Role of hippocampal volumetry in drug resistant epilepsy

Background: Hippocampus is a brain structure located deep in the temporal lobe. The structure is crucial for learning and memory and is a natural inhibitor of seizure activity in brain. In drug resistant epilepsy (DRE), there is shrinkage of the hippocampus leading to poor seizure control.Methods: Patients meeting the diagnostic criteria for drug resistant epilepsy between the age group of 10-60 years were enrolled in the study. Epileptic non drug resistant controls and normal healthy individuals were taken from same cohort. Selected patients underwent MRI Brain and their hippocampal volumes were estimated manually. Coronal oblique sections, perpendicular to the long axis of hippocampus were taken and hippocampal volume (HV) were calculated using region of interest approach with manual delineation . Results: There was increment in detecting hippocampal atrophy from 30% to 46.6% in DRE patients when manual hippocampal atrophy was used in addition to visual assessment. The mean right and left hippocampal volumes in drug resistant epilepsy cases were found to be 2.17+0.57 cc and 1.52+0.54 cc respectively. Left HV was found to be statistically significantly smaller than right side (p value < 0.05). DRE patients had smaller mean bilateral HV than healthy controls, the difference being 33%. The left HV loss was almost double the right HV loss among DRE cases. The hippocampal volumes were reduced in DRE patients compared to epileptic non-resistant patients; however the difference was found to be less than that of normal healthy controls.Conclusion: Manual hippocampal volumetry detected more patients with hippocampal atrophy in our study compared to visual assessment. Manual hippocampal volumetry should be routinely done in patients with Drug resistant epilepsy.

Correlation between hippocampal volumes and proton magnetic resonance spectroscopy of the posterior cingulate gyrus and hippocampi in alzheimer disease / Correlação entre os volumes hipocampais e a espectroscopia por ressonância magnética do giro do cíngulo posterior e dos hipocampos na doença de alzheimer

Prior studies have reported hippocampal volume loss, decrease in N-Acetylaspartate (NAA) concentration and increased myo-inositol (mI) concentration in patients with Alzheimer disease (AD). The purpose of this study was to evaluate hippocampal volumes of AD patients and their correlation with metabolic changes detected by proton spectroscopy (1H MRS) of hippocampal formations and the posterior cingulate region. Materials and Methods: 22 patients with probable AD (18 mild, 4 moderate) and 14 elderly controls without cognitive symptoms, were enrolled in the study. Hippocampal volumetric measurements, single-voxel 1H MRS of the posterior cingulate region and of hippocampal formations were obtained. The following metabolite ratios were evaluated: NAA/Cr, mI/Cr, mI/NAA. Statistical analysis was performed to detect differencesand correlations between these parameters in patients and controls. Results: The hippocampal volume of patientsand controls did not differ significantly. The results of 1H MRS differed significantly between patientsand controls in the hippocampal formations (mI/Cr, mI/NAA) and posterior cingulate region (NAA/Cr, mI/Cr, mI/NAA). The best predictor of AD diagnosis was NAA/Cr in the posterior cingulate region, having a sensitivity of 0.899 and specificity of 0.800. There was no correlation between hippocampal volumes and the results of 1H MRS in patients with AD. Conclusions: The results of 1H MRS differed significantly between patients and controls in hippocampal formations and the posterior cingulate region, with NAA/Cr proving to be the best predictor for AD. No correlation between hippocampal volumes and the results of 1H MRS in patients with AD was observed.

Estudos anteriores demostraram redução do volume hipocampal, redução da concentração de N- Acetilaspartato (NAA) e aumento da concentração de mio-inositol (mI) em pacientes com doença de Alzheimer (DA). O objetivo deste trabalho foi de avaliar os volumes hipocampais de pacientes com DA e correlacioná-los com as alterações metabólicas detectadas pela espectroscopia de próton das formações hipocampais e da região do cíngulo posterior. Material e Métodos: 22 pacientes com provável DA (18 leve, 4 moderada) e 14 controles sem sintomas cognitivos foram incluídos neste estudo . Medidas volumétricas hipocampais, espectroscopia de próton de voxel único das formações hipocampais e da região do cíngulo foram obtidos. As seguintes razões de metabólitos foram avaliadas NAA/Cr, mI/Cr, mI/NAA. Análise estatística foi realizada para detectar as diferenças e correlações entre estes parâmetros nos pacientes e nos controles. Resultados: Os volumes das formações hipocampais dos pacientes e dos controles não foram significativamente diferentes. Os resultados da espectroscopia de próton foram significativamente diferentes nas das formações hipocampais dos pacientes e controles (mI/Cr, mI/NAA) e na região do cíngulo posterior (NAA/Cr, mI/Cr, mI/NAA). O melhor indicador para DA foi a razão NAA/Cr na região do cíngulo posterior com sensibilidade de 0,899 e especificidade de 0,800. Não houve correlação entre os volumes das formações hipocampais e os resultados da espectroscopia de próton nos pacientes com DA. Conclusões: Os resultados da espectroscopia de próton foram significativamente diferentes entre pacientes e controles das formações hipocampais e na região do cíngulo posterior, sendo NAA/Cr o melhor indicador para DA. Não houve correlação entre os volumes das formações hipocampais e os resultados da espectroscopia de próton nos pacientes com DA.

The Relationship between Hippocampal Damage on MRI and Secondarily Generalized Tonic Clonic Seizures in Temporal Lobe Epilepsy : Quantitative and Qualitative MRI Study / 대한간질학회지

PURPOSE: It has been suggested that recurrent seizures may cause the hippocampal formation (HF) damage in temporal lobe epilepsy (TLE). To evaluate whether secondarily generalized tonic clonic seizure (SGTC) is related to the degree of the HF damage on MRI we performed this study. METHODS: We found 42 patients with TLE who had HS on qualitative MRI from epilepsy database. They were divided into unilateral HS (UHS) and bilateral HS (BHS) on qualitative MRI by visual analysis. We performed HF volumetry in 20 and T2 relaxometry in 22 (17 patients were lateralized by quantitative MRI and ictal or interictal EEG). RESULTS: The frequency of status epilepticus and SGTCs in BHS were significantly higher than that in UHS (14% vs 3%, p<0.05 and 60% vs 6%, p<0.05 respectively). Of 17 patients who were lateralized, the frequency of SGTCs was significantly correlated to the ipsilateral (r=0.58, p<0.05) and contralateral (r=0.35, p<0.05) T2 relaxometry as well as inversely to the ipsilateral (r=-0.59, p<0.05) and contralateral (r=-0.52, p<0.05) HF volume. CONCLUSIONS: BHS has the higher frequency of status epilepticus and SGTCs, and the frequency of SGTCs was related to the HF damage.