O uso da tomografia por emissão de pósitrons (PET-scan) na localização de foco epileptogênico: relato de caso / Localizing value of positron emission tomography in focal epilepsy: case report

Introdução: A tomografia por emissão de pósitrons(PET-scan) é uma modalidade superior na demonstraçãopor imagem dos tecidos biológicos, constituindo um valiosométodo na detecção de alterações metabólicas efisiológicas teciduais. Relato de caso: Paciente do sexofeminino, cinco anos, sem consanguinidade ou antecedentespatológicos, com desenvolvimento neurológiconormal. Iniciou aos quatro anos, quadro de crises epilépticascaracterizadas por perda súbita do tônus postural,extensão do membro superior direito, postura em opistótonoe desvio óculo-cefálico para a esquerda, com duraçãode 30 segundos. Os exames físico e neurológicoeram normais. O eletroencefalograma mostrou atividadeepileptiforme focal na região occipital do hemisfériocerebral direito. Exames neurorradiológicos usuais nãomostraram anormalidades. A fim de se determinar o focoepileptogênico, realizou-se PET-scan que demonstrouhipometabolismo glicolítico nas regiões têmporo-occipitaldireita e parietal alta posterior direita. Discussão:Na investigação etiológica das epilepsias é importante aavaliação radiológica para a identificação de alteraçõesestruturais ou funcionais. Na maioria dos casos, a RM écapaz de identificar a fonte das crises, entretanto, ematé 30% dos pacientes com epilepsia focal, muitos delespotenciais candidatos a tratamento cirúrgico, a RM énormal. Alterações microscópicas que antes só podiamser estudadas por exame histológico, podem ser evidenciadasatravés do PET-scan, que, realizado no período interictal,pode demonstrar alterações metabólicas provenientesdo foco epileptogênico. Conclusão: Relatamosum caso onde o PET foi fundamental na demostraçãodo foco epileptogênico, podendo ser considerado umaimportante ferramenta no auxílio da investigação etiológicae no tratamento dos vários tipos de epilepsia.

Background: Positron-emission tomography (PET)scan is a superior technique in the imaging evaluationof biological tissues being a valuable method in the detectionof physiological and metabolic alterations. Casereport: A 5-year old female patient, born to nonconsanguineousparents with normal neurologic development.At the age of four she started to present epileptic seizurescharacterized by subtle lost of postural tone,extension of the right superior limb, opistotonus, andhead and eye deviation to the left with duration of 30seconds. Physical and neurological exams were normal.The electroencephalogram showed epileptiform activityin the occipital lobe of the right cerebral hemisphere.Conventional neuroradiological exams were normal. Inorder to determine the epileptogenic focus a PET-scanwere performed showing a glucose hipometabolism inthe right temporal and occipital lobes as well as in theposterior part of the right parietal lobe. Discussion: Duringthe etiologic investigation of epilepsies, radiologicinvestigations are important to identify functional orstructural abnormalities. In most of the cases, MRI canidentify the source of epileptic discharges, however, upto 30% of potential surgical candidates with focal epilepsyhave normal MRI. Microscopic alterations whichcould only be studied through histological exams cannow be detected by the PET-scan that, when performedduring interictal periods, can demonstrate metabolicalchanges originated in the epileptogenic focus. Conclusion:We report on a case where the PET-scan was fundamentalto the determination of the epileptogenic focusand it can in turn, be considered na important tool in theevaluation and treatment of several types of epilepsies.

Optic nerve enlargement in infantile form of Krabbe disease.

Krabbe disease (KD) is an autosomal recessive lysosomal storage disorder caused by dysfunctional galactosylceramidase activity. Infantile form is the most common subtype, occurring at about 6-month of age. We present a rare case of infantile KD with magnetic resonance imaging showing white matter, thalamic and basal ganglia lesions rarely associated with an enlargement of the optic nerves bilaterally.

Neuroradiological findings of an adolescent with early treated phenylketonuria: is phenylalanine restriction enough?

Phenylketonuria is caused by mutations in the enzyme phenylalanine hydroxylase gene, that can result in abnormal concentrations of phenylalanine on blood, resulting in metabolites that can cause brain damage. The treatment is based on dietary restriction of phenylalanine, and noncompliance with treatment may result in damage of the brain function. Brain abnormalities can be seen on magnetic resonance imaging of these individuals. Studies indicate that the appearance of abnormalities in white matter reflects high levels of phenylalanine on the blood. This case will show the clinical and neuroradiological aspects of a teenager with constant control of phenylalanine levels. Despite the continuous monitoring and early treatment, the magnetic resonance imaging identified impressive abnormalities in the white matter. This leads us to one question: is the restriction of phenylalanine sufficient to prevent changes in the white matter in patients with phenylketonuria?

