Functional MR imaging in assessment of language dominance in epileptic patients.

The value of functional MR Imaging (fMRI) in assessing language lateralization in epileptic patients candidate for surgical treatment is increasingly recognized. However few data are available for left-handed patients. Moreover determining factors for atypical dominance in patients investigated with contemporary imaging have not been reported. We studied 20 patients (14 males, 6 females; 9 right handed, 11 left handed) aged from 9 to 48 years, investigated for intractable partial epilepsy. Epileptic focus location was temporal in 14 cases, extratemporal in 6, and lateralized in the left hemisphere in 11/20. Hemispheric dominance for language was evaluated by both Wada test and fMRI using a silent word generation paradigm in all patients. Furthermore, a postictal speech test was performed in 15 patients. An fMRI language lateralization index was calculated from the number of activated pixels (Student's t test, P < 0.0001) in the right and left hemispheres. The Wada test showed a right hemispheric dominance in 8 patients (6 were left handed and 2 right handed) and a left hemispheric dominance in 12 patients (5 were left handed and 7 right handed). These results were concordant with clinical postictal examination in 11/15 patients (73%). Clinical status did not allow a conclusion about hemispheric dominance for the remaining 4 patients. FMRI was concordant with the Wada test in 19/20 cases. For one left-handed patient, fMRI showed bilateral activation, whereas the Wada test demonstrated a right hemispheric dominance. Right language lateralization was significantly correlated with left lateralized epilepsy (P < 0.05) but was not correlated with age at epilepsy onset, early brain injury (before 6 years), and lobar localization of epileptogenic focus. However the lack of a significant relationship between these factors and atypical language lateralization may be related to the small sample size.

Using a bidimensional t test to compare simultaneous activations in functional brain MRI.

The aim of functional brain magnetic resonance imaging studies is to determine which regions of the brain are related to a given specific task. Different methods can be used to extract the functional signal and there is currently no consensus for this operation. Measures based on correlation are only relevant for a single task. In this paper, we propose a method based on a multivariable Student's t test that permits the comparison of the results of successive activations. This technique allows a qualitative analysis of complex tasks, making possible to deal with both similar and different activated cortical areas.

Sensorimotor cortical activity in patients with complete spinal cord injury: a functional magnetic resonance imaging study.

Residual activation of the cortex was investigated in nine patients with complete spinal cord injury between T6 and L1 by functional magnetic resonance imaging (fMRI). Brain activations were recorded under four conditions: (1) a patient attempting to move his toes with flexion-extension, (2) a patient imagining the same movement, (3) passive proprio-somesthesic stimulation of the big toes without visual control, and (4) passive proprio-somesthesic stimulation of the big toes with visual control by the patient. Passive proprio-somesthesic stimulation of the toes generated activation posterior to the central sulcus in the three patients who also showed a somesthesic evoked potential response to somesthesic stimulation. When performed under visual control, activations were observed in two more patients. In all patients, activations were found in the cortical areas involved in motor control (i.e., primary sensorimotor cortex, premotor regions and supplementary motor area [SMA]) during attempts to move or mental imagery of these tasks. It is concluded that even several years after injury with some local cortical reorganization, activation of lower limb cortical networks can be generated either by the attempt to move, the mental evocation of the action, or the visual feedback of a passive proprio-somesthesic stimulation.

Multimodal anatomic, functional, and metabolic brain imaging for tumor resection.

OBJECTIVE: Improvement of neurosurgical techniques with a more detailed description of brain tumors and their functional environment. METHODS: We performed: (1) anatomical magnetic resonance imaging (MRI) for reference, (2) functional sequences dedicated to the adjacent cortical structures (sensorimotor, visual, language paradigms), and (3) thallium 201 cerebral tomoscintigraphy to visualize active tumor invasion. Data were transferred to a workstation for automatic registration. RESULTS: All data were combined into one synthetic image showing the foci of high proliferative activity, which have to be completely resected, and the peritumoral functional structures, which have to be spared in order to minimize postoperative sequelae. This trimodal image is entered into a surgical neuronavigation computer for preoperative planning in order to outline tumoral target and functional risk areas. All this information is displayed in the operative microscope (Zeiss MKM) optically linked to MR images. This multimodality technique diminishes operative time by reducing electrocorticography and improves the operative short-term outcome. CONCLUSION: Multimodal imaging is useful for optimization of neurosurgical tumor resection.

