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**?
A. It reflects normal age-related changes in hippocampal myelination
B. It represents gliosis and neuronal loss within the sclerotic hippocampus, the most specific MRI sign of mesial temporal sclerosis
C. It indicates acute inflammation and edema secondary to recent ictal activity
D. It demonstrates reversible metabolic dysfunction that will resolve with seizure control
Explanation
Why option 1 is correct
The increased T2/FLAIR signal marked B in the atrophic hippocampus represents gliosis (astrocytic proliferation) and neuronal loss—the pathological hallmark of mesial temporal sclerosis (MTS). This signal abnormality, combined with hippocampal atrophy and loss of internal architecture, is the most specific MRI sign of hippocampal sclerosis. In this patient, the remote prolonged febrile seizure at age 4 likely triggered the cascade of neuronal injury and gliosis that culminated in MTS, making her an excellent candidate for anterior temporal lobectomy with amygdalohippocampectomy, which achieves seizure freedom in 65–70% of carefully selected patients (Adams and Victor's Principles of Neurology, 12th Edition, Chapter 16).
Why each distractor is wrong
Option 2 (acute inflammation and edema): While acute seizure activity can cause transient edema, the chronic T2/FLAIR hyperintensity in MTS reflects permanent structural changes (gliosis and neuronal loss), not reversible acute inflammation. The patient's 14-year disease course and imaging findings are consistent with chronic pathology, not acute post-ictal edema.
Option 3 (normal age-related myelination changes): Hippocampal T2/FLAIR hyperintensity is pathological, not a normal age-related finding. The signal abnormality in MTS is accompanied by atrophy and architectural distortion, which are not features of normal aging.
Option 4 (reversible metabolic dysfunction): The increased T2/FLAIR signal in MTS reflects irreversible neuronal loss and gliosis, not reversible metabolic dysfunction. Although seizure control may improve symptoms, the underlying structural pathology does not resolve with medical management alone, which is why this patient requires surgical intervention.
High-YieldNEET PG
Increased T2/FLAIR signal in an atrophic hippocampus with loss of internal architecture is the most specific MRI sign of mesial temporal sclerosis and indicates permanent gliosis and neuronal loss, not reversible edema.
Adams and Victor's Principles of Neurology, 12th Edition, Chapter 16: Epilepsy and Other Seizure Disorders
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