Disorders Chiasm• 3 SECTIONor Nerve Optic Acquired

Arteritic Anterior Ischemic Optic Neuropathy

Key Facts

•Sudden, often devastating, visual loss in one eye or both in a patient aged >60 years

•Caused by infarction of optic nerve from arteritic occlusion of ophthalmic artery (ciliary) branches

•Optic disc edema, often pallid, nearly always present in affected eye

•If visual loss affects only one eye, fellow eye will be affected by same process in ≤ 50% within days to weeks if patient is not adequately treated

•New headache, scalp tenderness, jaw claudication, fatigue, anorexia, and limb girdle aches often precede visual loss but ophthalmic manifestations may occur without any systemic symptoms

•Erythrocyte sedimentation rate and/or C-reactive protein elevated in 80%

•Definitive diagnosis depends on temporal artery biopsy showing inflammatory destruction of media–intima junction with or without giant cells

•Prompt high-dose corticosteroid treatment does not reverse visual loss but probably reduces chances of second eye involvement

Clinical Findings

•Painless monocular or binocular visual loss

•Marked reduction in visual acuity and/or visual field (nerve fiber bundle defects)

•Optic disc swelling (often pallid)

•Sometimes cotton wool spots

•Preceding systemic symptoms of polymyalgia rheumatica (fatigue, anorexia, limb

girdle aches) or cephalgia (new headache, scalp tenderness, jaw claudication) in ≥80%

Ancillary Testing

•Erythrocyte sedimentation rate and/or C-reactive protein elevated in 80%

•>2 cm temporal artery specimen shows inflammatory destruction of media– intima junction with or without giant cells in 96%

•Fluorescein angiography often shows choroidal filling defects

Differential Diagnosis

•Non-arteritic ischemic optic neuropathy

•Atypical optic neuritis

•Infiltrative optic neuropathy

Treatment

•Start intravenous methylprednisolone 1–2 g/day for 3–5 days followed by prednisone 1.5 mg/kg before obtaining temporal artery biopsy for strong presumptive diagnosis

•Discontinue treatment if biopsy is negative (obtain biopsy within 1 week of starting corticosteroid treatment to allow maximum sensitivity in diagnosis)

•Taper oral prednisone at rate of 10 mg/week according to systemic symptoms and acute phase reactants, keeping daily dose >10–15 mg/day for ≤1 year

Prognosis

•Visual loss irreversible but usually non-progressive in affected eye(s)

•Unaffected fellow eye may develop same process despite treatment but rarely after 1 year of adequate treatment

Fig. 3.10 Optic disc shows pallid (white) swelling refl ecting infarction of disc tissue.

Neuropathy Optic Ischemic Anterior Arteritic

Disorders Chiasm• 3 SECTIONor Nerve Optic Acquired

Posterior Ischemic Optic Neuropathy

Key Facts

•Acute visual loss (usually monocular) with features of optic nerve dysfunction

•No optic disc edema

•Common causes:

•previous cranial radiation

•intracranial surgery • acute systemic hypotension

•herpes zoster or sino-orbital fungal infection

•systemic vasculitis (Wegener granulomatosis, giant cell arteritis, lupus erythematosus, relapsing polychondritis, polyarteritis nodosa)

•Almost never occurs without a discoverable predisposing condition

Clinical Findings

•Acute (usually monocular) painless loss of visual acuity and/or visual field

•Nerve fiber bundle visual field loss

•Afferent pupil defect

•Normal optic disc

•Usually there is evidence of a predisposing cause:

•episode of systemic hypotension

•previous cranial radiation

•intracranial surgery

•trigeminal zoster

•known systemic vasculitis

Ancillary Testing

•Brain and orbit imaging may show enhancement of optic nerve and/or sino-orbital masses

•Laboratory tests to rule out:

•Wegener granulomatosis

•giant cell arteritis

•lupus erythematosus

•relapsing polychondritis

•polyarteritis nodosa

Differential Diagnosis

•Optic neuritis

•Compressive optic neuropathy

•Leber hereditary optic neuropathy

•Hypotensive optic neuropathy

•Infiltrative (neoplastic) optic neuropathy

•Paraneoplastic optic neuropathy

Treatment

• Directed at underlying condition

Prognosis

• Visual recovery usually negligible

A

B

Fig. 3.11 (A) Postcontrast axial T1 shows enhancement of the intraconal fat and optic nerve in the right orbit (arrow) in a patient with mucormycosis. (B) Postcontrast coronal T1 shows that the enhancement extends into the right cavernous sinus (arrow).

Neuropathy Optic Ischemic Posterior