Impact of Navigated Task-specific fMRI on Direct Cortical Stimulation.

BACKGROUND AND STUDY AIMS: Cortical mapping (CM) with direct cortical stimulation (DCS) in awake craniotomy is used to preserve cognitive functions such as language. Nevertheless, patient collaboration during this procedure is influenced by previous neurological symptoms and growing discomfort with DCS duration. Our study aimed to evaluate the impact of navigated task-specific functional magnetic resonance imaging (nfMRI) on the practical aspects of DCS. MATERIAL AND METHODS: We recruited glioma patients scheduled for awake craniotomy for prior fMRI-based CM, acquired during motor and language tasks (i.e., verb generation, semantic and syntactic decision tasks). Language data was combined to generate a probabilistic map indicating brain regions activated with more than one paradigm. Presurgical neurophysiological language tests (i.e., verb generation, picture naming, and semantic tasks) were also performed. We considered for subsequent study only the patients with a minimum rate of correct responses of 50% in all tests. These patients were then randomized to perform intraoperative language CM either using the multimodal approach (mCM), using nfMRI and DCS combined, or electrical CM (eCM), with DCS alone. DCS was done while the patient performed picture naming and nonverbal semantic decision tasks. Methodological features such as DCS duration, number of stimuli, total delivered stimulus duration per task, and frequency of seizures were analyzed and compared between groups. The correspondence between positive responses obtained with DCS and nfMRI was also evaluated. RESULTS: Twenty-one surgeries were included, thirteen of which using mCM (i.e., test group). Patients with lower presurgical neuropsychological performance (correct response rate between 50 and 80% in language tests) showed a decreased DCS duration in comparison with the control group. None of the compared methodological features showed differences between groups. Correspondence between DCS and nfMRI was 100/84% in the identification of the precentral gyrus for motor function/opercular frontal inferior gyrus for language function, respectively. CONCLUSION: Navigated fMRI data did not influence DCS in practice. Presurgical language disturbances limited the applicability of DCS mapping in awake surgery.

A randomized, rater-blinded, parallel trial of intensive speech therapy in sub-acute post-stroke aphasia: the SP-I-R-IT study.

BACKGROUND: There is conflicting evidence regarding the benefits of intensive speech and language therapy (SLT), particularly because intensity is often confounded with total SLT provided. AIMS: A two-centre, randomized, rater-blinded, parallel study was conducted to compare the efficacy of 100 h of SLT in a regular (RT) versus intensive (IT) treatment in sub-acute post-stroke aphasia. METHODS & PROCEDURES: Consecutive patients with aphasia, within 3 months of a left hemisphere ischemic stroke, were randomized to IT (2 h per day × 5 days per week, 10 weeks) or RT (2 h per week × 50 weeks). Evaluations took place at 10, 50 and 62 weeks. Primary outcome was the frequency of responders, defined by 15% increase of Aphasia Quotient (AQ) from the baseline to 50 weeks. Secondary outcomes were changes from the baseline in AQ and functional communication profile (FCP) at 50 and 62 weeks and improvement stability between 50 and 62 weeks. OUTCOMES & RESULTS: Thirty patients were randomized and 18 completed the study. No significant differences were found between groups in primary or secondary outcomes, although IT patients (N = 9) obtained higher scores in language measures between 10 and 62 weeks in per protocol analysis. The number of non-completions was identical between groups. CONCLUSIONS & IMPLICATIONS: This study suggests that, in the sub-acute period following stroke and controlling for the number of hours of SLT provided, there is a trend for a greater improvement in language and functional communication measures with IT compared with RT. The lack of statistical significance in results was probably due to the small sample size.

Neurological subtle signs and cognitive development: a study in late childhood and adolescence.

INTRODUCTION AND AIM: Neurological subtle signs (NSS) are often observed during the neurological examination of children and tend to disappear with age. Their persistence into late adolescence or young adulthood has been related to psychiatric and neurocognitive disorders. To provide a better understanding of their functional basis, a longitudinal correlational study with neurocognitive measurements was performed. METHOD: We conducted multiple regression and correlation analyses of NSS with demographic and cognitive measures on a subset of 341 healthy children (56% males), taking part in a longitudinal dental study. Participants, whose ages ranged between 11-15 years, at first evaluation, undertook yearly, during 5 years, a 6-item NSS exam (producing a total score ranging between 0-18) and a comprehensive battery of neurocognitive tests. Effects of age, gender, IQ, and 7 neurocognitive factors on NSS were analyzed. RESULTS: Over the years, NSS scores correlated consistently with selective attention (Stroop test), motor speed (finger tapping), and visuomotor speed (pegboard speed). DISCUSSION: These results suggest that the disappearance of NSS in late childhood and adolescence occurs primarily in parallel with the development of motor and visuomotor functions and secondarily in relation to higher order functions such as selective attention (Stroop) and executive control (B-A Trails difference).

Cross linguistic aphasia testing: the Portuguese version of the Aachen Aphasia Test (AAT).

