Hepatic manifestations of tuberous sclerosis complex: a genotypic and phenotypic analysis.

Hepatic manifestations of tuberous sclerosis complex: a genotypic and phenotypic analysis. A retrospective review of the clinical records and radiological images of 205 patients with tuberous sclerosis complex (TSC) was performed to evaluate the prevalence and progression of hepatic lesions; examine the association of hepatic phenotype with genotype, age, and gender; and investigate the relationships between hepatic, renal, and pulmonary involvement. Hepatic angiomyolipomas (AML), cysts, and other benign lesions were identified in 30% of the cohort, and some lesions grew significantly over time. However, no patient had clinical symptoms or complications from hepatic lesions. TSC2 patients exhibited a higher frequency of AML compared to TSC1 patients (p = 0.037), and patients with no mutation identified exhibited a higher frequency of cysts compared to TSC2 patients (p = 0.023). Age was positively correlated with frequency of hepatic involvement (p < 0.001), whereas hepatic phenotype was independent of gender. Presence of hepatic AML was associated with presence of renal AML (p = 0.001). These findings confirm a high rate of asymptomatic hepatic lesions in TSC and further characterize the TSC phenotype.

Distinct clinical characteristics of tuberous sclerosis complex patients with no mutation identified.

Tuberous Sclerosis Complex (TSC) is a multi-system disorder that is highly variable in its clinical presentation. Current molecular diagnostic methods permit identification of mutations in either TSC1 or TSC2 in 75-85% of TSC patients. Here we examine the clinical characteristics of those TSC patients who have no mutation identified (NMI). A retrospective review of our patient population that had comprehensive testing for mutations in TSC1/TSC2 identified 23/157 (15%) that were NMI. NMI patients had a lower incidence of brain findings on imaging studies, neurological features, and renal findings than those with TSC2 mutations. In contrast, NMI patients had a lower incidence of seizures than TSC patients with TSC1 mutations, but had a higher incidence of both renal angiomyolipomas and pulmonary lymphangioleiomyomatosis. This distinct constellation of findings suggest that NMI patients may have a unique molecular pathogenesis, different from that seen in TSC patients with the usual mutations in TSC1 and TSC2. We suggest that the mechanisms of disease in these patients include both mosaicism for a TSC2 mutation, and unusual non-coding region mutations in TSC2.

The role of area 17 in visual imagery: convergent evidence from PET and rTMS.

Visual imagery is used in a wide range of mental activities, ranging from memory to reasoning, and also plays a role in perception proper. The contribution of early visual cortex, specifically Area 17, to visual mental imagery was examined by the use of two convergent techniques. In one, subjects closed their eyes during positron emission tomography (PET) while they visualized and compared properties (for example, relative length) of sets of stripes. The results showed that when people perform this task, Area 17 is activated. In the other, repetitive transcranial magnetic stimulation (rTMS) was applied to medial occipital cortex before presentation of the same task. Performance was impaired after rTMS compared with a sham control condition; similar results were obtained when the subjects performed the task by actually looking at the stimuli. In sum, the PET results showed that when patterns of stripes are visualized, Area 17 is activated, and the rTMS results showed that such activation underlies information processing.

Magnetoencephalographic mapping of interictal spike propagation: a technical and clinical report.

Distinguishing propagated epileptic activity from primary epileptic foci is of critical importance in presurgical evaluation of patients with medically intractable focal epilepsy. We studied an 11-year-old patient with complex partial epilepsy by using simultaneous magnetoencephalography (MEG) and electroencephalography (EEG). In EEG, bilateral interictal discharges appeared synchronous, whereas MEG source analysis suggested propagation of spikes from the right to the left frontal lobe.

The value of multichannel MEG and EEG in the presurgical evaluation of 70 epilepsy patients.

OBJECTIVE: To evaluate the sensitivity of a simultaneous whole-head 306-channel magnetoencephalography (MEG)/70-electrode EEG recording to detect interictal epileptiform activity (IED) in a prospective, consecutive cohort of patients with medically refractory epilepsy that were considered candidates for epilepsy surgery. METHODS: Seventy patients were prospectively evaluated by simultaneously recorded MEG/EEG. All patients were surgical candidates or were considered for invasive EEG monitoring and had undergone an extensive presurgical evaluation at a tertiary epilepsy center. MEG and EEG raw traces were analysed individually by two independent reviewers. RESULTS: MEG data could not be evaluated due to excessive magnetic artefacts in three patients (4%). In the remaining 67 patients, the overall sensitivity to detect IED was 72% (48/67 patients) for MEG and 61% for EEG (41/67 patients) analysing the raw data. In 13% (9/67 patients), MEG-only IED were recorded, whereas in 3% (2/67 patients) EEG-only IED were recorded. The combined sensitivity was 75% (50/67 patients). CONCLUSION: Three hundred and six-channel MEG has a similarly high sensitivity to record IED as EEG and appears to be complementary. In one-third of the EEG-negative patients, MEG can be expected to record IED, especially in the case of lateral neocortical epilepsy and/or cortical dysplasia.

