Clinical and color Doppler imaging features of one patient with occult giant cell arteritis presenting arteritic anterior ischemic optic neuropathy

Anterior ischemic optic neuropathies (AIONs) represent a segmental infarction of the optic nerve head (ONH) supplied by the posterior ciliary arteries (PCAs). Blood supply blockage can occur with or without arterial inflammation. For this reason, there are two types of AIONs: non-arteritic (NA-AION), and arteritic (A-AION), the latter is almost invariably due to giant cell arteritis (GCA). GCA is a primary vasculitis that predominantly affects extracranial medium-sized arteries, particularly the branches of the external carotid arteries (including superficial temporal arteries - TAs). One patient with clinical suspicion of acute left AION was examined at admission following a complex protocol including color Doppler imaging (CDI) of orbital vessels, and color duplex sonography of the TAs and of the carotid arteries. She presented an equivocal combination of an abrupt, painless, and severe vision loss in the left eye, and an atypical diffuse hyperemic left optic disc edema. She had characteristic CDI features for GCA with eye involvement: high resistance index, with absent, or severe diminished blood flow velocities, especially end-diastolic velocities, in all orbital vessels, especially on the left side (A-AION). Typical sonographic feature in temporal arteritis as part of GCA was "dark halo" sign. On the other hand, she did not present classic clinical or systemic symptoms of GCA: temporal headache, tender TAs, malaise (occult GCA). The left TA biopsy confirmed the diagnosis of GCA. The ultrasound investigations enabled prompt differentiation between NA-AION and A-AION, the later requiring in her case immediate steroid treatment, to prevent further visual loss in the right eye.