Internal border zone injury predicts the functional outcome of acute MCA stroke patients.

BACKGROUND AND PURPOSE: Classification of deep (D), superficial (S) MCA territories and their junctional vascular area (the internal border zone, IBZ) can help to identify patients most likely to benefit from aggressive reperfusion therapy after stroke. We tested the prognostic value of an IBZ injury compared to DWI-ASPECTS and infarct volume. MATERIALS AND METHODS: DW lesions of 168 patients with acute (4.2±6.5 h) MCA strokes were retrospectively examined and manually delineated. Patients with haemorrhagic transformation or other neurological diseases were excluded. Clinical data were recorded within 24 h following symptom onset and 48 h for patients who benefited from reperfusion therapy. The occurrence of an IBZ injury was determined using a standardized stereotaxic atlas. Performance to predict a good outcome (mRS<3 at 3 months) was estimated through ROC curves for DWI-ASPECTS≤6, lesion volume≥100 mL and IBZ injury. Logistic regression models were performed to estimate independent outcomes for infarct volume and IBZ injury. RESULTS: Infarcts involving the IBZ were larger (94.9±98.8 mL vs. 30.2±31.3 mL), had higher NIHSS (13.8±7.2 vs. 7.2±5.7), more frequent MCA occlusions (64.9% vs. 28.3%), and worse outcomes (mRS 3.0±1.8 vs. 1.9±1.7), and were less responsive to IVtPA (34±47% vs. 55±48% of NIHSS improvement). The area under the ROC curves was comparable between the occurrence of IBZ injury (0.651), ASPECTS≤6 (0.657) and volume≥100 mL (0.629). Logistic regression analyses showed an independent effect of an IBZ injury, especially for superficial MCA strokes and for patients who benefited from reperfusion therapy. CONCLUSION: An IBZ injury is an early and independent marker of stroke severity, functional prognosis and treatment responsiveness.

Presurgical Assessment of the Sensorimotor Cortex Using Resting-State fMRI.

BACKGROUND AND PURPOSE: The functional characterization of the motor cortex is an important issue in the presurgical evaluation of brain lesions. fMRI noninvasively identifies motor areas while patients are asked to move different body parts. This task-based approach has some drawbacks in clinical settings: long scanning times and exclusion of patients with severe functional or neurologic disabilities and children. Resting-state fMRI can avoid these difficulties because patients do not perform any goal-directed tasks. MATERIALS AND METHODS: Nineteen patients with diverse brain pathologies were prospectively evaluated by using task-based and resting-state fMRI to localize sensorimotor function. Independent component analyses were performed to generate spatial independent components reflecting functional brain networks or noise. Three radiologists identified the motor components and 3 portions of the motor cortex corresponding to the hand, foot, and face representations. Selected motor independent components were compared with task-based fMRI activation maps resulting from movements of the corresponding body parts. RESULTS: The motor cortex was successfully and consistently identified by using resting-state fMRI by the 3 radiologists for all patients. When they subdivided the motor cortex into 3 segments, the sensitivities of resting-state and task-based fMRI were comparable. Moreover, we report a good spatial correspondence with the task-based fMRI activity estimates. CONCLUSIONS: Resting-state fMRI can reliably image sensorimotor function in a clinical preoperative routine. It is a promising opportunity for presurgical localization of sensorimotor function and has the potential to benefit a large number of patients affected by a wide range of pathologies.

Identification of the in vivo elastic properties of common carotid arteries from MRI: a study on subjects with and without atherosclerosis.

The stiffness of the arterial wall, which is modified by many cardiovascular diseases such as atherosclerosis, is known to be an indicator of vulnerability. This work focuses on the in vivo quantification of the stiffness of the common carotid artery (CCA) by applying the Magnitude Based Finite Element Model Updating (MB-FEMU) method to 13 healthy and diseased volunteers aged from 24 to 76 years old. The MB-FEMU method is based on the minimisation of the deviation between the image of a deformed artery and a registered image of this artery deformed by means of a finite elements analysis. Cross sections of the neck of each subject at different times of the cardiac cycle are recorded using a Phase Contrast cine-MRI. Applanation tonometry is then performed to obtain the blood pressure variations in the CCA throughout a heart beat. First, a time averaged elastic modulus of each CCA between diastole and systole is identified and a stiffening of the artery with age and disease is observed. Second, four elastic moduli are identified during a single heart beat for each artery, highlighting the nonlinear mechanical behaviour of the artery. A stiffening of the artery is observed and quantified at systole in comparison to diastole.

Neural correlates of olfactory processing in congenital blindness.