Effects of stimulation intensity, gender and handedness upon auditory evoked potentials.

Left handers and women show less anatomical brain asymmetry, larger corpus callosum and more bilateral representation of specific functions. Sensory and cognitive components of cortical auditory evoked potentials (AEP) have been shown to be asymmetric in right handed males and to be influenced by stimulus intensity. In this study the influence of sex, handedness and stimulus intensity upon AEP components is investigated under basal conditions of passive attention. 14 right handed males, 14 right handed females, 14 left handed males, and 14 left handed females were studied while lying awake and paying passive attention to auditory stimulation (series of 100 binaural clicks, duration 1 msec, rate 1/sec, at four intensities). Cz, C3 and C4 referenced to linked mastoids and right EOG were recorded. Analysis time was 400 msec, average evoked potentials were based on 100 clicks. Stimulus intensity and gender affect early sensory components (P1N1 and N1P2) at central leads, asymmetry is influenced only by handedness, right handers showing larger P1N1 amplitudes over the right hemisphere.

[Personality dimensions and cerebral evoked potential]. / Dimensiones de personalidad y potencial evocado cerebral.

Eysenck's personality theory postulates 3 orthogonal dimensions of personality: extraversion (E), neuroticism (N) and psychoticism (P), predicting conductual and physiological predispositions to suffer mental illness. Biological bases of Eysenck's personality traits have been documented electrophysiologically. Psychoticism, the latest described dimension, is controverted, since there is some evidence of common factors with the other two. In order to assess the relation between Eysenck's dimensions and sensorial reactivity and information encoding processes we studied 20 healthy young subjects (mean age 28.5 years) with flash visual cortical evoked potentials (VEP, 3 intensities, peak to peak amplitude of III, IV-V-VI, VII components), and auditory cognitive evoked potentials (odd ball paradigm, P300 latency). There was a positive correlation between N and P dimensions (Spearman, r = 0.52), between N and VEP amplitude at high intensity (r = 0.58) and a negative correlation between E and P300 latency (r = 0.58). In short we found that P is not an independent dimension, but is related to sensorial reactivity. E dimension was related to encoding processes supporting Eysenck's observations about memory and learning differences.

[Topography and reactivity of the visual evoked potential]. / Topografía y reactividad del potencial evocado visual.

Augmenting/reducing (A/R) of visual evoked potentials (VEP) has been repeatedly observed in central derivations, with some subjects increasing, and others decreasing, VEP amplitude with increasing intensity of stimulation. Central derivations also exhibit hemispheric lateralization regarding A/R. This paper explores central and occipital VEP in the same population of 16 healthy, right-handed male subjects, stimulated with binocular light flashes 10 usec in duration delivered by à Grass PS2 stimulator at a rate of 1/sec and at the intensities of 0.36, 0.72 and 1.44 joules at source. Amplitudes and latencies of components P1, N1 and P2 agreed with those reported in the literature. On the basis of amplitude/intensity slope functions of "peak to peak" amplitudes (P1N1 and NIP2) at Cz, 10 augmenters (slope greater than 0) and 6 reducers (slope smaller than 0) were found. Compared to central leads (C3 and C4) occipital ones (O1 and O2) did not exhibit significant interhemispheric differences. Vertex augmenters for N1P2 were occipital reducers and vice-versa. The different characteristics of A/R at occipital and central leads are interpreted in terms of stages of visual information processing in primary and association areas and functional significance of VEP components.

Cortical thickness in a case of congenital unilateral perisylvian syndrome.

In congenital perisylvian syndrome, there is polymicrogyric cortex distributed in variable extensions around the sylvian fissure. Unilateral cases usually present with congenital hemiparesis, while bilateral cases have pseudobulbar paralysis of the oropharingoglossal region. Both unilateral and bilateral cases have a high rate of epilepsy. Polymicrogyric cortex is characterized by too many small convolutions. Often there are no intervening sulci, and almost no white matter can be seen under them. On MRI they appear to have increased thickness. Bilateral and symmetric polimycrogiria can be hard to recognize on standard MRIs. Accurate and automated methods for measuring the thickness of cerebral cortex are available. They have mainly been used to study a variety of disorders with diminished cortical thickness. We studied a case of right perisylvian polymicrogyria, who presented in adult life with epilepsy and had a normal neurological exam. Fischl and Dale's automated cortical thickness analysis rendered a very clear picture of increased cortical thickness with values up to 9 mm in the affected areas (normal cortical thickness varies between 1 and 4.5 mm). The thickest areas were seen over grossly abnormal gyri on the reconstructed cerebral cortex. On MEG he presented a prominent and monotonous 9 Hz activity that was located within the limits of a thick gyrus. There was a significant difference of thickness between homologous hemispheric areas. To our surprise some areas of the left hemisphere also appeared to have increased thickness, raising the question of a bilateral asymmetric case.

