A Diffusion Tensor MRI Study OF Pediatric Patients With Severe Non-Traumatic Brain Injury (S35.001)

OBJECTIVE: In this study we: 1) investigated damage of white matter (WM) tracts in pediatric non-traumatic Unresponsive Wakefulness Syndrome/Minimally Conscious State (UWS/MCS) patients using Diffusion Weighted Imaging (DWI); 2) assessed the correlations between the severity of WM damage and clinical scores; and 3) explored the role of supra- and infra-tentorial district damage. BACKGROUND: Pediatric UWS/MCS are disconnection syndromes, due to combined damage to the brainstem (BS) and long-range cortico-cortical pathways. DESIGN/METHODS: DWI scans were obtained from 10 non-traumatic UWS, 6 MCS and 31 age-matched healthy children. Patients were tested by the Glasgow Coma Scale (GCS) and the Coma/Near Coma Scale (C/NCS). DWI scans were pre-processed before tensor estimate and tractography. Fractional anisotropy (FA), mean (MD), axial (AD) and radial (RD) diffusivities were calculated for the corpus callosum (CC), inferior (ICP), middle (MCP), and superior (SCP) cerebellar peduncles. We compared patients and controls, and patients in acute (< 1 year from injury) vs chronic (> 1 year from injury) condition. Correlations between clinical and MRI variables were assessed (Pearson’s correlation coefficient). RESULTS: Patients differed in all DWI parameters with respect to controls, except for FA of the MCP and ICP. Compared to acute, chronic patients had increased diffusivities and decreased FA of the MCP. Supra-tentorial compartment was more damaged than the infra-tentorial one in UWS vs MCS patients. Significant correlation was found between GOS scores and diffusivity indexes of the CC, MCP and ICP (r ranging between -0.77 to 0.73) as well as between C/NCS and MCP damage (r ranging between 0.62 and 0.70). CONCLUSIONS: In pediatric UWS/MCS patients, the severity of clinical disability correlates with structural damage to infratentorial and the long-range cortico-cortical tracts, suggesting that global, rather than focal damage, contributes to their clinical severity. Secondary Wallerian degeneration plays a major contribution to disease chronicization.