Functional MRI (fMRI) studies have shown increased activation of ipsilateral motor areas during hand movement in patients with multiple sclerosis (MS). We hypothesized that these changes could be due to disruption of transcallosal inhibitory pathways. We studied 18 patients with relapsing-remitting MS. Conventional T1- and T2-weighted images were acquired and lesion load (LL) measured. Diffusion tensor imaging (DTI) was performed to estimate fractional anisotropy (FA) and mean diffusivity (MD) in the body of the corpus callosum (CC). fMRI was obtained during a right-hand motor task. Patients were studied to evaluate transcallosal inhibition (TCI, latency and duration) and central conduction time (CCT). Eighteen normal subjects were studied with the same techniques. Patients showed increased MD (P < 0.0005) and reduced FA (P < 0.0005) in the body of the CC. Mean latency and duration of TCI were altered in 12 patients and absent in the others. Between-group analysis showed greater activation in patients in bilateral premotor, primary motor (M1), and middle cingulate cortices and in the ipsilateral supplementary motor area, insula, and thalamus. A multivariate analysis between activation patterns, structural MRI, and neurophysiological findings demonstrated positive correlations between T1-LL, MD in the body of CC, and activation of the ipsilateral motor cortex (iM1) in patients. Duration of TCI was negatively correlated with activation in the iM1. Our data suggest that functional changes in iM1 in patients with MS during a motor task partially represents a consequence of loss of transcallosal inhibitory fibers.

Diffusion tensor imaging (DTI) analyses the movement of water molecules within the cerebral white matter thus providing information on ultrastructural brain changes. We studied 18 patients with cervical dystonia (CD), 16 with blepharospasm (BSP) and 35 years age-matched healthy controls. DTI data were obtained with a Philips 1.5 Tesla scanner and then processed to obtain maps of fractional anisotropy (FA) and mean diffusivity (MD). Twenty-three square regions of interest of uniform size were positioned on the FA maps and then automatically transferred to the MD maps. FA and MD values in the corpus callosum, left and right putamen, right caudate, left and right pre-frontal cortical area and left supplementary motor area in CD patients differed significantly from those in healthy controls. No significant regional differences were found between patients with BSP and healthy controls. In the CD group, age, duration and severity of dystonia did not correlate with regional FA/MD values, whereas the duration of botulinum toxin treatment correlated significantly with the MD value in the right-pre-frontal cortex. The abnormal DTI findings in patients with CD suggest the presence of brain ultrastructural changes in adult-onset primary CD.

WM damage was detectable early and involved most fiber tracts in patients with MS, but it did not worsen significantly during the 1st year after clinical onset. In contrast, GM damage was not detectable at the time of clinical onset, but a significant decrease in cortical and deep GM volume was observed at 1 year.

BACKGROUND AND PURPOSE:Findings of standard MR imaging examinations are usually normal in primary CD. These findings are now increasingly challenged by studies using advanced neuroimaging techniques detecting abnormalities in brain areas that may be functionally involved in the pathophysiology of CD. Our purpose was to evaluate GM volumes in patients with CD at baseline and 5 years later.

Diffuse WM damage not accompanied by any change in GM or WM volume is observed in patients with CIS. This suggests that WM involvement plays a relevant role in the early phases of MS. Subsequently detected GM damage may be secondary to WM alterations.