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Neurology. 2011 Apr 19;76(16):1415-21. doi: 10.1212/WNL.0b013e318216712b.

Hippocampal size anomalies in a community-based cohort with childhood-onset epilepsy.

Author information

  • 1Department of Biology, Northern Illinois University, DeKalb, IL 60115, USA. atberg@niu.edu

Abstract

OBJECTIVES:

Epidemiologic evidence suggests the natural history of refractory mesial temporal lobe epilepsy is complicated, yet little is known about the hippocampus from the nontertiary center perspective.

METHODS:

In a community-based cohort, individuals with nonsyndromic focal epilepsy with onset <16 years and controls had research MRI scans. Hippocampal (HC) volumes were manually measured, corrected for total brain volume, and converted to Z scores (Z(HC)) based on the controls' values. Volumes in cases and controls were compared.

RESULTS:

Average volumes were not significantly different in cases with unknown cause (n = 117) relative to controls (n = 63). The group with structural and other conditions (n = 23) had significantly smaller volumes. Asymmetry (larger/smaller HC) did not vary among the 3 groups. Hippocampal variances were significantly larger in each epilepsy group relative to controls. In the unknown cause group, 25 (21%) had extreme() values: 15 (13%) with Z(HC) >1.96; 10 (9%) with Z(HC) <-1.96. By contrast, 2/63 (3%) controls had extreme values (p = 0.001). Within the unknown cause group, temporal lobe epilepsy (TLE) cases were more likely to have extreme hippocampal volumes than non-TLE (31% vs 15%, p = 0.03). Extreme volumes were generally interpreted as normal visually. These anomalies were not associated with seizure remission or pharmacoresistance.

CONCLUSIONS:

Classic mesial TLE with hippocampal sclerosis is an uncommon finding in the general population. Volume anomalies, both large and small, are often bilateral. The significance of these findings is unclear; however, speculations regarding preexisting hippocampal pathology (e.g., dysplasia) as a factor in TLE and other neocortical epilepsies have been made by others.

PMID:
21502602
[PubMed - indexed for MEDLINE]
PMCID:
PMC3087401
Free PMC Article
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