[Morphological imagery of the occipital lobe]. / Imagerie morphologique du lobe occipital.

After reviewing the anatomical and functional aspects of the occipital lobe, the authors detail its gyral and sulcal anatomy using MRI in the three planes, with particular attention given to the localization of the calcarine fissure.

[Clinical application of functional MRI: a strategic tool for neurosurgery]. / Application clinique de l'IRM fonctionnelle: aide à la stratégie neurochirurgicale.

The purpose was to incorporate preoperative functional imaging data into anatomic data of operative microscope for neurosurgical procedures of patients suffering from lesions contiguous to eloquent brain areas. The day before surgery, patients bearing scalp markers underwent fMRI, just before anatomical contrast-enhanced MR images. FMRI data analysis were realised using a t test (p<0.0001). The resulting functional-anatomical images were downloaded onto a surgical neuronavigation computer in order to outline tumoral target and functional areas. At surgery, cortical stimulation has been used to confirm functional data. Functional image-guided surgery of lesions abutting functional cortex can be safely performed.

Functional MR imaging and traumatic paraplegia: preliminary report.

PURPOSE: To evaluate residual activity in the sensorimotor cortex of the lower limbs in paraplegia. METHODS: 5 patients suffering from a complete paralysis after traumatic medullar lesion (ASIA=A). Clinical evaluation of motility and sensitivity. 1. Control functional MR study of the sensorimotor cortex during simultaneous movements of hands, imaginary motor task and passive hands stimulation. 2. Concerning the lower limbs, 3 fMRI conditions: 1-patient attempts to move his toes with flexion-extension, 2-mental imagery task of the same movement, 3-peripheral passive proprio-somesthesic stimulation (squeezing) of the big toes. RESULTS: Activations were observed in the primary sensorimotor cortex (M1), premotor regions and in the supplementary motor area (SMA) during movement and mental imaginary tasks in the control study and during attempt to move and mental imaginary tasks in the study concerning the lower limbs. Passive somesthesic stimulation generated activation posterior to the central sulcus for 2 patients. CONCLUSION: Activations in the sensorimotor cortex of the lower limbs can be generated either by attempting to move or mental evocation. In spite of a clinical evaluation of complete paraplegia, fMRI can show a persistence of sensitive anatomic conduction, confirmed by Somesthesic Evoked Potentials.

CT and MRI findings in primitive pituitary abscess: a case report and review of literature.

Pituitary abscess is not rare. Clinical and radiological features in a primitive pituitary abscess are reported. Transphenoidal surgery revealed an abscess. Preoperative diagnosis of pituitary abscess remains difficult. Sellar round cystic mass isointense to grey matter on T1, high intensity signal on T2, with a peripheral rim enhancement following gadolinium injection associated with thickened stalk and diabetes insipidus may be suggestive of pituitary abscess.

[Imaging of encephalic parasitic diseases]. / Imagerie des parasitoses encéphaliques.

We review the main cerebral parasitic diseases, with emphasis on the most frequently encountered in Europe.

Human African trypanosomiasis: MRI.

We report a case of human African trypanosomiasis caused by Trypanosoma brucei rhodesiense. After the febrile period of parasite dissemination, the patient had meningeal involvement but normal CT. MRI showed the appearances of meningitis. After two periods of arsenical treatment, a severe encephalopathy occurred suggesting post-therapeutic reactive encephalitis (PTRE). Nevertheless, T2-weighted MRI showed no oedema, but focal bilateral high signal areas in the white matter. PTRE was excluded and a third course of treatment was undertaken. The lesions progressively disappeared.

"Follow-up" method for processing of brain function MR images.

FMRI with standard 1.5 T scanners requires adapted algorithms because the time course of intensity signal showed a non-linearity of the baseline. The protocol contains sequential images covering periods of rest followed periods of stimulation. The images of each period of rest and stimulation were averaged, offering a series of averaged images. From this series, we conserved only the pixels which presented the alternated variations corresponding to the temporal pattern of the paradigm. A colour scale was used to present the average percentage of variations of each pixel selected. We have performed activation paradigms with a classical motor protocol. This simple "follow-up" method appears effective for the identification of activated areas.

Functional magnetic resonance imaging at 1.5 T during sensorimotor and cognitive task.

