Abstracts

Rationale:
The relation of preoperative memory deficits in temporal lobe epilepsy (TLE) patients to hippocampal (HF) sclerosis is uncertain. Some studies suggest greater HF head than tail or body atrophy in TLE patients. We tested the hypothesis that visual memory deficits are associated with posterior, and verbal with anterior HF atrophy. 
Method:
We examined 20 adults with mesial temporal lobe epilepsy (left foci=10; right foci=10). All patients had mesial temporal sclerosis by surgical pathology. HF head, body, tail volumes were calculated using an automated segmentation program (FreeSurfer). We corrected HF measurements for total cerebral volume using estimated total intracranial volume. Preoperative memory ability was assessed using the Wechsler Memory Scale (WMS-II: Logical Memory, Verbal Paired Associates, Family Pictures, and Faces subtests). We correlated memory ability with HF divisions volumes (head, body, and tail). Statistical analysis was conducted in SPSS 22.0 (repeated measures ANOVAs, one-way ANOVAs, Pearson r correlations).
Results:
In the repeated measures model, there was a main effect of HF division, with volume differences between head, body and tail, and with a two-way interaction of seizure focus and HF side (p< 0.001). For left foci, all three HF divisions were smaller ipsilaterally. For the right foci, the HF body and head were smaller ipsilaterally. There was also a three-way interaction of focus x HF side x HF division (p=0.001): for the left and right seizure foci groups respectively, head and body were smaller ipsilaterally. For left foci the tail was also smaller ipsilaterally. Logical Delayed Memory was significantly correlated with all left HF divisions (p< 0.05). Verbal Paired Associates Delayed was significantly correlated with all right HF divisions. Family Pictures Delayed was significantly correlated with left HF head and all right HF divisions (p< 0.05).
Conclusion:
Bilaterally, ipsilateral HF head and body appear most vulnerable to injury. The right HF divisions appear more susceptible to injury compared to left HF divisions. For some tests, there was a significant correlation with verbal and visual memory with left and right HF side respectively. Left anterior HF significantly correlated with visual memory. Our study suggests that while there may be functional differences along the HF longitudinal axis, left-right distinctions may be fluid. 
Funding:
:None