Optic Neuritis

• Affect 15 to 45 years of age, peak 30 to 50 years old
• Famale:male ratio 2-3:1
• Symptoms progress over hours to days
• In the optic neuritis treatment trial, 92% of the patients had ocular pain.
  • Young age and the presence of pain: strongly suggestive of optic neuritis
  • In middle aged patients without pain, distinction from ischemic optic neuropathy can be difficult

• 94% unilateral
• Usually improves over 4 weeks
• Inflammatory demyelination of the Optic nerve
• Initial manifestation of MS in 20%
• Developed during the course of MS in 50%

Description by patient:

• Blurred vision
• Decreased color perception
• Impaired depth perception

Examination

• Reduced visual acuity
• Reduced brightness perception
• Bright color desaturation
• Afferent defect not always present
• Fundoscopic exam frequently normal

Differential Diagnosis

• Idiopathic Optic neuritis
• Multiple Sclerosis
• Devic's Syndrome: with myelitis
• Postinfectious: viral, mycoplasma
• Post Immunization
• Systemic inflammatory disease: SLE, Sarcoidosis
• Infections: Lymes, Syphilis
• Ischemic optic neuropathy: usually painless, older, more acute onset
• Leber's Hereditary optic neuropathy: mitochondrial disease
  • subacute visual loss
  • usually becomes bilateral
  • young male, poor recovery
• Compressive lesion: more insidious onset

Testings:

• VER: prolonged P100 or reduction in amplititude or both
• Visual field: may show diffuse visual field loss
• CSF: mild mononuclear pleocytosis,
  • elevated IgG index or synthesis rate
  • Oligoclonal bands
• MRI of head
  • About two thirds of optic neuritis will have enhancing optic nerve lesions
  • Enhancement may also be seen in other inflammatory optic neuropathies such as sarcoidosis, meningeal processes and radiation optic neuropathy.

Prognosis

• Most show improvement in 2 weeks
• Increased risk for developing MS for these patients
  • female
  • Caucasians
  • Family history of MS
  • Nonspecific vague neuro symptoms
  • CSF abnormalities
  • Abnormal MRI
    • In ONTT, 51% of patients with three or more white matter lesions that were greater than 3 mm, ovoid, and in periventricular white matter developed multiple sclerosis within five years.
    • 16% of patients with normal MRI scans developed MS in the first five years.

Treatment

• IV Methylprednisone 1 g per day for 3 days, followed by oral prednisone taper IF
  • MRI of head suggestive of MS
  • bilateral Optic neuritis
  • Visual acuity < 20/60
• Oral prednisone alone has not been showed to be beneficial
• Controlled high risk Avonex multiple sclerosis study (CHAMPS)
  • Age of 18 to 50
  • Had an acute isolated demyelinating event involving either the optic nerve, spinal cord or brainstem/cerebellum.
  • Have at least two clinically silent brain MR lesions which were greater or equal to 3 mm in size. One of these lesions needed to be periventricular in location or ovoid in shape.
  • All patients received intravenous methylprednisolone, followed by an oral prednisone taper
  • Randomized by the nature of their clinical events and number of T2 lesions seen on their brain MRI scan. One group were given Avonex while the other group was given placebo.
  • Result: Avonex may reduce the conversion to multiple sclerosis in high risk patients by approximately 50%.