OBJECTIVES: The neuroanatomical basis and the neurochemical abnormalities that underlay juvenile myoclonic epilepsy (JME) are not fully defined. While the thalamus plays a central role in synchronization of widespread regions of the cerebral cortex during a seizure, emerging evidence suggests that all cortical neurons may not be homogeneously involved. The purpose of this study was to investigate the cerebral metabolic differences between patients with JME and normal controls. METHODS: All patients had a JME diagnosis based on seizure history and semiology, EEG recording, normal magnetic resonance neuroimaging (MRI) and video-EEG. Forty JME patients (JME-P) were submitted to 1.5 T MRI proton spectroscopy (1H-MRS), multi-voxel with PRESS sequence (TR/TE = 1500/30 ms) over the following locations: prefrontal cortex (PC), frontal cortex (FC), thalamus, basal nuclei, posterior cingulate gyrus (PCG), insular, parietal and occipital cortices. We determined ratios for integral values of N-acetyl aspartate (NAA) and glutamine-glutamate (GLX) over creatine-phosphocreatine (Cr). The control group (CTL) consisted of 20 age and sex-matched healthy volunteers. RESULTS: Group analysis demonstrated a tendency for lower NAA/Cr ratio of JME-P compared to CTL predominantly on FC, PC, thalamus and occipital cortex. When compared to CTL, JME-P had a statistically significant difference in GLX/Cr on FC, PC, insula, basal nuclei, PCG and on thalamus. When evaluating the relationship among the various components of this epileptic network among JME-P, the strongest correlation occurred between thalamus and PC. Also, we found a significant negative correlation between NAA/Cr and duration of epilepsy. CONCLUSION: Reductions in NAA may represent loss or injury of neurons and/or axons, as well as metabolic dysfunction while glutamate is considered to be an excitatory neurotransmitter in the brain which is involved in the pathogenesis of epileptogenic seizures.

Foram estudados 26 pacientes com epilepsia do lobo temporal clinicamente documentada por vários EEGs com atividade epileptiforme intercrítica e TC de crânio normal. SPECT com99mTC HMPAO e ressonância magnética (RM) foram realizados em todos os casos. 61.5% (n=16) das RM e 65.4% (n=17) dos SPECTs revelaram algum tipo de anormalidade. Atrofia hipocampal, nas imagens enfatizadas em Tl e presença de hipersinal nas imagens enfatizadas em T2, sugerindo esclerose mesial temporal, foram o principal achado (n=12; 75% das RM anormais). RM correlacionou-se ao EEG em 50% (n=13). Concordância entre RM e SPECT ocorreu em 30.7% (n=8) e entre SPECTe EEG em 57.7% (n=15). RM, SPECT e EEG foram congruentes em 26.9% (n=7). Estes resultados refletem o valor do SPECT intercrítico e RM na detecção e lateralização de anormalidades em epilepsia do lobo temporal. Por outro lado, em dois casos, o SPECT correlacionou-se mal com o EEG. Este método funcional não deve ser utilizado isoladamente na detecção de focos temporais. RM é mais útil do que a TC como recurso de neuroimagem na epilepsia do lobo temporal. Ela pode detectar pequenas lesões estruturais e esclerose mesial temporal, não facilmente identificáveis pela TC.

26 patients with temporal lobe epilepsy clinically documented by several abnormal interictal surface EEGs with typical unitemporal epileptiform activity and a normal CT scan were studied. Interictal99mTC HMPAO brain SPECT and MRI were performed in all subjects. Abnormalities were shown in 61.5% of MRI (n=16) and 65.4% of SPECT (n=17). Hippocampal atrophy associated to a high signal on T2-weighted MRI slices suggesting mesial temporal sclerosis was the main finding (n=12; 75% of abnormal MRI). MRI correlated well to surface EEG in 50% (n=13). There was also a good correlation between MRI and SPECT in 30.7% (n=8). SPECT and EEG were in agreement in 57.7% (n=l5). MRI, SPECT and EEG were congruent in 26.9% (n=7). These results support the usefulness of interictal brain SPECT and MRI in detecting lateralized abnormalities in temporal lobe epilepsy. On the other hand, in two cases, interictal SPECT correlated poorly with surface EEG. This functional method should not be used isolately in the detection of temporal lobe foci. MRI is more useful than CT as a neuroimaging technique in temporal lobe epilepsy. It may detect small structural lesions and mesial temporal lobe sclerosis which are not easily seen with traditional CT scanning.