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.
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.
Authors: A Mohamed; E Wyllie; P Ruggieri; P Kotagal; T Babb; A Hilbig; C Wylie; Z Ying; S Staugaitis; I Najm; J Bulacio; N Foldvary; H Lüders; W Bingaman Journal: Neurology Date: 2001-06-26 Impact factor: 9.910
Authors: Anne T Berg; Samuel F Berkovic; Martin J Brodie; Jeffrey Buchhalter; J Helen Cross; Walter van Emde Boas; Jerome Engel; Jacqueline French; Tracy A Glauser; Gary W Mathern; Solomon L Moshé; Douglas Nordli; Perrine Plouin; Ingrid E Scheffer Journal: Epilepsia Date: 2010-02-26 Impact factor: 5.864
Authors: Meng-Han Tsai; Heath R Pardoe; Yuliya Perchyonok; Gregory J Fitt; Ingrid E Scheffer; Graeme D Jackson; Samuel F Berkovic Journal: Neurology Date: 2013-06-07 Impact factor: 9.910