fibers sit peripherally in CN III
    - Mydriasis is often first symptom of compression
  - Pupil-sparing complete oculomotor nerve palsy:
    - Almost always ischemic from microvascular disease due to underlying diabetes, hypertension, and /or hyperlipidemia
    - Ischemic injuries often spare the pupil because the outer parasympathetics are not affected
    - Often benign and fully resolves in 3 mo
- Incomplete oculomotor nerve palsy (more common):
  - Partial loss of function of CN III
  - Most often caused by ischemia of vasa vasorum
Pathophysiology of oculomotor nerve palsy:
- Midbrain lesions of the oculomotor nucleus leads to bilateral CN III palsy (ischemia of the basilar artery)
- Lesions leaving CN III nucleus are often associated with other neurologic findings such as hemiplegia or ataxia (Weber syndrome, Benedikt syndrome)
- Lesions in the subarachnoid space cause complete palsy with pupil involvement (compressive aneurysms) or complete palsy with pupil sparing (ischemia due to risk factors)
- Lesions in the cavernous sinus and superior orbital fissure can cause isolated CN III palsy, but often are associated with CN IV, CN VI, and maxillary division of CN V dysfunctions
- Lesions in the orbit are associated with visual loss (CN II), ophthalmoplegia (CN III, IV, VI), and proptosis and caused by trauma, mass, inflammation:
  - Incomplete CN III palsy originates here as the nerve divides into superior and inferior divisions

Etiology

Acquired etiologies:
- Vascular disorders:
  - Diabetes mellitus (DM)
  - Hypertension and heart disease
  - Atherosclerosis
  - Aneurysm (esp posterior communicating artery)
  - Arteriovenous malformation (AVM)
  - Intracranial hemorrhage (nonaneurysmal)
  - Cerebral vascular accident
  - Cavernous sinus thrombosis
- Infectious:
  - Meningitis
  - Syphilis
  - Herpes zoster
- Inflammatory:
  - Sarcoidosis
  - Giant cell arteritis, vasculitis
  - Systemic lupus erythematous
- Neoplastic:
  - Intracranial tumor
  - Pituitary tumor
  - Orbital tumor
  - Leukemia
- Degenerative:
  - Myasthenia gravis
  - Guillain-Barre
- Trauma - head injury, recent or remote
- Migraine headache
- Iatrogenic:
  - Chemotherapy
  - Radiation therapy
- Idiopathic:
  - Idiopathic intracranial hypertension (IIH)
- Congenital etiologies are often unknown but some with familial tendency

Pediatric Considerations
Trauma is the most common cause of acquired oculomotor nerve palsies: Includes birth trauma Can also see in neurofibromatosis, ophthalmologic migraine with recurrent CN III palsy, and spontaneous intracranial hypotension

Diagnosis ⬆ ⬇

[Section Outline]

Signs and Symptoms
Essential Workup
Diagnostic Tests & Interpretation
Differential Diagnosis

Signs and Symptoms

Oculomotor nerve palsy is a clinical diagnosis

History

Most common complaints are:
- Double vision (diplopia)
- Eyelid drooping (ptosis)
- If pupillary involvement:
  - Pupil dilation (mydriasis)
  - Blurry vision (compromised accommodation)
  - Light sensitivity (photophobia)
Associated symptoms include:
- Headache
- Eye pain
May also have other neurologic signs:
- Hemiplegia
- Ataxia, tremor
- Altered mental status
History of:
- DM
- Hypertension
- Vasculitis
- Trauma
- Infection
- Tumor
- Smoking

Physical Exam

Ophthalmologic exam:
- Visual acuity:
  - Normal or slightly blurry
- Visual fields:
  - Normal
- Position and alignment of eyes:
  - Exophthalmos if orbital tumor
- Examine eyelids:
  - Ptosis
- Conjunctiva and sclera:
  - Normal
- Cornea, lens, pupils:
  - Anisocoria with mydriasis of affected eye
  - Sluggish pupil response to light
  - Photophobia
- Extraocular movements:
  - Binocular diplopia
  - Effected eye “down and out”
  - Unable to elevate, depress, or adduct eye
- Fundoscopic exam:
  - Papilledema
- Slit-lamp exam:
  - Observe structural abnormalities of iris or anterior chamber
Neurologic exam should include all CNs and a detailed motor, sensory, and gait exam looking for:
- Other cranial nerve dysfunction (especially CN VI)
- Extremity weakness
- Dysarthria
- Change in gate or coordination
Complete oculomotor palsy:
- Eye is “down and out”
- Ptosis
- Anisocoria with a mydriatic affected eye
Incomplete oculomotor nerve palsy:
- May have involvement of 1 or more extraocular muscles and may or may not involve the pupil

Essential Workup

CT/CTA/MRI of brain, orbit, sinuses:
- Rule out compressive aneurysm or mass

Diagnostic Tests & Interpretation

Lab

When indicated based on history and physical exam:
- CBC with differential
- CMP
- ESR
- Lipids
- Antinuclear antibodies (ANA) and rheumatoid factor (RF) to evaluate for vasculitis
- Lumbar puncture to evaluate for infection or IIH

Imaging

MRI/MRA of brain and cerebral vessels particularly when pupil is involved
CT angiogram if aneurysm concern
Cerebral arteriogram: Has associated risk of neurologic morbidity and mortality
Doppler imaging for AVMs, dural sinus thrombosis

Diagnostic Procedures/Surgery

Tonometry - intraocular pressure to exclude glaucoma

Differential Diagnosis

Intracranial infections
Malignancy
Vasculitis, giant cell arteritis
Aneurysms
Myasthenia gravis
Botulism
Orbital infections
Trauma
Lens pathology
Retinal pathology
Glaucoma
MS
Thyroid associated orbitopathy