Adaptive neuroplastic changes have been well documented in congenitally blind individuals for the processing of tactile and auditory information. By contrast, very few studies have investigated olfactory processing in the absence of vision. There is ample evidence that the olfactory system is highly plastic and that blind individuals rely more on their sense of smell than the sighted do. The olfactory system in the blind is therefore likely to be susceptible to cross-modal changes similar to those observed for the tactile and auditory modalities. To test this hypothesis, we used functional magnetic resonance imaging to measure changes in the blood-oxygenation level-dependent signal in congenitally blind and blindfolded sighted control subjects during a simple odor detection task. We found several group differences in task-related activations. Compared to sighted controls, congenitally blind subjects more strongly activated primary (right amygdala) and secondary (right orbitofrontal cortex and bilateral hippocampus) olfactory areas. In addition, widespread task-related activations were found throughout the whole extent of the occipital cortex in blind but not in sighted participants. The stronger recruitment of the occipital cortex during odor detection demonstrates a preferential access of olfactory stimuli to this area when vision is lacking from birth. This finding expands current knowledge about the supramodal function of the visually deprived occipital cortex in congenital blindness, linking it also to olfactory processing in addition to tactile and auditory processing.

[Neuro-anatomic activations of prepotent responses in schizophrenia in Hayling's task]. / Inhibition des réponses automatiques au test du Hayling dans la schizophrénie.

OBJECTIVES: In schizophrenia, alteration in the prefrontal cortex can induce some deficiencies of the executive functions, and among them errors in inhibition of prepotent responses. This type of inhibitory processes was called "restraint function" by Hasher et al. It implies a conscious and voluntary inhibition which demands attentional resources. Among the tasks exploring this function, the Hayling completion sentence task (Burgess and Shallice) appears to be the most specific. Moreover, healthy subjects performing this task in functional magnetic resonance imaging (fMRI) show activation of the prefrontal cortex. In this study, we investigated inhibitory processes in schizophrenic patients using two versions of the Hayling completion sentence task, a behavioural version and an fMRI version in order to assess both performance levels and brain correlates of inhibitory processes. METHODS: Forty-eight schizophrenic participants according to DSM-IV, (mean age: 32.8, S.D. 7.7), stabilized for at least one month, receiving antipsychotic medication and with IQ higher than 70 (mean: 96.86, S.D. 20.67) and education level (mean: 11.15, S.D. 3.26) participated in the behavioural study. They were matched on age (mean: 33.8, S.D. 7.6) and education level (mean: 12.28, S.D. 2.87) with thirty-two healthy controls. Nineteen of schizophrenic participants (mean age: 33, S.D. 6.9 and IQ: 99, S.D. 10.74) were assessed by an fMRI adaptation of the Hayling task, matched with 12 controls (mean: 33.9, S.D. 7.3). All the participants had to perform the Hayling task and a speed accuracy task. The Hayling task consists in sentences for which the last word is missing. In the initiation condition, the participants had to complete the sentence with the appropriate word, whereas in inhibition condition the participants had to complete the sentence with inappropriate and unrelated words. RESULTS: Compared to controls, schizophrenics showed an increased number of errors in the inhibition of prepotent responses associated with increased reaction times, even when considering information processing speed. fMRI results showed fairly similar frontal activations in both groups. Nevertheless, schizophrenic patients presented principally large activations in dorsolateral and ventrolateral frontal cortex, the superior frontal sulcus, the frontal pole and the premotor cortex, and stronger activations (bilateral) in the posterior parietal cortex. Control subjects demonstrated a network of deactivated brain regions whereas the schizophrenics did not. DISCUSSION: Our results are in favour of poorer efficacy of restraint function, sometimes comprising impairment of inhibitory processes inducing errors in schizophrenics. This deficiency might be considered as insufficiency in attentional resources and/or in working memory. Hence patients cannot simultaneously restrain prepotent response and find appropriate controlled strategy for correct completion of the task. Moreover, bilateral patterns of parietal hyperactivation and absence of patterns of deactivation seem also in favour of an attentional hypothesis. The Hayling task might be interesting for assessment of inhibitory processes in schizophrenia.

Prenatal diagnosis in Luxembourg.

Social and medical issues regarding prenatal diagnosis in Luxembourg are addressed. The organisation and the overall impact of amniocentesis on aneuploid births are described. Legal aspects are discussed as are future developments.

Computer applications in thermoregulatory research.

Thermoregulatory information is a frequently used parameter in both physiological and psychophysiological research. Specific software programs using accepted formulae are not readily available to the scientist as is the hardware. The program described here uses the well-established physiological model by Burton, calculating mean skin temperature and mean body temperature. The primary goal of this microsoft Basic program is to aid the researcher through speed of execution and quantitative reliability. A few command alterations will allow this program to be used with most microcomputer systems currently available. The time saved using this program will greatly enhance the efficiency of the researcher's thermoregulatory data analyses.