Dimensiones de personalidad y potencial evocado cerebral / Personality dimensions and cerebral evoked potential

La teoría de la personalidad de Eysenck postula 3 dimensiones ortogonales de personalidad: extraversion (E), neuroticismo (N), psicoticismo (P). Formula predicciones conductuales y fisiológicas relacionadas a la predisposición a ciertos trastornos. La base biológica de las dimensiones E y N se ha evidenciado en diferencias electrofisiológicas. La dimensión P, agregada posteriormente, ha sido más controvertida, postulándose que no es independiente de las dimensiones antes descritas. Con objetivo de estudiar las dimensiones de Eysenck, en particular P, en relacion a la reactividad sensorial y a procesos de codificación se registró potencial evocado visual (PEV) por flash a 3 diferentes intensidades y P300 auditiva en 20 voluntarios sanos (x28,5; ds 9,4 años). Se midió amplitud peak to peak y latencia de los componentes III, IV-V-VI y VII de PEV y de P300 mediante programa cursor. Hubo correlación positiva entre dimensiones N y P (spearman). r=0,52), entre P y amplitud del PEV (r=o,58) a intensidad alta y negativa entre E y latencia de P300 (r=0,58). Según nuestros hallazgos, la dimensión P no es independiente y demostró relación con la reactividad sensorial. La dimensión E se relacionó a la velocidad de codificación, apoyando las aseveraciones de Eysenck sobre memoria y aprendizaje

Topografia y reactividad del potencial evocado visual / Topography and reactivity of the visual evoked potential

El aumento - reducción (A-R) visual es evidente para las áreas centrales y exhibe diferencias hemisféricas. Este trabajo describe las características del potencial evocado visual (PEV) en derivaciones occipitales y su relación con A-R central: 16 sujetos de sexo masculino, diestros jóvenes y sanos recibieron flashes de 10 us, frec de de 1/s a intensidades de 0.36, 0.72 y 1.44 joules mediante estimulador Grass PS2. Se registró derivaciones Cz, C3, C4, Oz, O1, y O2 referidas a mastóides mediante electrodos subdérmicos. Un computador Nicolet CA-1000 promedió 100 respuestas para cada intensidad. Se midió latencia y amplitud peak to peak de los complejos P1N1 y N1P2 y se calculó pendiente intensidad/amplitud mediante regresión lineal. 10 sujetos tuvieron pendiente mayor que 0 en vertex (aumentadores) y 6 menor (reductores). P1N1 presenta reducción y asimetría hemisferíca en Cz, que no se observa en Oz. Los aumentadores de N1P1 a nivel de Cz son reductores a nivel de Oz y viceversa. Se discutem estos hallazgos en relación a las etapas en el procesamiento de la información visual y la significación funcional de los componentes del PEV

Pontenciales cerebrales endógenos y tiempo de reacción motora en relación con la edad / Cerebral endogenous evoked potentials and motor reaction time in relation to normal aging

La latencia de los componentes endógenos del potencial evocado auditivo (PEA) P2, N2 y P3 se relaciona al procesamiento del estímulo y a la selección de la respuesta conductual, pero no puede ser reducida a tales procesos. La posible asociación o disociación entre ellos puede ser explorada registrando simultáneamente PEA y tiempo de reacción (TR). Se formaron tres grupos de ambos sexos, de 14 Ss, cada uno: 1:17-27, II:29-40; III:41-63 años los Ss fueron sometidos al paradigma auditivo "Odball" con tarea de TR (con énfasis en la rapidez) con el fin de evocar potenciales ligados a eventos. TR y latencia de P2, N2 y P3 fueron significativamente menores en los grupos jóvenes comparados con el mayor, sugiriendo una diferencia cualitativa alrededor de los cuarenta años. Latencia de P3 no mostró correlación significativa con TR en ninguno de los grupos individuales, mientras N2 se correlacionó en todos ellos. Al restar latencia de N1 se producen correlaciones positivas significativas entre las latencias interpeak N1P3 con TR-N1. Estos datos apoyan la idea de procesos comunes subyacentes a los componentes endógenos N2 y P3 y a la generación del TR simple, ambos se iniciarían luego de un tiempo previo de procesamiento automático fijo (Lat N1)