Optic perineuritis

Optic perineuritis, also known as perioptic neuritis, refers to inflammation of the optic nerve sheath. Optic perineuritis may manifest on its own, or together with inflammation of adjacent ocular or orbital structures.

Epidemiology

Optic perineuritis is likely rare ¹, but the exact incidence is not known. It typically presents in middle-aged adults (40-60 years) and is more common in women ^1-3. 

Clinical presentation

Clinical features of optic perineuritis are often subacute in tempo (i.e. over weeks) and usually unilateral ^1,4. Bilateral optic perineuritis suggests a secondary systemic aetiology.

Clinical features include ^1-4:

• visual loss: peripheral visual field loss is common, with relative sparing of central vision

• ocular pain

• optic disc swelling

Additionally, patients may also have clinical features of concurrent optic neuritis (e.g. rapid afferent pupillary defect, dyschromatopsia), orbital inflammation (e.g. external ophthalmoplegia, exophthalmos, ptosis), and/or intraocular inflammation (e.g. scleritis, episcleritis) ^1-4.

Pathology

The exact pathogenesis of optic perineuritis depends on its underlying aetiology (see below), however, a common pathological outcome seems to be inflammation, usually lymphocytic, and fibrosis leading to thickening of the optic nerve sheath ^1-3.

Aetiology

• primary: idiopathic (accounts for most cases) ^1-4

• secondary ^1-6

  • inflammatory or autoimmune

    • connective tissue disorders (e.g. systemic lupus erythematosus)

    • Graves disease

    • IgG4-related disease

    • inflammatory bowel disease (e.g. Crohn disease)

    • myelin oligodendrocyte glycoprotein​ antibody-associated disease (MOGAD)

    • paraneoplastic (e.g. anti-CRMP-5 optic neuropathy)

    • sarcoidosis

    • vasculitis (e.g. giant cell arteritis, granulomatosis with polyangiitis, Behçet disease)

  • infective

    • cat-scratch disease

    • Lyme disease

    • syphilis

    • tuberculosis

    • viral infection (e.g. varicella zoster)

  • malignancy

Radiographic features

MRI

MRI brain/orbits is the imaging modality of choice to evaluate the optic nerve sheaths. In optic perineuritis, there is circumferential contrast enhancement of the optic nerve sheath around the optic nerve, best appreciated on fat-suppressed T1 C+ (Gd) ^1-5. On axial views, this results in the tram-track sign, while on coronal views this results in the doughnut sign ^1-5.

In association, there may be ^1-5:

• features of optic neuritis (not present in the idiopathic form)

• enhancement of the sclera

• enhancement of the extraocular muscles

• enhancement of orbital fat

• pachymeningitis

Treatment and prognosis

Specific management depends on the underlying aetiology, however, high-dose corticosteroids are generally considered to be first-line disease-modifying therapy ¹. The vast majority of patients with optic perineuritis improve rapidly with corticosteroid therapy, with an eventual favourable visual prognosis, although relapses can occur ¹.

Differential diagnosis

• normal enhancement of the dural sheath due to rich vascularity

• optic nerve sheath meningioma

• optic neuritis

• orbital inflammatory syndromes

See also

• idiopathic orbital inflammation