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Hippocampal abnormalities in malformations of cortical development: MRI study
G Kuchukhidze1, F Koppelstaetter, I Unterberger
1Department of Neurology, Medical University of Innsbruck, Innsbruck.
Objectives:
Hippocampal abnormalities may coexist with malformations of cortical development (MCD). This cross-sectional MRI study aimed at categorizing hippocampal abnormalities in a large group of MCD and comparing MCD patients with (group W) and without (group W/O) hippocampal abnormalities.
Methods:
Hippocampal anatomy, rotation, size, internal structure, and MRI signal alterations were assessed visually by 3 independent raters in patients with MCD and epilepsy. Four types of hippocampal abnormalities were examined in 220 patients (116 women, mean age 31 +/- 16.6, range 2-76 years): partially infolded/hypoplastic hippocampus (HH), hippocampal sclerosis (HS), malrotated hippocampus (MH), and enlarged hippocampus (EH). The commonest MCD in the cohort were focal cortical dysplasia (27%), polymicrogyria (PMG) (21%), developmental tumors (15%), and periventricular nodular heterotopia (PNH) (14%).
Results:
Hippocampal abnormalities were seen in 69/220 (31%) patients: HH in 34/69 (49%); HS in 18/69 (26%); MH in 15/69 (22%); and EH in 2/69 (3%). PNH (21/30 [70%]) and PMG (22/47 [47%]) were most commonly associated with hippocampal abnormalities. Compared to the W/O group, patients in the W group had a higher rate of learning disability (W 41/69 [59%] vs W/O 56/151 [37%]; p = 0.003) and delayed developmental milestones (W 36/69 [52%] vs W/O 53/151 [35%]; p = 0.025); groups did not differ otherwise with regard to clinical presentation. HH was associated with symptomatic generalized epilepsies (11/34 [32%]) and high rate of learning disability (27/34 [79%]), neurologic deficits (25/34 [73%]), and delayed developmental milestones (23/34 [68%]).
Conclusions:
About a third of patients with malformations of cortical development had hippocampal abnormalities. Patients with hypoplastic hippocampus had the most severe clinical phenotype.
Insights
Approximately one-third of patients with malformations of cortical development (MCD) exhibit hippocampal abnormalities. Those with a hypoplastic hippocampus showed the most severe clinical outcomes, including learning disabilities and developmental delays.
Area of Science:
- Neuroimaging
- Neurology
- Developmental Neuroscience
Background:
- Hippocampal abnormalities can co-occur with malformations of cortical development (MCD).
- Understanding the spectrum and clinical impact of these co-occurrences is crucial for patient management.
- Previous studies have indicated a potential link, but large-scale categorization is needed.
Purpose of the Study:
- To categorize hippocampal abnormalities in patients with MCD using MRI.
- To compare the clinical characteristics of MCD patients with and without hippocampal abnormalities.
- To identify specific MCD subtypes associated with particular hippocampal changes.
Main Methods:
- A cross-sectional MRI study involving 220 patients diagnosed with MCD and epilepsy.
- Visual assessment of hippocampal anatomy, rotation, size, internal structure, and signal alterations by three independent raters.
- Classification of four hippocampal abnormality types: partially infolded/hypoplastic hippocampus (HH), hippocampal sclerosis (HS), malrotated hippocampus (MH), and enlarged hippocampus (EH).
Main Results:
- Hippocampal abnormalities were identified in 31% (69/220) of patients.
- The most frequent abnormalities were HH (49%), HS (26%), and MH (22%).
- Periventricular nodular heterotopia (PNH) and polymicrogyria (PMG) were most commonly associated with hippocampal abnormalities.
- Patients with hippocampal abnormalities showed higher rates of learning disability and delayed developmental milestones compared to those without.
Conclusions:
- A significant proportion of patients with MCD present with coexisting hippocampal abnormalities.
- Partially infolded/hypoplastic hippocampus (HH) is linked to a more severe clinical phenotype, including epilepsy, learning disability, and developmental delays.
- These findings highlight the importance of evaluating hippocampal structure in patients with MCD for comprehensive clinical assessment.
