Temporal artery enhancement on cranial magnetic resonance imagingA 68-year-old white female presented to her outside ophthalmologist with acute vision loss in the left eye (OS) described as a “green line across the top half of her vision” and dull pain OS. She then experienced progressive worsening of vision OS, pain with chewing, temple pain, and scalp tenderness. The visual acuity was 20/20 in the right eye (OD) and counting fingers at 1/2-foot distance OS. There was a left relative afferent pupillary defect and optic disc edema OS. The right optic nerve was normal, but the cup-to-disc ratio was 0.4 OD.
Diffusion-weighted imaging in posterior ischemic optic neuropathyDiffusion-weighted imaging (DWI) is a magnetic resonance imaging (MRI) sequence that provides image contrast dependent on the molecular motion of water. Acute ischemia in the central nervous system (CNS) results in disruption of normal cellular metabolism with depletion of ATP causing failure of Na+/K+ ATPase ionic pumps with loss of ionic gradients across cellular membranes. This causes cytotoxic edema with a net shift of water from the extracellular to the intracellular space and changes in the relative volume of these compartments, as well as alterations in their microenvironments.