Abstracts

Rationale: In recent years drug-resistant epilepsy associated with amygdala enlargement(AE) has attracted significant attention. It is an important question that whether the seizure symptoms and memory changes seen in this pathology are different from those in temporal lobe epilepsy with hippocampal sclerosis(HS). We conducted a comparative investigation of seizure characteristics, neuropsychological test results and the cerebral glucose metabolism between a group of patients with enlarged amygdala without hippocampal sclerosis (AE group), and a group of those with hippocampal sclerosis (HS group). Methods: The subjects were 2 patients groups with drug-resistant temporal lobe epilepsy: with enlarged amygdala (without HS) and with HS. Findings were confirmed on MRI and all patients underwent detailed examination (including neuropsychological tests) and treatment between January 2010 and April 2016 at the Juntendo Epilepsy Center. There were 10 patients in the AE group (mean age: 31 years, left side: n=6), and 12 patients in the HS group (mean age: 35.5 years, left side: n=6). We compared both groups, looking at the age of initial onset of epileptic seizures, disease duration until the neuropsychological testing, seizure frequency, memory function using the WMS-R (Wechsler Memory Scale-Revised) and temporal lobe metabolism on the affected side using FDG-Positron Emission Tomography (PET). Results: The age of seizure onset was 25.2 years in the AE group compared to 18.1 years in the HS group, indicating that the AE group was significantly older at onset. Disease duration was 5.8 years in the AE group and 17.4 years in the HS group, being significantly longer for the HS group. Seizure frequency tended to be higher in the AE group than in the HS group, but it was not a statistically significant difference. With WMS-R, there was no memory impairment in the AE group, in spite of the higher seizure frequency, but both cases of left and right side in the HS group had distinctively poorer verbal memory, visual memory, general memory and delayed recall. Particularly, verbal memory was poor in patients with HS of dominant hemisphere. The PET scan demonstrated significantly reduced metabolism in not only the hippocampus but also amygdala in the HS group, however didn't reduced in the AE group. This was shown to correlate with memory impairment. Conclusions: We found that patients with temporal lobe epilepsy associated with AE had a later onset of seizures compared to those with HS, but their seizure frequency was comparatively higher. But, in spite of the higher seizure frequency, these patients did not manifest memory disorders and did not significantly reduce metabolism in not only the hippocampus but also amygdala, irrespective of focus side. From the above results, we believe that the clinical characteristics of temporal lobe epilepsy with amygdala enlargement are caused by the different pathological changes from those of hippocampal sclerosis. Funding: none