Diagnostic Imaging and Treatment of Optic Neuritis

Diagnostic Imaging

MRI of both orbits and brain with and without contrast is used to evaluate for T2 hyperintensity and enhancement of the optic nerve, and to assess for brain demyelinating lesions that may predict MS development, as recommended by the American College of Radiology 1
Magnetic resonance imaging (MRI) with specific sequences, including coronal images with fat suppression and T2 sequences with submillimetric resolution, is recommended to evaluate optic neuritis retrobulbar, with a slice thickness of 3-4 mm covering the entire length of the optic nerve, as recommended by the American Academy of Neurology 2
Typical findings on MRI include hyperintensity on T2-weighted images, inflammation of the optic nerve, and enhancement with contrast in acute lesions, and atrophy and persistent hyperintensity on T2-weighted images in chronic lesions 2
MRI is the preferred imaging modality for evaluating optic neuritis, with T1-weighted post-contrast images with fat suppression identifying abnormal enhancement in 95% of cases, as recommended by the American College of Radiology 3

Optic neuritis must be differentiated from other conditions, including neuropathic optic ischemia, hereditary optic neuropathy of Leber, compressive optic neuropathies, vascular disorders of the optic nerve, and infiltrative optic neuropathies, with hereditary optic neuropathy of Leber being a notable consideration 2
Differential diagnosis should also consider multiple sclerosis-associated optic neuritis, neuromyelitis optica (NMO) and NMO spectrum disorders, anterior ischemic optic neuropathy (AION), Leber's hereditary optic neuropathy, and infectious or granulomatous conditions 4, 5, 6

Acute optic neuritis requires prompt treatment with high-dose intravenous methylprednisolone as the standard of care, as recommended by the World of Neurosurgery and the American Academy of Neurology 7, 6
The recommended dose is 1000 mg daily for 3 days, followed by oral prednisone taper, as recommended by the World of Neurosurgery and the American Academy of Neurology 7, 6, 8
Early treatment with corticosteroids is essential, ideally within the first few hours of symptom onset, as recommended by the Annals of the Rheumatic Diseases guidelines 6
Plasmapheresis (plasma exchange) should be considered early in severe attacks for steroid-refractory cases, with clinical improvement seen in approximately 79.2% of patients, according to the World of Neurosurgery guidelines 7, 6
Rituximab is considered an effective treatment for neuromyelitis optica (NMO) and should be considered first-line therapy, particularly for patients with severe disease or those who have failed other immunosuppressive treatments, according to the World of Neurosurgery guidelines 7
High-risk patients (history of severe attacks, younger age at onset) should start with rituximab, which has superior relapse reduction compared to azathioprine, according to the World of Neurosurgery guidelines 7
Standard-risk patients can be treated with rituximab, azathioprine, or mycophenolate mofetil, which has demonstrated significant decrease in mean EDSS scores, according to the World of Neurosurgery guidelines 7

Relapses are common (50-60%) during corticosteroid dose reduction, highlighting the need for maintenance immunosuppressive therapy, as reported by the Annals of the Rheumatic Diseases guidelines and the European League Against Rheumatism, with a strength of evidence rated as high 6, 8
Poor prognostic factors include extensive spinal cord MRI lesions, reduced muscle strength or sphincter dysfunction at presentation, presence of antiphospholipid antibodies, delay (>2 weeks) in treatment initiation, and younger age at disease onset, according to the Annals of the Rheumatic Diseases guidelines, with a strength of evidence rated as moderate 6, 8
Mesenchymal stem cell infusion has shown marked reduction in relapses in clinical trials, according to the World of Neurosurgery guidelines 7

Screen patients for hepatitis B infection before initiating immunosuppressive treatment, and avoid corticosteroids in patients with active ocular herpes simplex, systemic fungal infections, or cerebral malaria 6, 8
Live or attenuated vaccines are contraindicated during immunosuppressive corticosteroid therapy, and high-dose IV methylprednisolone can rarely cause toxic hepatitis; discontinue if this occurs 6, 8
Oral prednisone alone (without prior IV methylprednisolone) at a dose of 1 mg/kg/day should be avoided as it may increase the risk of recurrent optic neuritis 6, 8