Reversible signal abnormalities in the hippocampus and neocortex after prolonged seizures

Area of Science:

• Neurology
• Radiology
• Neuroscience

Background:

• Medial temporal lobe structures and cerebral neocortex abnormalities on MRI can be associated with prolonged seizure activity.
• Reversible signal abnormalities on MRI require investigation to understand underlying mechanisms.

Purpose of the Study:

• To investigate reversible increased signal intensity in medial temporal lobe structures and cerebral neocortex on MRI scans.
• To analyze MR imaging findings in patients with recent prolonged seizure activity.

Main Methods:

• Retrospective review of clinical findings and MR studies of six patients with reversible signal abnormalities.
• Exclusion of patients with known causes of reversible signal abnormalities like hypertensive encephalopathy.
• Utilized T2-weighted spin-echo or short-tau inversion-recovery coronal MR imaging of the temporal lobes.

Main Results:

• All six patients exhibited increased signal intensity in the medial temporal lobe, with hippocampal involvement in five.
• Follow-up MR examinations demonstrated partial or complete resolution of hyperintensity in the medial temporal lobe and neocortex.
• Brain biopsy in one patient revealed severe cerebral cortical gliosis; temporal lobectomy showed moderate cortical gliosis and hippocampal cell loss.

Conclusions:

• Prolonged seizure activity can lead to demonstrable hyperintensity in the temporal lobe on MRI, indicative of seizure-induced edema or gliosis.
• Damage to medial temporal lobe structures following prolonged seizures may contribute to epileptogenic disorders.