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Updated: Jul 11, 2026
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Horizontal Hippocampal Slices of the Mouse Brain
Published on: September 22, 2020
Incomplete inversion of the hippocampus--a common developmental anomaly
Dragan Bajic1, Chen Wang, Eva Kumlien
1Department of Radiology, Uppsala University Hospital, SE 75185 Uppsala, Sweden. dragan.bajic@akademiska.se
European Radiology
|September 11, 2007
Summary
Incomplete hippocampal inversion, a fetal development variation, is common in people without epilepsy or brain abnormalities. This finding suggests it
Area of Science:
- Neuroanatomy
- Developmental Neuroscience
- Neuroradiology
Background:
- Incomplete hippocampal inversion (IHI) is typically associated with epilepsy or midline malformations.
- Previous studies have focused on IHI in patient populations with neurological conditions.
Purpose of the Study:
- To investigate the prevalence and characteristics of IHI in a nonepileptic population without apparent developmental anomalies.
- To determine if IHI is a common morphologic variant in the general population.
Main Methods:
- Analysis of coronal magnetic resonance imaging (MR) scans from 100 individuals (50 women, 50 men) without epilepsy.
- Participants included 20 healthy volunteers and 80 patients with no significant intracranial developmental anomalies.
- IHI was classified as total or partial based on the extent of hippocampal involvement and evaluated for laterality.
Main Results:
- Incomplete hippocampal inversion was identified in 19% (19/100) of the subjects.
- The condition was more frequent in men (10/50) than women (9/50) and predominantly unilateral on the left side.
- Bilateral IHI was observed in 6% of subjects, with a higher prevalence in women.
Conclusions:
- Incomplete hippocampal inversion is a relatively common morphologic variation in nonepileptic individuals without obvious intracranial abnormalities.
- The presence of a vertically oriented collateral sulcus correlated with deviating hippocampal shapes.
- IHI may represent a normal variant rather than solely a marker of pathology.
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