Cognitive Sequelae of Diffuse Axonal Injury

Abstract

Background: The results of recent studies on cognitive disability after traumatic brain injury-associated diffuse axonal injury (DAI) are inconsistent. In these studies, the diagnosis of DAI relied on cranial computed tomography. Objective: To further clarify the extent and severity of a possibly DAI-associated cognitive impairment by the use of magnetic resonance imaging (MRI) and detailed neuropsychological testing. Design and Participants: From a databank of 299 patients with traumatic brain injury, 18 patients (age range, 17-50 years; median initial Glasgow Coma Scale score, 5) who showed an MRI lesion pattern compatible with pure DAI were identified. All of the patients had undergone MRI on a 3-T system. Pure DAI was defined by the findings of traumatic microbleeds on T2*-weighted gradient-echo images in the absence of otherwise traumatic or nontraumatic MRI abnormalities. Main Outcome Measures: Neuropsychological performance in the categories of attention and psychomo-tor speed, executive functions, spans, learning and memory, and intelligence 4 to 55 months (median, 9 months) after traumatic brain injury. Results: All of the patients showed impairments of 1 or more cognitive subfunctions, and no cognitive domain was fundamentally spared. Memory and executive dysfunctions were most frequent, the former reaching a moderate to severe degree in half of the patients. In comparison, deficits of attention, executive functions, and short-term memory were mostly mild. Correlations between the amount of traumatic microbleeds and specific or global cognitive performance were absent. Conclusions: An MRI lesion pattern compatible with isolated DAI is associated with persistent cognitive impairment. The traumatic microbleed load is no sufficient parameter for the assessment of DAI severity or functional outcome.

Neuropsychology and clinical neuroscience of persistent post-concussive syndrome

“…Combining the imaging and neuronal injury biomarker studies discussed earlier, with the Bigler (2004) and Omalu et al (2005) post-mortem studies provide indisputable evidence that structural pathology can be present in mTBI. Additionally, these type of hemorrhagic lesions can be observed with specialized high-field MRI studies (see Ashwal et al, 2006;Scheid et al, 2006) as shown in Figure 4. As such, some aspects of the so-called "traceless injury" of concussion are being revealed with newer techniques.…”

Therapy Development for Diffuse Axonal Injury

“…Studies relating neuroradiologic evidence compatible with DAI have demonstrated chronic cognitive dysfunction, although the specific pattern of deficit may vary. 154 Although early studies of cognitive deficits attempted to link visible ''lesions'' with specific cognitive deficits, cognitive performance and functional outcome have been more recently presumed to be impacted not only by damage to specific cortical regions, but also by more general compromise of the integrity of underlying white matter, which may connect topographically distinct regions.…”

A Voxel-Based Analysis of FDG-PET in Traumatic Brain Injury: Regional Metabolism and Relationship between the Thalamus and Cortical Areas

“…Therefore, there is increasing interest in developing and applying new functional neuroimaging techniques that are specifically designed for the detection of DAI. [4][5] The integrity of cerebral cortico-subcortical connectivity is essential for maintaining normal brain function. [6][7] This connectivity is particularly vulnerable to the effects of traumatic injuries that can alter not only the individual components of the network (focal lesions) but also the connections between brain-nodes (DAI).…”