I Tropres

Parietal operculum and motor cortex activities predict motor recovery in moderate to severe stroke

While motor recovery following mild stroke has been extensively studied with neuroimaging, mechanisms of recovery after moderate to severe strokes of the types that are often the focus for novel restorative therapies remain obscure. We used fMRI to: 1) characterize reorganization occurring after moderate to severe subacute stroke, 2) identify brain regions associated with motor recovery and 3) to test whether brain activity associated with passive movement measured in the subacute period could predict motor outcome six months later. Because many patients with large strokes involving sensorimotor regions cannot engage in voluntary movement, we used passive flexion-extension of the paretic wrist to compare 21 patients with subacute ischemic stroke to 24 healthy controls one month after stroke. Clinical motor outcome was assessed with Fugl-Meyer motor scores (motor-FMS) six months later. Multiple regression, with predictors including baseline (one-month) motor-FMS and sensorimotor network regional activity (ROI) measures, was used to determine optimal variable selection for motor outcome prediction. Sensorimotor network ROIs were derived from a meta-analysis of arm voluntary movement tasks. Bootstrapping with 1000 replications was used for internal model validation. During passive movement, both control and patient groups exhibited activity increases in multiple bilateral sensorimotor network regions, including the primary motor (MI), premotor and supplementary motor areas (SMA), cerebellar cortex, putamen, thalamus, insula, Brodmann area (BA) 44 and parietal operculum (OP1-OP4). Compared to controls, patients showed: 1) lower task-related activity in ipsilesional MI, SMA and contralesional cerebellum (lobules V-VI) and 2) higher activity in contralesional MI, superior temporal gyrus and OP1-OP4. Using multiple regression, we found that the combination of baseline motor-FMS, activity in ipsilesional MI (BA4a), putamen and ipsilesional OP1 predicted motor outcome measured 6 months later (adjusted-R2 = 0.85; bootstrap p < 0.001). Baseline motor-FMS alone predicted only 54% of the variance. When baseline motor-FMS was removed, the combination of increased activity in ipsilesional MI-BA4a, ipsilesional thalamus, contralesional mid-cingulum, contralesional OP4 and decreased activity in ipsilesional OP1, predicted better motor outcome (djusted-R2 = 0.96; bootstrap p < 0.001). In subacute stroke, fMRI brain activity related to passive movement measured in a sensorimotor network defined by activity during voluntary movement predicted motor recovery better than baseline motor-FMS alone. Furthermore, fMRI sensorimotor network activity measures considered alone allowed excellent clinical recovery prediction and may provide reliable biomarkers for assessing new therapies in clinical trial contexts. Our findings suggest that neural reorganization related to motor recovery from moderate to severe stroke results from balanced changes in ipsilesional MI (BA4a) and a set of phylogenetically more archaic sensorimotor regions in the ventral sensorimotor trend, in which OP1 and OP4 processes may complement the ipsilesional dorsal motor cortex in achieving compensatory sensorimotor recovery.

Facial nerve tractography: A new tool for the detection of perineural spread in parotid cancers

ObjectivesTo determine whether facial nerve MR tractography is useful in detecting PeriNeural Spread in parotid cancers.MethodsForty-five participants were enrolled. Thirty patients with surgically managed parotid tumors (15 malignant, 15 benign) were compared with 15 healthy volunteers. All of them had undergone 3T-MRI with diffusion acquisition and post-processing constrained spherical deconvolution-based tractography. Parameters of diffusion-weighted sequences were b-value 1,000 s/mm2, 32 directions. Two radiologists performed a blinded visual reading of tractographic maps and graded the facial nerve average pathlength and fractional anisotropy (FA). We also compared diagnostic accuracy of tractography with morphological MRI sequences to detect PeriNeural Spread. Non-parametric methods were used.ResultsAverage pathlength was significantly higher in cases with PeriNeural Spread (39.86 mm [Quartile1: 36.27; Quartile3: 51.19]) versus cases without (16.23 mm [12.90; 24.90]), p<0.001. The threshold above which there was a significant association with PeriNeural Spread was set at 27.36 mm (Se: 100%; Sp: 84%; AUC: 0.96, 95% CI 0.904–1). There were no significant differences in FA between groups. Tractography map visual analyses directly displayed PeriNeural Spread in distal neural ramifications with sensitivity of 75%, versus 50% using morphological sequences.ConclusionsTractography could be used to identify facial nerve PeriNeural Spread by parotid cancers.Key Points• Tractography could detect facial nerve PeriNeural Spread in parotid cancers.• The average pathlength parameter is increased in case of PeriNeural Spread.• Tractography could map PeriNeural Spread more precisely than conventional imaging.

Endolymphatic hydrops imaging: Why oving from semi-quantitative to anatomical-based evaluation

INTRODUCTIONnRecently, the semi-quantitative ratio grading for endolymphatic hydrops (EH) was found as none specific of MD because all healthy subjects referred with at least one hydrops location with this grading method and 3D-FLAIR sequence. The objectives of this study were to assess the EH prevalence in MD using both the semi-quantitative ratio method of grading and the Saccule to Utricle Ration Inversion (SURI) technique with two 3D-FLAIR sequences, closely similar except for the inversion time of the sequence.nnnMATERIAL AND METHODSnWe performed two 3D-FLAIR sequences 4hours after a single intravenous dose of contrast agent with different inversion time (2300ms and 2400ms) in 10 patients with Menières disease and severe sensorineural hearing loss in comparison with 10 healthy subjects, to evaluate the variation of the endolymph to perilymph area ratio. We also assessed the SURI technique so as to evaluate prevalence of saccular hydrops on each sequence.nnnRESULTSnUsing the semi-quantitative method with TI set to 2300ms, at least one hydrops location was displayed in all healthy subjects and MD patients. With the TI set to 2400ms, the hydrops rate ranges from 35% for healthy patients to 55% for Menieres patients. The rate of EH is different according to the TI (P≤0.05). Conversely, using the SURI technique, saccular hydrops were not influenced by the sequence parameters.nnnCONCLUSIONnThe endolymph/vestibule ratio is highly dependent on the TI, by contrast with the SURI technique.