BACKGROUND: Hippocampal sclerosis (HS) is the most common surgical pathology associated with mesial temporal lobe epilepsy (MTLE). HS is typically characterized by mossy fiber sprouting (MFS) and reorganization of neuropeptide Y (NPY) fiber networks in the dentate gyrus. One potential cause of postoperative seizure recurrence following temporal lobe surgery may be the presence of seizure-associated bilateral hippocampal damage. We aimed to investigate patterns of hippocampal abnormalities in a postmortem series as identified by NPY and dynorphin immunohistochemistry. METHODS: Analysis of dentate gyrus fiber reorganization, using dynorphin (to demonstrate MFS) and NPY immunohistochemistry, was carried out in a postmortem epilepsy series of 25 cases (age range 21-96 years). In 9 patients, previously refractory seizures had become well controlled for up to 34 years prior to death. RESULTS: Bilateral MFS or abnormal NPY patterns were seen in 15 patients including those with bilateral symmetric, asymmetric, and unilateral HS by conventional histologic criteria. MFS and NPY reorganization was present in all classical HS cases, more variably in atypical HS, present in both MTLE and non-MTLE syndromes and with seizure histories of up to 92 years, despite seizure remission in some patients. CONCLUSION: Synaptic reorganization in the dentate gyrus may be a bilateral, persistent process in epilepsy. It is unlikely to be sufficient to generate seizures and more likely to represent a seizure-induced phenomenon.
BACKGROUND:Hippocampal sclerosis (HS) is the most common surgical pathology associated with mesial temporal lobe epilepsy (MTLE). HS is typically characterized by mossy fiber sprouting (MFS) and reorganization of neuropeptide Y (NPY) fiber networks in the dentate gyrus. One potential cause of postoperative seizure recurrence following temporal lobe surgery may be the presence of seizure-associated bilateral hippocampal damage. We aimed to investigate patterns of hippocampal abnormalities in a postmortem series as identified by NPY and dynorphin immunohistochemistry. METHODS: Analysis of dentate gyrus fiber reorganization, using dynorphin (to demonstrate MFS) and NPY immunohistochemistry, was carried out in a postmortem epilepsy series of 25 cases (age range 21-96 years). In 9 patients, previously refractory seizures had become well controlled for up to 34 years prior to death. RESULTS: Bilateral MFS or abnormal NPY patterns were seen in 15 patients including those with bilateral symmetric, asymmetric, and unilateral HS by conventional histologic criteria. MFS and NPY reorganization was present in all classical HS cases, more variably in atypical HS, present in both MTLE and non-MTLE syndromes and with seizure histories of up to 92 years, despite seizure remission in some patients. CONCLUSION: Synaptic reorganization in the dentate gyrus may be a bilateral, persistent process in epilepsy. It is unlikely to be sufficient to generate seizures and more likely to represent a seizure-induced phenomenon.
Authors: Martine M Mirrione; Dorothy K Konomos; Iordanis Gravanis; Stephen L Dewey; Adriano Aguzzi; Frank L Heppner; Stella E Tsirka Journal: Neurobiol Dis Date: 2010-04-09 Impact factor: 5.996
Authors: Claudia B Catarino; Joan Y W Liu; Ioannis Liagkouras; Vaneesha S Gibbons; Robyn W Labrum; Rachael Ellis; Cathy Woodward; Mary B Davis; Shelagh J Smith; J Helen Cross; Richard E Appleton; Simone C Yendle; Jacinta M McMahon; Susannah T Bellows; Thomas S Jacques; Sameer M Zuberi; Matthias J Koepp; Lillian Martinian; Ingrid E Scheffer; Maria Thom; Sanjay M Sisodiya Journal: Brain Date: 2011-06-29 Impact factor: 13.501
Authors: Maria Thom; Joan Y W Liu; Pam Thompson; Rahul Phadke; Marta Narkiewicz; Lillian Martinian; Derek Marsdon; Matthias Koepp; Luis Caboclo; Claudia B Catarino; Sanjay M Sisodiya Journal: Brain Date: 2011-09-08 Impact factor: 13.501
Authors: Maria Thom; Ioannis Liagkouras; Lillian Martinian; Joan Liu; Claudia B Catarino; Sanjay M Sisodiya Journal: Epilepsy Res Date: 2012-05-16 Impact factor: 3.045