Sequential analysis of fMRI images: A new approach to study human epileptic networks.

PURPOSE: The aim of this study was to introduce a new approach for analysis of functional magnetic resonance imaging (fMRI) data in order to illustrate the temporal development of the blood oxygenation level-dependent (BOLD) signal changes induced by epileptic seizures. METHOD: In order to sequentially analyze the fMRI images acquired during epileptic seizures, a continuous series of echo planar imaging (EPI) scans covering the complete period of a seizure was acquired. Data were segmented into 10-s blocks. Each block, representing a unique experimental condition, was contrasted with a neutral (no seizure) baseline condition. Visual comparison of the activations from one block to the next highlighted the course of activations and deactivations during the seizure event. This analysis was applied to three independent seizures of one patient with peri-rolandic epilepsy secondary to chronic encephalitis: one seizure before epilepsy surgery and two after unsuccessful tailored resection. Observations were compared to results from invasive subdural electroencephalography (EEG) monitoring, single-photon emission computed tomography (SPECT) coregistered to MRI (SISCOM), and independent component analysis (ICA), a model-free method of BOLD-signal analysis. RESULTS: The initial increase in BOLD signal occurred 10-40 s before clinical onset in the same location compared to the seizure-onset zone determined by invasive subdural evaluation and SISCOM. Sequential involvement of cortical and subcortical structures was in agreement with SISCOM, intracranial EEG recordings, and ICA results. DISCUSSION: In selected patients, sequential analysis of changes in BOLD signal induced by epileptic seizures might represent a useful approach for investigating the temporal development of brain activity during epileptic seizures, thereby allowing imaging of those cerebral structures involved in seizure generation and propagation.

Presurgical evaluation in refractory epilepsy secondary to meningitis or encephalitis: bilateral memory deficits often preclude surgery.

We investigated the clinical features and surgical outcome of 17 patients with refractory epilepsy secondary to CNS infection who were referred to a tertiary center for presurgical evaluation. Six patients had a history of meningitis and 11 patients had a history of encephalitis. Median age at infection was three years (40 days-40 years). Time to seizure onset was shorter in the encephalitis group (median of 0.9 years versus 5.9 years in the meningitis group). MRI showed unilateral mesial temporal sclerosis (MTS) in all but one patient with meningitis (5/6). MRI in the encephalitis group showed unilateral MTS (four patients), bilateral MTS (three), porencephalic cysts (one) or no significant findings (three). Seizure semiology, following analysis of 127 seizures, included automotor seizures, complex motor/hypermotor seizures, dialeptic seizures and bilateral asymmetric tonic seizures. Neuropsychological assessment in patients with MTS frequently showed bilateral memory impairment (7 out of 12 MTS-patients), even in 4 patients with unilateral MTS, precluding epilepsy surgery. Six patients (two meningitis and four encephalitis patients) underwent a temporal lobe resection. All patients are either seizure-free (Class 1a) or are having only auras after surgery. One patient from the meningitis group underwent functional hemispherectomy and he is also seizure-free. In our series, MTS was the most common finding in refractory epilepsy after CNS infections. Bilateral memory deficits were often encountered in patients with MTS, even when unilateral, these deficits being a limiting factor for surgery. Good surgical outcome can be expected in selected patients with unilateral MTS and congruent memory deficits.

Neuropsychological tests with lateralizing value in patients with temporal lobe epilepsy: reconsidering material-specific theory.

PURPOSE: To assess the ability of neuropsychological tests to determine the side of seizure onset for preoperative assessment in patients with drug-resistant temporal lobe epilepsy. METHODS: Twenty-nine consecutive patients diagnosed with temporal lobe epilepsy (TLE), in whom the epileptogenic focus was clearly identified and localized to either the right or left hemisphere. Patients underwent a full neuropsychological assessment as part of their pre-surgical investigation, including the Boston Naming Test (BNT) and a variety of Wechsler Adult Intelligence Scale-Third Edition (WAIS-III) and Wechsler Memory Scale-Third Edition (WMS-III) subtests. Two multivariate analyses of variance were carried out to assess differences on memory and language measures between groups according to side of epileptogenic focus. Binary logistic regression analysis was performed to find the sets of tests that best predicted the side of seizure onset (determined by EEG and MRI). RESULTS: Memory multivariate analysis of variance failed to show significant differences between the right- and left-sided groups. Among language measures, only the BNT revealed significant differences between the groups. The neuropsychological measures that best predicted the side of seizure onset were the BNT and Visual Reproduction II. CONCLUSIONS: Language measures predict the side of seizure focus better than memory measures. The results of this study in a sample of drug-resistant temporal lobe epilepsy patients challenge the memory material-specific theory for the side of seizure focus.