Pediatric Considerations
Consider congenital oculomotor nerve palsy

Treatment ⬆ ⬇

[Section Outline]

Prehospital
Initial Stabilization/Therapy
ED Treatment/Procedures
Medication

Prehospital

Without associated trauma, no specific prehospital care issues exist

Initial Stabilization/Therapy

Initial stabilization of trauma patient should concentrate on underlying injuries
Any patient with evidence of herniation should have the following measures to control intracranial pressure:
- Intubation using rapid-sequence induction and controlled ventilation to a PCO₂ of 35-40 mm Hg
- Elevate head of bed 30°
- Mannitol
Patch eye to alleviate diplopia discomfort

ED Treatment/Procedures

Treatment initially involves medical management of systemic predisposing factors and conservative measures to reduce pressure prior to surgical intervention:
- Differentiation between incomplete and complete oculomotor or pupil-involving vs. pupil-sparing nerve palsy guides focus of ED treatment
- All patients younger than 50 yr with any extent of oculomotor nerve palsy should be evaluated for a compressive lesion (aneurysm or mass)
- If pupil is involved, neuroimaging is indicated as well as consultation to determine cause
- If pupil is spared and the patient has diabetes or other risk for an ischemic third nerve, discharge is likely reasonable with outpatient follow-up:
  - If partial sparing or patient does not have risk factors, consultation and neuroimaging is indicated
Medication regimen determined by cause:
- Compressive lesion (aneurysm, intracranial tumor):
  - Control severe HTN
  - Decrease intracranial pressure
  - Controlled ventilation
  - Elevation of head
  - Mannitol
  - IV steroids
- Meningitis:
  - Rapid administration of IV antibiotics
  - IV steroids may be useful to decrease inflammatory response and edema
- IIH:
  - Acetazolamide
- Vasculitis and collagen vascular diseases:
  - Decrease inflammatory cell infiltration with IV steroids
- Myasthenia gravis:
  - Edrophonium chloride test
- Symptomatic anisocoria with photophobia:
  - Pilocarpine
Neurosurgical consultation as appropriate

Pediatric Considerations
MRI/MRA is indicated for all children with acquired oculomotor nerve palsy

Medication

Ceftriaxone: 1-2 g IV (peds: 50-100 mg/kg IV)
Dexamethasone: 10 mg IV (peds: 0.15-0.5 mg/kg IV single dose in ED)
Methylprednisolone: Adults/peds: 1-2 mg/kg IV single dose in ED
Mannitol: 1 g/kg IV (peds: Not routinely recommended)
Acetazolamide: 500 mg PO/IV b.i.d (peds: 25 mg/kg/d PO/IV divided q6-8h)
Edrophonium chloride: 5-8 mg IV (peds: 0.15 mg/kg IV; 1/10 test dose given first)
Pilocarpine: 1 gtt 1% in effected eye ×1 (peds: Not routinely recommended)

Follow-Up ⬆ ⬇

[Section Outline]

Disposition
Follow-up Recommendations

Disposition

Admission Criteria

Complete oculomotor nerve palsy of any cause requires admission and emergency neurosurgical evaluation
Incomplete oculomotor nerve palsy with abnormal CT or MRI, abnormal lab studies, or other focal neurologic or constitutional symptoms should receive prompt neurologic consultation and imaging

Discharge Criteria

Incomplete oculomotor nerve palsy with negative CT or MRI, normal lab studies, and no other symptoms can be referred for urgent outpatient neurologic evaluation
Complete pupil-sparing oculomotor palsy in patients with risk factors for microvascular disease (i.e., diabetic) can receive outpatient neurologic workup

Follow-up Recommendations

If the patient is being discharged, prompt neurologic and ophthalmologic follow-up is required

Pearls and Pitfalls ⬆ ⬇

Complete lesions must be assessed rapidly
Patients <50 yr old with any extent of CN III palsy should be evaluated for compressive lesions
If the pupil is involved, compressive lesions are often the cause and immediate CTA/MRI/MRA is indicated

Additional Reading ⬆ ⬇

LyonsCJ, GodoyF, ALQahtaniE. Cranial nerve palsies in childhood . Eye. 2015;29(2):246-251.
SadagopanKA, WassermanBN. Managing the patient with oculomotor nerve palsy . Curr Opin Ophthalmol. 2013;24(5):438-447.
VolpeNJ, LeeAG. Do patients with neurologically isolated ocular motor cranial nerve palsies require prompt neuroimaging?J Neuro-Ophthalmol. 2014;34(3):301-305.
WoodruffMM, EdlowJA. Evaluation of third nerve palsy in the emergency department . J Emerg Med. 2008;35(3):239-246.

Codes ⬆

ICD9

378.51 Third or oculomotor nerve palsy, partial
378.52 Third or oculomotor nerve palsy, total

ICD10

H49.00 Third [oculomotor] nerve palsy, unspecified eye
H49.01 Third [oculomotor] nerve palsy, right eye
H49.02 Third [oculomotor] nerve palsy, left eye
H49.03 Third [oculomotor] nerve palsy, bilateral
H49.0 Third [oculomotor] nerve palsy

SNOMED

388980004 third cranial nerve weakness (disorder)
3171005 Partial third nerve palsy (disorder)
194119004 Total oculomotor nerve palsy (disorder)

section name header

Basics ⬇

Pediatric Considerations

Diagnosis ⬆ ⬇

History

Physical Exam

Lab

Imaging

Diagnostic Procedures/Surgery

Pediatric Considerations

Treatment ⬆ ⬇

Pediatric Considerations

Follow-Up ⬆ ⬇

Admission Criteria

Discharge Criteria

Pearls and Pitfalls ⬆ ⬇

Additional Reading ⬆ ⬇

Codes ⬆