Hippocampal atrophy on MRI is predictive of histopathological patterns and surgical prognosis in mesial temporal lobe epilepsy with hippocampal sclerosis.
PURPOSE
To correlate hippocampal volumes obtained from brain structural imaging with histopathological patterns of hippocampal sclerosis (HS), in order to predict surgical outcome.


METHODS
Patients with mesial temporal lobe epilepsy (MTLE) with HS were selected. Clinical data were assessed pre-operatively and surgical outcome in the first year post surgery. One block of mid hippocampal body was selected for HS classification according to ILAE criteria. NeuN-immunoreactive cell bodies were counted within hippocampal subfields, in four randomly visual fields, and cell densities were transformed into z-score values. FreeSurfer processing of 1.5T brain structural images was used for subcortical and cortical volumetric estimation of the ipsilateral hippocampus. Univariate analysis of variance and Pearson's correlation test were applied for statistical analyses.


RESULTS
Sixty-two cases (31 female, 32 right HS) were included. ILAE type 1 HS was identified in 48 patients, type 2 in eight, type 3 in two, and four had no-HS. Better results regarding seizure control, i.e. ILAE 1, were achieved by patients with type 1 HS (58.3%). Patients with types 1 and 2 had smaller hippocampal volumes compared to those with no-HS (p<0.001 and p=0.004, respectively). Positive correlation was encountered between hippocampal volumes and CA1, CA3, CA4, and total estimated neuronal densities. CA2 was the only sector which did not correlate its neuronal density with hippocampal volume (p=0.390).


CONCLUSION
This is the first study correlating hippocampal volume on MRI submitted to FreeSurfer processing with ILAE patterns of HS and neuronal loss within each hippocampal subfield, a fundamental finding to anticipate surgical prognosis for patients with drug-resistant MTLE and HS.
['Jardim|Anaclara Prada|AP|', 'Corso|Jeana Torres|JT|', 'Garcia|Maria Teresa Fernandes Castilho|MT|', 'Gaça|Larissa Botelho|LB|', 'Comper|Sandra Mara|SM|', 'Lancellotti|Carmen Lúcia Penteado|CL|', 'Centeno|Ricardo Silva|RS|', 'Carrete|Henrique|H|', 'Cavalheiro|Esper Abrão|EA|', 'Scorza|Carla Alessandra|CA|', 'Yacubian|Elza Márcia Targas|EM|']
D000293:Adolescent D000328:Adult D000704:Analysis of Variance D034961:Antigens, Nuclear D001284:Atrophy D002452:Cell Count D000069279:Drug Resistant Epilepsy D004833:Epilepsy, Temporal Lobe D005260:Female D005500:Follow-Up Studies D006624:Hippocampus D006801:Humans D007150:Immunohistochemistry D008279:Magnetic Resonance Imaging D008297:Male D008875:Middle Aged D009419:Nerve Tissue Proteins D009929:Organ Size D011379:Prognosis D012598:Sclerosis D016896:Treatment Outcome D055815:Young Adult
Hippocampal atrophy Mesial temporal lobe epilepsy Hippocampal sclerosis Surgical outcome FreeSurfer analysis