Functional activations of the human brain cortex were observed with a standard 1.5-tesla MR imaging system using a long time echo fast low-angle shot sequence. Neural activation increases regional cerebral blood flow resulting in increased capillaries and venous blood oxygenation. Processing requires adapted algorithms because the time course of intensity signal showed fluctuations of the baseline. The use of a 'follow-up' method to generate activation maps is proposed. Brain activation was detected in striate cortex during photic stimulation and in sensorimotor areas while subjects were moving their hands. In mental imagery tasks, we observed a primary and secondary visual cortex activation during memory recall of the flashing light. Motor ideation showed an activation of the rolandic areas.

[Functional cerebral neuro-imaging at 1.5 Tesla. The results of visual, sensorimotor and auditory stimulations]. / Neuro-imagerie fonctionnelle cérébrale à 1,5 Tesla. Résultats de stimulations visuelles, sensitivo-motrices et auditives.

Functional activation of the cerebral cortex can be observed with a standard 1.5 Tesla MRI magnet. We used a repeated FLASH 2D one-section sequence with a long echo (TE = 60 ms) and a small passing band. Modification of regional cerebral oxygenation due to neurone activation seems to be the main source of contrast. Sensorimotor stimulation was effected by an unusual mobilization of the fingers. Visual stimulation was performed by intermittent lightings at a frequency of 8 Hz. Auditory stimulation relied on listening to speech sounds. Signal increases were localized on the cerebral cortex with precise anatomico-functional correlation. Using a clinical 1.5 Tesla magnet requires an adequate treatment of data. Thus, stimulated cerebral activity can be portrayed by MRI therapy opening a new way for anatomico-functional cerebral studies.

[Epidermoid cysts of the spleen. Apropos of two cases: review of the literature]. / Kystes épidermoïdes de la rate. A propos de deux cas: revue de la littérature.

Benign cysts of the spleen (excepting parasites) are rare. Less than 10% of the cases involve epidermoid cysts, as the two cases reported here. These lesions are often asymptomatic and can lead unspecific clinical manifestations. The diagnosis is based on echography and abdominal computed tomography. Generally, imagery can eliminate a hydatic cyst of the spleen but cannot differentiate between different types of non-parasite cysts. Major complications including rupture and intracystic haemorrhage, malignant transformation and the impossibility of obtaining a preoperative histological diagnosis make surgery the only possible treatment. A conservative approach with partial splenectomy is the usual option, but total splenectomy may be required. The question of whether surgery is always necessary for small asymptomatic cysts of the spleen in under debate. Certain authors suggest that only regular echographic monitoring is necessary.

[Spontaneous intramural hematoma of the esophagus. Apropos of a case]. / Hématome spontané intramural de l'oesophage. A propos d'un cas.

The authors report a case of spontaneous intramural haematoma of the oesophagus. This is a rare observation which usually occurs in association with oesophageal hyperpressure and sometimes with impaired haemostasis. The strategy for diagnosis is based on tomodensitography and also endosonography and magnetic resonance imagery.

[Unusual radiologic aspect of a hydatid cyst]. / Aspect radiologique inhabituel d'un kyste hydatique.

The authors report us about an unusual hydatid cyst of the liver. Ultrasound, CT and MRI exams were used, and showed an unusual fatty component inside the lesion. The development of the disease in steatosic liver is not enough to explain the unusual density.

[Marchiafava-Bignami's disease with a favourable course. Apropos of a case]. / Maladie de Marchiafava-Bignami d'évolution favorable. A propos d'un cas.

A resolving form of Marchiafava-Bignami disease is reported. This patient with a history of chronic alcoholism was hospitalised for a recent demential syndrome. Clinical examination did not show any signs of interhemispheric disconnection LP and EEG were normal. CT examination showed a low density area in the corpus callosum without any other anomaly. MRI examination confirmed the cystic area of the corpus callosum. The Marchiafava-Bignami disease was easily suggested on the basis imaging and clinical signs. Interhemispheric disconnection is not always found so MRI and CT examinations seem to be very useful tools for early diagnosis of Marchiafava-Bignami in the same way as neuropsychological tests.

[Eosinophilic gastroenteritis. Apropos of a case]. / Gastro-entérite à éosinophiles. A propos d'un cas.

The authors report a new case of this rare and not well-know disease, the eosinophilic gastroenteritis. The medical imaging techniques allowed to correlate all the clinical signs to the observed parietal lesions.