Brain neurodegeneration in the chronic stage of the survivors from severe non-missile traumatic brain injury: a voxel-based morphometry within-group at ?1 vs ?9 years from a head injury

The long-term time course of neuropathological changes occurring in survivors from severe traumatic brain injury remains uncertain. We investigated the brain morphometry and memory performance modifications within the same group of severe non-missile traumatic brain injury patients (nmTBI) after about ~1 year and at ~ 9 years from the head trauma. Brain Magnetic Resonance Imaging (MRI) measurements were carried out with voxel-based morphometry (VBM) to determine changes in the cerebral grey and white matter (GM and WM). Contemporarily memory tests were also administered. In comparison with normal control subjects, nmTBI patients showed a significant reduction in the GM and WM after ~1 year; conversely ~9 years after the neuropathological event, neurodegenerative changes spared the GM, but a prominent loss was detected in the WM, such as the superior longitudinal fasciculi, the body of the corpus callosum, the optic radiation and the uncinate fasciculus. Memory performance at ~1 year in comparison with ~9 years was stable with a subtle but significant trend towards recovery. These data demonstrate that nmTBI patients undergo neurodegenerative processes during the chronic stage affecting mainly the cerebral WM rather than GM. Despite these anatomical brain parenchyma losses, memory performance tends to be stable or even slightly recovered. These neuroanatomical results indicate the possible root for the cognitive disorders on survey traumatic brain injury patients and support new possible treatments to prevent long term WM degeneration of these patients.