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Characteristics of intractable seizures following meningitis and encephalitis
D A Marks1, J Kim, D D Spencer
1Department of Neurology, Yale University School of Medicine, New Haven, CT 06510.
Abstract:
We studied clinical seizure characteristics, seizure localization, and pathology in 38 patients who developed medically intractable partial seizures following meningitis (n = 16) or encephalitis (n = 22) and were evaluated for epilepsy surgery. Whereas meningitis in this group was commonly associated with mesial temporal sclerosis (MTS), most encephalitis patients had neocortical foci. The age of onset of the encephalitic illness was important in predicting mesial temporal or neocortical foci in that group: encephalitis before, but not after, age 4 years was associated with MTS. Since almost all meningitis occurred before age 4 years, these data support the hypothesis that the medial temporal lobe is particularly susceptible to early insults, establishing the initial pathologic entity of MTS and the subsequent cascade of partial seizures. Later-onset encephalitis produced extrahippocampal neocortical seizure foci, was rarely associated with MRI abnormality, and was difficult to localize precisely. In contrast, meningitis was commonly associated with MTS, aiding seizure localization and successful surgical intervention when seizures were medically uncontrolled.
Insights
Meningitis and encephalitis can cause intractable partial seizures. Early-onset encephalitis and meningitis are linked to mesial temporal sclerosis, aiding surgical treatment for epilepsy.
Area of Science:
- Neurology
- Neurosurgery
- Pathology
Background:
- Medically intractable partial seizures can arise after meningitis or encephalitis.
- Understanding the underlying pathology and seizure focus is crucial for surgical intervention.
Purpose of the Study:
- To investigate the clinical seizure characteristics, localization, and pathology in patients with post-infectious epilepsy.
- To determine if the type of infection (meningitis vs. encephalitis) and age of onset influence seizure focus and pathology.
Main Methods:
- Retrospective analysis of 38 patients evaluated for epilepsy surgery after meningitis or encephalitis.
- Correlation of infection type, age of onset, seizure characteristics, localization, and pathology (including mesial temporal sclerosis and neocortical foci).
Main Results:
- Meningitis was commonly associated with mesial temporal sclerosis (MTS).
- Encephalitis patients predominantly had neocortical foci.
- Encephalitis before age 4 was associated with MTS; later onset led to extrahippocampal neocortical foci, often with MRI abnormalities and difficult localization.
- Meningitis, often occurring before age 4, was linked to MTS, facilitating seizure localization.
Conclusions:
- Early-onset insults, particularly meningitis, predispose to mesial temporal lobe epilepsy via MTS.
- Later-onset encephalitis can lead to neocortical epilepsy, posing localization challenges.
- Identifying the specific pathology (MTS vs. neocortical) is key for successful epilepsy surgery in post-infectious cases.