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Updated: Jul 31, 2026
Investigations on Alterations of Hippocampal Circuit Function Following Mild Traumatic Brain Injury
Published on: November 19, 2012
The phenotype of bilateral hippocampal sclerosis and its management in "real life" clinical settings
Arjune Sen1, Patricia Dugan2, Piero Perucca3,4
1Oxford Epilepsy Research Group, National Institute for Health Research Biomedical Research Centre, Nuffield Department of Clinical Neuroscience, John Radcliffe Hospital, Oxford, UK.
Insights
This study details the clinical characteristics of bilateral hippocampal sclerosis (HS) in patients with drug-resistant epilepsy. Bilateral HS presents distinct features compared to unilateral HS, informing future research and treatment strategies.
Area of Science:
- Neurology
- Epileptology
- Neuroscience
Background:
- Bilateral hippocampal sclerosis (HS) is a significant cause of pharmacoresistant epilepsy.
- Detailed phenotypic characterization of bilateral HS is lacking, hindering optimal treatment strategies.
Purpose of the Study:
- To conduct a multicenter review of patients with pharmacoresistant epilepsy and bilateral HS.
- To determine the clinical characteristics of bilateral HS.
- To compare the phenotype of bilateral HS with unilateral HS.
Main Methods:
- Multicenter review of 11 EPIGEN centers.
- Anonymized data collection including clinical notes, imaging, and electroencephalographic (EEG) and neuropsychometric data.
- Comparison of phenotypic information between bilateral HS and unilateral HS cohorts.
Main Results:
- 96 patients with bilateral HS and pharmacoresistant epilepsy were identified.
- Compared to unilateral HS, bilateral HS patients had fewer febrile convulsions and status epilepticus.
- Focal aware seizures were less frequent in bilateral HS compared to unilateral HS.
Conclusions:
- This study provides a comprehensive phenotypic spectrum of bilateral HS in pharmacoresistant epilepsy.
- Significant clinical differences exist between bilateral and unilateral HS.
- The findings serve as a foundation for further epidemiological and genomic studies to understand etiopathogenesis and optimize treatment.
Objective:
There is little detailed phenotypic characterization of bilateral hippocampal sclerosis (HS). We therefore conducted a multicenter review of people with pharmacoresistant epilepsy and bilateral HS to better determine their clinical characteristics.
Methods:
Databases from 11 EPIGEN centers were searched. For identified cases, clinicians reviewed the medical notes, imaging, and electroencephalographic (EEG), video-EEG, and neuropsychometric data. Data were irretrievably anonymized, and a single database was populated to capture all phenotypic information. These data were compared with phenotyped cases of unilateral HS from the same centers.
Results:
In total, 96 patients with pharmacoresistant epilepsy and bilateral HS were identified (43 female, 53 male; age range = 8-80 years). Twenty-five percent had experienced febrile convulsions, and 27% of patients had experienced status epilepticus. The mean number of previously tried antiepileptic drugs was 5.32, and the average number of currently prescribed medications was 2.99; 44.8% of patients had cognitive difficulties, and 47.9% had psychiatric comorbidity; 35.4% (34/96) of patients continued with long-term medical therapy alone, another 4 being seizure-free on medication. Sixteen patients proceeded to, or were awaiting, neurostimulation, and 11 underwent surgical resection. One patient was rendered seizure-free postresection, with an improvement in seizures for 3 other cases. By comparison, of 201 patients with unilateral HS, a significantly higher number (44.3%) had febrile convulsions and only 11.4% had experienced status epilepticus. Importantly, 41.8% (84/201) of patients with unilateral HS had focal aware seizures, whereas such seizures were less frequently observed in people with bilateral HS, and were never observed exclusively (P = .002; Fisher's exact test).
Significance:
The current work describes the phenotypic spectrum of people with pharmacoresistant epilepsy and bilateral HS, highlights salient clinical differences from patients with unilateral HS, and provides a large platform from which to develop further studies, both epidemiological and genomic, to better understand etiopathogenesis and optimal treatment regimes in this condition.
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