Volumetric analysis of contralateral hippocampus after temporal lobe surgery: short-term and long-term evaluation

• Grant number: 15/10369-7
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): August 01, 2015
• Effective date (End): July 31, 2018
• Field of knowledge: Health Sciences - Medicine - Medical Clinics
• Principal Investigator: Clarissa Lin Yasuda
• Grantee: Bruna Ferreira Silva
• Host Institution: Faculdade de Ciências Médicas (FCM). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Associated research grant: 13/07559-3 - BRAINN - The Brazilian Institute of Neuroscience and Neurotechnology, AP.CEPID

Abstract

Rationale: Surgical removal of the mesial temporal lobe structures has been the treatment of choice for mesial temporal lobe epilepsy (TLE), resulting in good seizure control for approximately 65% of patients. Various surgical approaches have been used to remove mesial temporal structures like the amygdala and hippocampus, including selective amygdalohipocampectomy or more traditionally, anterior temporal lobectomy. Despite the good seizure control, there are few studies that show the progression of structural abnormalities after surgery, both in temporal and extra-temporal areas, specifically in white matter. However, little is known about the postoperative structural changes in the contralateral hemisphere, more particularly in the hippocampus and gray matter. Given the importance of the contralateral hippocampus for the performance of memory and other cognitive functions, the investigation of possible changes in the postoperative period is certainly of great importance. A better understanding of the dynamic changes that include the contralateral hippocampus can provide some insight into the cognitive alterations observed after surgery. We recently assessed the volume of the contralateral hippocampus after surgery for TLE and observed a significant reduction, after a mean interval of 8 years. However, there is a lack of information about the "timing" of the process that occurs in the development of such changes. Similarly, no data related to acute changes in the contralateral hemisphere (both temporal and extra-temporal) that occur soon after surgery. Therefore, in this study, we will perform the manual contralateral hippocampus volumetry three times (preoperative, acute postoperative period (first week) and long-term postoperative period (at least 6 months)) for patients undergoing temporal lobe surgery for refractory TLE with hippocampal sclerosis. We will also compare hippocampal volumes in patients undergoing corticectomy due to other causes of refractory epilepsy (cortical dysplasia) and in healthy volunteers.Our hypothesis is that the reduction of hippocampal volume specifically occurs in patients undergoing surgery for refractory TLE and that acute changes can predict hippocampal late volume, as well as cognitive changes.Methods: Longitudinal Analysis of TLE patients undergoing amygdalohipocampectomy (15 patients), patients with other epilepsy undergoing corticectomy (15 patients) and 15 healthy volunteers with two MRIs.We will perform the manual volumetry of the contralateral hippocampus using Display software (Montreal Neurological Institute), with T1-weighted images with high resolution (voxel 1x1x1mm), acquired in 3Q PHILIPS scanner. For patients, we willl perform volumetry in scans in 3: 1) preoperative, 2) acute postoperative (1 week maximum) and 3) long-term postoperative period (6 months minimum). The student will perform the manual volumetric "blindly"; ie without prior knowledge about the condition of subjects (seizure control), the time elapsed after surgery (acute or chronic), or information on the state control of postoperative seizures.MRI scans and clinical data have been collected as part of routine monitoring of patients operated on our Epilepsy Service.For statistical analysis, we will use SPSS 22, using General Linear Models (GLM) ANOVA (repeated measures) for analysis of 2 times and mixed models (Mixed Models) for the analysis of 3 points over time.