title: Comparison of Cognitive Parameters Between Bilateral and Unilateral Hippocampal Sclerosis.
abstract: BACKGROUND
  Recent studies showed that hippocampal sclerosis (HS) patients with unilateral involvement had more diffuse cognitive impairment than expected. Therefore, we aimed to compare the cognitive profiles of bilateral HS (BHS) patients with unilateral HS (UHS) patients.
  
  
  METHODS
  Consecutive patients, diagnosed with epilepsy, who fulfilled two major magnetic resonance imaging (MRI) criteria (T1 atrophy and T2-FLAIR hyperintensity) for HS were included. Standard neuro-psychological test (NPT) battery consisted of the Turkish version of 15-word verbal memory processes test, Wechsler memory scale visual reproduction subtest, forward and backward digit span, phonemic and semantic fluency, and Stroop test were applied; and the groups with right HS, left HS, and bilateral HS were compared statistically.
  
  
  RESULTS
  Ninety-one patients, completing the NPT (34 males, 57 females)-16 with BHS, 36 with right HS, and 39 with left HS-were included. Six out of 43 operated patients had BHS. There were no significant differences in education and handedness of the groups. Even though NPT performances of the BHS group were found to be poor compared to UHS subgroups, this was beyond statistical significance. Comparison of BHS with the right HS group showed a significant difference in the learning score of the Verbal Memory Processes Test, but recognition scores were found to be similar in all groups. Compared to the BHS group, both right and left HS groups revealed a significant difference in delayed recall score of the Verbal Memory Processes Test. Although there were no significant differences in the postoperative parameters of the BHS group, UHS subgroups had deficits in many postoperative parameters.
  
  
  CONCLUSIONS
  Our study revealed that bilateral involvement of the hippocampi was correlated with a poor cognitive performance. Retrieval failure, rather than a total recall problem, in the memory of the patients resembles a more diffuse involvement not only limited to limbic structures.
authors.affiliation: Department of Neurology, İstanbul University İstanbul School of Medicine, İstanbul, Turkey.
authors.forename: Ebru Nur
authors.initials: EN
authors.lastname: Vanli Yavuz
authors.affiliation: Department of Neurology, İstanbul University İstanbul School of Medicine, İstanbul, Turkey.
authors.forename: Başar
authors.initials: B
authors.lastname: Bilgiç
authors.affiliation: Department of Neurology, İstanbul University İstanbul School of Medicine, İstanbul, Turkey.
authors.forename: Zeliha
authors.initials: Z
authors.lastname: Matur
authors.affiliation: Department of Neurology, İstanbul University İstanbul School of Medicine, İstanbul, Turkey.
authors.forename: Nerses
authors.initials: N
authors.lastname: Bebek
authors.affiliation: Department of Neurology, İstanbul University İstanbul School of Medicine, İstanbul, Turkey.
authors.forename: Candan
authors.initials: C
authors.lastname: Gürses
authors.affiliation: Department of Neurology, İstanbul University İstanbul School of Medicine, İstanbul, Turkey.
authors.forename: Ayşen
authors.initials: A
authors.lastname: Gökyiğit
authors.affiliation: Department of Neurology, Laboratory of Neuropsychology, İstanbul University İstanbul School of Medicine, İstanbul, Turkey.
authors.forename: Öget
authors.initials: Ö
authors.lastname: Öktem
authors.affiliation: Department of Neurology, İstanbul University İstanbul School of Medicine, İstanbul, Turkey.
authors.forename: Betül
authors.initials: B
authors.lastname: Baykan
keywords: Epilepsy; bilateral hippocampal sclerosis; cognition; hippocampal sclerosis