Optic neuritis

Background

• Inflammatory, demyelinating condition of the optic nerve highly associated with MS
  • 50% will go on to develop MS
• Presenting feature of MS in 15-20% of patients

Causes

• Idiopathic
• Multiple sclerosis
• Postchildhood vaccination
• Viral infection
  • Measles, mumps, varicella zoster virus, EBV
• Inflammation of structures contiguous with the optic nerve
  • Meninges, orbit, sinuses
• Other infections
  • Syphilis, Tuberculosis, Crypto
• Sarcoidosis, uveitis
• Temporal arteritis
• Vasculitides
• Ischemic optic neuropathy
• Hypertensive retinopathy, papilledema
• DM retinopathy
• Intracranial tumor, orbital tumor
• Glaucoma

Clinical Features

• Acute, usually monocular, vision loss occurring over days (occasionally over hours)
  • May range from mildly reduced to no light perception whatsoever
• Retro-orbital headache
• Pain (esp with eye movement)
• Loss of color vision out of proportion to loss of visual acuity
• Pulfrich effect - swing object side to side like pendulum, but patient feels like the object is coming at them in elliptical fashion; suggestive of demyelination

Differential Diagnosis

Acute Vision Loss (Noninflamed)

• Painful
  • Arteritic anterior ischemic optic neuropathy
  • Optic neuritis
  • Temporal arteritis^†
• Painless
  • Amaurosis fugax
  • Central retinal artery occlusion (CRAO)^†
  • Central retinal vein occlusion (CRVO)^†
  • High altitude retinopathy
  • Open-angle glaucoma
  • Posterior reversible encephalopathy syndrome (PRES)
  • Retinal detachment^†
  • Stroke^†
  • Vitreous hemorrhage
  • Traumatic optic neuropathy (although may have pain from the trauma)

^†Emergent Diagnosis

Evaluation

Physical Exam

• Red desaturation test
  • Have patient look with one eye at a dark red object
  • Test the other eye to see if the object looks the same color
    • Affected eye often will see the red object as pink or lighter red
• Normal intraocular pressures
• Normal slit lamp exam (no evidence of uveitis)
• Afferent Pupilary Defect (APD)
• Optic disc swelling and edema (papillitis)
  • Elevated optic nerve disk on US = papilledema
  • Increased ON sheath diameter > ~5mm measured 3mm behind globe on US

Work-up

• MRI of brain and orbits with gadolinium, plus fat suppression
• CBC
• CMP
• ESR, CRP
• RPR, FTABS
• CXR
• May consider LP to rule out neuromyelitis optica (Consult with neuro regarding CSF and serum studies):
  • Typically protein/glucose, gram stain/culture, cell count/differential
  • Plus angioconverting enzyme, IgG indices, myelin basic protein, oligoclonal bands
  • Plus SERUM IgG indices, oligoclonal bands, angioconverting enzyme, NMO antibodies

Disposition

• Consult neuro and ophthalmology
• Inpatient admission for IV methylprednisolone, 1 g qd x3 days

See Also

• Multiple Sclerosis (MS)

References

• Petzold A et al. The investigation of acute optic neuritis: a review and proposed protocol. Nat Rev Neurol. 2014 Aug;10(8):447-58.
• Voss E et al. Clinical approach to optic neuritis: pitfalls, red flags and differential diagnosis. Ther Adv Neurol Disord. 2011 Mar; 4(2): 123–134.