Hippocampal Sclerosis in Temporal Lobe Epilepsy

A 28-year-old woman with a 14-year history of drug-resistant focal seizures presents to the epilepsy clinic. She had complex febrile seizures at age 4 and now experiences 3–5 seizures per month despite adequate trials of levetiracetam, lamotrigine, and carbamazepine. Her seizures begin with an epigastric aura and fear, followed by behavioral arrest and oral automatisms. Dedicated epilepsy-protocol MRI shows marked atrophy of the right hippocampus with loss of internal architecture and dilation of the temporal horn. The structure marked **B** (increased T2/FLAIR signal in the hippocampus) is a key finding on this MRI. Which of the following best describes the pathophysiological significance of the signal abnormality marked **B**?