Diffusion MRI and tensor tractography in ischemic optic neuropathy
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- Cauquil, C., Souillard-Scemama, R., Labetoulle, M. et al. Acta Neurol Belg (2012) 112: 209. doi:10.1007/s13760-012-0013-5
Ischemic optic neuropathies (IONs) are among the most prevalent diseases causing visual impairment in middle-aged and elderly people. While arteritic ION is an ocular emergency and requires early diagnosis and immediate treatment with systemic high-dose corticosteroids to prevent further visual loss, treatment options for non-arteritic ION remain limited. We describe the case of a woman with unilateral right-sided non-arteritic posterior ischemic optic neuropathy. The diagnosis was made on clinical and radiographic grounds. Diffusion-weighted sequences and apparent diffusion coefficient maps revealed markedly restricted diffusion in the right optic nerve. It was very helpful to precise the posterior topography of the optic nerve lesion. Furthermore, we reported the diffusion tensor tractography study which appears to be an objective tool to assess the incomplete visual recovery. These MRI techniques including tensor tractography remain to be evaluated in large cohort of ION patients’ particularly in future therapeutic trials.
KeywordsIschemic optic neuropathyAIONPIONDiffusion MRTensor tractography
Ischemic optic neuropathies (IONs) are the most frequent acute optic neuropathy in patients older than 50 years . ION is classified into anterior and posterior according to the affected part of the optic nerve . While anterior ION (AION), by far the most common type, presents with sudden, painless visual loss associated with a swollen optic nerve head, posterior ION (PION) is characterized by acute vision loss without disc edema but with subsequent optic disc atrophy. To date, treatment for non-arteritic ION remains limited, while arteritic ION is an ocular emergency which requires corticosteroids to prevent further visual loss . Hitherto, no treatment of known value is available for non-arteritic ION; systemic steroid therapy helping to improve vision only in a minority of these patients . Currently, more tools are needed in order to individually predict spontaneous evolution. In this report, we describe the clinical and neuroradiological features of PION. MR imaging was very helpful: diffusion sequences to highlight the posterior topography of the optic nerve lesion and MR tractography to objectively evaluate the incomplete visual recovery.
High-signal intensity on diffusion imaging in the optic nerve has been previously described in rare patients with ION in the setting of hypotension, infection, thrombocythemia or in spontaneous non-arteritic cases [2–8]. In our case of PION, MR imaging was very helpful, including (1) diffusion sequences to confirm optic nerve infarction and precise topography, and (2) tractography to objectively assess the incomplete recovery.
These MRI techniques including tensor tractography remain to be evaluated in large cohort of ION patients’ to help for their management and perhaps predict recovery in future therapeutic trials .
Conflict of interest