We report the adaptation of the Aachen Aphasia Test (AAT) to the Portuguese language (PAAT) and the results of its standardization in 125 persons with aphasia and 153 healthy controls. Patients with aphasia had a previous syndromic diagnosis, obtained through a Portuguese aphasia battery, which served as a reference. The control group was stratified by age and educational level. Hierarchical cluster analyses showed good construct validity. The increasing degree of difficulty and complexity throughout the item sets comprising subtests was confirmed. The discriminatory power of the PAAT for the selection of aphasic from non-aphasic persons proved to be as high as for the AAT versions in other languages. Classification of standard aphasic syndromes by means of discriminant analyses was good. Internal consistency, measured by means of Cronbach's alpha coefficient, was high to very high for the different PAAT subtests. Performance differences caused by age or educational level among the healthy control persons emphasized the need for correction factors. In conclusion, the PAAT showed robust psychometric properties, comparable to the original German and to adaptations to other languages. It constitutes a useful tool for cross-linguistic and multicenter studies.

A longitudinal study of neurological soft signs from late childhood into early adulthood.

Neurological examination of children includes the screening for soft neurological signs (NSS). There is little knowledge about their evolution during adolescence, except that their lasting presence has been associated with developmental, psychological, and cognitive disorders. We report the results of a NSS exam (assessing gross and fine motor function and the presence of hyperactivity and motor impersistence) over a 5-year period, among a group of healthy children who were followed annually as part of a dental study. Their ages ranged from 11 to 15 years at onset to 14 to 18 years at the end. Participants were divided into four groups by age (younger and older) and sex. At the first evaluation there were 191 males and 150 females. NSS score diminished both with increasing age and follow-up time in both groups, but at different rates in males and females. Females reached the lowest scores two years before the younger subgroup of males. These results show that NSS change rapidly in adolescence and at different rates in males and females, which must be taken into account in clinical contexts. The evolution of NSS suggests that they are a signature of neural development.

Neurological outcomes in children with and without amalgam-related mercury exposure: seven years of longitudinal observations in a randomized trial.

BACKGROUND: Although large-scale, randomized trials involving children have been completed and their results demonstrate an absence of neurobehavioral effects from clinical exposure to mercury amalgam, neurological findings from such studies have not been reported. METHODS: The authors conducted a randomized, prospective trial examining the safety of dental amalgam in which 507 children aged 8 through 12 years were assigned to treatment with either amalgam or resin-based composite. During seven years of follow-up, the authors performed annual clinical neurological examinations, including an evaluation of neurological hard signs (NHSs), presence of tremor and neurological soft signs (NSSs). RESULTS: The authors found no significant differences between treatment groups in any of the neurological measures. Groups did not differ with respect to the presence or absence of NHSs or tremor, nor the presence or absence or severity of NSSs at any point. As expected, NSS severity scores diminished with increasing age. CONCLUSIONS: Even at the levels of amalgam exposure in this study (a mean of 7.7-10.7 amalgam surfaces per subject across the seven years of follow-up), the authors conclude that exposure to mercury from dental amalgam does not adversely affect neurological status. CLINICAL IMPLICATIONS: The current evidence is that potential neurobehavioral or neurological effects from dental amalgam mercury exposure in children are inconsequential.

fMRI binary detection of brain activated regions with graph-cuts.

The functional Magnetic Resonance Imaging (fMRI) is a technique with increasing applications in studying the brain function. The blood-oxygenation-level-dependent (BOLD) is a fMRI method that allows the detection of brain activated regions after the application of an external stimulus, e.g., visual or auditive. This technique is based on the assumption that the metabolism increases in activated areas as well as the oxygen uptake. Analising this information is a challenging problem because the BOLD signal is very noisy and its changes due to the application of a stimulus are very weak. Therefore, the detection of temporal correlations with the applied stimulus requires sophisticated statistical algorithms to understand if the changes on the BOLD signal are pure noise or are related with the applied stimulus, called paradigm in the fMRI scope.

Neural physiological modeling towards a hemodynamic response function for fMRI.

The BOLD signal provided by the functional MRI medical modality measures the ratio of oxy- to deoxyhaemoglobin at each location inside the brain. The detection of activated regions upon the application of an external stimulus, e.g., visual or auditive, is based on the comparison of the mentioned ratios of a rest condition (pre-stimulus) and of a stimulated condition (post-stimulus). Therefore, an accurate knowledge of the impulse response of the BOLD signal to neural stimulus in a given region is needed to design robust detectors that discriminate, with a high level of confidence activated from non activated regions. Usually, in the literature, the hemodynamic response has been modeled by known functions, e.g., gamma functions, fitting them, or not, to the experimental data. In this paper we present a different approach based on the physiologic behavior of the vascular and neural tissues. Here, a linear model based on reasonable physiological assumptions about oxygen consumption and vasodilatation processes are used to design a linear model from which a transfer function is derived. The estimation of the model parameters is performed by using the minimum square error (MSE) by forcing the adjustment of the stimulus response to the observations. Experimental results using real data have shown that the proposed model successfully explains the observations allowing to achieve small values for the fitting error.