DESCRIPTION 
- Typical presentation of a 3rd cranial nerve (CN) palsy:
- Eyelid drooping
- Blurred or double vision
- Light sensitivity
- May also have other neurologic signs/symptoms:
- CN III controls elevation, adduction and depression of the eye. This nerve also raises the lid and mediates pupillary constriction and lens accommodation:
- Medial rectus:
- Moves eye medially toward nose (adduction)
- Superior rectus:
- Moves eye upward
- Rotates top of eye toward nose
- Slight adduction
- Inferior rectus:
- Moves eye inferiorly
- Rotates top of eye away from nose
- Slight adduction
- Inferior oblique:
- Rotates top of eye away from nose
- Slight elevation and abduction
- Levator palpebrae superioris:
- CN IV innervates the superior oblique:
- Moves eye down when looking medially
- Rotates eye internally
- CN VI innervates the lateral rectus:
- Moves eye laterally (abduction)
- Lesions categorized as:
- Complete vs. incomplete
- Pupil involving vs. pupil sparing
- Complete: Total loss of CN III function ("down and out"):
- Compressive lesions:
- Aneurysms
- Tumors
- Brainstem herniation with compression
- Increased intracranial pressure
- Incomplete: Partial loss of CN III function:
- Vascular infarction of vasa vasorum
- Pupil involving:
- 95–97% of compressive lesions (aneurysm, tumor, etc.) involve the pupil
- Parasympathetic fibers sit peripherally in CN III
- Pupil sparing:
- Ischemic injury to nerve
- Diabetics, uncontrolled hypertension
ETIOLOGY
Pediatric Considerations
Trauma is the most common cause of acquired oculomotor nerve palsies
[Outline]
SIGNS AND SYMPTOMS
A careful history and physical exam are vital to narrow down the differential diagnosis
History
History is of utmost importance in determining cause:
- Headache
- Pupillary dilation
- Eye pain
- Diplopia
- Blurry vision
- History of long-standing diabetes mellitus
- Head trauma, either recent or distant
- Unintentional weight loss
- Signs and symptoms of infection
- Sudden onset of severe headache, meningeal signs, photophobia
- Proptosis
- Lid swelling
Physical Exam
- Ophthalmologic exam:
- Extraocular movements
- Fundoscopic exam for papilledema
- Ipsilateral and contralateral pupillary reaction
- Ptosis
- Diplopia
- Chemosis or conjunctival injection
- Tenderness
- Visual acuity
- Exophthalmos
- Pupil sparing lesion:
- Ptosis
- Globe is "down and out"
- No elevation, depression, or adduction
- Normal pupil exam
- CN IV, V, VI intact
- Usually no other neurologic signs/symptoms
- Most commonly caused by ischemia in adults
- Also consider giant cell arteritis and trauma
- Pupil-involving lesion:
- Anisocria is present with a dilated pupil on affected side
- Need to rule out compressive aneurysm
- Incomplete, 3rd CN palsy:
- May have involvement of 1 or more extraocular muscle and may or may not involve pupil
- Look for associated symptoms:
- Extremity weakness
- Changes in speech
- Dysfunction of other CNs
- Gait or coordination
ESSENTIAL WORKUP
CT/MRI of brain, orbit, sinuses
DIAGNOSIS TESTS & INTERPRETATION
Lab
When indicated based on history and physical exam:
- CBC with differential
- ESR
- Antinuclear antibodies, rheumatoid factor to evaluate for vasculitis
- Lumbar puncture
Imaging
- MRI/MRA of brain and cerebral vessels particularly when pupil is involved
- CT angiogram
- Cerebral arteriogram: Has associated risk of neurologic morbidity and mortality
- Doppler imaging for arteriovenous malformations, dural sinus thrombosis
Diagnostic Procedures/Surgery
- Intraocular pressure to exclude glaucoma
- Slit-lamp exam:
- Observe structural abnormalities of iris or anterior chamber
DIFFERENTIAL DIAGNOSIS
Pediatric Considerations
Consider congenital oculomotor nerve palsy
[Outline]
PRE-HOSPITAL
Without associated trauma, no specific pre-hospital 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 level of 35–40 mm Hg
- Elevate head of bed 30°
- Mannitol
ED TREATMENT/PROCEDURES
- 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 3rd nerve palsy should be evaluated for a compressive lesion
- 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 3rd nerve, discharge is likely reasonable with outpatient follow-up:
- If partial sparing or patient does not have these risk factors, consultation and neuroimaging is indicated
- Medication regimen determined by cause:
- Aneurysm:
- Control severe HTN.
- Decrease intracranial pressure
- Controlled ventilation
- Elevation of head
- Mannitol
- Intracranial tumor: Control increasing intracranial pressure
- Inflammation and edema: Decrease with IV steroids.
- Meningitis:
- Rapid administration of IV antibiotics
- IV steroids may be useful to decrease inflammatory response and edema
- Vasculitis and collagen vascular diseases: Decrease inflammatory cell infiltration with IV steroids
- Neuropathy: Myasthenia gravis—edrophonium chloride test
- Neurosurgical consultation as appropriate
Pediatric Considerations
MRI/MRA is indicated for all children with a 3rd nerve palsy
MEDICATION
- Ceftriaxone: 1–2 g (peds: 50–100 mg/kg) IV
- Dexamethasone: 10 mg IV (peds: 0.15–0.5 mg/kg IV single dose in ED)
- Edrophonium chloride: 5–8 mg IV (peds: 0.15 mg/kg IV; 1/10 test dose given 1st)
- Mannitol: 1 g/kg IV (peds: Not routinely recommended)
- Methylprednisolone: Adults/peds: 1–2 mg/kg IV single dose in ED
[Outline]
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 follow-up is required
[Outline]