title: Is 'burned-out hippocampus' syndrome a distinct electro-clinical variant of MTLE-HS syndrome?
abstract: To study the clinical, electrophysiological and imaging characteristics of patients with unilateral mesial temporal lobe epilepsy (MTLE) with contralateral ictal onset on scalp EEG, viz. 'burned-out hippocampus' syndrome (MTLE-BHS).
  
  
  
  MTLE-BHS was defined as TLE with unilateral hippocampal sclerosis (HS) without any dual pathology on MRI and contralateral ictal onset on scalp EEG, unlike in classical hippocampal sclerosis (HS). Consecutive "MTLE-BHS" patients evaluated at our Centre for Comprehensive Epilepsy Care from January 2005 to July 2014 were studied. Twenty-five cases of classic MTLE-HS operated during the same period were also analyzed for comparison.
  
  
  
  Seventeen patients were diagnosed to have MTLE-BHS. Mean age of seizure onset was 9.5±7.7years and the mean duration of epilepsy was18.2±7.3years. Epigastric aura was more common in MTLE-HS and fear, secondary generalized seizures and temporal polar changes on MRI were more prevalent in the MTLE-BHS subgroup. In the latter group, five (29%) exhibited seizure semiology and 2 (12%) had interictal discharges discordant to the side of MTS. Eight (47%) patients in the MTLE-BHS sub-group had normal medial temporal volume on Scheltens scale. Eight patients among MTLE-BHS underwent surgery (4 following intracranial monitoring that localized to the side of HS) with Engel class I outcome at 1year follow-up in 6 and Engel class II outcome in 2.
  
  
  
  Attenuation of ipsilateral fast ictal rhythms on scalp EEG as well as neocortical changes are likely to be deterministic factors for MTLE-BHS as opposed to the severity of hippocampal atrophy. Considering good post-operative outcomes, intracranial monitoring for surgical selection is not mandatory in MTLE-BHS despite discordant semiology and ictal onset, in the presence of inter-ictal, functional imaging and neuropsychology data concordant to the side of HS.
authors.affiliation: Dept. of Neurology, Jawaharlal Institute of Post Graduate Medical Education & Research, Puducherry 605006, India.
authors.forename: Pradeep P
authors.initials: PP
authors.lastname: Nair
authors.affiliation: R Madhavan Nayar Centre for Comprehensive Epilepsy Care, Department of Neurology, SreeChitraTirunal Institute for Medical Sciences and Technology, Thiruvananthapuram 695011, India. Electronic address: rsnmenon@sctimst.ac.in.
authors.forename: Ramshekhar N
authors.initials: RN
authors.lastname: Menon
authors.affiliation: R Madhavan Nayar Centre for Comprehensive Epilepsy Care, Department of Neurology, SreeChitraTirunal Institute for Medical Sciences and Technology, Thiruvananthapuram 695011, India.
authors.forename: Ashalatha
authors.initials: A
authors.lastname: Radhakrishnan
authors.affiliation: R Madhavan Nayar Centre for Comprehensive Epilepsy Care, Department of Neurology, SreeChitraTirunal Institute for Medical Sciences and Technology, Thiruvananthapuram 695011, India.
authors.forename: Ajit
authors.initials: A
authors.lastname: Cherian
authors.affiliation: R Madhavan Nayar Centre for Comprehensive Epilepsy Care, Department of Neurology, SreeChitraTirunal Institute for Medical Sciences and Technology, Thiruvananthapuram 695011, India.
authors.forename: Mathew
authors.initials: M
authors.lastname: Abraham
authors.affiliation: R Madhavan Nayar Centre for Comprehensive Epilepsy Care, Department of Neurology, SreeChitraTirunal Institute for Medical Sciences and Technology, Thiruvananthapuram 695011, India.
authors.forename: George
authors.initials: G
authors.lastname: Vilanilam
authors.affiliation: R Madhavan Nayar Centre for Comprehensive Epilepsy Care, Department of Neurology, SreeChitraTirunal Institute for Medical Sciences and Technology, Thiruvananthapuram 695011, India.
authors.forename: C
authors.initials: C
authors.lastname: Kesavadas
authors.affiliation: R Madhavan Nayar Centre for Comprehensive Epilepsy Care, Department of Neurology, SreeChitraTirunal Institute for Medical Sciences and Technology, Thiruvananthapuram 695011, India.
authors.forename: Bejoy
authors.initials: B
authors.lastname: Thomas
authors.affiliation: R Madhavan Nayar Centre for Comprehensive Epilepsy Care, Department of Neurology, SreeChitraTirunal Institute for Medical Sciences and Technology, Thiruvananthapuram 695011, India.
authors.forename: Aley
authors.initials: A
authors.lastname: Alexander
authors.affiliation: R Madhavan Nayar Centre for Comprehensive Epilepsy Care, Department of Neurology, SreeChitraTirunal Institute for Medical Sciences and Technology, Thiruvananthapuram 695011, India.
authors.forename: Sanjeev V
authors.initials: SV
authors.lastname: Thomas
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D004569:Electroencephalography / Q000379:methods; D004833:Epilepsy, Temporal Lobe / Q000145:classification / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D005260:Female; D006624:Hippocampus / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D006801:Humans; D007223:Infant; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods; D011446:Prospective Studies; D012189:Retrospective Studies; D012640:Seizures / Q000503:physiopathology; D013577:Syndrome; D016896:Treatment Outcome
keywords: EEG; Epilepsy surgery; Hippocampal sclerosis; Ictal rhythms; Temporal lobe epilepsy