[Effects of kidney and pancreas transplantation on neurophysiological rates of polyneuropathy and autonomous cardiac function in diabetic patients with end-stage renal disease]. / Efectos del trasplante de riñón y páncreas en los índices neurofisiológicos de polineuropatía y función autonómica cardiorreguladora en pacientes diabéticos con insuficiencia renal terminal.

BACKGROUND: Patients with type 1 diabetes mellitus (DM1) and end-stage renal disease (ESRD) usually exhibit a severe polyneuropathy (PNP) whose progression can be halted after kidney and pancreas transplantation (KPT). We studied the evolution of both PNP and autonomous cardioregulatory function (ACF) in patients with DM1 and ESRD within the first year after KPT. PATIENTS AND MEHTOD: The study was carried out in 26 patients who underwent KPT and whose organs were functioning normally at least during one year after KPT. They were examined neurophysiologically in three different periods: a) before KPT; b) 1-3 months after KPT, and c) 12 months after KPT. We evaluated PNP by measuring the conduction velocity (CV) and the amplitude of the compound action potentials (ACAP) of common peroneal, posterior tibial and sural nerves. ACF was evaluated by measuring the change in the interval separating two consecutive QRS complexes in the electrocardiogram during quiet breathing and Valsalva manoeuvre. RESULTS: All patients had a severe PNP before KPT. Ten patients (38.4%) showed a significant reduction in ACAP and ACF in the exam carried out within 1 to 3 months after KPT, whereas all patients showed an increase in the CV, ACAP and ACF at 1 year after KPT. CONCLUSIONS: KPT induces a significant improvement of neurophysiological signs of PNP and of ACF, which is statistically significant at 1 year after KPT. In some patients, the improvement is heralded by an increase in the axonal damage, occurring in the first months after KPT, which may be due the aggression from the surgical treatment and related events.

Presurgical evaluation and cognitive functional reorganization in Fishman syndrome.

Fishman syndrome, also known as encephalocraniocutaneous lipomatosis (ECCL), is a rare, congenital neurocutaneous syndrome characterized by unilateral skin, eye, and brain abnormalities. Epileptic seizures and developmental delay are usually present. We report the clinical, radiological, and, for the first time, neurophysiological findings in a 24-year-old woman diagnosed with ECCL who was evaluated for epilepsy surgery. Functional magnetic resonance imaging revealed transfer of memory and language functions to the nonaffected hemisphere, providing evidence that functional reorganization and restoration of cognitive functions may occur in the context of extensive malformations, such as neurocutaneous syndromes.

Cerebrovascular disease as a complication of cardiac transplantation.

BACKGROUND AND OBJECTIVES: To characterize the frequency, risk factors, clinical presentation and etiological subtypes of cerebrovascular diseases (CVD) following cardiac transplantation (CTX). METHODS: In a retrospective review of our CTX database (period 1984-2002), we assessed demographic data, vascular risk factors, surgery and donor details. We classified ischemic stroke (IS) using the clinical criteria of the Oxfordshire Community Stroke Project and the etiological criteria of the TOAST study. Logistic regression analysis and survival curves were carried out. RESULTS: CTX was performed in a total of 314 patients (age 46 +/- 14 years, 78% male) and mean follow-up was 54 +/- 57 months. Twenty-two patients (7%) presented CVD: hemorrhagic stroke in 12%, transient ischemic attack in 28% and IS in 60%. CVD were early postoperative (less than 2 weeks) in 20% of patients and late in 80%. The clinical presentation in patients with IS was total anterior circulation (23.1%), partial anterior (38.4%), lacunar (15.4%) and posterior circulation (23.1%), and the etiological classification was large artery atherosclerosis (15.4%), cardioembolism (14.4%), small vessel disease (15.4%), unusual causes (15.4%) and undetermined cause (38.4%). The only independent predictor of CVD was a prior CVD event with an odds ratio of 8.2 (95% CI, 2.2-30.2, p < 0.02). The estimated risk of CVD at 5 years was greater (p < 0.02) in patients with prior CVD (4.1%) than in those without (1.1%). CONCLUSIONS: CVD are a relatively frequent complication after CTX (7%) and usually occur in the late postoperative phase. CVD prior to transplantation increase the risk of CVD after this procedure.