title: Variability of sclerosis along the longitudinal hippocampal axis in epilepsy: a post mortem study.
abstract: Detailed neuropathological studies of the extent of hippocampal sclerosis (HS) in epilepsy along the longitudinal axis of the hippocampus are lacking. Neuroimaging studies of patients with temporal lobe epilepsy support that sclerosis is not always localised. The extent of HS is of relevance to surgical planning and poor outcomes may relate to residual HS in the posterior remnant. In 10 post mortems from patients with long histories of drug refractory epilepsy and 3 controls we systematically sampled the left and right hippocampus at seven coronal anatomical levels along the body to the tail. We quantified neuronal densities in CA1 and CA4 subfields at each level using Cresyl Violet (CV), calretinin (CR), calbindin (CB) and Neuropeptide Y (NPY) immunohistochemistry. In the dentate gyrus we graded the extent of granule cell dispersion, patterns of CB expression, and synaptic reorganisation with CR and NPY at each level. We identified four patterns of HS based on patterns of pyramidal and interneuronal loss and dentate gyrus reorganisation between sides and levels as follows: (1) symmetrical HS with anterior-posterior (AP) gradient, (2) symmetrical HS without AP gradient, (3) asymmetrical HS with AP gradient and (4) asymmetrical cases without AP gradient. We confirmed in this series that HS can extend into the tail. The patterns of sclerosis (classical versus atypical or none) were consistent between all levels in less than a third of cases. In conclusion, this series highlights the variability of HS along the longitudinal axis. Further studies are required to identify factors that lead to focal versus diffuse HS.
authors.affiliation: Department of Clinical and Experimental Epilepsy, UK. M.Thom@ion.ucl.ac.uk
authors.forename: Maria
authors.initials: M
authors.lastname: Thom
authors.forename: Ioannis
authors.initials: I
authors.lastname: Liagkouras
authors.forename: Lillian
authors.initials: L
authors.lastname: Martinian
authors.forename: Joan
authors.initials: J
authors.lastname: Liu
authors.forename: Claudia B
authors.initials: CB
authors.lastname: Catarino
authors.forename: Sanjay M
authors.initials: SM
authors.lastname: Sisodiya
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D048588:Benzoxazines; D056547:CA1 Region, Hippocampal / Q000378:metabolism / Q000473:pathology*; D064032:Calbindin 2; D064026:Calbindins; D002452:Cell Count / Q000379:methods; D004396:Coloring Agents; D018891:Dentate Gyrus / Q000378:metabolism / Q000473:pathology*; D004833:Epilepsy, Temporal Lobe / Q000473:pathology*; D005260:Female; D006801:Humans; D007395:Interneurons / Q000378:metabolism / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009478:Neuropeptide Y / Q000378:metabolism; D010078:Oxazines; D017966:Pyramidal Cells / Q000378:metabolism / Q000473:pathology; D064030:S100 Calcium Binding Protein G / Q000378:metabolism; D012598:Sclerosis / Q000473:pathology
chemical_list: D048588:Benzoxazines; C576764:CALB2 protein, human; D064032:Calbindin 2; D064026:Calbindins; D004396:Coloring Agents; D009478:Neuropeptide Y; D010078:Oxazines; D064030:S100 Calcium Binding Protein G; C028911:cresyl violet