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282 - Le Signe du Spot Lumineux : un nouveau signal IRM pour le diagnostic précoce de la Neuropathie ischémique antérieure aigue Artéritique

A rapid identification of the etiology of anterior ischemic optic neuropathy is crucial because it determines therapeutic management. Our aim was to assess magnetic resonance imaging to study the optic nerve head in patients referred with anterior ischemic optic neuropathy, due to either giant cell arteritis or the nonarteritic form of the disease, compared with healthy subjects.

Fifteen patients with giant cell arteritis-related anterior ischemic optic neuropathy and 15 patients with nonarteritic anterior ischemic optic neuropathy from 2 medical centers were prospectively included in our study between August 2015 and May 2016. Fifteen healthy subjects and patients had undergone contrast-enhanced, flow-compensated, 3D T1-weighted magnetic resonance imaging. The bright spot sign was defined as optic nerve head enhancement with a 3-grade ranking system. Two radiologists and 1 ophthalmologist independently performed blinded evaluations of magnetic resonance imaging sequences with this scale. Statistical analysis included interobserver agreement.

Magnetic resonance imaging scores were significantly higher in patients with giant cell arteritis-related anterior ischemic optic neuropathy than in patients with nonarteritic anterior ischemic optic neuropathy (P ≤ .05). All patients with giant cell arteritis-related anterior ischemic optic neuropathy (15/15) and 7/15 patients with nonarteritic anterior ischemic optic neuropathy presented with the bright spot sign. No healthy subjects exhibited enhancement of the anterior part of the optic nerve. There was a significant relationship between the side of the bright spot and the side of the anterior ischemic optic neuropathy (P ≤ .001). Interreader agreement was good for observers (κ = 0.815).

Here, we have demonstrated the early presence of a new magnetic resonance imaging sign in the acute phase of anterior ischemic optic neuropathy. All patients with arteritis-related anterior ischemic optic neuropathy exhibited optic nerve head enhancement, compared with only 50% of patients with nonarteritic anterior ischemic optic neuropathy and 0% of healthy volunteers. Therefore, in our series, the absence of optic nerve head enhancement in patients with AION precluded a diagnosis of giant cell arteritis.

This preliminary study suggests that patients with suspected ischemic optic neuropathy can potentially benefit from magnetic resonance imaging in the emergency setting, to differentiate anterior ischemic optic neuropathy due to giant cell arteritis and nonarteritic anterior ischemic optic neuropathy and definitively exclude the arteritic form.