Herpes simplex type 1 encephalitis restricted to the brainstem in a pediatric patient.

Herpes simplex encephalitis is a potentially fatal infection of central nervous system that typically involves frontal and temporal lobes. Occasionally, it presents an extratemporal involvement and in rarer cases, it is limited to the brainstem. We describe a case of an adolescent who presented with fever, sore throat, and vertigo. Clinical picture evolved to lethargy, tetraparesis, consciousness impairment, and respiratory failure. MRI showed lesions restricted to the brainstem. PCR of CSF was positive for herpes simplex type 1.

Magnetic resonance spectroscopy reveals an epileptic network in juvenile myoclonic epilepsy.

PURPOSE: To investigate the cerebral metabolic differences between patients with juvenile myoclonic epilepsy (JME) and normal controls and to evaluate to what extent these metabolic alterations reflect involvement of an epileptic network. METHODS: Sixty patients with JME were submitted to multi-voxel proton spectroscopy (1H-MRS) at 1.5 T over medial prefrontal cortex (MPC), primary motor cortex (PMC), thalamus, striatum, posterior cingulate gyrus (PCG), and insular, parietal, and occipital cortices. We determined ratios for integral values of N-acetyl-aspartate (NAA) and glutamate-glutamine (GLX) over creatine-phosphocreatine (Cr). The control group (CTL) consisted of 30 age- and sex-matched healthy volunteers. RESULTS: The NAA/Cr ratio, a measure of neuronal injury, was reduced in PMC, MPC, and thalamus among patients. In addition, they had an altered GLX/Cr ratio, which is involved in excitatory activity, on PMC, MPC, and PCG, where it was reduced, whereas it was increased on insula and striatum. Multiple regression analysis revealed the strongest correlation between thalamus and MPC, but the thalamus was also correlated with insula, occipital cortex, and striatum among patients. Lower NAA/Cr was observed with advancing age and duration of epilepsy, regardless of frequency of seizures and antiepileptic drug therapy in thalamus and frontal cortex. DISCUSSION: The identification of a specific network of neurochemical dysfunction in patients with JME, with diverse involvement of particular structures within the thalamocortical circuitry, suggests that cortical hyperexcitability in JME is not necessarily diffuse, supporting the knowledge that the focal/generalized distinction of epileptogenesis should be reconsidered. Furthermore, evidence is provided toward progressive neuronal dysfunction in JME.

Atividade da adenosinadeaminase no líquido cefalorraquiano / Adenosine deaminase activity in cerebrospinal fluid

Introdução. A adenosinadeaminase (ADA) é uma enzima que participa no metabolismo das purinas e, quando aumentada, foi tida por alguns autores como útil e até mesmo patognomônica da meningoencefalite tuberculosa (MTB). O objetivo deste trabalho é determinar o nível da atividade da adenosinadeaminase no líquido cefalorraquiano (LCR) em diversas condições patológicas, com especial referência a MTB. Métodos. A atividade da ADA foi estudada em 321 amostras de LCR de pacientes com meningite de diversas etiologias e outras alterações do LCR. Resultados. Amostras obtidas de pacientes portadores de MTB apresentaram um aumento estatisticamente significante entre a média da atividade da ADA e a média do grupo controle, e também em relação à média dos outros grupos: meningite séptica, meningite linfocitária e amostras em que se adicionou sangue humano fresco. Quando comparado ao grupo controle, amostras provenientes de pacientes com meningites de outras etiologias que não a tuberculosa também apresentavam aumento na atividade da ADA. Discussão. Verificou-se que há correlação direta entre a atividade da ADA e o número de linfócitos presentes na amostra de LCR. Assim sendo, o aumento da atividade desta enzima não é patognomônico de MTB, aumentando inclusive com a mistura de sangue acidental no LCR. Entretanto, verificou-se que a atividade da ADA acima de 24,1U/L em amostra de LCR é altamente sugestiva do diagnóstico de MTB.

Introduction. Adenosine deaminase (ADA) is an enzyme that participates in the metabolism of purines and, when its levels are high, some authors considered that it is useful or even pathognomonic of tuberculous meningitis (TBM). The objective of this study is to evaluate the levels of ADA activity in cerebrospinal fluid (CSF) of several pathologic conditions, especially TBM. Methods. Adenosine deaminase activity was studied in 321 samples of CSF from patients with meningitis from several etiologies and with other CSF alterations. Results. Samples from patients with TBM presented high ADA activity when compared with controls and when compared with the other groups. When compared to the controls, samples of CSF from patients with meningitis other than TBM also presented high ADA activity. Discussion. There is a direct correlation between ADA activity and the number of CSF lymphocytes, showing that a high ADA activity is not pathognomonic of TBM, increasing even with accidental blood mixture. However, ADA levels above 24.1U/L in a CSF sample are highly suggestive of TBM.