Occurrence of Hippocampal Sclerosis: Is One Hemisphere or Gender More Vulnerable?

Abstract

Summary: Purpose:We analyzed a large group of patients investigated for suspected seizures to test whether gender or side are important factors in the origins of hippocampal sclerosis (HS). Methods:We studied 996 consecutive patients (48% men, 52% women) by using standard hippocampal T,-relaxometry methods.Results: HS was associated with a highly abnormal T, time ( I 1 13 ms). Categoric analysis showed that hippocampal T, time was independent of gender and side. T, time was bilaterally normal in 81% of men and in 79% of women; it was unilaterally abnormal in 15% of both men and women; and bilaterally abnormal in 4% of men and in 6% of women. Highly abnormal T, relaxometry, suggesting HS, occurred with equal frequency in men and women and on the right and left sides. Quantitative analysis of hippocampal T, times showed values not differing significantly between men and women or between the right and left hemispheres. There was no significant interaction between gender and side.Conclusions: In patients with seizure disorders, hippocampal T, relaxometry is not different in adult men and women and in the right and left hemispheres. Key Words: Temporal lobe epilepsy-Magnetic resonance imaging-Hippocampal sclerosis-Seizures-Gender.An initial epileptogenic insult such as a prolonged febrile convulsion is, in retrospective studies, frequently documented in temporal lobe epilepsy (TLE) patients who have hippocampal sclerosis (HS) (1). Five to ten percent of the general population will have a -potential brain insult in childhood (such as a febrile convulsion) (2). Nevertheless, prospective studies of people with such an insult show that most of them will not develop HS or epilepsy (2). These insults usually occur before the age of 5 years. During these early years of life, the brain is vigorously developing, and development differs in boys and girls and in the right and left hemispheres (3). The vulnerability to external damage of each hemisphere is highest at certain phases of development. On the left side, and in boys, this phase is believed to be longer (4). Geschwind and Galaburda ( 3 ) suggested a biologic basis for the higher vulnerability of the male brain, particularly of the left hemisphere. In TLE, there is indeed emerging evidence of complex interactions between gender, side of the focus, and age of onset in TLE, particularly when associated with HS (5-7). Therefore the occurrence and severity of HS may be related to gender or side. Such differences may be small; therefore analysis must be quantitative and include a large series of patients.The magnetic resonance imaging (MRI) features of HS are reduced hippocampal volume, abnormal hippocampal signal, and disturbed internal architecture (8). Volumes and T, signal can be quantitated, and critical values have been established to indicate HS (8,9). Hippocampal T, relaxometry and volumes inversely correlate with each other (9,lO). Although both methods reliably quantitate HS, the required time to process a result is very different. Calculating T, times from the dat...

Right hippocampal sclerosis is more common than left after febrile seizures

“…8 Although some authors noticed that HS occurred more frequently on the left side, 1 others found this trend nonsignificant. 9 In our previous study investigating hippocampal malrotation, a common hippocampal developmental abnormality, a highly significant left-sided predominance was found. 10 These data suggest that focal epilepsy is more often associated with left hippocampal abnormalities.…”

“…1 We found no sex predisposition for HS and no difference in men versus women for the laterality of HS or history of FC in accordance with other studies. 9 Others found that the severity of HS also shows no relationship to the history of FC. 2 Consequently, the association of FC with right-sided HS cannot be explained by these factors.…”

Interaction between sex and early-life stress: Influence on epileptogenesis and epilepsy comorbidities

“…With respect to mesial temporal lobe epilepsy (MTLE), the epilepsy syndrome most relevant to the studies in animal models that have shown that exposure to early life stress results in an increased vulnerability to epileptogenesis, no gender difference has been found in the prevelance of patients having the hallmark pathology -hippocampal sclerosis -detected on MRI scans (Briellmann et al, 1999). However such data comes from epilepsy surgery centres, rather than population epidemiological studies, and so any gender differences that might exist could be obscured by referral biases.…”

Sex differences in seizure types and symptoms

“…[4, 8, 12] There are no sex differences for patients with hippocampal sclerosis on MRI. [13] Sex disparities after epilepsy surgery are reported with more favorable outcomes in women[14] as well as men. [15-18]…”