Combination of diffusion tensor and functional magnetic resonance imaging during recovery from the vegetative state

Abstract

BackgroundThe rate of recovery from the vegetative state (VS) is low. Currently, little is known of the mechanisms and cerebral changes that accompany those relatively rare cases of good recovery. Here, we combined functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) to study the evolution of one VS patient at one month post-ictus and again twelve months later when he had recovered consciousness.MethodsfMRI was used to investigate cortical responses to passive language stimulation as well as task-induced deactivations related to the default-mode network. DTI was used to assess the integrity of the global white matter and the arcuate fasciculus. We also performed a neuropsychological assessment at the time of the second MRI examination in order to characterize the profile of cognitive deficits.ResultsfMRI analysis revealed anatomically appropriate activation to speech in both the first and the second scans but a reduced pattern of task-induced deactivations in the first scan. In the second scan, following the recovery of consciousness, this pattern became more similar to that classically described for the default-mode network. DTI analysis revealed relative preservation of the arcuate fasciculus and of the global normal-appearing white matter at both time points. The neuropsychological assessment revealed recovery of receptive linguistic functioning by 12-months post-ictus.ConclusionsThese results suggest that the combination of different structural and functional imaging modalities may provide a powerful means for assessing the mechanisms involved in the recovery from the VS.

Multimodal neuroimaging in patients with disorders of consciousness showing “functional hemispherectomy”

“…A comparable pattern of functional impairment in the default network concomitant to a relative preservation of the white matter, has been previously reported for a UWS/VS patient who, afterward, regained consciousness (Fernández-Espejo et al, 2011). Similarly, Newcombe et al (2010) have shown that DTI-MRI may help to characterize differences in UWS/VS patients of different etiologies and Fernández-Espejo et al (2010), using a similar approach albeit restricted to mean diffusivity indices from specific regions of interest have demonstrated differences between UWS/VS and MCS patients.…”

The ascending reticular activating system from pontine reticular formation to the hypothalamus in the human brain: A diffusion tensor imaging study

“…Since introduction of DTI, many studies have demonstrated the clinical usefulness of DTI by estimating some areas of the lower portion of the ARAS from pontine RF to thalamus in patients with impaired consciousness [8,9,15,18,[22][23][24]. In addition, several studies have reconstructed some portions of the ARAS three-dimensionally: the RF -the thalamus -the cerebral cortex [6,7,10,11,27].…”

Finding a way in: A review and practical evaluation of fMRI and EEG for detection and assessment in disorders of consciousness

“…While the results of the patients differ from those of the control group for the reversenarrative condition, the results are still suggestive that the patients are processing speech signal as distinct from acoustically identical non-linguistic sound. Fernández-Espejo et al (2008) used a similar paradigm in a group of 3 VS and 3 MCS patients compared to 19 healthy controls, and subsequently in another single VS patient (Fernández-Espejo et al, 2010). The results suggested that there is not a clear distinction between VS and MCS patients in terms of fMRI markers of speech recognition.…”