Seizures may be associated with acute changes on neuroimaging studies. MRI may reveal transient hyperintense lesions on T2-weighted images, restricted diffusion, or cortical enhancement at the site of seizure onset. Functional imaging studies typically reveal transient hyperperfusion or hypermetabolism in these sites followed by decreased function in the postictal period. These changes are most pronounced with repeated uncontrolled seizures, and are probably the result of accelerated metabolic activity caused by neuronal excitation with subsequent hyperemia, release of vasoactive mediators, and blood-brain barrier dysfunction. Awareness of the phenomenon of seizure-related transient neuroimaging changes can help avoid potentially unnecessary diagnostic procedures in ruling out other causes such as stroke, tumor, or infection. The imaging abnormalities are often reversible, and merit clinical and neuroimaging follow-up before further evaluation is undertaken.
Pestana and colleagues from the Cleveland Clinic Foundation, Cleveland, Ohio, performed volumetric MRI studies in 3 patients with temporal lobe epilepsy both before, during, and after status epilepticus. During status epilepticus, the volume of the amygdala and hippocampus increased 16.5% to 45.6% compared with baseline volume. Several months to years after status epilepticus, these volumes decreased to below baseline values. These data indicate that acute seizures are associated with increased volume of gray matter structures, most likely reflecting hyperemia and edema. Status epilepticus appears to lead to decreased volume in the long term, suggesting neuronal loss and atrophy.
Medscape Neurology. 2003;5(1) © 2003 Medscape
Cite this: Highlights of the 26th Annual Meeting of the American Society of Neuroimaging - Medscape - Mar 27, 2003.