Relationship between cerebral cortical volume and limbic structures in memory and treatment response in patients with mesial temporal lobe epilepsy

Author(s)

Denise Pacagnella

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Ciências Médicas
• Defense date: 2016-03-18

Examining board members

Fernando Cendes; Americo Ceiki Sakamoto; Luiz Henrique Martins Castro; Carlos Alberto Mantovani Guerreiro; Maria Augusta Santos Montenegro

• Advisor: Fernando Cendes; Clarissa Lin Yasuda

Abstract

Rationale: Mesial Temporal Lobe Epilepsy (MTLE) is the most frequent form of focal epilepsy in adults. Mesial temporal sclerosis is the underlying pathology in 50-70% of cases. Patients are often refractory to clinical treatment and targeted to surgery for seizure control. Material-specific memory impairment is a common finding on neuropsychological assessment (NPA). However, few studies evaluated the influence of seizure frequency in these main clinical findings. Purpose: To assess cortical thickness, progression of hippocampal volume (HV), T2 signal and episodic memory in MTLE patients with hippocampal atrophy (HA) having frequent (FS) or infrequent seizures (IS) and patients who underwent surgery (SUR). Methods: We considered FS as, at least, one dyscognitive seizure per month. IS were considered as, three or less dyscognitive seizures per year and no event evolving to a bilateral convulsive seizure. All had high resolution MRIs acquired on a 3 Tesla - Philips Achieva System. HVs were obtained in 17 patients with FS, 26 patients with IS, 20 SUR patients and 55 controls by FreeSurfer software. T2 relaxometry was performed in 18 patients with FS, 26 patients with IS, 19 SUR patients and 23 controls through Aftervoxel program. Cortical thickness was compared between 67 MTLE patients and 57 controls according to the HA laterality, seizure frequency and memory performance. NPA consisted of subtests from Wechsler Memory Scale Revised, subtests from Wechsler Adult Intelligence Scale Revised and the Rey Auditory Learning Test Verbal. Two NPAs were performed in 20 patients with FS, 23 patients with IS and 21 SUR patients. Results: We did not observe changes in the ipsilateral HV over time, however, there was a decrease of contralateral VH in SUR patients (p=0.007). Regarding to T2 relaxometry, we found an increase of signal in the ipsilateral hippocampus of IS patients (p=0.034), however, T2 signal was higher in FS patients since the first MRI acquisition. There were no changes in the contralateral hippocampal signal. We observed cortical thinning of ipsilateral parietal lobe in patients with Right-HA and bilateral cortical thinning of occipital lobe in patients with Left-HA. We also observed cortical thinning of parietal and occipital lobe regions on the hemisphere ipsilateral to the HA and cortical thinning of frontal and occipital lobe regions on the hemisphere contralateral to the HA, particularly in FS and patients with memory impairment. Regarding the NPA, longitudinally, patients with IS had better scores in General Memory (p=0.01) and Visual Reproduction I (p=0.045) than FS. Finally, SUR patients showed better scores on Logical Memory II (p=0.008) and Visual Reproduction I (p=0.021). Conclusions: Recurrent seizures may be associated with extratemporal cortical damage. However, changes in the hippocampus appear to occur regardless of seizure frequency. In patients with MTLE and HA, memory impairment may be more associated with extratemporal cortical damage than the seizure frequency. However, good seizure control seems to help on memory performance of MTLE patients over time (AU)

• FAPESP's process: 11/20856-1 - Relationship between the volume of the cerebral cortex and limbic structures in memory and treatment response in patients with mesial temporal lobe epilepsy
• Grantee: Denise Pacagnella
• Support Opportunities: Scholarships in Brazil - Doctorate