Hemodynamic-informed parcellation of fMRI data in a joint detection estimation framework.

Identifying brain hemodynamics in event-related functional MRI (fMRI) data is a crucial issue to disentangle the vascular response from the neuronal activity in the BOLD signal. This question is usually addressed by estimating the so-called hemodynamic response function (HRF). Voxelwise or region-/parcelwise inference schemes have been proposed to achieve this goal but so far all known contributions commit to pre-specified spatial supports for the hemodynamic territories by defining these supports either as individual voxels or a priori fixed brain parcels. In this paper, we introduce a joint parcellation-detection-estimation (JPDE) procedure that incorporates an adaptive parcel identification step based upon local hemodynamic properties. Efficient inference of both evoked activity, HRF shapes and supports is then achieved using variational approximations. Validation on synthetic and real fMRI data demonstrate the JPDE performance over standard detection estimation schemes and suggest it as a new brain exploration tool.

[Thrombotic microangiopathies in the intensive care unit]. / Les microangiopathies thrombotiques en réanimation.

OBJECTIVES: To analyze the clinico-biological manifestations, identify the causes and evaluate the outcome of patients with severe thrombotic microangiopathies admitted in a Tunisian intensive care unit. METHODS: Retrospective study over a period of 10 years (1995-2004) in an intensive care unit. RESULTS: Were included in this study 9 cases with a mean age of 29.2+/-9 years (range 15-44 years). Fever was observed in 5 patients, neurological impairment in 5 and digestive manifestations in 6. Haemolytic anaemia, thrombocytopenia and acute renal failure were observed in 100% of the cases. In our study, the aetiologies of thrombotic microangiopathies were: complicated pregnancy in 6 cases, systemic lupus erythematosus in 1 case. In contrast, no aetiology was found in 2 patients. Plasma exchange was performed in 5 patients, while 4 patients received only plasma infusion. After an average stay of 18+/-12.5 days, evolution was marked by the death 3 patients. CONCLUSION: The incidence of severe thrombotic microangiopathies is rare in Tunisian ICU. The clinical manifestations are not specific. Despite the improvement in the outcome by exogenous plasma supply, thrombotic microangiopathies with severe organ dysfunctions leading to hospitalization in the intensive care unit are associated with a high mortality rate.

[Celiac disease, cerebral venous thrombosis and protein S deficiency, a fortuitous association?]. / Maladie coeliaque, thrombose veineuse cérébrale et déficit en protéine S, une association fortuite?

INTRODUCTION: Celiac disease is a pathology which is rarely associated with thrombosis complications. Cerebral vascular thrombosis has never been described in patients with a celiac disease. OBSERVATION: We report an observation of a 21-year-old girl with a history of celiac disease who was hospitalized in the intensive care unit for convulsive status epilepticus secondary to a cerebral venous thrombosis. The etiologic investigation of this thrombo-embolic complication revealed protein S deficit. Our patient improved under symptomatic treatment. COMMENT: This original observation confirms that celiac disease can be associated with cerebral venous thrombosis.