Optic Neuritis

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Disease

  • A typical optic neuritis is often the initial episode of a Multiple Sclerosis (MS) in previously healthy patients
  • Incidence in Central Europe: 5 per 100,000/year

Typical Clinical Presentation

  • Idiopathic or associated with Multiple Sclerosis
  • Age 18 – 45 years, female > male (3:1)
  • Unilateral mild to moderate visual impairment
    • Deterioration over hours to days for 1-2 weeks, followed by improvement
    • Visual acuity rarely <0.1
  • Pain with eye movement
  • 2/3 normal optic disc, 1/3 optic disc swelling

Atypical Clinical Presentation

  • Bilateral involvement
  • Severe visual impairment <0.1
  • <18 or >45 years of age
  • No pain with eye movement
  • Optic disc with significant swelling, haemorrhages, hard exudates, cotton wool spots, or initial atrophy
  • No improvement within four weeks
  • Early recurrence in the same or partner eye

Other Symptome

  • Reduced color and contrast vision
  • Periorbital pain exacerbated by eye movement
  • No diplopia or other neurological symptoms (except in known MS)
  • Uthoff phenomenon (symptom exacerbation with heat/physical exertion) during the course
  • Approximately 30% experience phosphenes (light flashes triggered by eye movements or sounds)
  • Pulfrich phenomenon (pendulum movements appear elliptical)

Work-up

  • Visual acuity
  • Pupil examination (RAPD?)
  • Contrast vision (Pelli-Robson), colour vision (red desaturation, Ishihara)
  • Visual field (no specific defect, any defect possible)
  • Motility (painful)
  • Slit-lamp examination (normal)
  • Fundus examination (pupil dilation not mandatory)
    • 2/3 normal optic disc, 1/3 mild disc swelling
    • Macula normal
  • OCT Macula + Optic Disc (typically papillo-macular bundle affected, thinning of RNFL temporally in the course, decrease in ganglion cells)
  • Pattern-VEP (optional)

Imaging

  • MRI Orbit + Head + FLAIR sequences within 2-3 days
    • Demyelinating lesions?
    • Active lesions visible in T1 with contrast, older lesions in FLAIR
    • Optic nerve lesions with fat suppression
  • Findings in typical optic neuritis
    • Periventricular hyperintensities in the white matter
    • Short lesions of the optic nerve
  • Findings in atypical optic neuritis
    • Longitudinal enhancement of the optic nerve (> 50% of the length between disc and chiasm)
    • Chiasma involvement or posterior part of the optic nerve
    • Longitudinally extensive spinal cord lesions ≥3 vertebral segments (LETM)

Treatment

  • Steroids (usually only after imaging):
    • 1g/d SoluMedrol i.v. for 3 days if visual acuity drops < 0.5/0.6; if only 1 seeing eye, consider treating from 0.8
    • Subsequently, consider Spiricort 1mg/kg body weight/d

Follow-up

  • Follow-up after 2, 4 weeks, then individually
  • No progressive visual deterioration expected after 2 weeks; visual improvement from about 4 weeks, possibly even faster recovery (depending on severity)

Approach to Atypical Optic Neuritis

  • Clinically or radiologically atypical?
  • Rule out NMOSD
    • Laboratory
      • Aquaporin-4 antibodies (AQP4-AB)
      • Myelin-Oligodendrocyte-Glycoprotein antibodies (MOG-AB)
    • Spinal MRI and Head MRI (if not yet performed)
  • Neurological consultation, consider lumbar puncture, initiation of immunotherapy

Differential Diagnoses

  • Neuromyelitis-optica-Spectrum-disorders (NMOSD)
    • Classification
      • Aquaporin-4 antibodies (AQP4-AB) – seropositive (approx. 70%)
      • AQP4-seronegative (approx. 30%)
      • Myelin-Oligodendrocyte-Glycoprotein antibodies (MOG-AB) associated
        • About 25% of AQP4-negative cases
    • Often severe optic neuritis, which often leads to blindness without therapy
    • Another autoimmune disease is often known
    • Symptoms
      • Acute or subacute severe visual impairment (<0.1)
      • Unilateral, bilateral simultaneously, or sequentially
      • Transverse Myelitis
    • Work-up: AQP4-AB, MOG-AB, MRI Skull and Spine
    • Treatment: Steroids i.v. in the acute stage; as prophylaxis Rituximab/Azathioprine/Mycophenolate mofetil or others
  • others

Sources