What is the most common cause of optic neuritis in a 60-year-old?

Most Common Cause of Optic Neuritis in a 60-Year-Old

Giant cell arteritis (GCA) is the most common cause of optic neuritis in a 60-year-old patient. 1

Epidemiology and Risk Factors

• GCA is the most common form of aortitis in individuals older than 60 years 1
• Predominantly affects White women of advanced age 1
• In Olmsted County, Minnesota, the average age- and sex-adjusted incidence of GCA in individuals 50 years or older was 18.8 per 100,000 per person-year 1
• Risk factors include:
  • Advanced age (most significant)
  • Female gender
  • Northern European descent

Clinical Presentation

GCA-related optic neuritis typically presents with:

• Acute onset of visual loss, which can be severe and permanent if not promptly treated 1, 2
• Scalp or temporal region tenderness 1
• Pain with chewing (jaw claudication) 1
• Headache
• Systemic symptoms (fatigue, weight loss, fever)

Differential Diagnosis

Other causes of optic neuritis to consider in a 60-year-old:

1. Demyelinating disorders (less common in this age group):

   • Multiple sclerosis (MS) - more common in younger adults 3, 4
   • Neuromyelitis optica spectrum disorders 3, 5

2. Ischemic optic neuropathy:

   • Anterior ischemic optic neuropathy (AION) 3, 2
   • Posterior ischemic optic neuropathy 2

3. Other inflammatory conditions:

   • Sarcoidosis
   • Systemic lupus erythematosus 3
   • IgG4-related disease 3

4. Infectious causes:

   • Viral (herpes viruses, COVID-19) 1, 6
   • Bacterial (syphilis, tuberculosis)

Diagnostic Approach

1. Clinical examination:

   • Visual acuity testing
   • Color vision assessment (dyschromatopsia) 7
   • Fundoscopic examination (may show optic disc edema in anterior optic neuritis) 3
   • Assessment for temporal artery tenderness

2. Laboratory testing:

   • Erythrocyte sedimentation rate (ESR) - typically elevated in GCA
   • C-reactive protein (CRP) - typically elevated in GCA
   • Complete blood count

3. Imaging:

   • MRI of the orbits and brain with and without contrast 3
   • Look for:
     • Abnormal enhancement and signal changes within the optic nerve
     • T2 hyperintensity, optic nerve swelling, and contrast enhancement 3

4. Temporal artery biopsy:

   • Gold standard for GCA diagnosis

Treatment

1. Immediate treatment:

   • High-dose intravenous methylprednisolone (1g/day for 3-5 days) 3
   • Do not delay treatment while awaiting biopsy results if GCA is strongly suspected

2. Maintenance therapy:

   • Oral prednisone in tapering doses 3
   • Long-term immunosuppression may be needed

Prognosis and Complications

• Without prompt treatment, GCA can lead to permanent visual loss 1
• Poor prognostic factors include:
  • Delayed treatment initiation 3
  • Extensive lesions on MRI 3
  • Bilateral involvement

Key Points to Remember

• In patients over 60 years with acute visual loss, GCA must be considered first
• Visual loss in GCA is often irreversible if not treated promptly
• The classic triad of optic neuritis (visual loss, periocular pain, and dyschromatopsia) may not always be present in GCA-related optic neuritis 7
• Temporal artery biopsy should not delay treatment initiation if clinical suspicion is high

Remember that while demyelinating optic neuritis (associated with MS) is the most common form in younger adults, GCA becomes the predominant cause in patients over 60 years of age.