Shock-induced anterior ischemic optic neuropathy (SIAION) is a known type of optic neuropathy in patients who experienced shock related to different etiologies such as anemia and severe intradialytic hypotension like in our patient. Nonarteritic anterior ischemic optic neuropathy (NAION) is the most common acute unilateral known type of optic neuropathy in older patients with vasculopathic risk factors such as hypertension, diabetes mellitus, and obstructive sleep apnea. Although SIAION and NAION are similar optic neuropathies due to ischemia and, in particular, hypotension, they may have different pathogenic mechanisms (e.g., acute shock or intradialytic hypotension vs nocturnal hypotension), laterality (e.g., unilateral vs bilateral), and severity (e.g., light perception or worse vision). We presented a case with restricted diffusion on the apparent diffusion coefficient and the diffusion weighted imaging confined to the optic disc head in a patient with pallid edema after intradialytic hypotension. Although DWI of the optic nerve is neither 100% specific nor 100% sensitive for ischemia, we believe that restricted diffusion of the optic nerve head in our case is a clinico-radiologic correlate to pallid edema in SIAION.

中文翻译：

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休克诱发的前部缺血性视神经病变后视神经头的弥散受限。

休克诱发的前部缺血性视神经病变 (SIAION) 是一种已知类型的视神经病变，患者因不同病因如贫血和严重透析中低血压而经历过休克，就像我们的患者一样。非动脉性前部缺血性视神经病变 (NAION) 是具有血管病变危险因素（如高血压、糖尿病和阻塞性睡眠呼吸暂停）的老年患者中最常见的急性单侧已知类型的视神经病变。尽管 SIAION 和 NAION 是由缺血引起的类似视神经病变，尤其是低血压，但它们可能具有不同的致病机制（例如，急性休克或透析中低血压 vs 夜间低血压）、偏侧性（例如，单侧 vs 双侧）和严重程度（例如，光感或更差的视力）。我们介绍了一个病例，在透析中低血压后出现苍白水肿的患者，表观弥散系数弥散受限，弥散加权成像仅限于视盘头部。尽管视神经的 DWI 对缺血既不是 100% 特异性也不是 100% 敏感，我们认为在我们的病例中视神经乳头的弥散受限与 SIAION 苍白水肿的临床放射学相关。