Structural abnormalities of the thalamus in juvenile myoclonic epilepsy.

Studies have suggested that the thalamus is a key structure in the pathophysiology of juvenile myoclonic epilepsy. The objective of the present investigation was to examine the thalami of patients with juvenile myoclonic epilepsy using a combination of multiple structural neuroimaging modalities. The association between these techniques may reveal the mechanisms underlying juvenile myoclonic epilepsy and help to identify the neuroanatomical structures involved. Twenty-one patients with juvenile myoclonic epilepsy (13 women, mean age=30±9 years) and a control group of 20 healthy individuals (10 women, mean age=31±8 years) underwent MRI in a 2-T scanner. The volumetric three-dimensional sequence was used for structural investigation. Evaluation of the thalamus comprised voxel-based morphometry, automatic volumetry, and shape analysis. Comparisons were performed between patient and control groups. Voxel-based morphometry analysis identified areas of atrophy located in the anterior portion of the thalamus. Post hoc analysis of automatic volumetry did not reveal significant differences between the groups. Shape analysis disclosed differences between patients and controls in the anterior and inferior portions of the right thalamus and in the anterior portion of the left thalamus. The present investigation confirms that thalami of patients with juvenile myoclonic epilepsy are structurally abnormal with impairments located mainly in the anterior and inferior sections.

Voxel-based morphometry in patients with idiopathic generalized epilepsies.

Idiopathic generalized epilepsies (IGE) are a group of frequent age-related epilepsy syndromes. IGE are clinically characterized by generalized tonic-clonic, myoclonic and absence seizures. According to predominant seizure type and age of onset, IGE are divided in subsyndromes: childhood absence and juvenile absence epilepsy (AE), juvenile myoclonic epilepsy (JME) and generalized tonic-clonic seizures on awakening (GTCS). The limits between these subsyndromes are not well defined, supporting the existence of only one major syndrome. Visual assessment of routine magnetic resonance imaging (MRI) in patients with IGE is normal. MRI voxel-based morphometry (VBM) uses automatically segmented gray and white matter for comparisons, eliminating the investigator bias. We used VBM to study 120 individuals (47 controls, 44 with JME, 24 with AE and 15 with GTCS) to investigate the presence of subtle structural abnormalities in IGE subsyndromes. VBM was performed searching for abnormalities on gray matter concentration (GMC) between patients groups and controls. Compared to controls, JME presented increased GMC in frontobasal region and AE showed increased GMC in the superior mesiofrontal region. The GTCS group did not differ from controls. There were no areas of reduced GMC with the statistical level selected. Region of interest analysis showed increased GMC in the anterior portion of the thalamus in patients with absence seizures. Our results support subtle GMC abnormalities in patients with JME and AE when compared to controls. These findings suggest the existence of different patterns of cortical abnormalities in IGE subsyndromes.

EEG features in idiopathic generalized epilepsy: clues to diagnosis.

PURPOSE: To investigate the EEG profile and its contribution for diagnosis and management in a group of patients with a clinical diagnosis of idiopathic generalized epilepsy (IGE) who were referred to a tertiary hospital. METHODS: We retrospectively studied clinical and EEG features of 180 consecutive patients with IGE. Eighty patients were diagnosed with juvenile myoclonic epilepsy (JME), 35 had absence epilepsy (AE), 13 had generalized tonic-clonic seizures on awakening (GTCS-A), 28 had generalized tonic-clonic seizures only (TCS), and 24 had adult-onset idiopathic generalized epilepsy (AIGE). The EEGs were classified in typical (synchronous generalized spike or polyspikes-and-wave discharges with normal background), atypical (with clear focalities or asymmetries), and normal. RESULTS: The 493 EEG exams were analyzed. The first EEG was normal in 45% of the 180 patients, and only 33% had typical abnormalities. AE had a higher proportion of typical examinations and needed fewer sequential examinations to register a typical abnormality compared with the other groups. By contrast, the serial EEG profile of TCS and AIGE showed a higher proportion of normal and atypical EEG findings. CONCLUSIONS: These findings support previous recommendations that IGE patients should be treated with appropriate therapy based on clinical history. Waiting for a typical abnormal EEG pattern can generate an unacceptable delay in the correct diagnosis and treatment of these patients. In patients with long-term epilepsy, the diagnosis may be difficult. Furthermore, serial EEGs can help to elucidate the syndromic diagnosis, especially in patients with TCS and AIGE.

MRI volumetry shows increased anterior thalamic volumes in patients with absence seizures.

The interaction between thalamus and cortex appears to be critical to the pathophysiology of idiopathic generalized epilepsies (IGEs). The objective of this study was to investigate thalamic volumes of a group of patients with IGEs using high-resolution MRI. Thalamic segmentation was performed by the same rater, who was unaware of the diagnosis. Thalamic volumes were divided into anterior half and posterior half. One hundred forty-seven patients were scanned (71 with juvenile myoclonic epilepsy, 49 with generalized tonic-clonic seizures only, and 27 with absence epilepsy). Subgroup analyses with corrections for multiple comparisons showed that, when compared with those of controls, anterior thalamic volumes were increased in patients with absence epilepsy and juvenile myoclonic epilepsy with absence seizures, but not in patients with generalized tonic-clonic seizures only and juvenile myoclonic epilepsy without absence seizures. Our results demonstrated that the anterior thalamus is structurally different in patients with IGEs and absence seizures as compared with patients with IGEs without absence seizures.

Estudo da açäo depressora inespecífica do suco extraído das folhas de Bryophyllum calcynum Salisb. (Crassulaceae) sobre o sistema nervoso central: comparaçäo com os efeitos da difenidramina / Study on the innespecific depressive action of the leaves juice of Bryophillum calycinum Salisb. (Crassulaceae) in the central nervous system: comparison whith diphenhydramine effects

Bryophyllum calcynum Salisb (Crassulaceae) é uma planta largamente utilizada em regiöes tropicais e subtropciais como medicaçäo tópica em afecçöes cutäneas de natureza alérgica. Tal utilizaçäo foi fundamentada sob o ponto de vista farmacológico, por um trabalho (NASSIS, 1991) que demonstra ser o suco extraído das folhas desta planta, um potente antagonista dos receptores H1 a nível periférico em ratos. Durante a realizaçäo do referido trabalho, foi verificada uma aparente açäo depressora central exercida pelo suco caracterizada por sonolência e imobilidade dos animais. No presente trabalho, a proposta foi estudar tal açäo, verificando se realmente o suco exercia açäo depressora significativa sobre o SNC. Os experimentos realizados demonstraram que o suco (4,0g/Kg) inibe a atividade locomotora em campo aberto, e potência o tempo de sono induzido por pentobarbital em ratos. Resultados similares foram obtidos com a administraçäo de difenidramina (20mg/Kg), indicando a necessidade de realizaçäo de experimentos mais especificos para a verificaçäo de uma eventual açäo anti-histamínina central