Rosen & Barkin's 5-Minute Emergency Medicine Consult (492 page)

CODES

• 018.90 Miliary tuberculosis, unspecified, unspecified
  
• 136.3 Pneumocystosis
  
• 136.9 Unspecified infectious and parasitic diseases
  

BASICS

• Optic nerve dysfunction due to an inflammatory process, commonly associated with myelin destruction
  
• Highly associated with multiple sclerosis (MS); presenting feature in 15–20% of MS patients
  
• Grouped by site of inflammation:
  
  • Papillitis: Inflammation of the optic disk
    
  • Retrobulbar neuritis: Inflammation of the optic nerve proximal to the globe
    
• 5 yr risk for clinically definite MS following optic neuritis:
  
  • Normal MRI—16%
    
  • >3 lesions on MRI—51%
    
• Recurrence is seen in 35% of patients.
  

High prevalence of A23, B7, and DR2 HLA alleles in patients with optic neuritis:

• Especially those that progress to clinically definite MS
  

• Idiopathic:
  
  • Most common
    
  • Single isolated events
    
• MS:
  
  • 20–50% of patients with optic neuritis
    
• Viral infections:
  
  • Chicken pox
    
  • Measles
    
  • Mononucleosis
    
  • HSV and HZV
    
  • Encephalitis
    
• Postviral optic neuritis:
  
  • Usually occurs 4–6 wk after a nonspecific viral illness
    
• Granulomatous inflammation:
  
  • TB
    
  • Syphilis
    
  • Sarcoidosis
    
  • Cryptococcal infection
    
• SLE
  
• HIV:
  
  • Cytomegalovirus
    
  • Toxoplasmosis
    
  • Histoplasmosis
    
  • Cryptococcus
    
• Lyme disease
  
• Contiguous inflammation of meninges, orbit, sinuses, and intraocular inflammation
  
• Drug induced:
  
  • Amiodarone
    
  • Ethambutol
    
  • Tamoxifen
    

DIAGNOSIS

• Vision loss and pain most common symptoms
  
• Visual loss occurring over days (rarely over hours), peaks in 1–2 wk:
  
  • Adults usually unilateral (70%)
    
  • Bilateral visual loss more common in children
    
• Retrobulbar pain: Increased with movement of the affected eye
  
• Light, color vision, and depth perception loss more pronounced than visual acuity loss
  
• Afferent pupillary defect almost always occurs in unilateral cases if other eye is healthy.
  
• Visual field defects:
  
  • Usually characterized by central scotoma
    
  • Deficits resolve by 1 yr in 56% of patients, and 73% resolve by 10 yr
    
• Funduscopic exam usually reveals either swollen (papillitis) or normal disk
  
• Uhthoff sign:
  
  • Visual deficit occurring with exercise or increased body temperature
    
  • Unusual sign seen occasionally
    

• Age (typically women 18–45 yr)
  
• Pain on eye movement
  
• Speed of onset of symptoms
  
• Associated symptoms
  
• Previous episodes
  
• Family history of optic neuritis, MS
  

• Check BP.
  
• Complete ophthalmologic and neurologic exam, especially assessment of:
  
  • Pupillary function
    
  • Afferent pupillary defect
    
  • Visual field defect
    
  • Color vision (Ishihara color plates)
    
  • Evaluation of the vitreous body for cells
    
  • Dilated retinal exam (swollen optic disk)
    

• CBC
  
• ESR
  
• Rapid plasma reagin, fluorescent treponemal antibody-absorption (FTA-ABS)
  
• Lyme titer
  
• Antinuclear antibody
  
• Purified protein derivative
  
• HIV
  

• CXR for TB, sarcoid
  
• CT scan or MRI of brain and orbits:
  
  • Inflammation of the retrobulbar optic nerve during the acute phase may appear as enlargement, thus falsely raising the issue of an optic nerve mass.
    
  • Optic nerve inflammation is seen in 95% of gadolinium-enhanced MRIs.
    
  • Visual field testing (preferably automated testing, such as Octopus or Humphrey)
    

• Acute papilledema
  
• Ischemic optic neuropathy
  
• Severe systemic hypertension
  
• Intracranial tumor compressing the afferent visual pathway
  
• Orbital mass compressing the optic nerve
  
• Toxic or metabolic neuropathy:
  
  • Heavy metal poisoning
    
  • Anemia
    
  • Malnutrition
    
  • Ethanol/Methanol
    
  • Chloroquine
    
  • Ethambutol
    
  • Isoniazid
    
• Leber hereditary optic atrophy
  

In children, infectious and postinfectious causes should be considered.

In patients >50 yr, ischemic optic neuropathies (e.g., diabetes and giant cell arteritis) are more common, and appropriate workup should be obtained.

TREATMENT

• Early ophthalmologic and neurologic consultations
  
• IV steroid pulse followed by oral steroids:
  
  • Recommended for those with ≥2 demyelinating lesions on MRI without a prior history of MS or optic neuritis, or severe vision loss
    
  • Decreases recurrence and progression to MS over 2 yr and shortens duration of visual impairment, but does not affect visual outcome at 1 yr nor rate of progression at 5 yr
    
  • Treatment should be individualized for those with 1 lesion on MRI.
    
  • Oral steroids used alone increases recurrence and should be avoided.
    

Methylprednisolone: 250 mg IV q6h for 3 days, followed by oral prednisone (1 mg/kg/d) for 11 days with subsequent 4 day taper

FOLLOW-UP

• Bilateral vision loss
  
• If other sources of acute vision loss cannot be ruled out
  
• IV steroid pulse treatment needed
  

• Unilateral visual impairment
  
• Good home support systems
  
• Neurology and ophthalmology follow-up arranged
  

Referral for interferon β-1a treatment as outpatient for high-risk patients (those with ≥2 demyelinating lesions on MRI):

• Reduces progression to MS
  

Needs Ophthalmology referral

• Rule out space-occupying lesions before making the diagnosis of optic neuritis.
  
• Acute bilateral loss with a severe headache or diplopia should raise concern for pituitary apoplexy.
  
• The true benefit of corticosteroids in the treatment of optic neuritis is unclear, and emergency physicians should consult with appropriate specialists to determine the local standard of practice.
  
• Brain MRI is the most useful predictor of subsequent development of MS.
  

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