Thalamic proton magnetic resonance spectroscopy in vegetative state induced by traumatic brain injury

Abstract

Objectives: To determine whether proton magnetic resonance spectroscopy (MRS), a newer radiographic technology, would be useful in the evaluation of the thalamus of patients in vegetative states resulting from traumatic brain injury. Methods: 14 victims of severe traumatic brain injury who were in the vegetative state and whose magnetic resonance images of the thalamus were normal underwent bilateral thalamic proton (MRS) studies. The N-acetyl aspartate to creatine (NAA:Cr) and choline to creatine (Cho:Cr) ratios were obtained for each patient. The proton thalamic MRS findings of patients who were in a persistent vegetative state (n = 8) and in patients who had regained awareness after being in the vegetative state (n = 6) were compared with proton thalamic MRS findings in five healthy volunteers. Results: While conventional magnetic resonance imaging suggested that each patient had a normal thalamus, proton MRS indicated that the thalamus of each patient in the series was damaged. The NAA:Cr ratio was significantly lower in the thalami of both the patients who remained in a persistent vegetative state for the duration of the study and in those who regained awareness after being in the vegetative state (p < 0.001). In addition, NAA:Cr ratios were lower in the group of patients who remained in a persistent vegetative state than in the group of patients who regained awareness after being in the vegetative state (p < 0.001). Conclusions: Results suggest that the NAA:Cr ratio within the thalamus is significant and that thalamic MRS may be helpful when attempting to determine the degree of severity of neuronal and axonal injury in patients in the vegetative state.

Sleep in the Unresponsive Wakefulness Syndrome and Minimally Conscious State

“…This would be in line with brain imaging studies showing not only the correlation between the extent of thalamus damage and the behavioral disability and outcome in DOC, but also the restoration of the thalamocortical connectivity during recovery of consciousness. [30][31][32][33] Otherwise, REMS is sensitive to cortical injury, so the amount of this stage may be related to the severity of the cortical injury and behavioral impairment in brain-injured patients, but our results don't support this hypothesis.…”

Disorders of consciousness after acquired brain injury: the state of the science

“…A recent ASL-MRI study in patients in MCS showed a profound decrease in blood flow in anterior cortical midline structures. 101 Finally, MRI spectroscopy, a measure of biochemical changes in the brain, has uncovered severe metabolic cortical 102 and thalamic 103 neuronal dysfunction in DOC, with probable prognostic value. …”

Evaluation of Delayed Neuronal and Axonal Damage Secondary to Moderate and Severe Traumatic Brain Injury Using Quantitative MR Imaging Techniques

“…Thus, NAA is considered a neuronal and axonal marker, and its concentration decreases in brain lesions that cause neuronal or axonal loss. Decreased NAA after TBI was already demonstrated in the WM, [30][31][32][33][34] CC, 13,35 gray matter, [30][31][32]36 thalamus, 37 and hippocampus and basal ganglia, 38 in both subacute 28,30,33 and late phases. [31][32][33][34][35]38 Our results showed a significantly decreased NAA/Cr ratio mean value in the CC of the posttraumatic patient group, re- flecting axonal loss in this location due to TBI.…”