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Hippocampal sclerosis studied in identical twins
G D Jackson1, A M McIntosh, R S Briellmann
1Centre for Brain Imaging Research and Department of Neurology, Austin and Repatriation Medical Centre, University of Melbourne, Victoria, Australia.
Neurology
|July 23, 1998
Summary
Hippocampal sclerosis (HS) is not genetic. This twin study suggests acquired HS results from prolonged childhood seizures, not prenatal or perinatal factors, with associated intracranial volume changes.
Area of Science:
- Neurology
- Genetics
- Radiology
Background:
- Conflicting evidence exists regarding the etiology of hippocampal sclerosis (HS).
- Hypotheses include genetic predisposition, prenatal or perinatal insults, or consequences of prolonged seizures.
Purpose of the Study:
- To investigate the etiological hypotheses of hippocampal sclerosis (HS).
- To differentiate between genetic and acquired causes of HS using advanced MRI in monozygotic twins.
Main Methods:
- Studied three monozygotic (MZ) twin pairs discordant for temporal lobe epilepsy and HS.
- Utilized optimized, quantitative MRI and compared affected twins with their unaffected co-twins and 30 controls.
- Assessed subtle differences between affected and unaffected twins.
Main Results:
- All affected twins experienced prolonged febrile seizures in childhood; unaffected twins did not.
- Hippocampal sclerosis was present in affected twins but absent in unaffected co-twins across all MRI criteria.
- Affected twins showed relatively smaller ipsilateral intracranial volumes compared to their co-twins.
Conclusions:
- Absence of HS in unaffected twins strongly refutes a genetic etiology.
- This twin study supports an acquired cause for HS, linked to prolonged early childhood seizures.
- Regional intracranial volume abnormalities are associated with HS.